IWA Specialist Group Directory - Nieuwe Sanitatie - Stowa

Global Trends & Challenges in Water Science, 

IWA Specialist Group 

Research and Management 

Directory 

A compendium of hot topics and features from 

IWA Specialist Groups

IWA Specialist Groups 

Global Trends & Challenges in 

Water Science, Research 

and Management 

A compendium of hot topics and 

features from IWA Specialist Groups 

International Water Association 

January 2012


Editor: Hong Li 

Book title set by Keith Robertson 

Copy-editing and type-setting: The Clyvedon Press Ltd, Cardiff, UK 

Published by 

International Water Association (IWA) 

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United Kingdom 

Telephone: +44 207 654 5500 

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Email: water@iwahq.org 

First published 2012 

© 2012 IWA and the IWA Specialist Groups 

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Disclaimer 

The information provided and the opinions given in this publication are not necessarily those of IWA and should not be acted 

upon without independent consideration and professional advice. IWA and the authors will not accept responsibility for any 

loss or damage suffered by any person acting or refraining from acting upon any material contained in this publication. 

ISBN 9781780401065

Contents 

Preface 


Anaerobic Digestion 1 

Assessment and Control of Hazardous Substances in Water 4 

Biofi lms 8 

Design, Operation and Maintenance of Drinking Water Treatment Plants 10 

Disinfection 12 

IAHR/IWA/IAHS Hydroinformatics Joint Committee 20 

Groundwater: Perspectives, Challenges and Trends 27 

Institutional Governance and Regulation 33 

Outfall Systems 37 

Marketing and Communications 42 

Membrane Technology 44 

Metals and Related Substances in Drinking Water 49 

Microbial Ecology and Water Engineering 52 

Off-Flavours in the Aquatic Environment: A Global Issue 58 

Resources-Oriented Sanitation 64 

Decentralised Wastewater Management: An Overview 68 

Sludges, Residuals and Biosolids: Global Trends and Challenges 71 

Statistics and Economics 77 

Sustainability in the Water Sector 79 

Rainfall Extremes and Urban Drainage 83 

Wastewater Pond Technology 86 

Water and Wastewater in Ancient Civilizations 90 

Water Reuse: A Growing Option to Meet Water Needs 95 

Watershed and River Basin Management 100 

Winery Wastewater Treatment in a Sustainable Perspective 105 

Page


Preface 

Specialist Groups represent the core vehicle for issue-based interaction on scientifi c, technical and management topics 

within the International Water Association (IWA). Specialist Groups facilitate cooperation, networking and knowledge 

generation, primarily through regular conferences and publications. They are a major source of channelling the 

energy that is in the water professional community to organize events, spread news through regular newsletters, to generate 

collaboration on a voluntary basis, etc. One of the larger voluntary efforts that fi nd an outlet through the Specialist Groups are 

Task Groups that are formed within a hosting Specialist Group to perform a defi ned task, for example the production of a IWA 

Scientifi c and Technical Report that describes the state-of-the-art in a certain discipline or a consensus to move forward on 

a certain topic. 

IWA’s Specialist Groups are self-managed and cover all-important topics in the water management sector. In total some 

50 Specialist Groups have been formed. They are an exceptionally effective means of information and knowledge sharing. To 

improve the quality of knowledge sharing, for the fi rst time, the IWA has produced this report on Global Trends & Challenges 

in Water Science, Research and Management. It is a compendium compiled from the submissions of IWA Specialist Groups. 

This report aims to raise the profi les of the IWA Specialist Groups and let Specialist Groups be better known by water professionals 

in the world, as well as to supply better knowledge dissemination. It is composed of papers from each group summarizing 

the current state of knowledge within the SG topic/subtopics and future trends and challenges. It creates an understanding 

of the topic for the reader, and shows the trends and challenges within the Specialist Groups by identifying, for example, three 

hot topics that are expected to surface in the next fi ve years. No particular format was imposed, allowing the Specialist Groups 

to develop their messages freely to the community. 

There are in total 25 Specialist Group contributions in this fi rst compendium, to be distributed to IWA members, partners and 

other water professionals. This effort will be continued periodically in order to keep information and knowledge up to date. 

The work of the Specialist Groups is coordinated and supported by IWA Specialist Groups Manager Dr Hong Li. Please feel 

free to contact her by email at hong.li@iwahq.org if you require any further information or have any questions about the 

content of this report. 

Enjoy the read and get an update on where things are and are moving to! 

Professor Peter Vanrolleghem, PhD. 

modelEAU – Université Laval, Québec, Canada 

Chairman IWA Strategic Council Sub-Committee on Specialist Groups

Anaerobic Digestion 

Written by Damien Batstone, Henri Spanjers, Jorge Rodriguez, Jules van Lier, Eberhard 

Morgenroth, M.M. Ghangrekar, R. Saravanane on behalf of the Specialist Group 

Anaerobic Digestion is one of the most active Specialist 

Groups, with over 1000 members, active sponsorship of 

three task groups or working groups, and organisation of, 

on average, one Specialist Group conference per year. 

This is highlighted by our recent triennial conference – 

AD12 in Guadalajara, Mexico – where some 500 delegates 

attended, and 200 papers were presented, of which 80 

were considered for publication in Water Science and 

Technology. The themes at the AD conferences provide a 

very good review of major themes of interest in anaerobic 

digestion. Over the years, we have always observed a large 

number of papers focusing on specifi c aspects related 

to the themes of (a) solid waste and energy crop management, 

(b) biosolids and sludge management and (c) 

industrial wastewater. These application areas have been 

strongly supported by investigation into microbial ecology, 

mathematical modelling, chemical analysis, process innovations 

and novel technologies. Over the 10 years though, 

we have seen several major new themes emerge. These 

have been driven by both market opportunity and scientifi 

c advances. The goal of this report is to further outline 

challenges and opportunities for wastewater treatment 

researchers and practitioners in these areas, as well as 

the specifi c role of anaerobic digestion technologies within 

these application areas. 

Major emerging themes 

The key topics we as a Specialist Group can identify as 

major developing areas are the role of anaerobic processes 

in waste mining and resource recovery, production of 

chemicals through bioprocessing and bioproduction, and 

integration of anaerobic digestion processes into the larger 

evaluation framework, including upstream and downstream 

environmental systems, and advanced wastewater 

treatment through emerging processes such as anaerobic 

membrane bioreactor systems. 

(a) Anaerobic processes for resource 

recovery 

Over the past two years there have been considerable fl uctuations 

in phosphorus and nitrogen pricing, which has 

emphasised the realisation that, in particular, phosphorus 

is a non-renewable resource, with the peak in mineral 

production expected to occur around 2030 (Cordell 

et al. 2009). Added to this, nitrogen is very expensive 

energetically to produce, and the other macronutrient 

potassium is becoming depleted in major agricultural 

zones. Although fl uctuations have stabilised, pricing 

is currently of the order of $US5/kgP and $US1/kgN, 


and steadily rising. Although manure is a classic and 

signifi cant source of nitrogen and phosphorus worldwide 

(Cordell et al. 2009), for industrial agriculture, the 

phosphorus market is dominated by mineral resources. 

This has energised research into recovery of phosphorus 

from waste streams, mainly as calcium and magnesium 

phosphates, including struvite (MgNH 4 PO 4 .6H 2 O) 

(Le Corre et al. 2009). Even in highly industrialised 

countries, such as Australia, with essentially 50% of food 

(phosphorus) export, 25% of phosphorus and nitrogen, 

and 100% of potassium, can be recovered from waste 

streams (Tucker et al. 2011). 

Anaerobic digestion is the only biochemical process that 

removes carbon, while converting this into a useful energy 

carrier, but has minimal impact on nutrient concentrations. 

This has been previously seen as a limitation, but is 

now emerging as a benefi t, with the energy content being 

used in an integrated process to drive full nutrient recovery 

(Verstraete et al. 2009). This will result in changes in 

the modes of operation of anaerobic digestion to enhance 

nutrient recovery further, and the focus is likely to move 

beyond simply phosphorus to full recovery of nitrogen, 

potassium and water by a range of novel techniques. 

Nutrient recovery will also require a higher degree of 

operational fl exibility and understanding of the underlying 

anaerobic process, in order to enable treatment of different 

waste streams (wastewater through to agroindustrial 

solid wastes), as well as to cater for downstream processes 

such as water recovery. 

(b) Bioprocessing and bioproduction 

Anaerobic processes have been used for thousands of 

years to ‘value add’ to organic feedstocks by converting 

them to a wide range of largely fermented foods and 

beverages. This has also been widely used in the 20th century 

in industrial biotechnology to produce bulk industrial 

chemicals such as ethanol and organic acids, as well as 

high-value products, including pharmaceuticals. Over the 

past 10 years, we have seen two signifi cant and genuine 

innovations that are dramatically changing the landscape 

of industrial biotechnology. 

Until recently, biotechnology focused on the use of pure 

or highly enriched cultures to generate speciality products 

from very pure feedstocks. This has limited application 

of industrial biotechnology to higher value chemicals, 

including higher cost feedstocks that compete with 

food, and which often require expensive sterilisation of 

both the reactor and the feed. In contrast, mixed culture 

1

2 


biotechnology uses environmentally ubiquitous microbes 

to produce a mixture of chemicals (Kleerebezem and van 

Loosdrecht 2007). These organisms are faster, can convert 

more complex feedstocks and are capable of working 

under different hydraulic regimes. The mixture of products 

needs to be directed by manipulation of concentration, 

temperature, pH and redox, and there needs to be a degree 

of downstream separation. Research is now moving from 

a focus on systems analysis to a deeper understanding of 

how mixed culture fermentations (and biotechnology) is 

infl uenced by environmental conditions, and how control 

handles can be best manipulated. This should be combined 

with further research into downstream processing 

to develop the concept of a biorefi nery that can generate 

multiple products from raw feedstocks with a high degree 

for market driven fl exibility. 

Bioelectrochemical systems have been one of the major 

developments in the anaerobic process world over the 

past 10 years, with an initial focus on direct generation of 

electricity from anodic biological processes (Lovley 2006). 

The current cost of bioelectrochemical systems (approximately 

100 times that of conventional anaerobic systems), 

and relatively low performance makes them (currently) a 

limited proposition for electricity generation. A far more 

compelling application appears to be use of electrochemical 

systems with either pure or enriched cultures to generate 

specifi c products. These can either be done via 

partial oxidation at the anode to generate partially oxidised 

products (e.g. 1-3 propanediol from glycerol), or by reduction 

at the cathode (e.g. generation of CO 2 from methane) 

(Rabaey and Rozendal 2010). The exciting thing about this 

is not just the enhanced and highly effi cient use of electricity. 

There is also the range of capabilities derived from the 

enormous fl exibility of this technology, including the ability 

to set potential, electrode material and cell geometry, the 

ability to favour specifi c organisms, or planktonic versus 

electrode biofi lms, and the ability to manipulate ion fl ow 

through the membrane. 

The two issues of mixed culture biotechnology and 

bioelectrosynthesis are highly complementary, as mixed 

culture biotechnology is generally needed as a pretreatment 

process for bioelectrosynthesis, and both can 

operate in complementary processes within the overall 

biorefi nery process. 

(c) Integrated systems assessment 

This review has focused so far on the promise of anaerobic 

processes to replace existing technologies, including 

activated sludge wastewater treatment, mineral fertiliser 

production, and industrial chemical manufacturing. However, 

there will clearly be longer-term applications for both 

practical integration of anaerobic digestion with larger 

systems, as well as its integration with larger process 

models. Integrated systems modelling, life cycle assessment 

and integrated environmental assessment not need 

to include the whole water and energy cycle, and anaerobic 

processes are emerging as a clear segment within 

overall systems modelling. A clear example is emerging 

methods to model larger wastewater treatment plants, 

with adaptation and integration of biochemical models 

such as the IWA developed Anaerobic Digestion Model 

No. 1 (Batstone et al. 2002) into key integrated models 

such as the Benchmark Simulation Model (Jeppsson et al. 

2007). The process of integrating models has been very 

complementary, not only providing important tools such 

as interface models, but demonstrating the strengths of 

each sub-model. As an example, the advanced pH model 

within the Anaerobic Digestion Model No. 1 is clearly relevant 

to the whole water cycle, and this has led to establishment 

of a new IWA task group on physicochemistry 

modelling (Batstone 2009), which will not only enrich 

modelling of aquatic chemistry, but is applicable to all 

topics raised in this review. 

(d) Advanced wastewater treatment 

Modern high-rate technologies are successfully implemented 

at a large variety of industries. Granular sludge 

bed based systems are most commonly applied, whereas 

China seems to be the most rapidly growing market. Very 

high loading rates reaching 40 kg COD/m 3 reactor per 

day are feasible reducing reactor volumes to a minimum. 

Current applications are limited by the maximum specifi 

c conversion capacity and/or effi cient separation of 

the produced biogas from the sludge. For more ‘extreme’ 

types of the wastewaters these limitations are more pronounced 

resulting in disappointing loading potentials. 

Examples are wastewaters characterised by high temperatures, 

high salinity, presence of toxic compounds, 

high fat, oil and grease content, high solids content, etc. 

Various research groups are presently focusing on the 

development of anaerobic membrane bioreactors making 

use of either submerged or cross fl ow confi gurations 

(Liao et al. 2006). The full retention of anaerobic biomass 

prevents specifi c rinsing of key organisms for specifi c 

substrate conversion, whereas the membrane assisted 

separation process provides a solids-free effl uent. The 

growing number of research papers has led to separate 

conference sessions at the anaerobic digestion specialist 

triennial. Working at relatively high sludge concentrations, 

cake layer management seems to determine membrane 

fl uxes (Jeison and van Lier 2007; Lin et al. 2010). At 

present, the impact of increased shear-forces on anaerobic 

microbiology, physiology and biochemistry is currently 

being investigated (e.g. Menniti et al., 2009). With the 

drop in membrane prices and the relatively low required 

fl uxes with concentrated wastewaters, anaerobic membrane 

bioreactor systems seem to be of particular interest 

for those applications where successful granular sludge 

bed systems cannot be guaranteed. 

Conclusions 

Anaerobic processes have a major role in future sustainable 

water management, and across all areas of human activity, 

including agriculture, industrial chemicals and energy generation. 

There are clearly novel areas to apply the basic 

principles we have developed over the past 50 years of 

research, including mixed culture biotechnology and electrochemically 

mediated processes. In addition, new science 

will be needed to fully enable resource recovery and 

provide new downstream processing options for the biorefi 

nery of the future. At the same time, we need to recognise 

that there has been an enormous amount of work done 

already, which is particularly applicable to other fi elds such 

as domestic wastewater treatment, including upstream 

sewer processes. It will be important to retain this knowledge 

as we move into new and exciting applications.

References 

Batstone, D.J. (2009). Towards a generalised physicochemical 

modelling framework. Reviews in Environmental Science and 

Biotechnology 8(2), 113–114. 

Batstone, D.J., Keller, J., Angelidaki, I., Kalyuzhnyi, S., Pavlostathis, 

S.G., Rozzi, A., Sanders, W., Siegrist, H. and Vavilin, V. 

(2002). Anaerobic Digestion Model No. 1 (ADM1), IWA Task 

Group for Mathematical Modelling of Anaerobic Digestion 

Processes. London, IWA Publishing. 

Cordell, D., Drangert, J.O. and White, S. (2009). The story of 

phosphorus: global food security and food for thought. Global 

Environmental Change 19(2), 292–305. 

Jeison, D. and van Lier, J.B. (2007). Cake formation and consolidation: 

main factors governing the applicable fl ux in anaerobic 

submerged membrane bioreactors (AnSMBR) treating 

acidifi ed wastewaters. Separation and Purifi cation Technology 

56(1), 71–78. 

Jeppsson, U., Pons, M.N., Nopens, I., Alex, J., Copp, J., Gernaey, 

K.V., Rosen, C., Steyer, J.-P., Vanrolleghem, P.A. (2007). 

Benchmark simulation model no 2: general protocol and exploratory 

case studies. Water Science & Technology 56(8), 

67–78. 

Kleerebezem, R. and van Loosdrecht, M.C.M. (2007). Mixed culture 

biotechnology for bioenergy production. Current Opinion 

in Biotechnology 18(3), 207–212. 

Le Corre, K.S., Valsami-Jones, E., Hobbs, P. and Parsons, S.A. 

(2009). ‘Phosphorus recovery from wastewater by struvite 


crystallization: a review.’ Critical Reviews in Environmental 

Science and Technology 39(6), 433–477. 

Liao, B.Q., Kraemer, J.T. and Bagley, D.M. (2006). Anaerobic 

membrane bioreactors: applications and research directions. 

Critical Reviews in Environmental Science and Technology 

36(6), 489–530. 

Lin, H., Xie, K., Mahendran, B., Bagley, D., Leung, K., Liss, S. 

and Liao, Q. (2010) Factors affecting sludge cake formation 

in a submerged anaerobic membrane bioreactor. Journal of 

Membrane Science 361(1–2), 126–134. 

Lovley, D.R. (2006). Bug juice: harvesting electricity with microorganisms. 

Nature Reviews Microbiology 4(7), 497–508. 

Menniti, A, Kang, S., Elimelech, M. and Morgenroth, E. (2009) 

Infl uence of shear on the production of extracellular polymeric 

substances in membrane bioreactors. Water Research 

43(17), 4305–4315. 

Rabaey, K. and Rozendal, R.A. (2010). Microbial electrosynthesis 

— revisiting the electrical route for microbial production. 

Nature Reviews Microbiology 8(10), 706–716. 

Tucker, R., Poad, G., et al. (2011). Fertiliser from waste: phase 1 

GRDC project UQ00046 output 1 report (fi nal). Brisbane, 

Australia, Grains Research and Development Corporation, 

Australia. 

Verstraete, W., Van de Caveye, P. and Diamantis, V. (2009). 

Maximum use of resources present in domestic “used 

water”. Bioresource Technology 100(23), 5537–5545. 

3

4 


Assessment and Control of 

Hazardous Substances in Water 

Written by M. Fürhacker, A. Bruchet, S. Martin, F. Leusch, T. Ternes on behalf of the Specialist Group 

Introduction 

Micropollutants: A global issue 

For the Assessment and Control of Hazardous Substances 

in Water Specialist Group, the biggest challenge is the 

risk evaluation and management of the real or perceived 

increasing contamination of freshwater or marine systems 

with thousands of industrial and natural chemical 

compounds. This is one of the key environmental questions 

for the safety of human and environmental health. 

Besides well-known contaminants such as heavy metals, 

pesticides or polycyclic aromatic hydrocarbons, for which 

monitoring and management strategies are already set in 

different legal regulations, there is another group of contaminants 

for which less information is available. These 

so-called ‘emerging contaminants’ are potentially toxic substances 

whose effects or presence is poorly known, either 

because they are new and just starting to spread out, or 

they are well-known contaminants but their environmental 

fate gained more attention with better instrumentation. 

Therefore ‘emerging contaminants’ can be defi ned as contaminants 

that are currently not included in routine monitoring 

programs and which may be candidates for future 

regulation, depending on research on their (eco)toxicity, 

potential health effects, public perception and monitoring 

data revealing their occurrence in different environmental 

compartments (Petrovic and Barceló 2006). 

Advances in the area 

Sources of micropollutants 

Sources of hazardous substances may include wastewater 

from industry or manufacture of e.g. metal, pulp and paper, 

chemicals, food, drugs as well as many others. For point 

sources best available technologies are already worked out 

or will be defi ned in the near future. Environmentally hazardous 

substances are increasingly released from diffuse 

sources and consumer-related municipal sources rather 

than from production-related industrial point-sources. Diffuse 

sources are deposition, agriculture (e.g. pesticide 

application, groundwater recharge, sewage sludge application 

to land), traffi c, power generation, mining, waste 

disposal (e.g. incineration, landfi lls) or could be accidental 

releases (e.g. spills). 

For a long time, eutrophication and oxygen depletion were 

critical conditions in surface water and contamination 

with nitrate, solvents and selected pesticides, especially 

lipophilic substances, was in the focus of groundwater 

contamination. In sewage sludge the interesting substances 

were mainly heavy metals, polychlorinated dibenzodioxins 

and furans and polychlorinated biphenyls. Nowadays 

chemists have improved the analytical methods and are 

able to detect concentrations of drugs, polar personal 

care products (e.g. musk fragrances, repellents), technical 

products (e.g. bisphenol A, tributyl tin compounds, 

lubricants, dyes, motor oils, paint thinners and removers, 

creosote, wood preservers, lipophilic and hydrophilic 

pesticides and metabolites, perfl uorinated compounds 

(PFS), detergents (linear alkyl sulphonates), alkylphenol 

ethoxylates and metabolites, quaternary ammonium compounds), 

contaminations from construction materials (e.g. 

pesticides, titanium dioxide), contamination from traffi c 

(e.g. heavy metals, oxygenates, polycyclic aromatic hydrocarbons, 

nitro-polycyclic aromatic hydrocarbons, mineral 

oils), food ingredients (artifi cial sweeteners) and biocides, 

nanoparticles and other persistent organic pollutants and 

their metabolites, transformation products and chemical 

by-products generated during production usually in the 

nanogram and sub-nanogram range per litre (Daughton 

and Ternes 1999; Giger 2009; Richardson 2009). 

Although many of the new compounds are present in the 

aquatic environment at low to very low concentrations 

(picograms per litre to nanograms per litre), some of these 

contaminants show carcinogenic or mutagenic reactions 

or are toxic for reproduction (CMR substances) or are allergens 

or endocrine disruptors; but others are less toxic or 

do not show toxic effects in the measured concentrations. 

Identification and monitoring methods 

Advances in analytical methods have been a major driver 

for the identifi cation and monitoring of emerging contaminants. 

Gas chromatography (GC) or liquid chromatography 

coupled with mass spectrometry (MS) remain the ‘gold 

standards’ for trace organics analysis. The cost of GC/ 

MS systems have drastically dropped and GC–MS/MS 

systems that yield ultimate sensitivity for the determination 

of traces in complex matrices can now be acquired 

for the cost of a single GC/MS instrument from 2 years 

ago. GC-high resolution MS is necessary to quantify contaminants 

at ultratrace levels such as dioxins and dibenzofurans. 

This approach could prove necessary to reach the 

very low environmental quality standards defi ned in specifi 

c regulations (e.g. 0.5 ng/L for polybrominated diphenylethers 

in natural waters as defi ned in the European 

Water Framework Directive). GC combined with inductively 

coupled plasma mass spectrometry (ICP/MS) seems 

to emerge as the method of choice to detect organotins

at their extremely low environmental quality standards. 

Although GC/MS is restricted to non-polar and semi-polar 

contaminants, liquid chromatography (LC)–MS/MS has 

allowed the determination of much more polar substances 

(pharmaceuticals, illicit drugs, estrogenic hormones …) at 

levels of parts per trillion. Once restricted to target compound 

analysis, with the advent of very high resolution 

instruments, LC tandem MS and LC-Orbitrap MS now 

offer the possibility of identifying and quantifying unknown 

polar compounds in all kinds of environmental matrices, a 

feature that will contribute to the discovery of an increasing 

number of emerging contaminants and hopefully their 

transformation and degradation by-products. Another 

trend lies in the miniaturisation of laboratory-scale instruments 

such as GC/MS, which will likely allow on-line monitoring 

in the future. A miniature GC/MS with a submersible 

purge-and-trap probe is already commercially available 

with potential application for on-line monitoring of volatile 

organic compounds. 

On the other hand, with the exception of fullerene nanoparticles 

that can be determined by LC–MS, there are no 

adequate methods to determine other organic nanoparticles 

such as carbon nanotubes at environmental levels. 

Bioanalytical methods, common in the pharmaceutical 

industry, are growing in popularity for water quality and 

treatment effi cacy monitoring. These in vitro bioassay 

tools can provide an integrative measure of mixture toxicity. 

Although several practical questions remain to be 

answered, in particular their exact role in regulation (if 

any), bioanalytical tools are a promising development in 

water quality testing. 

Treatment methods 

The removal performances of existing treatment processes 

are currently well known for an increasing number 

of substances (Poseidon 2004; Snyder et al. 2007; Joss 

et al. 2008; Choubert et al. 2011). 

• Coagulation and settling can be effi cient for very 

adsorbable substances (e.g. polychlorinated biphenyls), 

but few emerging compounds are retained. 

• Biological processes like activated sludge or fi xedfi 

lm processes can achieve a signifi cant reduction of 

micropollutant loads in wastewater treatment plants. 

Removal mechanisms like biotransformation, stripping 

and adsorption on sludge are involved. Parameters like 

sludge age and nitrifying capacity appear to be critical 

to maximise removal effi ciencies. Membrane separation 

of sludge seems to bring additional retention performance 

towards several emerging compounds. However, 

substances are generally not really removed in biological 

treatments: about two-thirds of the regulated substances 

are mainly transferred to sludge, whereas many polar 

emerging compounds are partly biodegraded with formation 

of by-products. Thus, complementary advanced 

tertiary processes are generally required to guarantee 

an effi cient removal. 

• Oxidation with ozone appears an effi cient advanced treatment, 

with more than 80% removal, for most emerging 

substances so long as their molecular structure presents 

accessible electrons. However, the fate and toxicity of 

by-products still remains an issue to be investigated. 

Optimisation of ozone dose depending on water quality 


and combination with ultraviolet light and hydrogen peroxide 

through advanced oxidation processes are still 

being studied, especially for wastewater applications. 

Other oxidants (chlorine, chlorine dioxide, permanganate, 

ultraviolet light alone) are generally not effi cient 

for micropollutant removal, and may present the risk of 

generating more harmful by-products. 

• Activated carbon adsorption (granular or powder) 

appears as well as an interesting treatment for micropollutants. 

Again, more than 80% removal for 

most substances is achievable. Substance properties 

(log Kow , pKa ) and operating conditions (dose, contact 

time) will determine the actual effi ciency of retention. 

Only a few molecules like iodinated contrast media or 

some antibiotics present limited affi nity for activated 

carbon. In the fi eld of wastewater treatment, more returns 

of experience in terms of life duration in fi lters or 

achievable polyaluminium chloride recovery rates are 

still needed. The fate of used activated carbon, either in 

sludge or in fi lters, may also be an issue. 

• Membrane retention processes like reverse osmosis and 

nanofi ltration allow the most effi cient retention of a wide 

range of substances, but they need an extensive pretreatment 

and they are the most energy intensive. Additionally, 

the fate of the concentrate should be mastered 

to get a completely sustainable process. Their high cost 

makes their application to wastewater treatment very 

limited, except in conditions of high water stress. In large 

potable water treatment plants, the combination of different 

advanced processes in a multi-barrier approach 

is already applied to ensure a maximum removal. 

The best solution remains the reduction at the source to 

avoid the introduction of emerging contaminants in the 

water cycle. 

Regulation trends 

In general, the standard setting is either based on the 

precautionary principle, on risk assessment or on technical 

feasibility. The precautionary principle has the big 

advantage that it allows legal action without the comprehensive 

knowledge on the fate and effects of the respective 

substance as required for risk assessment. In the risk 

assessment approach, for the identifi cation of hazardous 

substances we distinguish between substances with and 

substances without threshold, e.g. the cancerogenic, 

mutagenic and substances toxic for reproduction. These 

different assumptions are made as well in human risk 

assessment (WHO 2006, 2008) as also in environmental 

risk assessment (TGD 2003; ECHA 2010). For some 

substances there are already suffi cient signifi cant ecotoxicological 

data to suggest that the compound can cause 

adverse effects on wildlife, or that there is a signifi cant 

risk to human health. For example, in the European Union 

those compounds are listed under the EC Water Framework 

Directive 2006/60/EC (EC 2006) as priority substances or 

priority hazardous substances as they are bioaccumulative, 

persistent and toxic. Also the UNEP compiled a list of 

persistent organic pollutants that fulfi l the defi ned criteria 

for persistence, bioaccumulation and long-range transport. 

Both lists have international reporting and minimisation/phase 

out requirements and are under rolling revision. 

Pharmaceuticals and polar personal care products are not 

subject to any regulation yet and have not been monitored 

within the European Water Frame Work Directive (Directive 

5

6 


2000/60/EC). Also the new policy on chemicals REACH 

(Regulation on Registration, Evaluation, Authorisation and 

Restriction of Chemicals), which entered into force on 1 

June 2007, will increase the information on chemicals in 

the European Union. 

The challenges and future research 

directions 

The detection of so many new compounds in surface 

water, groundwater and drinking water raises considerable 

public concern. Especially when guideline values are 

not available, the questions are whether detected concentrations 

will affect human or environmental health at low 

concentrations and how these components will react in 

complex mixtures. 

One of the biggest challenges for the near future will be the 

effect assessment and risk evaluation for human health 

and the aquatic environment for the thousands of synthetic 

and natural trace contaminants that may be present 

in water at low to very low concentrations (picograms per 

litre to nanograms per litre). 

The chemical monitoring of single substances will be very 

time consuming and costly, without giving the satisfying 

answers as we see additional effects beside carcinogenic, 

mutagenic and reprotoxic substances properties, 

for example endocrine-disrupting, neurotoxic or allergic 

effects. Therefore a tiered approach of effect monitoring 

should be developed. Especially for substances with 

insuffi cient data, a quick evaluation method is required. 

This can be based, for example, on the concept of the 

‘threshold of toxicological concern’, which applies also in 

the case of an incomplete human toxicological database. 

Health-related indication values could also be applied for 

all substances based on information on the structural and 

activity relations, which are not primarily genotoxic, but 

at the same time cannot be toxicologically assessed on 

the basis of chronic or subchronic animal experiments, 

and which show no signs, however, of neurotoxic, immunotoxic 

or germ-cell toxic potential (Umweltbundesamt 

2008). Such new policy is applied in Germany for quick 

assessment of non-relevant metabolites of pesticides. In 

this case, the guidance value of 0.1 µg/L based on the 

precautionary principle can be exceeded when it is proven 

that the substance is neither genotoxic nor neurotoxic. This 

change in paradigm would be also potentially applicable 

for complex samples instead of multiple single-substance 

measurements. 

Another challenge is the answer of the question, do we 

need to remove the trace contaminants from waste water 

and drinking water – should we effort it and to which 

extent? Will micrograms per litre be suffi cient or do we have 

to go below? Are our risk assessment methods adequate 

to answer this question? Which drinking water treatment 

processes shall we apply and what will be the trade off in 

terms of re-growth or other effects? 

Conclusions 

The ongoing and future challenges like the risk evaluation, 

decision making, risk management and communication 

cannot be handled by the Assessment and Control of 

Hazardous Substances in Water Specialist Group alone, 

but need to be harmonised between different other IWA 

Specialist Groups such as those on Diffuse Pollution, 

Modelling, Institutional Governance and Regulation, Membrane 

Technologies, Design, Operation and Costs of Large 

Wastewater Treatment Plants, Design, Operation and 

Maintenance of Drinking Water Treatment Plants, Sludge 

Management, Nano and Water, Pretreatment of Industrial 

Wastewaters and many others. 

References 

Daughton, C. and Ternes, T. (1999). Pharmaceuticals and personal 

care products in the environment: agents of subtle 

change? Environmental Health Perspectives, 907–938. 

ECHA (2010). Guidance on Derivation of DNEL/DMEL from 

Human Data DRAFT (Rev.:2.1)http://guidance.echa.europa.eu/docs/draft_documents/R8_DNEL_HD_Draft_ 

Rev2.1_fi nal_clean.pdf. 

Choubert J.M., et al. (2011). Limiting the emissions of micropollutants: 

what effi ciency can we expect from wastewater 

treatment plants? Water Science and Technology 63(1), 

57–65. 

Giger, W. (2009). Hydrophilic and amphiphilic water pollutants: 

using advanced analytical methods for classic and emerging 

contaminants. Anal Bioanal Chem 393, 37–44. 

Grummt, T. and Fuerhacker, M. (2011). Risk Assessment 

for Emerging Contaminants in the Water Cycle: Recent 

Advances and Future Needs. In Chapter ‘Theme 4: Emerging 

contaminants and micropollutants’, Proceedings of the 

14th International Conference, IWA Diffuse Pollution Specialist 

Group: Diffuse Pollution and Eutrophication (DIP- 

CON) – OECD Co-operative Research Programme sponsored 

conference, Beaupré, QC, Canada, September 12–17, 

2010. In press. 

Joss A., Siegrist H. and Ternes T.A. (2008). Are we about to upgrade 

wastewater treatment for removing organic micropollutants? 

Water Science and Technology 57(2), 251–255. 

Petrovic, M. and Barceló, D. (2006). Liquid chromatographymass 

spectrometry in the analysis of emerging environmental 

contaminants. Analytical and Bioanalytical Chemistry 

385, 422–424. 

POSEIDON (2004). Assessment of Technologies for the removal 

of Pharmaceuticals and personal care products in sewage 

and drinking water facilities to improve the indirect potable 

water reuse. Contract EVK1-CT-(2000-00047. Detailed 

report, 58 p. 

Richardson, S. (2009). Water analysis: emerging contaminants 

and current issues. Analytical Chemistry 81, 4645–4677. 

Snyder S.A. et al. (2007). Role of membranes and activated 

carbon in the removal of endocrine disruptors and pharmaceuticals. 

Desalination 202(1–3), 156–181. 

REACH (2006). Regulation (EC) No 1907/2006 of the European 

Parliament and of the Council of 18 December 2006 concerning 

the Registration, Evaluation, Authorisation and 

Restriction of Chemicals (REACH), establishing a European 

Chemicals Agency, amending Directive 1999/45/EC 

and repealing Council Regulation (EEC) No 793/93 and 

Commission Regulation (EC) No 1488/94 as well as Council 

Directive 76/769/EEC and Commission Directives 91/155/ 

EEC, 93/67/EEC, 93/105/EC and 2000/21/EC. 

TGD (2003). Technical guidance document, Technical Guidance 

Document (TGD) on Risk Assessment in support of 

Commission Directive 93/67/EEC on Risk Assessment 

for new notifi ed substances, Commission Regulation 

(EC) No 1488/94 on Risk Assessment for existing substances, 

Directive 98/8/EC of the European Parliament 

and of the Council concerning the placing of biocidal 

products on the market. http://ecb.jrc.it/cgi-bin/reframer. 

pl?A=ECB&B=/tgdoc/.

Umweltbundesamt (2008). Trinkwasserhygienische Bewertung 

stoffrechtlich nicht relevanter Metaboliten von Wirkstoffen 

aus Pfl anzenschutzmitteln im Trinkwasser. Empfehlung 

des Umweltbundesamtes nach Anhörung der Trinkwasserkommission 

des Bundesministeriums für Gesundheit beim 

Umweltbundesamt. http://www.umweltdaten.de/wasser-e/ 

empfnichtbewertbstoffe-english.pdf http://resources.metapress. 

com/pdf-preview.axd?code=21n1042mv8327820&size 

=largest und Bundesgesundheitsbl-Gesundheitsforsch- 

Gesundheitsschutz 51:797-801 (2008) English: http://www. 

umweltdaten.de/wasser-e/hygiene-related_assessment_ 

of_non-rele-vant_metabolites_recommondation_april_ 

2008.pdf. 


WHO (2008). Guidelines for drinking water quality. 3rd edition; 

Geneva. 

WHO (2006). Guidelines for the safe use of wastewater, excreta 

and greywater. Volume 2: Wastewater use in agriculture. 

7

8 


Biofilms 

Written by Zbigniew Lewandowski on behalf of the Specialist Group 

The mission of the Biofi lms Specialist Group is to provide a 

forum for the exchange of scientifi c and technical information 

among researchers and practitioners involved in the 

fi eld of bio fi lms. The scope of the Group’s interests includes 

on the one hand all engineered and natural aquatic systems, 

in which sessile bacteria are found, and on the other 

all biological, chemical and physical processes, which are 

relevant for biofi lm behaviour. The Management Committee 

of the Specialist Group organises specialised biofi lm 

conferences, conference sessions, workshops, courses, 

and runs a Biofi lm Scientifi c Discussion Group. The Discussion 

Group facilitates fast transfer of information and 

news. It is a forum to ask questions, exchange ideas, share 

experiences, and discuss solutions for everyday workplace 

problems encountered by researchers and practitioners 

dealing with biofi lms. 

The description of the Biofi lms Specialist Group can be 

found o the IWA homepage at http://www.iwahq.org/ 

Home/Networks/Specialist_groups/List_of_groups/Biofi 

lms/. 

The Biofi lms Specialist Group also runs its own homepage 

at http://www.iwa-biofi lm.org/ where more details about 

our activities can be found. The Biofi lm Discussion Group 

can be reached at biofi lm-group@eawag.ch. 

One of the perpetual activities of the Specialist Group is to 

organise specialised biofi lm conferences. These themes of 

the conferences are alternating to cover (a) biofi lm processes 

and (b) biofi lm technologies. The most recently 

organised conference by the Biofi lms Specialist Group was 

dedicated to biofi lm processes and was held from 27 to 30 

October 2011 in Shanghai, China. The website of the conference 

at www.iwabiofi lm2011.com specifi es the main 

topics of the conference: 

• methods and tools to study biofi lms; 

• extracellular polymeric substances; biofi lm structure 

and activity; 

• biofi lm microbiology and ecology; 

• mathematic modelling of biofi lm processes; 

• biofi lm technologies in water and wastewater treatment; 

• biofouling and biofi lm control. 

We also offered a workshop dedicated to aerobic granulated 

sludge, which is one of the most promised technologies 

based on the biofi lm-type microorganisms. 

To engage young researchers we had dedicated sessions 

run entirely by the Young Water Professionals. 

Terminology 

There is no commonly accepted defi nition of the term 

biofi lm. Although self-explanatory to biofi lm researchers, 

it is regarded as controversial by many in other fi elds of 

research. The most popular defi nition says that biofi lms are 

microorganisms attached to surfaces although some biofi 

lm researchers argue that biofi lms should be regarded as 

a mode of microbial growth, in the same manner as microbial 

growth in suspension is, rather than as physical structures 

formed by microorganisms attached to surfaces. 

The term biofi lm refers only to the microbial deposits on a 

surface imbedded in the matrix of extracellular polymers. 

The broader term, biofi lm system, includes other components 

affecting the biofi lm formation: 

• the surface to which the microorganisms are attached; 

• the biofi lm (the microorganisms and the matrix of extracellular 

polymers); 

• the solution of nutrients; 

• the gas phase (if present). 

Another term often used when referring to the attached 

microbial growth is biofouling (of surfaces). It is derived 

from the term fouling of surfaces, which refers to the 

process of contaminating surfaces with (usually) mineral 

deposits. In principle, the term refers to the same process 

as the term fouling does, but it emphasises the fact 

that the deposits on the fouled surfaces are composed of 

mineral substances mixed with living microorganisms and 

macro organisms and with extracellular polymers excreted 

by the microorganisms. 

The term biofouling deposits is sometimes considered an 

equivalent of the term biofi lms, particularly in industrial 

settings, where it is used to emphasise the presence of 

scaling deposits or corrosion products imbedded in the 

extracellular polymers excreted by the microorganisms 

attached to surfaces. 

When larger organisms accumulate on surfaces, as is 

common in marine environments for example, the term 

macrofouling is used. 

Existing Specialist Group knowledge 

Biofi lms are ubiquitous and develop on water-immersed 

surfaces whether we want them or not. Depending on the 

effect of the biofi lm – desirable or not – in engineered systems 

we try to control its development by either promoting

or inhibiting the microbial growth in the biofi lm. Often physical 

removal of biofi lms is used as well, which is considered 

an effective way of controlling undesirable biofi lms. 

Several technologies taking advantage of biofi lms have 

been developed in the water and wastewater treatment. 

They often offer benefi ts over the more traditional technologies 

based on the suspended growth of microorganisms. 

Designing and operation of the large-scale biofi lm 

reactors poses many challenges. Most advances in understanding 

biofi lm processes resulted from laboratory- and 

bench-scale studies. Implementing these advances to the 

design and operation of full-scale reactors is not trivial and 

the rules for a scale-up of biofi lm processes are not clear. 

Applied research exists that provides a basis for the mechanistic 

understanding of biofi lm reactors. Unfortunately, 

little information exists to bridge the gap between our current 

understanding of biofi lm fundamentals derived from 

the bench-scale studies and the empirical information 

derived from operating large-scale reactors. The empirical 

information derived from applied research has been used 

to develop design criteria for biofi lm reactors and remains 

the basis for biofi lm reactor design despite the emergence 

of mathematical models as reliable tools for research and 

practice. We are experiencing an exponential increase in 

the number of biofi lm based technologies applied in the 

water and wastewater treatment. One of our goals is to 

develop reliable procedures based on mathematical models 

of the processes in biofi lms and use them to design 

biofi lm reactors in water and wastewater treatment. 

Biofi lms also develop on surfaces where their presence has 

negative effects, such as the biofi lms developing on the 

surfaces of the fi ltration membranes, for example. There 

is a variety of undesirable effects the biofi lms may cause. 

Depending on the affected processes, biofi lms may increase 

the mass transport resistance, increase the heat transfer 

resistance, increase the pressure drop in pipes, have a 

negative effect on the material performance by accelerating 

corrosion, and have negative effects on human health 

by harbouring pathogens. Traditional methods of controlling 

microbial contamination, mostly based on the use of antimicrobials, 

are much less effective when used to control biofi 

lms. The unusual resistance of biofi lms to antimicrobials 

remains mysterious and much research has been devoted 

to understanding and overcoming this effect. 

General trends and challenges 

It is diffi cult to point out a few of the most important topics 

to be addressed in complex biofi lm systems, but it is 

much easier to point out a group of topics that need to be 

addressed in the near future to achieve progress toward 

implementing biofi lm-based technologies in water and 

wastewater industries: 

1. Developing rational criteria for the design and operation 

of biofi lm reactors, based on the mathematical models 

of biofi lm processes. 


2. Developing rational and effective approaches to biofi lm 

control. 

3. Determining the structure and function of the extracellular 

polymeric substances in biofi lms and their role in 

biofi lm processes. 

Conclusions 

One of the emerging conclusions from our discussions is 

that several IWA Specialist Groups have been converging 

on similar problems, and they all have a common 

denominator: biofi lms. We see therefore the most promising 

progress in integrating the knowledge developed in 

the Specialist Groups dealing with problems related to our 

activities. Examples of these Specialist Groups are Membrane 

Technology, Microbial Ecology and Water Engineering 

(formerly Activated Sludge Population Dynamics), 

Nutrient Removal and Recovery, and Water Reuse. 

Rapid progress in molecular biology opens new perspective 

and offers new insights to the processes studied by 

several specialist groups, including the Biofi lm Specialist 

Group. The implementation of the new insights into 

the practice depends largely on the rate of transferring 

the knowledge developed by the groups dedicated to 

life sciences to the groups dominated by engineers, and 

focused on the technical aspects of biofi lm processes 

and biofi lm-based technologies in water and wastewater 

treatment. To provide a platform for the discussion among 

the life scientists and engineers, IWA initiated the Bio- 

Cluster initiative, of which the Biofi lm Specialist Group is 

a member. The charter for the Bio-Cluster initiative was 

discussed at the IWA meeting in Lisbon, the concepts 

were further distilled at the Water Congress in Montreal 

in 2010, and the fi rst Bio-Cluster meeting, dedicated to 

biofi lms on fi ltration membranes, was held in Singapore 

in July 2011. 

Because one of our goals is to develop rational criteria for 

the design and operation of large-scale biofi lm reactors 

for water and wastewater treatment, we make conscious 

efforts to exchange information with those who actually 

design and operate them. Some of our conferences 

emphasise the microbial processes in biofi lms whereas 

other emphasise the design and operation of the biofi lm 

reactors. In 2010 we organised a joint WEF/IWA conference 

on Biofi lm Reactor Technology with the mission ‘to 

provide a forum for biofi lm researchers and practitioners 

to exchange ideas, to review recent advances in biofi lm 

reactor technologies, and to assess the impact of biofi lms 

on natural and engineered processes in water and wastewater 

treatment’. We received very positive feedback after 

this conference and we plan to continue such joint meetings 

as these types of events put together researchers 

and practitioners and allow them to determine the gaps 

in knowledge that need to be fi lled to provide progress 

in implementing biofi lm-based technologies. Our next 

conference dedicated to biofi lm reactors will be in Paris, 

France, in 2013. 

9

10 


Design, operation and maintenance 

of drinking water treatment plants 

Objectives 

• Prepare reports and newsletters of Group activities and 

developments. 

• Convene conferences and workshops. 

• Support young professionals. 

• Cooperate with other Specialist Groups (e.g. Natural 

Organic Matter (NOM) Removal, Strategic Asset Management, 

Wastewater Treatment). 

• Contribute to share experience and operational feedback 

in the fi eld of different practical issues related to 

full-scale water treatment plants everyday operation and 

management. 

Management 

At the end of 2010 the management committee was 

re-organised after Joël Mallevialle retired from his position 

as Chair. Nominations for the new Specialist Group management 

team were received and the current offi cers of 

the Specialist Group are as follows: 

• Chair: Dr Zdravka Do Quang 

• Secretary: Dr John Bridgeman 

The Management Committee of the Specialist Group comprises 

• Dr Joël Mallevialle (Past Chair) 

• Zuhair T. Al-Shaikhli 

• Ms Svetlana Karabas 

The Management Committee is now working on the development 

of a programme of work for the Specialist Group 

for the next few years. This will include further conference 

and workshop organisation and the production of relevant 

position papers, the need for which will be identifi ed by 

the Specialist Group membership. 

Group Past Activities 

Over the past three years, the Specialist Group has organised 

the following events. 

• It organised a workshop on ‘Assessment and management 

of health risk related to emerging parameters 

on drinking water treatment plants: case studies and 

examples of application to full-scale operations’ during 

the World Water Congress in Vienna in September 

2008. 

• In 2010 during the IWA World Water Congress in 

Montreal the Specialist Group organised a workshop 

on ‘Assessment and application of biological tools and 

new technologies for water quality surveillance related to 

emerging pollutants effects’. 

Joint Activities with other Specialist 

Groups 

• Together with the Specialist Group on NOM Removal 

our group organised the 4th IWA specialist conference 

on NOM in Bath, UK (September 2008). A total 

of 94 abstracts were submitted from all over the world. 

The Specialist Group submitted three abstracts on 

operational issues related to the NOM (by-products, 

membranes). Three members of the Specialist Group 

were on the Programme Committee in charge of the 

abstracts’ review, the establishment of the scientifi c programme 

and chairing the conference sessions. 

• Together with the Specialist Group on AOP, a conference 

was organised during the Wasser Berlin exhibition 

in April 2009 on the application of Ozone and Related 

Oxidants for Innovative & Current Technologies. 

• Specialist Group on Wastewater Treatment Plants: 

organisation in 2009 and 2010 of the IWA specialised 

conference ‘Water and Wastewater Treatment Plants 

in Towns and Communities of the XXI Century: Technologies, 

Design & Operation’ during the ECWATECH 

exhibition and conference in June 2010 in Moscow. 

The contribution of the Specialist Group was in the constitution 

of the scientifi c programme of the conference 

for the drinking water part applications, the constitution 

of the scientifi c committee, in the research of speakers 

and sponsors, and in the review of the abstracts and 

papers. More than 500 abstracts were submitted. 

Existing Specialist Group Knowledge 

on Priority Topics 

• Solving operational issues (e.g. case studies) on regulated 

water quality issues (e.g. turbidity, NOM, etc.). 

• Deployment of tools (technologies and recommendations) 

for practical application by the operators. 

• Collection and sharing of operational feedback (operators’ 

training). 

• Maintenance procedures (e.g. asset management). 

General Trends and Challenges 

• Assessing the future waterborne health risks (e.g. 

emerging parameters) by integrating the new regulatory

changes (e.g. new approaches such as health risk 

management tools operational deployment) and 

anticipating water treatment plants evolution (upgrading 

and retrofi tting) to cope with the new water quality 

targets (e.g. emerging pollutants, non-regulated water 

quality parameters) by implementing new treatment 

strategies. 


• Securing the produced and distributed water quality by 

on-line measure and control with micro-sensors (realtime 

network monitoring). 

• Prevent water resources from pollution and associated 

economic issues (CAPEX and OPEX): What cost for 

which quality of water? 

11

12 


Disinfection 

Written by A. Cabaj, Ch. Chen, Th. Haider, B. Jiménez, K. O’Halloran, G. Hirschmann, Ch. Shang, 

H. Shuval, R. Sommer, S.K. Tiwari and R.R. Trussell on behalf of the Specialist Group 

Introduction 

Disinfection is one of the most important steps in the treatment 

of water, wastewater and sludge. In any treatment 

scheme this step is always included. Moreover, many text 

books present the treatment of water and wastewater 

as a series of steps to prepare water for disinfection, as 

this is considered as key to protect public health. Even 

though the disinfection of drinking water is considered to 

have been mastered in developed countries, new challenges 

have arisen such as the need to look for different 

approaches to disinfect water in order to remove Cryptosporidium, 

an ‘emerging pathogen’ that has been the 

cause of outbreaks and even deaths in some countries 

(McKenzie et al. 1994; Goldstein et al. 1996, Yamamoto 

et al. 1996; Willocks et al. 1998; Semenza and Nichols 

2007). Something similar can be said for developing countries, 

where new challenges are adding to existing ones. 

For instance, Helicobacter pylori, a bacterium recently 

linked to gastric ulcers and cancers (Watanabe et al. 

2005) has been the cause of diseases in children under 

10 years of age with rates up to 15 times higher than those 

observed in developed countries and these rates are 10% 

higher in rural than in urban areas and may be linked 

to unsafe water consumption (Klein et al. 1991; Mitchel 

et al. 1992; Pounder and Ng 1995), Although humankind 

has made great progress in research on the macroscopic 

scale, the microbial fi eld remains a challenge. There is 

a need for research and technology to develop different 

and more effi cient ways to disinfect water, wastewater and 

sludge and avoid the production of side effects. This text 

is intended to present the state of the art and outline the 

future challenges in this fi eld. 

Main challenges 

It may sound trite but the fi rst and greatest challenge for 

disinfection is to defi ne the expectations of the process. 

Disinfection is often mistaken for sterilisation in which 

there is an expectation of a complete kill of all microorganisms. 

This is clearly not the case and it is widely agreed 

that a risk based multi-barrier approach to water purifi cation 

is the most sensible approach to providing water that 

is fi t to drink. 

Having understood that disinfection is one part of an integrated 

approach to water purifi cation, albeit perhaps the 

most important part, there is now the challenge of understanding 

the strength and limitations of disinfection. In 

other words clearly understanding what disinfection can 

and cannot do defi nes the links between disinfection 

and upstream and downstream processes. For example 

most disinfection processes are far more effective with 

a minimisation of solids load in the water, this therefore 

creates the link with the effi cacy of upstream fi ltration. 

Similarly, the characteristics of the downstream reticulation 

and governing regulation will defi ne the link between 

primary disinfection and downstream processes such as 

secondary or residual disinfection, corrosion control and 

fl uoridation. 

Once the integration map for disinfection has been established 

then the operational aspects of disinfection can 

be examined in detail, and performance criteria and 

minimum standards can be established. Herein lies the 

next key challenge; how do we assess the performance 

of disinfection and what standards are adequate? A useful 

way to approach this is in the context of the environment 

in which disinfection is practised, for example, what 

are the main microbial challenges present in the water to 

be disinfected, viral, bacterial, protozoan, or all of these? 

There has been much discussion amongst learned colleagues 

regarding the effi cacy of different disinfectants 

and in truth there is no one disinfection process that is 

the best in all cases, but it is true that chlorination remains 

the most widely used form of disinfection and it is usually 

targeted towards acceptable inactivation of chlorine 

resistant viruses, hereby accepting that attaining this level 

of disinfection will accommodate adequate inactivation of 

bacteria as well. In this case there will be an inherent reliance 

on the upstream fi ltration process for the removal of 

protozoan challenges. 

There now remains a key challenge of disinfection which 

virus do we target to establish our disinfection performance 

targets? Again there is no one choice that is best 

for all as viral prevalence in raw water catchments varies 

greatly throughout the world and indeed between neighbouring 

catchments with different land uses. However, 

taking tropical and sub-tropical environments as an example 

the coxsackieviruses have been the target pathogens 

of choice due to their prevalence and resilience in the 

environment. 

Finally, we arrive at the challenge of determining an acceptable 

performance for disinfection. Certainly a CT-based 

approach based on log inactivation has gained widespread 

popularity however, it is not universally accepted and again 

a risk based approach involving full consultation between 

all stakeholders is essential from the very beginning of 

designing a disinfection process and should be maintained 

as the vehicle for management for disinfection reviews and 

responses to changing environments.

Drinking water disinfection 

The issues that drinking water disinfection needs to 

account for include not just pathogen elimination but also 

bio-stability and corrosion control in the distribution system 

as well as the DBP formation. In some cases, disinfectants 

were applied as the oxidants to help the coagulation 

performance in the water treatment plants. The multiple 

requirements and subtle balance between each requirement 

have made drinking water disinfection one of the 

most troublesome and comprehensive tasks in water 

industry although the direct cost of disinfectant addition 

is very limited. 

Pathogen elimination is the fi rst goal of disinfectants. 

The existence of chlorine-resistant pathogens, such as 

Cryptosporidium, Giardia, Legionella, Mycobacteria, have 

driven the development of new disinfectants or process 

in the past and forward decades (Corona-Vasquez et. al., 

2002; Haas & Kaymak, 2003; Kim et. al., 2002; Hilborn 

et. al., 2006). Free chlorine, as liquid chlorine or sodium 

hypochlorite, will still serve as the primary disinfectant due 

to its high effi ciency to inactivate the majority of bacteria 

and viruses. Chlorine dioxide has better performance 

on bacteria including Legionella and Mycobacteria than 

chlorine (Huang et. al., 1997). Its application increased 

rapidly in small water treatment plants but limited in large 

WTPs due to the concern of chlorite where high dosage 

needed. UV radiation has been proven to be the best available 

technology for Cryptosporidium and Giardia control 

(Linden et. al., 2002). However, UV disinfection does not 

improve the chemical quality of water. Therefore it cannot 

lower down the subsequent chlorine demand. Ozone, 

potassium permanganate and potassium monopersulfate 

will be applied more as oxidants rather than disinfectants 

although they have better inactivation effi ciency on 

the mentioned chlorine-resistant pathogens (Roy 2010). 

Physical barrier, esp. membrane fi ltration could also be 

regarded as the effective disinfection method in the sense 

that it is very effi cient at removing relatively high size pathogens 

from water. 

However, the majority of disinfectant consumption was 

due to requirement of maintaining the residual disinfectant 

till the tap rather than inactivating the pathogens. Control 

of bacteria re-growth and biofi lm, or bio-stability problem 

were even more diffi cult than inactivation since the microorganism 

existed in the complex niche such as scale and 

sediments. Chlorine and chlorine dioxide decayed quickly 

due to the reaction with organics in bulk water and reductive 

matters such as ferrous on the wall. They are applied 

in small scale networks or low-DOC-concentration atmosphere. 

That is the reason why chloramination performed 

well as secondary disinfectant in metropolitans with huge 

networks. Ozone and UV cannot satisfy the residual 

requirement in the distribution system. 

One of the other side effects of disinfectant addition is the 

corrosion control. Strong oxidants support the formation of 

passivation layer on the pipe wall (Kuch, 1988). However, 

the replacement of chloramines instead of free chlorine 

led to the release of lead or iron in some cases (Lytle & 

Shock, 2005). 

DBP formation has been the main driving force of alternative 

disinfectants development since 1970s. However, the 


high-expected chloramination has been proven to yield 

more toxic DBPs, such as nitrosamines and iodo-DBPs in 

some cases (Krasner et. al., 2006). The new generation 

of DBPs reminds that DBP precursor removal might be 

safer than developing new disinfectants. 

In all, drinking water disinfection can never be simply 

regarded as one single step for pathogen inactivation. 

The combination of multiple disinfectants and precursor 

removal by enhanced water treatment processes could 

be the only fi nal solution for comprehensive water safety. 

Enhance conventional process will guarantee the effl uent 

turbidity as low as 0.1 NTU which will benefi t the inactivation 

of pathogen. Ozone and GAC are applied for DBP 

precursor removal on the basis of conventional process. 

UV is used for Cryptosporidium and other pathogen control 

and limit dosage of chlorine, chloramines or chlorine 

dioxide is added to maintain the residual disinfectant and 

suppress the biofi lm formation in the distribution system 

with the aid of nutrient removal during the water treatment 

process. 

Requirements on drinking water disinfection 

by UV irradiation 

The disinfection of water by UV irradiation has become 

a credible alternative to chemical disinfection procedures 

using chlorine or ozone, especially since it was demonstrated 

that this technology is very effective against (oo) 

cysts of the protozoa Cryptosporidium and Giardia. Another 

reason for the increased acceptance of UV drinking water 

disinfection throughout the world is attributed to the better 

understanding of the process and the higher quality 

assurance of the UV disinfection plants. Establishment of 

quality standards on the requirements as well as validation 

testing and certifi cation of commercial UV plants have provided 

the basis for the safe application of drinking water 

disinfection by UV irradiation. Two different techniques 

of UV irradiation have been established for water disinfection: 

low pressure lamps with quasi monochromatic 

emission at 253.7 nm and medium pressure lamps with 

polychromatic emission. In the latter case, it is even more 

complex to determine the microbicidal UV fl uence, since 

the wavelengths account differently for the inactivation of 

microorganisms (Cabaj et al. 2001). As an example a 3-log 

reduction of spores of Bacillus subtilis requires a fl uence of 

800 J/m² at a wavelength of 254 nm, whereas at a wavelength 

of 334 nm a fl uence of 2.000.000 (2 million) J/m² 

is needed (Cabaj et al. 2002). Owing to the differences 

in lamp emission and the consequences thereof the UV 

fl uence generated by UV low pressure lamps and that by 

UV medium pressure lamps cannot be compared directly. 

Therefore is advisable to deal with these two techniques 

separately. 

Although UV inactivation is already known since 100 years 

many concerns have been raised regarding its reliability for 

water disinfection. This lack of trust hampered the application 

and the distribution of this technology for a long time. 

The main objections have been the following: 

• no objective criteria for the effi ciency of UV disinfection 

systems and therefore no possibility to compare different 

types of commercially available UV plants (competition 

on the market distorted); 

13

14 


• no possibility of an independent check of the proper 

function of the UV plant during practical operating (lack 

of confi dence); 

• no direct measurement of the ‘disinfectant’ possible 

(lack of control). 

Besides the many advantages of the UV technology, it 

became evident that the UV fl uence (dose) delivered by 

a UV system can still not be directly measured nor can 

it be calculated. This is because during UV irradiation in 

a fl ow-through system several factors act in a complex 

combination: the output of the UV lamps, the water fl ow, 

the UV transmittance of the water being irradiated and 

– especially important – the hydraulic properties of the 

UV device. As a consequence of inhomogeneous irradiation 

geometries and UV plant specifi c, unpredictable 

hydraulic behaviour each microorganism receives an individual 

UV fl uence. Therefore large fl uence distributions 

within the microorganisms may occur (Cabaj et al. 1996). 

New technologies like computational fl uid dynamics or 

Lagrangian Actinometry with dyed microspheres provide 

additional information, verifi cation with biodosimetry is 

still essential. 

For the quality assurance of safe UV water disinfection a 

four-step approach has been proven useful: (a) the knowledge 

of the UV resistance of pathogenic microorganisms 

transmittable by water to choose a suffi cient high UV fl uence 

(UV dose); (c) a standardised measuring window 

and a UV sensor for the measurement of the UV irradiance 

which allows checks against offi cial specifi cations 

(W/m²), (c) a standardised evaluation of the microbicidal 

effi cacy of commercial UV plants by biodosimetric testing 

and (d) the surveillance of the operating parameters (fl ow, 

irradiance, UV transmittance) during practical operation 

by means of defi ned alarm points. 

UV irradiation proved being broadly effective against 

all pathogens (bacteria, viruses and protozoa) that can 

be transmitted through drinking water. Of these pathogens, 

viruses (especially Adenovirus 40) are more UV 

resistant than bacteria, which are more resistant than 

Cryptosporidium and Giardia (Clancy et al. 2000; Craig 

et al. 2000; Meng and Gerba 1996). Inactivation studies 

under controlled laboratory conditions have been performed 

in recent decades providing a valuable data base. 

For an overview see Hijnen et al. (2006). 

In view of the factors mentioned above, it was necessary to 

develop and establish standard protocols for the validation 

of UV disinfection systems. This has been carried out by 

three organisations: 

• the US Environmental Protection Agency (USEPA 

2006); 

• the German Association for Gas and Water (DVGW 

2006); 

• the Austrian Standards Institute (ÖNORM M 5873- 

1:2001, low pressure systems and ÖNORM M 5873- 

2:2003, medium pressure systems). 

The use of biodosimetry to measure the disinfection 

capacity of commercial UV disinfection plants is common 

to the UV disinfection standards of all three organisations 

(Sommer et al. 2008). The investigation is performed in 

full scale under controlled operating conditions usually 

at a test centre (Sommer et al. 1993). In biodosimetry a 

UV-253,7 nm calibrated microorganism (e.g. spores of 

Bacillus subtilis or phage MS2) is introduced to the UV 

irradiation chamber under different operating conditions. 

The resulting reduction of the biodosimeter is converted by 

means of the UV-254,7 nm calibration curve into Reduction 

Equivalent Fluence, REF (J/m²) with the following formula, 

where N/No is the survival rate, k is the slope of the 

linear part of the survival curve in m²/J (UV-sensitivity) and 

d is the distance between the intercept of the linear part 

with the ordinate and the origin. 

Owing to the different history of origins specifi c distinctions 

occur between these UV disinfection standards. The 

following highlights some important differences of the 

approaches. 

Considering the general goal of safe drinking water disinfection, 

represented by a reduction of the concentration 

of drinking water transmittable, relevant pathogenic parasites 

and viruses by 3 and 4 log, respectively, a UV fl uence 

(253.7 nm) of 400 J/m² is demanded in the Austrian 

and German standards (Austrian Standards Institute 2001 

2003; Deutsche Vereinigung für das Gas- und Wasserfach 

2006). The UV fl uence of 400 J/m² also covers photorepair 

of bacteria possessing the enzyme photolyase (Sommer 

et al. 2000) and includes a 4-log inactivation of most of the 

relevant viruses, e.g. hepatitis A virus, rotavirus, poliovirus 

and calicivirus (Sommer et al. 1989; De Roda Husman 

et al. 2004). The high UV resistance of adenovirus is not 

taken into account. In Austria and Germany UV irradiation 

often represents the only disinfection step. Therefore 

especially high requirements have to be demanded. 

The drinking water disinfection in the USEPA standard is 

based on the inactivation of target pathogens individually 

defi ned for a specifi c water treatment plant. Therefore the 

demanded UV-253,7 nm fl uences vary and are as low as 

120 J/m² for a 3 log inactivation of Cryptosporidium and 

Giardia but even high as 1860 J/m² for a 4 log reduction of 

adenovirus. In this regard UV disinfection is often used for 

the inactivation of parasites and combined with chlorination 

to cover the inactivation of viruses as well. According 

to USEPA UV systems validated according to ÖNORM 

and DVGW are granted 3 log inactivation of (oo)cysts of 

Cryptosporidium and Giardia. 

Wastewater disinfection 

History 

1 

REF = – − · log 1− 11−10 

K 

log N 10 

N 

−d 

The world’s population has signifi cantly surpassed the 

extent to which the natural environment is able to adequately 

assimilate pathogens that are present in wastewater. 

Although wastewater is not universally disinfected, 

many countries have implemented disinfection efforts to 

protect recreational and drinking water systems, as well 

as waterways supporting natural resources such as fi sh, 

shellfi sh and wildlife. Traditionally, chlorine has been the 

disinfectant of choice to mitigate acute health risks associated 

with the oral-fecal route of disease transmission 

N 0

through water (Tchobanoglous et al. 2003). In the past 

three decades, concerns have arisen in relation to the use 

of chlorine and chloramines that are formed when chlorine 

is added to wastewater. These concerns include: resistance 

of some pathogens (such as spores, (oo)cysts and 

some enteric viruses), as well as the formation of an array 

of toxic disinfection by-products (DBPs), namely THMs, 

HAAs and NDMA, and the need to address trace organic 

pollutants. These fi ndings have fuelled the consideration 

of alternative disinfectants (U.S. EPA, 1986; Tang et al. 

2010; Tchobanoglous et al. 2003). 

Alternative disinfection options 

In light of the current knowledge base, the ideal disinfection 

process, removes a wide range of target pathogens, 

minimises the unintended consequences of disinfection 

(i.e. DBPs formation) and reduces trace organic pollutants 

(i.e. a modern concern as drinking water resources and 

wastewater become more integrated) (Tang et al. 2011). 

Established disinfection options include: chloramination, 

breakpoint chlorination, ultraviolet irradiation (UV) and 

ozonation (Leong et al. 2009). It is important to note that 

the majority of disinfection processes pose a DBP challenge, 

so the goal is to minimise the formation of DBPs. An 

attractive alternative to any single disinfectant is the combination 

of disinfectants, which is advantageous because 

a wider spectrum of pathogens are attenuated, the extent 

of DBP formation is often reduced and trace organics are 

typically better addressed. The following combinations are 

gaining popularity: sequential chlorination (Maguin et al. 

2009); peracetic acid (a peroxide) and UV; ozone and UV; 

and chlorine and UV (Leong et al. 2009). 

Emerging concerns 

Several developments have unveiled and continue to 

unveil several unforeseen challenges in relation to the disinfection 

of wastewater. Recent fi ndings and trends that 

deserve additional attention include: 

• As challenges with water and wastewater begin to amalgamate, 

with increased indirect potable and de facto (or 

unplanned) reuse, proper disinfection becomes increasingly 

critical. The natural barriers that we once relied 

upon are disappearing quickly and need to be augmented 

through treatment barriers. 

• The characteristics of the wastewater are rapidly changing 

as the world become more integrated, leading to the 

need to address a wider variety of contaminants, because 

diseases prevalent in one region, are apt to show 

up in another region. 

• The discovery of new contaminants is expanding much 

faster than we are able to address them and adequately 

understand their effect on human health. For example, 

prions are known to exist in wastewater, but their signifi - 

cance and the treatment mechanism for their removal 

are poorly understood, and potential interference of 

nanoparticles with disinfection is also not well understood. 

• Continued research efforts are necessary for innovative 

technologies, which include peracetic acid, ferrate, 

brominated chemicals, pasteurisation and combined 

treatment options. Combined treatment options are 

especially promising, because the unique effi cacies of 


different disinfection options can be capitalised in one 

process. 

• Given that there are still things yet to be discovered and 

constituents of concern continue to grow steadily, it is 

important to implement an on-going program to assess 

new contaminants in wastewater, as well as treatment 

by-products. Given this situation, most changes and 

developments are likely to emerge out of necessity. 

New products for disinfection 

The need for effective new 

secondary – residual disinfectants: 

hydrogen peroxide/silver (HP/AG) 

formulations 

The approaching end of the chlorine era is already resulting 

in a move by the water industry, worldwide, to evaluate 

and introduce alternative primary disinfectants with less 

negative public health and taste and odour problems. The 

most likely candidates for alternative primary disinfectants 

to replace chlorine are ozone, UV radiation and ultra/nanofi 

ltration. These are all effective water disinfection processes 

but they do not provide residual disinfection effects 

which are required by regulations in the USA, England and 

many other countries. However, USEPA regulations specify 

chlorine as the sole residual disinfectant. Thus, with the 

growing interest in ending the use of chlorine, and chloramines 

there is a need for the approval of new secondary-residual 

disinfectants. The USEPA has the authority to 

develop the protocol required for the testing and approval 

of effective alternative secondary disinfectants, but to date 

has not been done so. This has resulted in an obstacle 

in the development of alternative non-chlorine secondary 

disinfectants. 

Bromine, Iodine and Ag used as disinfectants in camping 

and private homes have not been approved for municipal 

water supplies in any country. Hydrogen peroxide-silver 

(HP/AG) formulations have been approved for drinking 

water disinfection in Europe and have been registered as 

safe from a toxicological point of view by FIFRA-EPA (FIFRA 

Sec (c) April 18th 2008-EPA Registration No.84526-1). 

Hydrogen peroxide (HP) is a well known, mild disinfectant. 

HP used alone has not been found to serve as an 

effective drinking water disinfectant. Research and development 

work initially in Europe (Deak and Kadar, 1987) 

and later in Israel (Pedhazur et al. 1995; Pehazur et al. 

1997) revealed that formulations of HP combined with 

very small concentrations of oligodynamic silver (AG) as 

an activating/potentiation agent (HP/AG) provide a disinfectant 

power some 100 times greater against faecal indicator 

organisms, such as E. coli bacteria, than HP alone 

and has a long lasting residual disinfectant-bactericidal/ 

bacteriostatic effect in water distribution systems, tanks, 

and reservoirs lasting many days and months.(Shuval 

1999; Liberti et al. 2000) The HP/AG formulations have 

been found to be particularly effective in cooling towers 

and in controlling Legionella bacteria in hot water systems 

since their effi cacy increases with increasing temperature 

(Armon et al. 2000; Shuval, et al. 2009). Other advantages 

are taste and odour control and reduction of THM 

residuals (Batterman et al. 2000). Studies have indicated 

15

16 


that the probable bactericidal mode of action of the combined 

formulation is a biological potentiation interaction at 

the molecular level which apparently increases the entry 

and penetration of the biocide through the bacterial cell 

wall and facilitates intra-cellular inactivation (Pedhazur 

et al. 1997, 2000). 

In drinking water disinfection HP/AG formulations are 

generally applied so that the initial concentration of HP 

is from 5-30 ppm, and the initial concentration of AG is 

from 5-30 ppb. While not yet widely used in drinking water 

treatment, especially in Europe, HP/AG formulations most 

probable future niche in the world water treatment fi eld is 

as an effective, non-toxic long acting secondary – residual 

drinking water disinfectant used in conjunction with ozone, 

UV or nanofi ltration which provide no residual disinfectant 

action (Shuval 1999; Warila et al. 2001). In the USA this 

would require EPA approval as an equivalent to chlorine 

for residual treatment. Studies show that HP/AG meets 

those criteria. The patented HP/AG formulations provide 

a stable product with a long shelf life (Gitye and Gomori 

2010). Further information is available from the commercial 

fi rms. There may well be other promising alternative 

secondary residual disinfectants waiting in the pipeline for 

the opportunity to be tested and approved and enter into 

the market. An initiative by the USEPA and/or WHO on this 

could be of value. 

By-products 

After the recognition of chloroform as a probable carcinogen 

and by-product produced after chlorine disinfection of 

natural waters in 1970s (Rook, 1974), balancing the risk of 

communicable disease transmission spread by waterborne 

microorganisms against the risk of toxicity from exposure 

to disinfection by-products (DBPs) has long become an 

important task in water quality control. The over 30 years 

of efforts from water professionals allow us to understand 

the signifi cance and health risks of some DBPs including 

trihalomethanes (THMs), haloacetic acids (HAAs) 

and others, leading to the promulgation of regulations 

and guidelines (USEPA 2006; WHO 2008) and the follow-up 

development of technological solutions for control 

of these DBPs. In general, the common practices for byproduct 

control fall into three categories: the use of alternative 

disinfectants such as chloramines, UV, ozone and 

chlorine dioxide; modifi cation of the operating condition 

(e.g., changing pH) to suppress the formation; and further 

reduction of precursors by processes such as enhanced 

coagulation and granular activated carbon adsorption. 

Nevertheless, new knowledge of toxicity, formation, and 

control of DBPs have been continuously being revealed. 

Several emerging DBPs have been recognised for their signifi 

cance. The most well-known one is N-nitrosodimethylamine, 

which is favourably formed from chloramination 

and in wastewater (Mitch and Sedlak 2002; Mitch et al. 

2003). Other emerging nitrogenous DBPs include other 

nitrosamines, heloacetonitriles, haloamides, and helonitromethanes, 

many of which have be found more genotoxic 

and cytotoxic than the regulated DBPs (Plewa et al. 2008; 

Richardson et al. 2007). Iodinated DBPs, which are formed 

in signifi cant higher quantity in chloraminated drinking 

water (Krasner et al. 2006), are found more toxic than the 

brominated and chlorinated analogues (Richardson et al. 

2007). The discovery of these emerging DBPs with higher 

health risk suggests the need for looking into their formation 

and control, although their concentrations in waters 

are much lower than those of the regulated ones. 

Attention is also being paid to discover new DBPs from different 

disinfection means and in different water matrices 

including disinfected potable water, wastewater effl uents 

and swimming pool water. Although there are about 700 

polar and non-polar DBPs reported in the literature, little 

is known about their quantities, after disinfection, and 

their health impacts. Alternatives including assessing total 

organic halogens, overall toxicity, and precursor availability 

in fi nished waters are being considered. Efforts are also 

being made to understand the ecological impacts of DBPs 

in receiving waters and, for potable and swimming pool 

waters, the signifi cance of our exposure to some DBPs 

through inhalation and dermal contact. Combining two 

disinfection means is being considered to provide both 

multiple disinfection barriers and by-product control. 

Sludge disinfection 

The treatment of sludge is commonly presented as a stabilisation 

process in which treatment is applied to produce 

a ‘semi-solid material’ which does not cause harm when 

disposed of into the soil or to a land fi ll. The objective is 

to produce a material that biodegrades easily, does not 

leach and does not contain pathogenic microorganisms. 

Owing to climate change concerns, the disposal of municipal 

sludge to landfi lls is becoming increasingly diffi cult. 

The disposal of sludge to agricultural land may therefore 

increase, especially as a tool to sequester carbon. Reclamation 

of sludge in agricultural fi elds is still the most 

common way to dispose of municipal biosolids worldwide 

(Leblanc, et al. 2008). Among the problems to safely 

reclaim sludge in this way is the need to produce cleaner 

biosolids and properly disinfect the sludge. In contrast to 

wastewater, disinfection requirements for sludge in developed 

and developing countries are dramatically different. 

The microbial sludge content refl ects public health conditions. 

The disinfection of sludge is and will be an important 

challenge in developing countries as the microbial content 

is not only notably higher but also includes a wider variety 

of extremely resistant microorganisms (Jiménez-Cisneros 

2011, Table 1). The complexity of the matrix in sludge 

(high organic matter and particle content) poses a real 

challenge to effi ciently inactivate pathogens. This occurs 

particularly in basic sanitation processes intended for low 

income regions, for which non-sophisticated but highly 

robust technology must be used. 

Conclusions 

Disinfection is one of the most important steps in the treatment 

of water, wastewater and sludge as it is included in 

any treatment scheme. Even though disinfection might be 

considered as a mastered practice, challenges remain to 

proper disinfect water, wastewater and sludge face to new 

pollutants and the production of disinfection by-products. 

The impressive scientifi c and technical work performed 

in the past 20 years in the fi eld of UV drinking water 

disinfection has led to a high enhancement of quality

esulting in acceptance and trust in this disinfection technique. 

Owing to this progress UV disinfection fi ts into 

modern approaches for safe drinking water based on 

risk assessment and water safety plans. The operating 

parameters UV irradiance (W/m²) and water fl ow (optional 

additional water transmittance-253,7 nm) serve as critical 

control points in the HAACCP concept of the water safety 

plan protecting public health. Biodosimetry is a powerful 

tool to determine germicidal fl uence of a UV fl ow through 

system. One may deduce that the quality assurance of UV 

disinfection reached by the international quality standards 

is meanwhile superior to other disinfection methods as 

treatment with chlorine or ozone. 

In contrast to wastewater, disinfection requirements for 

sludge in developed and developing countries are dramatically 

different. The disinfection of sludge is and will be an 

important challenge in developing countries as the microbial 

content is not only notably higher but also includes a wider 

variety of extremely resistant microorganisms demanding 

for more effi cient but low cost procedures to disinfect. 

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IAHR/IWA/IAHS HydroInformatics 

Joint Committee 

This was Hydroinformatics vision 2011, the synoptic report of the working group, 

edited by K.P. Holz, WG Chair, J.A. Cunge, R. Lehfeldt and D. Savic 

Hydroinformatics –where do we 

stand? 

Hydroinformatics has a tradition and remarkable merits in 

the development of computational simulation software for 

physical processes of the water-environment world. Nevertheless 

it is felt that for a long time now there has been a 

limitation in innovation areas as compared to developments 

and evolution of what is called “water sector”. Hydroinformatics, 

which within the IAHR stemmed from the activities 

of numerical simulation and hydrodynamic modelling, is 

still, within this environment, generally understood in such 

limited way. Steps are now needed to reshape Hydroinformatics 

to the needs of today and, even more important, of 

the future. 

Indeed, already now and more in the future there is the 

need for creative solutions to the challenges coming about 

with the move of society towards open information, to globalisation 

of business and markets and to networking in 

the Internet. The potential and options of modern Information 

and Communication Technologies (ICT) will be implemented 

everywhere within the water domain. Question is: 

will these future developments occur without being based 

on, infl uenced, helped by the experience of the IAHR/IWA 

hydroinformatics currently existing community or does 

this community steps aside and constraints its interest to 

modelling technologies in hydrodynamics? In other terms, 

there is an alternative: 

• Either this community concentrates on academic 

research in hydraulics and hydrology using to that end 

all ICT developments available and leaving water sector 

industry and stakeholders to “use the results of the 

research”. 

• Or this community will participate proactively, offer and 

use its past experience, in developing a new approach 

to water sector activities of research, implementation, 

applications, communication, information management, 

in common with all stakeholders (engineering, management, 

political, citizens), through innovative interwoven 

way of collaboration ? 

For the second possibility of the alternative (second 

bullet point above) the framework of the existing (since 

1992) IAHR/IWA Hydroinformatics Committee is obviously 

too limited. That is why fi rst of all enlargement of 

the Committee to the IAHS (International Association for 

Scientifi c Hydrology) was decided couple of years ago 

but up to now has not been implemented effectively. 

More signifi cantly the Committee, choosing to follow the 

second possibility of the alternative decided to create a 

Working Group with the purpose to try to defi ne a Vision 

for this domain. With obvious background thinking that 

the future must not be constrained by IAHR/IWA/IAHS 

limits but must extend bridges towards all domains of 

interest concerning water where hydroinformatics concepts 

exist or will appear. 

HydroInformatics Vision aspects as 

perceived by the Working Group 

What is a “vision”? Various aspects of HydroInformatics 

(HI) vision as conceived by the authors of the Report are: 

• General aspects: 

HI is a domain of science and technology 

covering the management of information on 

the fi eld of water and related subjects. This does not 

provide clear cut frontiers and allows for overlapping 

with other domains. It does not defi ne any specifi c 

(except for the word “water”) clarifi cation or limitations. 

Both drinking water pressurised pipe networks 

and socio-economic consequences down to legislation 

concerning water use may serve here as a typical 

examples of this domain. Vision: What this domain 

will become within next, say, 10 years? 

• Specifi c aspects: 

HI ambitions to coordinate sciences 

and technologies related to water and water sector thus 

assuming horizontal role in interweaving the fi ndings, 

initiatives, policies. Vision: The interweaving, coordinating 

and synergetic use of fi ndings and technology 

will become conscious and organised activity. In other 

words: post industrial ICT revolution and increasing 

importance for humanity of water will at any rate tend 

automatically to link all strings together. This unavoidable 

evolution can be guided, accelerated and aided 

to reduce as much error as possible fi rst through the 

wide recognition of that situation by concerned stakeholders 

and then thanks to their conscious attitudes 

and activities. This can be considered as the vision 

for ambitious community. The vision leading to ally 

and unite concepts in ways most useful for human 

purposes. It involves the problems of ethics, sustainability, 

future of the planet earth, etc., etc., although 

the Report has no ambition to develop them all. 

• Organisational aspects: 

Related to HI ambitions but, 

this time, to coordinate and interweave organisations, 

governments and individuals such as IAHR/IWA/IAHS 

Committee on Hydroinformatics, governmental agencies, 

etc. Those are many visions, not just one! Vision: 

Staying within our (current HI community) frontiers

of possibilities and competences the ambition could 

be limited to build bridges over the gaps, to act upon 

educational aspects, to encourage research in certain 

directions, to convince the stakeholders from and outside 

of engineering domains to work together using 

means of information management and of exchange 

that we can supply. 

Changes that condition 

HydroInformatics vision-background 

The background against which one must consider the 

place of HydroInformatics changed dramatically during last 

decade. Essential characteristic of the change in water/ 

environmental areas is the reciprocal interactive evolution 

of societal and technical domains. 

Water/environment issues, within these present days of climate 

change and growing global population have become 

a major challenge for human economies and their social 

organisations. They necessitate more and more complex 

approaches at a more and more trans-national level. The 

essential aim of such management is to avoid, if possible 

or at least minimise, the risks of crises in water supply and 

waste water treatment for populations, in water scarcity for 

irrigation, in management of consequences of fl oods, and 

so forth. The traditional vision of a “water domain” founded 

on a separation of problems and cycles (small/large) on 

one hand and “professions” (drinking water, sewage and 

evacuation, hydrology, fl uvial, maritime, groundwater...) on 

the other hand seems to fade away, leaving the room for 

unifi cation/integration of all of this into a coherent unity. 

Society over recent decades has become much more aware 

of the threatened sustainability of “the second economy” 

which we commonly call the “natural environment”. Most 

built infrastructures are considered as interferences in the 

environment and their impacts must be correspondingly 

minimised and, if possible, made controllable. This trend 

is supported in more recent times by the long-ongoing discussion 

on climate change. The water world, especially, 

has become much more sensitive to and aware of these 

issues. A new awareness of the notion of “environmental 

footprints” introduced itself in the society. 

Awareness and sensitivity in a society which is becoming 

more open, transparent and communicative, has been 

multiplied by modern developments of the ICT. The Internet 

is accessible nearly everywhere at any time providing 

Web-services for communication, information and sharing 

on documents, pictures, music and videos. Because of 

ease of access to and variety of information and views the 

citizens in a post-modern condition of society (commonly 

associated with what the European Union Lisbon agenda 

likes to call an ‘information society’) have become more 

curious and active, and even proactive about upcoming 

changes and the consequences of these for their futures, 

and even for their lives. Politically-oriented developments 

within societies that are, ostensibly at least, directed 

towards more educated and more engaged citizens, have 

led to more individuals and public interest groups who 

want to understand what is happening within their environments: 

what is being planned on the local or global political 

level and why this should be good and benefi cial to them. 

Groups want to be heard and to participate in decision 


making processes: they want to be involved in matters 

about which they care and communicate. It is essential, 

however, that they clearly understand if and which are the 

objective constraints related to physical laws or political/ 

economic reasons and that whatever is done or wished is 

the subject to these constraints. The technical means for 

communication and information necessary to these ends 

are at hand. ICTs have dramatically changed whole economies 

and societies, system components are becoming 

smaller and increasingly network-orientated and mobile 

and the fl exibility of software is opening new dimensions. 

“Information-sharing” and “Cooperation” between citizens 

and stakeholders, consultants, authorities and lawmakers 

have become a central and feasible issue of the day. 

Professional engineering and business are unthinkable today 

without the evolution of the Internet and mobile devices 

meanwhile representing the dominant infrastructure of ICT. 

Networking-embedded systems and networking services 

are offering new perspectives in nearly all fi elds from engineering 

to households; they are pushing developments in 

all areas, representing an enormous business market which 

will also refl ect mentally on societal developments. 

In view of these societal and technological changes, all 

of what is called “water sector” activities (including all 

activities and aspects of use, management, legislation and 

directives, protection and political decisions concerning 

water) is being completely transformed and modifi ed. 

These transformations are founded on three pillars: 

(i) Dealing with water problems on different scales of 

structures and the integration in face of foreseen 

scarcity, generalised pollution, climate change and 

the growth of mega-cities. 

(ii) Change in the composition of decision making bodies: 

instead of engineers only, a whole new entity 

composed of stakeholders including the general population, 

elected bodies, NGOs, the media etc. is now 

evolving. 

(iii) Penetration of all activities, structures, behaviour and 

refl exes of the whole water industry and indeed of all 

concerned groups and individuals by ICT, Internet 

and mobile communication networks. 

It is in this context that the defi nition of HydroInformatics as 

collection (including data surveys, etc.), creation (including 

modelling), interpretation (including integration of various 

domains inputs), communication (including projection of 

the results and impacts towards large public) and management 

(including aid in participation of decision makers) 

of information concerning water sector activities should 

be used. This is new and to underscore this evolution the 

Working Group proposes to use from now onwards the term 

HydroInformatics (with capital I) rather than traditional one 

of Hydroinformatics. Indeed, HydroInformatics, for becoming 

an accepted player in these fi elds, has to change mentality 

and views; it has to implement techniques and methods 

from ICT and information science to collaborate intensively 

with other disciplines, not only on the technical level. Only 

in this way can relevant aspects of socio- economics, law 

and regulations, culture and traditions as well as workfl ow, 

psychology, information policies and media be integrated 

into ‘system’ approaches. Such systems will change the 

working situation of engineers, their education objectives, 

21

22 


create job opportunities and infl uence societies; they will 

support decision making in collaboration with the public 

showing benefi t and risk to involved citizens and stakeholders 

and help generating consensus. 

HI takes and will take advantage of the general progresses 

of ICT (hard and soft), as all human activities do. Clearly, 

the increase of CPU power (massive parallel computing, 

cloud computing, etc.) extends the possibilities of our 

numerical models, and of 3-D displays; clearly Web 2.x 

opens the access to our information to millions of new 

users; and the new products in the fi elds of micro-sensors, 

alternative power supply, wireless telecoms, revolutionise 

the whole domain of real-time monitoring and, consequently 

real-time management. But the evolution in HI is 

fi nally driven, not by these techno-progresses, but by the 

growing awareness that, even if modelling is historically the 

centre of HI, it should be connected-interwoven with all 

the various aspects-businesses of the Water- Environment 

domain. 

Viewed like that HI is the template to business process 

approach of all projects as well as implementation of management 

systems within water sector. 1 

HydroInformatics and its main areas 

of interest and activities against 

the background 

Informatics and Information in the 

Water Sector 

“HydroInformatics” comprehends all information technologies, 

methods, models, processes and systems applied 

in the “water-sector” and water-issues related neighbouring 

fi elds. Information is understood in an abstract 

sense; it may be about physics, environment, economy, 

social issues, organisation, law, regulations and more. 

Models and processes concern physics, business, workfl 

ow, communication, management and more again. Thus 

HydroInformatics applies, generates, models, manages, 

transforms, condenses and archives information concerning 

the “water-sector”. 

Traditionally HydroInformatics has been focused on the 

numerical simulation of physical processes in so-called 

“models”. This limitation is too narrow. The term model 

has to be widened up to any kind of information to be modelled 

in the water sector. As information combines data, 

methods, syntax and semantic, any simulation model is 

just a piece of information in the same manner as an engineering 

report, a digital elevation model (DEM), a water 

level monitoring application, an operational plan of a treatment 

plant or a workfl ow map. 

Activities in the water sector are oriented towards building, 

managing and operating water-related infrastructure 

and utilities as well as towards observation/understanding/ 

management of hydro environment for providing water, 

for improving its quality, for managing its quantity and for 

protecting against damages in view of sustainability and 

climate change. The activities are embedded in the objectives 

of a sustainable socio-economic development of 

society and communication processes between citizens, 

stakeholders, companies and politicians. 

We are at a time when the infl uence of modelling is growing 

rapidly. Models of complex physical and human behaviour 

are coming into routine use. Ordinary, everyday devices 

contain inbuilt processors running embedded models. 

We barely notice the insidious spread of models into our 

lives. HydroInformatics community should be leading the 

way by embracing and promoting many and varied uses 

of models in water and environmental management and 

engineering. 

Besides techniques and methods directed towards the 

description and functioning of systems, models remain 

the core technological elements of HydroInformatics, but 

have to be understood, however, in a wider than traditional 

sense. Traditionally they described the physics of fl ow and 

transport and its interaction with other aspects such as the 

growth and decay of species, habitats and populations, 

and then in terms of quality and quantity. These models 

interact with further models about socio-economic and 

societal developments of regions, generating a nonlinearly 

interacting system of models of whatever is supposed to 

constitute “the real world”. 

Projects, infrastructure and the business of organisational 

units have to be managed and coordinated. Strategies for 

workfl ow and for running processes of technical, business, 

fi nancial and communication systems have to be 

designed for in-house and public and political environments. 

The transformation and interfacing of information 

from various fi elds has to be modelled by descriptions and 

methods which support their implementation in digital 

form. To create tools and methods allowing all water sector 

stakeholders to conceive and interweave (if not normalise) 

integrated and coherent Information Systems is no doubt 

the future. 

Models of physics and organisational processes might be 

seen just as generators of information providing raw data 

from diverse application fi elds. In “HydroInformatics” this 

information has to be cultivated according to the pragmatics 

for which it has been produced. It has to be processed 

and adapted to the needs and objectives of the water sector. 

Important aspects are of course the diverse nature of 

interacting simulation models of physics, environments, 

societies, economies and organisations. 

Models, however, are not the only aspects: information, be 

it raw from observation or from simulation, has to be transformed 

in such a way as to be communicated in a transparent 

manner to professionals, politicians and citizens for 

decision making and consensual understanding. Moreover, 

“models” are not necessarily in the form of software; 

they may be also be intellectual concepts which, if they 

concern the water sector and if they ask for informatics 

1 A business process or business method is a collection of related, structured activities or tasks that produce a specifi c service or product 

(serve a particular goal) for a particular customer or customers. Business Processes can be modeled through a large number of methods 

and techniques.

to be forwarded, must be put into action or disseminated 

within the HydroInformatics domain. 

HydroInformatics domain, activity or movement embraces 

the full range of what is commonly called business models 2 

from public open-source developments through to private 

commercial developments, without bias towards any particular 

business model. 

Some explicit examples of the subjects that HydroInformatics 

is related to and with which close interactivity, already 

existing, will develop tremendously: 

(i) Major role played by GIS as system structuring all 

information, as pivotal point of integrated Information 

System. Note that GIS as specifi c tool fades away, 

becomes a part of other bases like ORACLE Spatial. 

(ii) Real time problems: sensors, SCADA, Real Time 

databases, related telecom systems; 

(iii) Tools of operational management (work management 

systems), of the maintenance and of asset 

Management. 

Whenever water related problems, or, more widely, the environmental 

questions are concerned , there is continuity in 

the background of all of the activities that follow. Typically in 

most situations there is an initial “problem” stemming from 

engineering needs, from political or investment projects, 

etc. Then one tries to fi nd “solutions” that are nothing else 

but elements leading to or aiding the decisions. This logical 

chain from “generating fact” to the solution-decision goes 

across a number of “businesses” or “stakeholders” and 

must be repeatable at any time. So it is obviously highly 

desirable to maintain strong consistency in concepts, data, 

and information along this chain. Such is not necessarily 

the case but precisely this is a major point for HydroInformatics 

because it is its “natural role” to ensure such consistency, 

mainly by conservation of uniqueness of data and 

information. When one considers the chain beginning with 

projects conceived by, say, administration or politicians 

and continuing through design, impact studies, decision to 

implement, construction and operation there is a need for 

guidelines ensuring the consistency. HydroInformatics can 

supply means and ways to elaborate such guidelines for 

various types of activities related to water sector. 

Research and Science 

The sustainable development of the water sector comes 

down, in implementation and praxis, to engineering tasks 

and thus “HydroInformatics” must be seen as an engineering 

discipline. In this sense, “HydroInformatics” has 

its own research objectives which aim at the foundation 

and promotion of the water sector in all its aspects. 

In short, research in HI domain might be summarised, 

albeit very unconventionally, under the term: “information 


and its model building”. This may be understood in the 

sense of structuring information about physical and organisational 

processes. New techniques have to be developed, 

new methods designed, the range of validity and 

performance investigated and models be interfaced by a 

standardisation of procedures and data. Innovative concepts 

about geometrical representation and informationdefi 

ned objects using by modern ICT must be investigated, 

with virtual communication and collaboration processes 

considered with emphasis on non-engineering clients, 

such as partners, as well as processes for education and 

promoting understanding in decision making. Integrated 

processes refl ected in HI tools, which are suffi ciently 

interconnected, may open new request and necessities 

for further applied research, basically in the bottle necks 

of existing technologies (such as new features in graphical 

tools, much faster computational engines, wireless nets 

and mobility etc.). 

Education and Life Long Learning 

HydroInformatics aims at the education of staff to do these 

kinds of jobs; such persons might even be seen as “information 

managers and advisors”. Their profi le is not one that 

is supposed to “manage” people or organisations: they are 

supposed to manage information within the complex areas 

of the water sector and to that end they must be knowledgeable 

in specifi c domains of this area. They must be knowledgeable 

enough to understand the constraints, diffi culties, 

limitations and possibilities of these domains in order to be 

able to coordinate the information coming from each such 

domain and to organise the feedbacks and interactions that 

will be benefi cial to the further development of both. 

These persons must have a suffi cient knowledge about 

water and environmental processes to run and validate the 

corresponding models; they must understand the processes 

that are mapped in the related models; they must be 

able to condense and interface information; they must be 

able to organise workfl ow and information processes; they 

must be able to manage documentation and presentation; 

they must be able to make information transparent so as to 

advice decision makers and communicate with the public. 

Social skills in collaborating with people of different professional 

and cultural backgrounds are needed. To optimise 

this whole they must be able to make information and fi ndings 

fl ow in interactive ways from one domain to another 

so that the knowledge, the progress, the innovations and 

the applications in a domain can be improved thanks to 

information coming from other domains. 

This profi le demands knowledge about the physics of water 

in hydraulics, hydrology and the environment, about mathematics 

and computational methods, about information 

modelling and communication as well as about the supportive 

means of ICT. Complementary to these are methods of 

geometrical modelling, presentation, documentation and 

a spectrum of selected topics from computer and social 

science, economy and psychology, the latter supporting 

2 

A business model describes the rationale of how an organization creates, delivers, and captures value – economic, social, or other forms 

of value. The process of business model design is part of business strategy. 

In theory and practice the term business model is used for a broad range of informal and formal descriptions to represent core aspects of 

a business, including purpose, offerings, strategies, infrastructure, organizational structures, trading practices, and operational processes 

and policies. Hence, it gives a complete picture of an organization from high-level perspective. 

23

24 


the skills necessary for a multicultural interdisciplinary collaboration 

in an international, sometimes virtual, environment. 

Those concerned should have a minimum of culture 

in civil engineering because of its central role in project 

implementation but also in water/environmental legislation 

as well as in geography and cartography. The education 

should be “hands on” with models of all kind. The process 

of taking responsibilities should be inculcated through 

training by internships in companies. The outcome of such 

curricula should be an engineer who can support consensual 

views and actions of decision makers and users, on 

the one hand, and executive professionals and engineers, 

on the other hand, with respect to science, engineering 

and social environments. The engineer should be able to 

maintain this qualifi cation life-long by corresponding learning 

periods. 

This leads to an intensive demand for HydroInformatics 

educated engineers, managers and, above all, leaders in 

public services and in the private sector in a rapidly changing 

society. 

Universities, Research and Professions 

Universities are changing in modern times with the transition 

towards an “information society”, under the “Bologna 

Declaration” and as mass education institutions. They are 

reacting to their new role by introducing new profi les and 

grades of professionalism. In Europe the “Bachelor” is 

seen as a fi rst profession qualifi cation degree while the 

“Master” has become the second degree that may or may 

not be sought by the future professionals, whether praxis 

or research-oriented. The “Dr.-Thesis” is a grade awarded 

at the end of a system of corresponding courses and a 

research project that in many cases is trivial or formal; 

in most cases it has nothing common with requirements 

of new contribution to the fi eld as it used to be until the 

middle of second part of 20th century. This requires 

universities to react correspondingly in terms of numbers 

and qualifi cations and this requires a clear profi le and 

defi nition of “HydroInformatics education”. At present, 

the profi le is pretty vague and differs from place to place. 

Therefore, due to the international character of HydroInformatics 

and in order to guarantee as much as possible 

the sanity of the Profession some standards concerning 

the educational profi le are needed. The Universities in 

the short term (some 10–15 years) should “standardise” 

their ideas about what is an objective and professional 

“HydroInformatics” profi le. Without this the Profession 

cannot interact or provide feedback to the University and 

the University cannot satisfy the needs of the Profession. 

Today’s most common idea on both sides is that “HydroInformatics 

= modelling and/or GIS and/or programming, 

etc. etc.” and that is clearly not suffi cient. 

Standards cannot be imposed formally: they have to be 

developed by Academia in collaboration with the Profession 

and its Praxis. If there is a known curriculum framework 

and if the Water Sector professions recognise in 

practice the minimum content of this curriculum, such as 

is necessary to be called a “HydroInformatics diploma”, 

then the profi le of “HydroInformatician” will need to be 

clearly defi ned and founded. Note that, following Bologna 

agreement the fundamental change of concept concerning 

doctor’s degree opens the way to better specifi cation 

of HydroInformatics curricula in the sense that it gives 

3 years more for specialised studies that replace original 

research required in time for Dr. degree. 

Currently the link between the research and practice is 

weak and the time necessary to transfer the R&D results 

towards practice is shockingly long if one compares it with 

ICT domain. To improve the situation there is a need to open 

existing HydroInformatics community to (or even more: to 

create larger HI community inclusive of) engineering consultants 

that do the bulk of water-related engineering as 

well as to the water systems management companies and 

institutions (specifi cally urban water utilities). 

And the IAHR/IWA Committee 

It should be remembered that the present document is 

elaborated by a Working Group of the joint IAHR/IWA 

Committee and both IAHR and IWA have an obvious role 

in the future of HydroInformatics. This role should be 

experienced through a number of activities: 

• The research within the aquatic domain in areas such 

as modelling, measuring, surveying and computational 

hydraulics is traditional within the IAHR/IWA membership. 

However, the task to promote the links between 

this research and the requirements, quests and problems 

coming from Water Sector through HydroInformatics 

should be better understood and carried out within 

all concerned groups. 

• University Education: IAHR, by its very composition of 

a majority of university researchers and teachers should 

proactively participate in the “Universities and Profession” 

activities described above. 

• Within the Water Sector many HydroInformatics activities 

have been implemented and created (e.g. within 

IWA, but this is only an example). It should be the 

IAHR’s role to try to bridge the relational gaps between 

these groups and institutions by offering them what the 

IAHR in this domain has been developed during the last 

decades. 

The above points can be considered as the tasks for the 

HI Committee. 

HydroInformatics - Quo vadis? 

What to do? 

There are two aspects of the future that are concerned in 

our present initiative. One is objective: whatever we wish, 

whatever we do, what is going to happen within next, say, 

10–15 years; another one is subjective: what we wish, what 

we can do, what we shall try to do during this period. 

(i) What is going to happen? It seems clear today that 

the whole water sector is going to be completely 

penetrated by ICT and Internet-like technologies. All 

this may lead in a more or less distant future to the 

unifi cation and possibly the standardisation of management 

of information within areas of water industry. 

The things will converge towards the concept of 

“smart water networking” including of course projects 

and implementation of works in coastal areas and 

river basins, for food and agriculture, for industrial 

use, energy production and biogas, for drinking and

waste processing. Nevertheless it is very likely that the 

driving force towards this will be urban water management 

and utilities. This is so because the population 

needs today are greatest in this area, because most 

of human population is going to be regrouped in the 

megacities, because this area is today very far behind 

the sophistication of ICT tools used in other water 

domains (e.g. numerical modelling) and, hence, the 

gradient of implemented innovative applications will 

be the steepest. Quite obviously all other domains will 

join in the run and the driving forces will come from 

the ICT industry, not from the hydraulic research, 

because the former produces industrially applicable, 

often off-the-shelf systems and devices that may 

modify the whole systemic approach while the latter 

can only produced embeddable tools like 4th generation 

modelling software. Because of the importance 

of the water these developments will very quickly 

penetrate the domain of decision making, i.e. politics, 

fi nancing of investments, social sciences, information 

& communication with citizens etc. On the other side 

of the spectrum they will most likely completely modify 

current (traditional) way of working of consulting 

and also the relationship between the applications/ 

industry (including consulting and contractors) and 

university research on the fi eld of hydraulics, hydrology 

and water management: 

• It is very likely that today’s market of the modelling 

software will decline and possibly fade away. It 

may well be replaced by “Modelling Software and 

Expertise as a Service”. All recent developments of 

“Software as a Service”, “Infrastructure as a Service”, 

“Development as a Service” that so far have 

been limited to the area of computer and informatics 

applications will no doubt overfl ow into the water 

domain within next couple of years. Already most 

of applications we use on our laptops are stored 

somewhere in the cyberspace. And “cloud computing” 

will help it. 

• This will lead to a pressure from “modelling software 

& expertise” business on the water-oriented 

research to go beyond today’s limitations in mathematical 

theory computational hydraulics and 

computational fl uid dynamics. Same will happen 

to physics, e.g. sedimentation theories. This will 

also lead to a pressure on the university education 

and curricula. Indeed, such enormous, revolutionary 

changes will ask for different technical 

leadership within the structures of water sector 

industry, i.e. for different generation of engineers. 

Given minimal 5 years cycle of engineering education, 

given the delay necessary to the education 

institutions to adapt themselves (at least another 

5 or 10 years) there will be enormous push, coming 

from the needs of industry, towards LLL and 

postgraduate specialisation in specifi c courses 

and institutions. 

• Networking-embedded systems and networking 

services are offering new perspectives in 

nearly all fi elds of technological infrastructure 

from engineering to households; they are pushing 

developments in all areas, representing an enormous 

business market. This also holds for the fi eld 

3 Taken from aa paper in Forbes Magazine but seems correct! 


of HydroInformatics. Integrated intelligent electronic 

nets of all components and services must be designed 

and operated for generation, management, 

distribution and billing of fresh and waste water in 

cities, on the level of water-basins, for the management 

of fl oods and droughts beyond the regional 

level. But also the interlinking of water systems with 

other areas such as power generation, cooling and 

intermediate storage of energy under ever changing 

conditions has to be considered. Only through 

the use of such technologies the challenges put by 

global warming and climate change could possibly 

be faced in the future. 

As an example of what would happen whatever we do 

consider the one of currently predominant business models: 

the sale or granting of in-perpetuity (generally 20 or 

25 year) licenses to use software packages. We defi nitely 

see the demand for pay-by-use software and technology 

advances now supports this business model in a reasonable 

way. But we are already on the way towards Software 

as a Service becoming a regular business model for 

HydroInformatics. There are already few companies doing 

just this, the information confi rmed by the comments from 

1st and 2nd Circles of persons participating in elaboration 

of present Reports. It is clear that current “model” based 

on selling packages is changing and will not last in the 

future. What we do not know is what will replace it – there 

are a number of possibilities! 

(ii) What we wish or can do? We, i.e. what we used to 

call up to now and typically within IAHR/IWA territory, 

the HydroInformatics Community? Assuming that 

what will happen at any rate within the near future 

was correctly described above, there are two possibilities: 

either we stay where we are and look on this 

new world from the top of our ivory towers; or we try to 

accompany the movement, to accelerate it as much 

as possible, to make some parts of it more coherent, 

take the leadership of our immediate neighbourhood 

towards integrating these changes. Incidentally 

it means of course to stretch our networks beyond 

IAHR trying, however, to keep intellectual leadership 

in order not to lose the experience and tradition 

gained during last 30 years of existence of our “IAHR 

HydroInformatics Community”. 

In this context, assuming that we chose the second way 

and that we can consider ourselves as leaders (among 

others) in the area, what should we do? “One may identify 

three skills that are necessary for leading strategically for 

long-term growth: understanding the operational environment, 

making clear decisions and involving others in the 

strategic process.” 3 . 

• Actually the most of the preceding paragraphs are 

devoted to “understanding the operational environment”. 

The very attempt to describe (in a lengthy way) 

what we understand by “HydroInformatics”, as well as 

the present situation in industry and education, is precisely 

that. 

• “Making clear decisions”. In our case it is fi rst to state 

clearly the ambitions we have, and next the decisions of 

actions that we should take. 

25

26 


Ambitions, even though we limit their extension to our 

domain of possible infl uence (that is rather limited…) 

are considerable. Namely, we wish to promote and maintain 

the name of HydroInformatics. We wish to make it 

accepted as a domain, the essence of which is to coordinate 

the results and the contents of a number of various 

fi elds of knowledge (including some “soft science” 

fi elds); to facilitate interactive transfers of concepts and 

ways of thinking from one fi eld to another; to help in 

the elaboration of decisions (projects, actions, and policies) 

based on synergetic considerations of the results 

of various fi elds; to pave feedback paths from social 

requirements, through HydroInformatics ways, tools and 

means, towards various fi elds while transferring concepts 

from one fi eld to another in order to enrich them 

and to progress. Conceived as such HydroInformatics is 

enriching itself through the progress of other domains 

and directing them towards applications. HydroInformatics 

is itself a generator of innovations by the very fact of 

being a transversal approach that uses the progress of 

various disciplines. Our ambition is to push this concept 

through and participate in its development. 

There would seem to be a role for the Hydroinformatics 

Community not only to adapt to improved ICT but also to 

propose, test and communicate changing business and 

delivery models. This can be done through exchanges of 

opinions, criticism, etc. Such exchanges imply some kind 

of permanent correspondence “platform” or “forum”. 

New business models will be imposed by the market 

following ICT progress but the HI Community can help to 

discard what` is not so good. 

The actions we can take: 

– To develop a wide (as wide as possible, within and 

outside of IAHR/IWA/IAHS) network of people and 

institutions interested and willing to participate in 

discussions, exchanges of view, of information. 

– To infl uence the education (LLL, graduate, undergraduate), 

both the institutions and curricula in order 

to help the advent of new engineering leadership. 

– To accompany, as individuals and members of institutions, 

of projects, of associations the “objective” 

developments and events as described above, trying 

to make those that are within our area as coherent 

and bold as possible. 

– To use as a springboard to this the IAHR/IWA/IAHS 

HydroInformatics Committee, International Journal 

of HydroInformatics, HydroInformatics bi-annual 

conferences. 

• “Involving others in the strategic process”. This of 

course is the essence of leadership activity (as distinct 

from management). It actually is the way of implementing 

the actions enumerated above. Our Working 

Group activity is the fi rst step. The further steps would 

follow stemming from our Report.We should take more 

of a coordination role by more actively making links 

with other organisations involved in the development 

of HydroInformatics. For example, there is considerable 

overlap between the activities of the integrated 

environmental modelling community and HydroInformatics. 

Because of this situation the HI Working 

Group will initiate, before the formal end of its activities, 

launching contacts with a number of organizations. 

The full Report will be sent to them and they will 

be asked to participate in setting up together some 

kind of the mailing-exchange list of addresses to contact. 

But then again it will be for the “HI community”, 

with the IAHR/IWA/IAHS Committee as the basis, to 

organize and act.

Groundwater: perspectives, 

challenges and trends 

Introduction 

Most liquid freshwater available on Earth is stored in aquifers; 

groundwater therefore dominates, by volume. It is 

estimated that groundwater is a primary source of drinking 

water for as many as two billion people and drives a signifi - 

cant part of the world’s irrigated agriculture (Morris et al. 

2003; Kemper 2004). Groundwater is broadly defi ned as, 

‘The excess soil moisture that saturates subsurface soil or 

rock and migrates downward under the infl uence of gravity. 

In the literal sense, all water below the ground surface 

is groundwater; in hydrogeologic terms, however, the top of 

this saturated zone is called the water table, and the water 

below the water table is called groundwater. Under natural 

conditions, groundwater moves by gravity fl ow through 

rock and soil zones until it seeps into a streambed, lake, 

or ocean, or discharges as a spring’ (Encyclopedic Dictionary 

of Hydrogeology, Poehls and Smith 2009). Subsurface 

hydrology is mainly concerned with the quantity and fl ow 

of water and other fl uids and the transport of solutes and 

energy through porous media (RNAAS 2005). Subsurface 

hydrology includes the following: 

• groundwater hydrology; 

• contaminant hydrology; 

• unsaturated zone hydrology. 


Written by S. Adams, M. Dimkić, H. Garduño and M.C. Kavanaugh on behalf of the Specialist Group 

TERMINOLOGY 

Adaptive management. An iterative process of optimal decision making in the face of uncertainty, with an aim to reducing 

uncertainty over time via system monitoring. 

Aquifer. A geological formation which has structures or textures that hold water or permit appreciable water movement 

through them. 

Hydrogeology. The study of the interrelationship of geologic materials and processes with water. 

Unsaturated zone. That part of the geological stratum above the water table where interstices and voids contain a 

combination of air and water. 

Droughts and increased demands have triggered the 

search for alternative water supply options. This has led 

to an increase in the exploitation of groundwater supplies, 

especially in semi-arid and arid regions, often with little 

understanding and management of the consequences (e.g. 

saltwater intrusion, mining of groundwater and impacts on 

linked systems). In some places poor land-use planning 

threatens the quality of the groundwater or increases the 

cost of treating the usually good quality water. In many areas 

of the world, groundwater still receives very little protection 

within water laws and is often considered to be only linked 

to the land above the aquifer being exploited (i.e. considered 

as private water). Groundwater should be managed 

within an integrated framework that takes into account 

the impacts on and by linked systems and the effects of 

land-use planning. It should be noted that groundwater 

systems are more complex and thus inherently more diffi 

cult to manage than surface water. The perceptions of 

the public and policy-makers or their lack of awareness 

of groundwater, as well as the generally poor understanding 

of its behaviour and occurrence, represent important 

causes of emerging problems (Burke and Moench 2000; 

Quevauviller 2007). It is not unusual to fi nd potential and 

real polluting activities above the most productive parts of 

an aquifer or that aquifers are pumped at unsustainable 

rates. This paper will highlight some of the challenges and 

trends within the discipline of subsurface hydrology. 

Perspectives on subsurface hydrology 

Over the past number of decades hydrogeology has 

evolved from a science of how to fi nd and exploit groundwater 

into the integrated management of this fi nite and 

interconnected resource as well as emphasis on the quality 

of the water. This can be seen by the progressive laws 

and regulations, governing groundwater use and protection, 

being developed across the world. Advances in subsurface 

hydrology include, among others: 

• Estimation techniques for hydraulic properties 

• Groundwater-surface water interactions 

• Mapping and modelling of large-scale aquifer systems 

• The nature and variability of groundwater recharge 

• Vulnerability assessments 

27

28 


• Techniques for enhancing recharge, storage and 

recovery 

• Transboundary aquifer management 

• Groundwater- or aquifer-dependent ecosystems 

• Fractured and heterogeneous aquifer behaviour 

• Improved monitoring techniques (including remote 

sensing) 

• Improved modelling systems 

• Unsaturated zone linkages 

Challenges and Trends 

Environmental stress is driven by the growth in population 

and urbanisation and the resulting energy, transport and 

development trends at country and global levels (World 

Bank 2010). High-level challenges, that are not necessarily 

unique to groundwater, include: 

• Global change (e.g. climate change and variability) 

• (Ground)water pollution and depletion 

• Rapid urbanisation with increasing supply demands and 

higher pollutant loads 

• Coupling of the various reservoir fl uxes in time and 

space 

• Governance of water and related resources 

• Groundwater valuation and fi nancing 

• Data collection (monitoring) and data availability (management) 

• Uncertainty quantifi cation (e.g. model and parameter 

uncertainties) 

• Poor land-use planning 

• Scale and heterogeneity 

• Capacity development 

• Complete description of complex systems 

Challenges related to groundwater management are 

numerous and overlapping; we will only deal with some 

of the key challenges. Giordano (2009) and Morris et al. 

(2003) give a more detailed global assessment of the 

issues and solutions facing groundwater. Groundwater 

is often poorly understood because of its hidden nature 

and assessments often rely on indirect measurements 

and long-term investigations and investments to determine 

fully the behaviour of complex aquifer systems. 

The invisibility of the resource may be complicating the 

management thereof. However, groundwater cannot be 

considered a mysterious phenomenon or resource anymore; 

it can be described using established scientifi c laws 

(Narasimhan 2009). Standard groundwater management 

approaches depend on the presence of basic data and 

on institutional capacities (FAO 2003). Data, and the collection 

and management thereof, remain a major area of 

concern. Remotely sensed information is used routinely 

for characterisation and extrapolation but cannot be seen 

as a substitute for ground-based programmes or detailed 

fi eld w o r k. 

The integrated water resource management (IWRM) 

approach should strengthen frameworks for water governance 

to foster good decision making in response to changing 

needs and situations (Cap-Net 2010) and provide 

mechanisms for the adaptive and holistic management 

of the water cycle over time. However, different funding 

approaches are followed in managing the two resources 

due to the inherent diffi culty with quantifying the economic 

value of groundwater resources and the general lack of 

appreciation of groundwater as a resource. IWRM as a 

concept has its own set of challenges (e.g. Medema et al. 

2008) and perceptions and will not be discussed here. 

Changing patterns of precipitation and evapotranspiration 

will inevitably alter groundwater fl ow patterns through 

changes in recharge-discharge relationships (Narasimhan 

2009). Groundwater systems are affected by climate 

change in various ways, depending on whether an 

area becomes wetter or drier. Groundwater availability is 

less sensitive to annual and inter-annual rainfall fl uctuations 

(i.e. climate variability) than surface water (Giordano 

2009). However, the overall impact of climate change on 

groundwater and surface water resources is expected to 

be negative over the long term. The role that ground water 

can play in mitigating climate change threats is also signifi 

cant (Foster et al. 2010b). Adaptation strategies will 

rely on investment in better and more accessible information, 

stronger and cooperating institutions, and natural 

and man-made infrastructure to store, transport and treat 

water (Sadoff and Muller 2009). 

Future research trends mainly deal with reducing uncertainty 

and risk and are intimately linked with the challenges 

faced. The dearth of information on most aquifer 

systems often results in poor management plans. The 

trend is towards adaptive management strategies and 

this pragmatic approach is now recognised as an alternative 

solution for systems where we have an incomplete 

understanding of the behaviour of a system (Gleeson 

et al. 2011; Holman and Trawick 2010; Brodie et al. 2007; 

Seward et al. 2006). However, it is also evident from the 

literature that adaptive management can be understood 

from a variety of perspectives and is often perceived as 

yet another catch phrase (Allan and Curtis 2005). The 

adaptive or learning-by-doing approach is a fl exible management 

framework that allows for changing conditions 

of the (ground)water and institutional systems. To ensure 

the success of the approach existing institutional and 

cultural constraints will have to be mapped and changed 

to effectively transition into an adaptive management 

approach. The continuous monitoring of these systems 

remains crucial for the provision of background data and 

information to evaluate and validate adaptive management 

approaches. For planned high-risk activities the adaptive 

management or monitoring approach must be preceded 

by detailed studies and a good grasp of how the system 

behaves; adaptive management is about urgency and 

reducing uncertainty and risk over time. Clean-up of a 

contaminated system is extremely diffi cult and costly. In 

the absence of local information and protocols, international 

best practices should be adapted to local conditions 

(Adams 2009). 

The remainder of this paper gives an overview of the 4 

main issues that have been identifi ed to be the focus of 

the Groundwater Restoration and Management Specialist 

Group for the next few years. 

Urban groundwater management: the 

institutional challenge in developing nations 

Half of the world’s population reside in cities and, within 

two decades, nearly 60% of the world’s population will 

be urban dwellers. The following paragraphs provide a

summary of the main on-the-fi eld lessons learnt from work 

carried out in the groundwater/urban interface under the 

World Bank’s GW-Mate Programme (Strategic Overview 

Series No. 3) based on Foster et al. (2010c). Ground water 

is generally more signifi cant for urban water supply in 

developing cities and towns than is commonly appreciated 

and is also often the ‘invisible link’ between various facets 

of the urban infrastructure. Regrettably, organisations 

concerned with urban water supply and environmental 

management often have a poor understanding of groundwater 

– this needs to be corrected. Groundwater is a fundamental 

component of the urban water cycle and there is 

always need for it to be integrated when making decisions 

on urban infrastructure planning and investment. But this 

is not as simple as it might at fi rst appear, because it is 

widely acknowledged that there has been little recognition 

of the groundwater dimensions of urban water and land 

management. 

In most developing cities the installation of mains 

sewerage systems and wastewater treatment facilities 

lags considerably behind population growth – meanwhile 

shallow groundwater can become contaminated from 

inadequate in situ sanitation. It may be years before the 

full extent of pollution becomes apparent, because contamination 

of large aquifers is a gradual and hidden process, 

and full remediation of entrenched problems may 

be prohibitively expensive. Thus it is critically important 

to recognise the incipient signs of groundwater pollution 

at an early stage and put in place groundwater protection 

measures. 

Urban groundwater tends to affect everybody, but is often 

the responsibility of no ‘body’. There are clear examples 

of places where action is being taken with support of the 

World Bank to fi ll this institutional vacuum and to remedy 

lack of concern or defi cient coordination regarding urban 

groundwater: 

• Brazil – Agencia Nacional de Águas established a national 

programme in 2008 to strengthen groundwater management 

at state-government level, including pro active 

consideration of urban groundwater use policy 

• India – a recent in-depth study for the Ministry of Water 

Resources on pragmatic action to address groundwater 

overexploitation, recommended substantial strengthening 

of state groundwater management agencies, and 

one of their key roles would be the required institutional 

coordination for addressing urban groundwater 

(although in this case the question of powers on pollution 

control are not yet included) 

• Sub-Saharan Africa – an initiative of the SADC (Southern 

African Development Community), is the establishment 

of a ‘Groundwater Management Institute of Southern 

Africa’, geared to practical approaches for ground water 

management, including urban groundwater use and 

protection issues 

However, these ‘top-down’ initiatives should be complemented 

with ‘bottom-up’ provisions. Mechanisms for 

groundwater stakeholder participation are usually much 

less defi ned in urban than in rural areas (where groups 

tend to nucleate around a common interest in groundwater 

use for irrigated agriculture or groundwater conservation 

to support dependent aquatic ecosystems). 

Nevertheless, the representation and engagement of 


major stakeholder groups will be an essential component 

of any ‘action plan’ for urban groundwater resource 

management and protection. 

Groundwater contamination and restoration 

Throughout the world, aquifers capable of providing water 

of high quality for potable use are threatened by organic 

and inorganic contamination emanating from human activities. 

Worldwide, numerous examples can be cited of water 

supply aquifers rendered un-useable without treatment 

due to releases of contaminants from various agricultural, 

industrial, commercial and other sources. Contamination 

of aquifers presents major technical, regulatory and management 

challenges. Treatment of contaminated groundwater 

is also complex due to the type and concentrations 

of contaminants that may result from these releases. The 

extent of anthropogenic contamination of groundwater 

aquifers worldwide is not known. 

Current and future challenges for urban groundwater 

basin managers include regulatory options for oversight of 

drinking water projects treating severely impaired groundwater 

sources, use of groundwater models to evaluate 

management options for contaminated aquifers, fate and 

transport of organic and metal contaminants of signifi cant 

concern, and current options for source control, including 

both soil and groundwater remediation technologies to 

prevent continued or future contamination of water supply 

aquifers. Other potential future topics of interest include 

vulnerability assessments of groundwater resources, use 

of aquifers for recharge and recovery of treated water or 

wastewaters, assessment of the treatment capabilities of 

subsurface environments, and groundwater remediation 

and treatment options for chemicals known to be recalcitrant 

in aerobic aquifers such as perchlorate, 1,4-dioxane, 

1,2,3-trichloropropane, and other emerging and unregulated 

contaminants such as pharmaceuticals and personal 

care products reaching groundwater through natural or 

artifi cial groundwater recharge. 

Despite signifi cant advances in subsurface characterisation 

and remediation technologies over the past few 

decades, there are signifi cant technical barriers to restoration. 

These barriers have been thoroughly reviewed in the 

literature, and summarised in several reports issued by the 

National Research Council of the National Academies in 

the USA (see NRC 1994, 1999, 2005). Subsurface heterogeneities 

render certain portions of an aquifer inaccessible 

to fl uids used to fl ush out or destroy contaminants. Several 

recalcitrant chemical compounds have proven resistant 

to remediation efforts, including chlorinated solvents and 

other organic compounds present as organic liquids, 

and with a density greater than water. These dense nonaqueous 

phase liquids or ‘DNAPLs’ (e.g. trichloroethene) 

can penetrate signifi cant depths through low-permeability 

layers, are diffi cult to locate, and are diffi cult to remove 

from the subsurface. 

Management of large urban groundwater basins becomes 

particularly challenging in the context of past, continuing 

and future contamination of aquifers from residual contamination 

that remains persistent at detectable levels. 

Some of these issues have been summarised in a recent 

IWA publication on this topic (Kavanaugh and Krecic 

2008; Dimkić et al. 2008). 

29

30 


Importance of oxic conditions in 

groundwater, especially in alluvial aquifers 

Alluvial groundwater is extremely important, both for 

human society and for the natural environment. In an alluvial 

aquifer, its degree of oxicity is very important both for 

the formation of a baseline groundwater quality, and for 

processes of its transformation. In water supply, the bank 

fi ltration method is most widely applied and very important 

(Schmidt et al., 2003). The level of groundwater oxicity 

attained in this case depends on the oxygen saturation 

of the river water, the oxidation-reduction processes of 

organic and inorganic matter, as well as the level of oxygen 

renewal in the aquifer. Oxic conditions more frequently 

occur in aquifers in the upper part of the river basin, less 

so in the medium part, and the least in the lower part of 

the basin. Besides the degree of loading with organic matter, 

the mineralogical consumption of oxygen should also 

be taken into consideration. Minerals with ferrous iron content 

are particularly signifi cant. 

In oxic conditions, oxidation takes place through oxygen 

dissolved in water. In anoxic conditions, biochemical oxidation 

is based mainly on nitrates, compounds of ferric 

iron and tetravalent manganese, as well as sulphates. 

Oxic environments are generally more favourable for selfpurifi 

cation processes. However, some substances can 

also degrade in anoxic conditions. Knowledge of the effects 

of the degree of groundwater oxicity on the baseline quality 

of groundwater, as well as the process of purifi cation of 

river water to the baseline quality level, is fundamental for 

the design, use and protection of groundwater resources 

(Dimkić et al., 2011c). 

In this regard it is necessary to consider the fi ltration process 

that takes place starting from the water source (river, 

infi ltration basin) towards the groundwater abstraction 

structure (well, drainage gallery). While defi ning the protection 

zone and appropriate measures during the establishment 

of the groundwater source, it is necessary to consider 

the aquifer as a unique physico-biochemical reactor, 

complementary to the other elements of water treatment. 

Besides the basic properties of the aquifer, while solving 

the related problems, it is necessary to take account of 

the behaviour of typical substances, classifi ed according to 

their pronounced characteristics, such as toxicity, sorbicity, 

degradation in oxic and anoxic conditions, etc. Such substances 

are, for instance, pesticides, pharmaceuticals, or 

some substances that are very mobile in groundwater. The 

knowledge of the well colmatations is equally important for 

the development of water sources and their maintenance, 

and is usually linked to considerable investments (Dimkić 

et al. 2011a, b). Among these, biochemical colmatation is 

largely linked to the level of aquifer oxicity. 

In general, in the world more than 50% of water supply 

is from groundwater sources, and of these 50% originate 

from alluvial aquifers. In order to resolve issues related 

to the protection and use of these waters it is necessary 

to adequately take into account factors related to aquifer 

oxicity. Here, there is a need for better understanding of 

relations between: 

1. Genesis of aquifers, their mineralogical composition on 

the one hand, and oxygen consumption on the other 

hand. 

2. Hydrochemical, hydrological and hydrodynamic conditions 

in the aquifer - and oxygen consumption. 

3. Process of quality transformation of different (characteristic) 

substances and their adequate inclusion into 

problem solving. 

4. Linking the intensity and kinetics of the well-ageing 

process, through the change of hydraulic losses taking 

place on well fi lters, with oxic and other related conditions 

in the aquifer. 

Fluxes between reservoirs 

Groundwater is still managed and legislated separately 

from surface water resources – the trend worldwide is to 

manage it as a single resource. The two systems behave 

differently in time and space and must be studied separately 

at the fundamental level. However, a major challenge 

among water resource practitioners as well as among soil 

scientists is the use of different terminologies or different 

understanding of a common terminology instead 

of common understanding of the terminology and the 

different terms used. The Cap-Net (2010) report notes 

that: ‘Traditional institutional separation of surface water 

from groundwater has created fundamental communication 

barriers that now extend from technical expertise to 

policy developers, operational managers and water users. 

These barriers impede the understanding of the processes 

and consequences of groundwater-surface water 

interactions’. 

Integrated water resource management and the increasing 

impact of groundwater abstractions on linked surface 

water bodies call for an improved understanding and 

quantitative description of the interactions between the 

different components of the hydrological cycle (atmosphere, 

surface and subsurface).The main challenge is 

the issue of scale, especially temporal scales, as surface 

water responses are generally faster than those of groundwater. 

Various approaches and methods have been developed 

to study the interactions at different temporal and 

spatial scales – usually involving modelling approaches. 

Exchanges between reservoirs are often invisible and the 

fl uxes measured indirectly. Quantifi cation of the fl uxes is 

extremely diffi cult and fraught with uncertainty. Because 

of the differences in approaches for surface water and 

groundwater the incompatibility of data sets and conceptual 

understanding complicates groundwater-surface 

water assessments. The NRC (2004) gives a detailed 

account of the challenges and research focus to solve 

these problems. The main challenges identifi ed were 

(NRC 2004): 

1. Our ability to quantify spatial and temporal variability in 

recharge and discharge is inadequate. 

2. The roles of groundwater storage, and recharge and 

discharge fl uxes in the climate system are underappreciated 

and poorly understood. 

3. Groundwater measurements are needed across a range 

of temporal and spatial scales. 

Modellers are continuously developing tools to integrate 

the various reservoirs at different scales using various,

often manipulated, data sources obtained from direct and 

indirect measurements. The main challenges that affect 

hydraulic and hydrological modelling are improper formulation 

of conceptual models (NRC 2001) and the lack of 

uncertainty estimation (Pappenberger and Beven 2006) 

which is inherent in the modelling process. 

Conclusions 

Effi cient management of groundwater relies on the effectiveness 

of applicable legislation and institutional arrangements 

as well as good understanding of the behaviour of 

the aquifer or well-fi eld being managed (i.e. quality and 

quantity) (Dimkić and Milovanović 2008). Groundwater 

management has developed into an interdisciplinary science 

and is not just the purview of the hydrogeologist. The 

discipline-specifi c approach to solving specifi c research 

questions is important but on its own it cannot address 

current environmental problems. A coordinated approach 

that links various disciplines is important. It is thus good 

to see that water research is becoming more multidisciplinary 

in nature (see Kamalski 2010; Foster et al 2010a). 

However, there seem to be very few management tools 

that are able to coordinate such activities at the local scale. 

Research on a country and global level often takes place in 

parallel and is uncoordinated. Managing groundwater over 

multigenerational timescales will require management that 

is integrated, adaptive, inclusive and local (Gleeson et al. 

2011). The challenge to all stakeholders is how we translate 

our ever-growing scientifi c knowledge into improved 

management of all resources and bringing about change 

in human behaviour. 

References 

Adams, S. (2009) Basement aquifers of southern Africa: 

Overview and research needs. In: Titus et al. (eds.) 

The Basement Aquifers of Southern Africa. WRC Report No. 

TT428/09, Water Research Commission, Pretoria, South 

Africa. 

Allan, C. and Curtis, A. (2005) Nipped in the bud: Why regional 

scale adaptive management is not blooming. Environmental 

Management 36(3), 414–425. 

Brodie, R., Sundaram, B., Tottenham, R., Hostetler, S. and 

Ransley, T. (2007) An Adaptive Management Framework 

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basins: water quality threats and aquifer restoration. In: 

Dimkic M. et al. (eds.) Groundwater Management in Large 

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to practice: a critical assessment of integrated water resources 

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Institutional Governance 

and Regulation 


Water resources management in the conditions of global climate change: set-up, 

trends and challenges 

Written by Slava Dineva and Jennifer McKay on behalf of the Specialist Group 

“Warming of the climate system is unequivocal, as is 

now evident from observations of increases in global 

average air and ocean temperatures, widespread 

melting of snow and ice and rising global average 

sea level” 

Intergovernmental Panel on 

Climate Change (2007) 

Scientists have high confi dence that global temperatures 

will continue to rise for decades to come, largely owing to 

greenhouse gasses produced by human activities. According 

to the IPCC, the extent of climate change effects on 

individual regions will vary over time and with the ability of 

different societal and environmental systems to mitigate or 

adapt to change. However, there is not general agreement 

about climate change in all jurisdictions so there is confl 

ict between and within nations.Policy makers in several 

nations are looking at adaptive policy mechanisms and 

seeking new ways to manage this confl ict and the risk. 

In some places the increases in temperatures with produce 

benefi cial growing seasons and in others there could 

be an increased risk of fl ooding, yet in others dryness will 

increase. 

During the remainder of this century, different locations 

will experience greater or lesser increases in temperature, 

with the greatest impact toward the North Pole and the 

least increase toward the South Pole and in the tropics. In 

terms of global climate change, future trends are shown 

in Table 1. 

Table 1 Global climate change: future trends according to IPCC 

Carbon dioxide levels in our atmosphere are rising. Both 

images in Figure 1 show the spreading of carbon dioxide 

around the globe as it follows large-scale patterns of circulation 

in the atmosphere. The atmospheric carbon dioxide 

has increased since the Industrial Revolution. 

The current warming trend is of particular signifi cance 

because most of it is very likely human-induced and proceeding 

at a rate that is unprecedented in the past 1,300 

years. 

The heat-trapping nature of carbon dioxide and other 

gases was demonstrated in the mid-19th century. They 

have ability to affect the transfer of infrared energy through 

the atmosphere. Increased levels of greenhouse gases 

must cause the Earth to warm in response. 

Ice cores drawn from Greenland, Antarctica, and tropical 

mountain glaciers show that the Earth’s climate responds 

to changes in solar output, in the Earth’s orbit, and in 

greenhouse gas levels. They also show that in the past, 

large changes in climate have happened very quickly, in 

tens of years, not in millions or even thousands. 

Water resources management in the 

conditions of climate change 

Water and its scarcity or over abundance will impact 

people, ecosystems and economies. Therefore, water 

Phenomena Likelihood of trend* 

Contraction of snow cover areas, increased thaw in permafrost regions, decrease 

in sea ice extent 

Virtually certain 

Increased frequency of hot extremes, heat waves and heavy precipitation Very likely to occur 

Increase in tropical cyclone intensity Likely to occur 

Precipitation increases in high latitudes Very likely to occur 

Precipitation decreases in subtropical land regions Very likely to occur 

Decreased water resources in many semi-arid areas, 

including western USA and Mediterranean basin 

High confi dence 

*Defi nitions of likelihood ranges used to express the assessed probability of occurrence: virtually certain >99%; very likely >90%; 

likely >66%. 

Source: IPCC (2007). 

33

34 


Figure 1 (A) Carbon counter. Left: July 2003. Right: July 2007. Images from the Atmospheric Infrared Sounder (AIRS) instrument 

onboard NASA’s Aqua spacecraft. Credit: NASA/JPL. (B) Carbon dioxide increasing since the Industrial Revolution. 

Source: NOAA. 

resources management should be a focus for adaptation 

to climate change through adaptation strategies and 

frameworks for actions at the local, regional and international 

transboundary domains. McKay 2011. Sustainable 

development is needed and regimes to promote this and 

ensure international cooperation are needed. There are 

many ways to do this at all levels and examples exist and 

are available on the websites of IWA member governments 

and the private sector. 

Climate change adaptation in water management is 

related to fi nding the right mix of the three I’s (information, 

institutions and infrastructure) to achieve the desired 

balance between the three E’s (equity, environment and 

economics). Water management is weakest in the poorest 

countries. It is predicted they to face the greatest negative 

impacts of climate change in the future. Therefore, investment 

in national water resources, management capacity, 

institutions and infrastructure should be a priority. Mainstreamed 

funding will help ensure that long term capacity is 

built and retained in the institutions. The environment has 

a crucial role in building resilience to climate change and 

reducing the vulnerability of communities and economies. 

As water is at the centre of climate change impacts, this 

demands a focus on resilience to impacts on water. Wellfunctioning 

watersheds and intact fl oodplains and coasts 

provide water storage, fl ood control and coastal defence. 

Water resources management implies the integration and 

stable development of both natural and social systems. 

Sustainability is related to the balance between economic 

development, lifestyle and protecting the water environment 

from irreversible damage. Managers need correct 

quality and quantity data on water resource at spatial and 

temporal scales. Such records are maintained in most 

countries and there are some international sets as well. 

Furthermore, sociological information is necessary on 

non-hydrological drivers and impacts, such as ownership, 

the real or implicit cost of land and water. Water resource 

managers are on the pressure owing to the variable climatic 

regimes in many areas, ever-increasing demands for 

better quality water by expanding populations. Mathematical 

models are essential operational tools. 

Governance and management for sustainable water 

resources comprise issues such as the following: 

• governance processes and organisations; 

• institutional framework for water management; 

• water management tasks: planning, development, 

monitoring; 

• fi nance, pricing, and economic regulation; 

• water allocation and use; water supply and public 

health; wastewater and water quality; river basin management 

and regional authorities, irrigation and drainage; 

ins tre am fl o w management ; fl o o d dis as ter manage - 

ment, and dam ownership; 

• utility and water agency management and organisation; 

• public-private relationships; 

• environmental governance and social equity;

• governance of water services in developing countries; 

• trans-boundary water problems; 

• water law and regulation; 

• administrative law and processes for governance; 

• stewardship and social responsibility. 

Increasing global pressure on water resources requires 

actions by governments to achieve sustainable water use 

(Grigg 2010). That involves management tasks such as 

project development and utility operation. The degree of 

interdependence among the many participants in water 

management is so great that additional regulatory and 

coordination mechanisms are needed to control water 

development and uses. 

Integrating Water Resources Management (Gooch et al. 

2010) implies the following: 

• developing guidelines for interdisciplinary methods; 

• assessing of transferability of case study results; 

• enhancing the dialogue between decision-makers, 

stakeholders and scientists; 

• disseminating data and information to stakeholders to 

promote planning and integrated decision-making. 

Water security refer to early adaptation strategy that will 

deliver immediate benefi ts to vulnerable and underserved 

populations, and strengthening systems and capacity 

for climate risk management. It will need investment 

in stronger and more adaptable Institutions, and natural 

and man-made infrastructure to store, transport and treat 

water. Information, consultation and adaptive management 

will be essential. 

The best adaption investments for any country in transboundary 

basins might be outside its borders - in basinwide 

monitoring systems, investments in joint infrastructure 

and operating systems in a neighbouring country. Strategies 

should promote cooperative transboundary river basin 

solutions to generate public goods, keeping the best interest 

of all riparians by means of cost-effective tools. 

Overall management of water incorporates all available 

water resources to meet the country’s water demands. 

Water management solutions should encompass problem 

identifi cation and data collection, hydrological, hydrogeological 

and engineering investigations, economic 

feasibility studies and Implementation. 

Measurement and monitoring imply maximising effi ciency 

through water loss prevention. Basic ineffi ciencies such 

as leaking pipes result in enormous wastefulness in water 

infrastructures. In regions short of water, the local water 

technology solutions should lead to a wide range of products, 

systems and applications to monitor and measure 

water and identify leakages. Preventing of water loss is 

dependent on the quality and reliability of the system’s 

infrastructure. 

Developing of resilience of communities to climate change 

impacts on water resources requires investments in decision 

making processes that consider current and potential 

future users. In terms of climate change adaptation, the 

water and climate change community realise the importance 

of empowerment for adaptation and the need to 

make institutions fi t for uncertainty. 

Future challenges 


Creation of new water professionals 

This is the key issue to be worked on by the SG. 

Climate adaptation challenges and the 

coordination of water quality objectives and 

carbon reduction 

The basic climate adaptation challenges that arise are 

water quality (Bogaart 2009) infrastructure inadequacy, 

water scarcity, fl oods, increasing competition for water, 

pollution risk, health risk, and reducing the emissions of 

greenhouse gases. Local governments have very different 

powers and responsibilities but the case studies underscore 

important commonalities. 

Adapting water management to climate 

change and the energy water nexus 

For many decades the governing paradigm for urban water 

management has been reliability. Water supply, sanitation, 

and storm water control in cities should be engineered for 

a high level of reliability over the historic range of climate 

variables. Climate change has already shifted that paradigm 

(Reiter 2009; Glassmann et al. 2011). Now we must 

fi nd a way to resilience – developing adaptive strategies 

that reduce vulnerability to uncertain but changing climate 

scenarios. System adaptation is a job for water engineers, 

climate experts, governments. National governments bear 

the primary responsibility for funding and regulation to 

ensure water security. 

Setting the adaptation agenda 

Mayors and local elected offi cials have to rally and inform 

citizens, convene businesses and civil society, and promote 

cross-jurisdictional collaboration. Adaptation and 

resilience will require new values, changed consumer and 

business choices, and a mix of regulations and incentives. 

Local governments have to build the political will to support 

this work. 

Mainstreaming adaptation and resilience 

strategies in multiple city agencies 

Effective urban adaptation to climate change requires the 

participation of the whole range of municipal agencies, 

not just the water department. Health, solid waste, roads, 

parks, building regulators, fi re and emergency services, 

and more – all should be active in implementing changes 

for water security and water safety. Local offi cials have to 

ensure that adaptation priorities are mainstreamed in all 

city programs. 

Localising risk and vulnerability 

assessments 

Water-related climate risks are highly localised in cities 

since half the world’s population living in urban areas. In 

35

36 


order to ensure realistic risk and vulnerability assessments, 

downscaled climate information from climate experts must 

be matched with locally-generated data from city agencies 

– demographics, mapping of infrastructure and public 

services, topography, land uses, neighbourhood profi 

les, socio-economic statistics, and cultural norms. Local 

offi cials have to provide and analyze this information. 

Increasing in demand for water in arid and 

semi-arid regions of the world 

Serious water crisis is becoming in Western Asia, the Middle 

East and, in some cases, North Africa. Water resources 

have now become the dividing line between life and death. 

In many of that countries, the water crisis is caused by 

both water shortage or even water scarcity and wrong 

water management. Considering these regional conditions, 

future will probably be more dependent on desalination 

plants, long distance water transfer, and also recycling 

and reusing of unconventional water resources, especially 

in agriculture. 

References 

Bogaart, M. (2009). The coordination of water quality objectives 

and carbon reduction: the possibilities for less stringent 

obligations under the WFD and the IPPC Directive. Journal 

of Water Law 186. 

Gooch, G., Rieu-Clarke, A. and Stalnacke, P. (eds) (2010). 

Integrating Water Resources Management. London: IWA 

Publishing. 

Glassmann, D. et al. (2011) The Water Energy Nexus: Adding Water 

to the Energy Agenda (New York and Zurich: World Policy 

Institute & EBG Capital) and World Economic Forum, Energy 

Vision Update 2009 - Thirsty Energy: Water and Energy in the 

21st Century (Geneva: WEF 2009). For recent references, 

as well as US Department Of Energy, Energy Demands on 

Water Resources: Report to Congress on the Interdependency 

of Energy And Water, December 2006, http://www. 

Sandia.Gov/Energy-Water/, accessed 11 August 2011 for 

the seminal reference on this topic. 

Grigg, N. (2010). Governance and Management for Sustainable 

Water Systems. London: IWA Publishing. 

IPCC (2007). Summary for Policymakers. IPCC Synthesis 

Report. 

Reiter, P. (2009). Water, Climate and Energy. IWA Member 

Newsletter, no. 38. 

McKay J 2011 “Evidentiary Issues with the Implementation of 

the Sustainability Duty of Care in the Basin Plan”, chapter 

published in the book Basin Futures: Water reform in the 

Murray-Darling Basin, by Daniel Connell and R.Quentin 

Grafton. ANu E Press ISBN 9781921862250. 

NASA. Global Climate Change. 

NOAA. Paleoclimatology.

Outfall Systems 

Written by T. Bleninger and P.J.W. Roberts on behalf of the Specialist Group 

Introduction 

Worldwide, the use of marine outfall systems is increasing 

rapidly. Submerged multiport diffusers are gaining 

increased acceptance as effective means for the disposal 

of treated municipal or industrial wastewater, storm water 

and combined sewer overfl ows, cooling water, and brine 

concentrate from desalination plants into coastal waters. 

Although this global trend has triggered advances in science 

and technology for the design and construction of 

such installations there are still considerable challenges for 

Water Science, Research and Management. 

The recent International Symposium on Outfall Systems, 

held from 15 to 19 May 2011, in Mar del Plata, Argentina 

(ISOS 2011) provided in its technical sessions information 

on the state of the art of outfall system science and technology, 

and discussed and defi ned the challenges during openforum 

meetings. Both will be summarised in this article. 

Characteristics of outfall systems 

A typical engineering system for marine wastewater disposal 

is shown schematically in Figure 1. It usually consists 

of a treatment plant and a discharge structure - the outfall. 

The outfall is a pipeline or tunnel, or combination of the 

two, which terminates in a diffuser that effi ciently mixes 

the effl uent in the receiving water. It thus follows two main 

principles: (1) locate the disposal area into environmentally 

less sensitive, and anthropogenically less used, offshore 

regions, which in addition have higher mixing and assimi- 


lative characteristics, and (2) enhance the initial mixing by 

multiport diffuser systems, providing effi cient and fast initial 

mixing in a limited zone that reduces pollutant levels to 

ambient standard requirements, and facilitates the natural 

assimilative processes. 

The size and discharge rates of these schemes vary 

widely, but the outfalls typically range from 1 to 4 km long 

and discharge into waters 20–70 m deep. Some may lie 

outside these ranges, for example lengths of 500 m or 

less and discharge depths of 150 m or more when the 

seabed slope is very steep, or lengths of more than 5 km 

when the slope is very gradual. The disposal system can 

be thought of as the treatment plant, outfall, diffuser, and 

also the region round the diffuser (known as the near fi eld) 

where rapid mixing and dilution occurs. 

Marine wastewater discharges through outfalls have unique 

characteristics that are shown in Figure 1. The waste water 

is usually ejected horizontally as round turbulent jets from 

a multiport diffuser. The ports may be spaced uniformly 

along both sides of the diffuser or clustered in risers 

attached to the outfall pipe. 

Buoyancy and oceanic density stratifi cation play fundamental 

roles in determining the fate and transport of marine 

discharges. Because the density of most effl uents (i.e. 

domestic sewage) is close to that of fresh water, it is very 

buoyant in seawater. The jets therefore begin rising to the 

surface and may merge with their neighbours as they rise. 

The turbulence and entrainment induced by the jets causes 

rapid mixing and dilution. The region in which this occurs is 

called the ‘near fi eld.’ If the water is deep enough, oceanic 

Figure 1. A marine outfall system: Treatment plant, outfall pipe, diffuser, and near fi eld (Roberts et al. 2010) 

37

38 


density stratifi cation may trap the rising plumes below the 

water surface; they stop rising and begin to spread laterally. 

The wastefi eld then drifts with the ocean current and is diffused 

by oceanic turbulence in a region called the ‘far fi eld.’ 

The rate of mixing, or increase of dilution, is much slower in 

the far fi eld than in the near fi eld. As the wastefi eld drifts, 

particles may deposit on the ocean fl oor and fl oatables 

may reach the ocean surface to be transported by wind 

and currents. Finally, large-scale fl ushing and chemical 

and biological decay processes removes contaminants and 

prevents long-term accumulation of pollutants. 

The mixing performance is usually expressed by a dilution 

value, which is a measure of contaminant concentration 

reduction. It is generally defi ned as the reciprocal of 

the volume fraction of effl uent in a sample (i.e. total sample 

volume ÷ volume of effl uent in the sample). Dilutions 

achieved within the near fi eld are typically of the order of 

hundreds to even thousands to one. Multiport diffuser outfalls 

are effi cient mixing devices and if they are located 

in regions with high transport and assimilative capacities 

they can have minimal environmental impacts. 

The fate and transport of discharged effl uents is infl uenced 

by processes that operate over a wide range of 

length and time scales. The orders of magnitude of these 

processes are tens of metres and minutes for the nearfi 

eld, and kilometres and hours to days for the far-fi eld. 

The ‘near-fi eld’ is governed by the initial jet discharge 

momentum and buoyancy fl uxes and outfall geometry 

which infl uence the effl uent trajectory and mixing. Outfall 

designers can usually affect the initial mixing characteristics 

through appropriate manipulation of design variables, 

thus infl uencing effects within the near-fi eld region. In the 

‘far-fi eld’, ambient conditions control plume trajectory and 

dilution through buoyant spreading motions and density 

currents, passive diffusion, and advection by the usually 

time-varying velocity fi eld. 

Treatment and disposal: Public 

involvement and Regulations 

Wastewater systems, namely sewage collection and 

wastewater treatment, have been growing rapidly in countries 

with advancing economies. Reports from the United 

Nations Environmental Program (UNEP 2002, 2004) 

and the World Bank (2007) indicate continuous growth 

especially in South America and Asia. The fi rst keynote 

given at the International Symposium on Outfall Systems 

Figure 2. Mar del Plata shoreline discharge 

(ISOS 2011) by Henry Salas (Salas 2011), formerly of the 

Pan American Health Organization (PAHO), however, 

indicated that many wastewater projects in Latin America 

did not yet conclude the outfall system. More than 

10 large-scale projects (each more than 1 million population 

served) were mentioned where almost completely raw 

sewage has been continuously discharged at the shoreline 

for more than 10 years. One example was observed by 

the participants of ISOS 2011, as shown in Figure 2. Mar 

del Plata (approximately 1 million inhabitants served) is 

a major tourist resort of Argentina, currently discharges 

their effl uent (2.8 m³/s) 9 km north the city, directly on 

the shoreline. 

Studies presented during ISOS 2011 showed considerable 

degradation of the shoreline ecosystem (Sanchez 

et al. 2011, Haeften et al. 2011), including public health 

risks due to high bacteria levels along the beaches, which 

are currently controlled by effl uent chlorination (Comino 

et al. 2011). Studies on outfall systems for Mar del Plata 

(Gyssels et al. 2011, Scagliola et al. 2011) indicated that 

an optimal solution would be construction of a preliminary 

treatment plant followed by an outfall 3.2 km long made 

of high- density polyethylene (HDPE) with 2 m diameter 

terminating in a diffuser 526 m long (Cardini 2011) 

discharging in about 14 m water depth. The construction 

of the outfall is currently in the fi nal phase, where pipe 

sections are welded and stored in the harbor before laying 

them in a dredged trench (see Figure 3). 

The delays of wastewater and outfall projects seem to be 

mainly related to political and administrative problems, 

as well as poor understanding of those systems. There is 

often a misconception that treatment results in a ‘pure’ 

and ‘clean’ effl uent which can be discharged directly on 

the beaches. This leads often to underutilisation of outfall 

technologies. On the other hand, this can lead to overly 

expensive wastewater systems, as has been shown in 

a second keynote on the ISOS (2011) given by Burton 

H. Jones, Department of Biological Sciences, University 

of Southern California, USA, on ‘Huntington Beach: 

an in-depth study of sources of coastal contamination 

pathways and newer approaches to effl uent plume 

dispersion’. He described intensive fi eld studies 

showing that the political decision to upgrade the treatment 

plant for the existing outfall did not solve the water 

quality problems because the existing problems are not 

related to the outfall (Jones 2011). Around 1 billion US 

dollars was spent that could have been invested much 

more productively.


Figure 3. Mar del Plata outfall pipes. Top left: Transport in lengths of 12m. Top right: welding in harbor. Bottom: Storing pipe 

sections 500 m long in the harbour for transport to the fi nal outfall location. 

Further technical papers (Bleninger et al. 2011, Baptistelli 

& Marcelino 2011, Menendez et al. 2011) also illustrated 

defi cient projects, but also presented solutions for 

improved water quality regulations that will enhance the 

effi ciency of controlling and managing such projects from 

the regulatory side. 

The open-forum sessions concluded that for coastal 

wastewater systems there are no ‘one size fi ts all’ solutions. 

Instead coastal effl uent management strategies should be 

a blend of technologies to meet the environmental objectives 

of the particular coastal region and water body uses, 

and they should be fi tted to the particular characteristics 

of the receiving waters. Thus, the focus should be on the 

receiving waters, and not on treatment technology which 

is mainly only needed to avoid discharges of acutely toxic 

substances, fl oatables and settlable solids. It has been 

shown in several cases that well planned outfall systems 

are cost effi cient solutions for coastal cities that have minimal 

environmental impacts. 

These conclusions allow formulation of the challenges facing 

Water Science, Research and Management in coastal 

regions related to effl uent discharges. Whereas coastal 

water quality criteria (ambient standards) are nowadays 

sometimes already set to regional characteristics and 

uses, it is more diffi cult to set standards for public health 

protection (Kay et al. 2004). There are still numerous 

outfall system projects where faecal indicator bacteria 

concentrations are used as the only design criteria. And 

often the commonly used WHO standard (World Health 

Organization 2003) is used without regional validation. 

Furthermore, beach and outfall monitoring worldwide 

is based on counting bacterial growth of samples taken 

in the target areas (with different statistical implications 

related to sample frequencies and analysis). Results, and 

the related consequences for public health protection are 

thus delayed, and cannot be clearly related to pollution 

sources nor characterised by their risk for public health. 

Challenges are thus related to the improvement of genetic 

(DNA) analyses of water samples to enable the detection 

of viruses and pathogens directly and faster, allowing for 

more effi cient monitoring and risk management. 

Another challenge is to improve public involvement and 

the interactions between planners, designers, politicians, 

administrators, and the public. Conventional planning, 

bidding, and contracting schemes are quite defi cient in 

that regard, and can result signifi cant (fi nancial) damages 

to some projects. Public involvement from the beginning 

needs to be improved to avoid the mentioned misconceptions 

and to improve the understanding of outfall systems. 

39

40 


Advances in measuring environmental 

systems 

Coastal water quality management using outfall systems 

requires detailed knowledge of the receiving water characteristics. 

Various authors of ISOS 2011 unfortunately 

reported that in Latin America there are several largescale 

projects where receiving water data is missing, 

and not planned for in the project budgets. This puts 

these projects in a critical position as designs cannot 

be properly made nor project benefi ts properly measured 

after commissioning. It is like building a hydropower 

plant without good knowledge of the hydrology. 

They may not result in environment or public health risk, 

because of often conservative design estimates. But they 

may cause oversized and non-optimised systems, which 

leads to much higher costs than detailed fi eld measurements 

complemented with numerical studies would have 

allowed. Thus, missing data can be barriers to outfall 

system projects. 

The missing data and the often missing complementary 

use of physical and numerical modeling methods is 

in direct contrast to recent advances in obtaining data 

for environmental fl uid systems. The second keynote on 

the ISOS (2011) given by Burton H. Jones (Jones 2011) 

and the third keynote presented by Peter Scanes, Offi ce 

of Environment and Heritage, Australia (Scanes 2011) 

showed examples from the US and Australia on the development 

and application of new measurement instruments, 

combined with conventional fi eld campaigns and comprehensive 

mathematical modeling. Particular technical 

advances are related to applications of surface current 

radar, integrated observation schemes, submarine gliders 

and autonomous underwater vehicles (AUV’s, Rogowski 

et al. 2011) for mapping submerged plumes and related 

phenomena. The improvement and applications of tracer 

studies using turbidity or salinity as alternatives (Pecly and 

Roldão 2011a) to conventional fl uorescent tracers (Correa 

& Yassuda 2011; Pecly and Roldão 2011b, c) are providing 

valuable data on ambient dispersion characteristics 

and plume movement. The latter can be studied by using 

GPS-equipped drifters set at different water depths, which 

can be very helpful to validate mathematical hydrodynamic 

models of coastal circulation and pollutant transport 

(Roberts & Villegas 2011; Botelho et al. 2011; Miller 

2011; Morelisson et al. 2011), particularly integrating 

fi xed site current observations (Villegas & Roberts 2011). 

In addition, technologies for laboratory experiments have 

experienced signifi cant advances related to non-intrusive 

optical measurement techniques, such as Particle-Image 

Velocimetry (PIV), Particle-Tracking Velocimetry (PTV) 

and Laser Induced Fluorescence (LIF) in 3D. These provide 

necessary validation data for mathematical models, 

and can also be used to study complex fl ow phenomena 

related to near fi eld mixing. 

Challenges remain in applying the new laboratory 

techniques at the fi eld level and to improve temporal 

and spatial resolutions in the highly variable natural 

environment. More fi eld studies are required, especially 

related to improving the understanding of effl uents other 

than domestic sewage, for example, produced water, 

desalination brine, LNG discharges (cold water), and intermittent 

stormwater discharges. 

Conclusions 

Outfall systems are often perceived as polluters instead 

of ‘clean’ treatment systems, using the ocean as the fi nal 

destination. However, considering the types of substances 

discharged and the considerable assimilative capacities of 

coastal waters, an outfall will always be part of a blend of 

technologies for coastal water quality management. The 

public’s common misconceptions of disposal systems 

and their associated public health risks, also related to 

diffi culties in measuring them, are barriers for more effi - 

cient coastal water quality control. Challenges are related 

to improved understanding and communication of public 

health and environmental risks and continuous monitoring 

of associated parameters using advanced techniques in 

the fi eld and the laboratory. 

Challenges related to associated fi elds are related to construction 

issues in coastal waters, where larger continuously 

extruded HDPE pipes up to 2.5 m diameter, larger 

spiral-wound pipes, and continuing development of tunneling 

and directional drilling techniques are now becoming 

available. Better understanding of the receiving water 

dynamics is also improving installation of outfalls (e.g. forecast 

systems for installation periods, Clauzet et al. 2011), 

submarine robot installations, and measurements during 

installation (Cots et al 2011). 

The challenge for the IAHR/IWA Joint Committee on 

Marine Outfall Systems (www.outfalls.net.ms) are to 

advance the science and technology of all aspects of discharges 

from outfalls and their design, and to facilitate 

communication between the diverse groups of practitioners, 

regulators, and fi nancing agencies in the fi eld. This 

is especially important as the design and siting of submarine 

outfalls is a complex task relying on many disciplines 

including oceanography, civil and environmental 

engineering, marine biology, construction, economics, 

and public relations. 

Acknowledgements 

The authors gratefully acknowledge the organisers and 

sponsors of the recent International Symposium on Outfall 

Systems, which allowed us to summarise its state of the art 

information. In particular, we thank Ana Paula Comino and 

Marcelo Scagliola for their continuous support, and Ente 

Nacional de Obras Hídricas de Saneamiento, ENOHSA 

(National Entity of Water and Sanitation Works, Argentina, 

Eng. Edgardo Bortolozzi), Obras Sanitarias Mar del Plata 

Sociedad de Estado, OSSE (Mar del Plata Public Works, Eng. 

Mario dell`Olio), Municipalidad de General Pueyrredón, MGP 

(Municipality of General Pueyrredón Party, Public Accountant 

Gustavo Pulti), AIDIS, the Inter-American Association of 

Sanitary and Environmental Engineering, the World Bank in 

cooperation with the Spanish Government, and the Inter- 

American Development Bank for their sponsorship. 

References 

Baptistelli, S.C., Marcelino, E.B., The regulatory issue of outfall 

discharge in Brazil, Proc. Intl. Symposium on Outfall 

Systems, 15–19 May 2011, Mar del Plata, Argentina (www. 

outfalls.info.ms).

Bleninger. T., Jirka, G.H., Roberts, P.J.W., Mixing Zone Regulations 

for Marine Outfall Systems, Proc. Intl. Symposium on 

Outfall Systems, 15–19 May 2011, Mar del Plata, Argentina 

(www.outfalls.info.ms). 

Botelho D. A., Barry M. E. Collecutt G. C., Brook J. and Wiltshire 

D., Linking near and far fi eld hydrodynamic models for 

simulation of desalination plant brine discharges. Proc. Intl. 

Symposium on Outfall Systems, 15–19 May 2011, Mar del 

Plata, Argentina (www.outfalls.info.ms). 

Cardini, J.C. The challenge of installing an outfall in the surf 

zone. Mar del Plata case. Proc. Intl. Symposium on Outfall 


outfalls.info.ms). 

Clauzet G., Rodrigues A. P. F. & Yassuda E. Metocean operational 

modeling to support outfall construction along the coastal 

water of Brazil. Proc. Intl. Symposium on Outfall Systems, 

15–19 May 2011, Mar del Plata, Argentina (www.outfalls. 

info.ms). 

Comino, A.P., Scagliola, M.O., Frick, W., Ge Z., The use of Virtual 

Beach empirical model for Mar del Plata beaches as a 

management tool. Proc. Intl. Symposium on Outfall Systems, 


info.ms). 

Corrêa M.A., Yassuda E., Tracer dispersion study: diffusion 

coeffi cient and modeling results. Proc. Intl. Symposium on 



Cots R., Garcia L., Devesa D., Estudios previos del medio marino 

necesarios para la redacción de proyectos de conducciones 

submarinas. Proc. Intl. Symposium on Outfall Systems, 


info.ms). 

Gyssels P., Corral M., Rodriguez A., Patalano A., Fernandez R. 

Estudio de la dilucion en el campo cercano de vertidos 

cloacales para el diseño de un emisario submarino en Mar 

Del Plata. Proc. Intl. Symposium on Outfall Systems, 15–19 

May 2011, Mar del Plata, Argentina (www.outfalls.info.ms). 

Haeften van G., Scagliola M., Comino A. P., Gonzalez R. Marine 

sediment quality in Mar del Plata city sewage discharge 

area – period 1999-2007. Proc. Intl. Symposium on Outfall 



ISOS. Proc. Intl. Symposium on Outfall Systems, 15–19 May 

2011, Mar del Plata, Argentina (www.outfalls.info.ms). 

Jones B. H. Huntington Beach: an in-depth study of sources 

of coastal contamination pathways and newer approaches 

to effl uent plume to dispersion. Proc. Intl. Symposium on 



Kay, D., Bartram, J., Pruess, A., Ashbolt, N., Wyer, M. D., 

Fleisher, J. M., Fewtrell, L., Rogers, A. and Rees, G. (2004). 

Derivation of numerical values for the World Health Organization 

guidelines for recreational waters. Water Research 

38, 1296–1304. 

Menéndez A. N., Lopolito M. F., Badano N. D. and Re M. Infl uence 

of projected outfalls in the plata river on limited water 

use zones. Proc. Intl. Symposium on Outfall Systems, 15–19 


Miller B., Numerical modeling and fi eld trials for the Christchurch 

ocean outfall. Proc. Intl. Symposium on Outfall Systems, 


info.ms). 

Morelissen R., Kaaij T. van der, Bleninger T., Waste water discharge 

modelling with dynamically coupled near fi eld and far fi eld 

models. Proc. Intl. Symposium on Outfall Systems, 15–19 



NRC (1993). Managing Wastewater in Coastal Urban Areas. 

National Research Council. Committee on Wastewater 

Management for Coastal Urban Areas, National Academy 

Press, Washington, DC. 

Pecly J. O. G. and Roldão J. S. F. (2011b). Dye tracers as a tool 

for submarine outfall studies associated with mathematical 

modeling. Proc. Intl. Symposium on Outfall Systems, 15–19 


Pecly J. O. G. and Roldão J. S. F. (2011c). Dye tracers as a tool for 

outfall studies: dilution measurement approach. Proc. Intl. 



Pecly J. O. G., and Roldão J. S. F. (2011a). Using the effl uent 

turbidity as an environmental tracer: application to a 

domestic sewage outfall and comparison with dye tracer 

data. Proc. Intl. Symposium on Outfall Systems, 15–19 May 

2011, Mar del Plata, Argentina (www.outfalls.info.ms). 

Roberts P. J. W. and Villegas B. E. The proposed Buenos Aires 

outfalls: outfall design. Proc. Intl. Symposium on Outfall 



Roberts, P. J. W., Salas, H. J., Reiff, F. M., Libhaber, M., Labbe, 

A. and Thomson, J. C. (2010). Marine Wastewater Outfalls 

and Treatment Systems. London: International Water 

Association. 

Rogowski P., Terrill E., Otero M., Hazard L., Middleton B., Mapping 

ocean outfall plumes and their mixing using autonomous 

underwater vehicles. Proc. Intl. Symposium on Outfall 



Salas, H. Marine wastewater disposal in Latin America. Proc. Intl 



Sanchez M.A., M.L. Jaubet, G.V. Garaffo, M.S. Rivero, E.A. 

Vallarino & R. Elias, Massive polychaete reefs as indicator 

of both increase sewage-contamination and chlorination 

process: Mar del Plata (Argentina) as a case not of study. 

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Mar del Plata, Argentina (www.outfalls.info.ms). 

Scagliola M., Comino A.P., Haeften G., Gonzalez R., Integrated 

coastal management strategy of Mar del Plata city and the 

sewage outfall project. Proc. Intl. Symposium on Outfall 



Scanes Peter, Monitoring environmental impact of ocean disposal 

of sewage: experience from New South Wales, Australia, 

Proc. Intl. Symposium on Outfall Systems, 15–19 May 2011, 

Mar del Plata, Argentina (www.outfalls.info.ms). 

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Regional Seas, Need for Regional Wastewater Emissions 

Targets? http://www.gpa.unep.org/documents/RS%20 

Sanitation%20&%20WET%20draft%20report. 

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version 3, http://www.gpa.unep.org/documents/ 

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version3.pdf. 

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hydrodynamic modelling. Proc. Intl. Symposium on 



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Guidelines. 2007. 

41

42 


Marketing and Communications 

Written by Brita Forssberg on behalf of the Specialist Group 

Communications: an important tool for 

successful water management 

The members of this Specialist Group are ‘specialised generalists’ 

and they work in different types of water organisations. 

They have a university education in technical or 

other disciplines, often including communications or journalism. 

Their strength is to follow relevant occurrences 

and trends in society and use this information to infl uence 

organisations, activities and services. They know how to 

inform and communicate proactively with different types 

of interest groups (management, employees, customers, 

suppliers, owners, fi nancers, society etc.) using their 

capacity to adapt language and messages to the needs of 

each group. They use a wide spectrum of activities related 

to the present management visions and goals. 

The group will be a forum or network for the exchange and 

sharing of experiences and best practice among communication 

specialists in water services organisations (both 

water and sanitation) as there is a lot to learn from the 

experience of others in order to understand what works 

and what does not, e.g. in crisis management. It is worth 

considering that researchers state that 70% of crisis work 

is communications! 

Short definitions 

Communication: the transfer of information between persons. 

Communications: the different media through which the 

information is transmitted. 

Information: the strategic messages that are the prerequisite 

for increased knowledge. 

Communication: the message process that leads to 

changes in attitudes or behaviour. 

Relation: Mutual engagement that leads to action and 

result. 

Water management must change the 

way people think 

More and more water utilities realise that ‘water management 

is not rocket-technology; it is much more: you have 

to change the way people think!’ 

Water from the tap is still an anonymous product that is 

too much taken for granted. We who work in the water 

sector have to do some serious work to change the images 

of water and sanitation into the attractive resources they 

really are. We have to enter the dynamic, public discussion 

using a language that everybody can understand and 

associate with. 

The Specialist Group sees the need to raise the profi le, 

status and esteem with which communications specialists 

are viewed in the water industry, and to demonstrate their 

contribution to improving the management of water services 

in a wide perspective. 

Many water managers are convinced that effective communications 

create values and are decisive success factors. 

Many water managers engage in making their organisations 

more communicative. They develop their qualities as 

communicators, leading and inspiring their employees to 

communicate effectively in their different work situations. 

It demands time and energy but in the longer run it is cost 

effective. 

Sign board in Accra, Ghana: 

‘You say that education is expensive. But how about 

ignorance?’ 

Modern technology and 

communications 

Professor Norihito Tambo said at the IWA Congress in 

Montreal that people in general have understood the 

energy agenda – but not understood and not accepted the 

water agenda. 

The intent of the Marketing and Communications Group 

is to put water higher on the public agenda by building 

good relations and understanding between water utilities 

and stakeholders - the wide range of customers and 

water users who have many other (water) infl uential roles 

in society. 

IWA members interested in marketing and communications 

increase in numbers. Many of them are involved in 

Specialist Groups that focus on issues that are likely to 

include or involve water users. It is important to realise, 

though, that every water user is also a water polluter and 

in reality part of the sanitation system or wastewater treatment 

process. This puts extra weight on management and 

communications.

New technology affects water. New technology attracts 

interest from media and the public, especially if it affects 

health and the environment. We as a Specialist Group are 

interested in sharing our professional experiences from 

communications with experts in other fi elds at relevant 

workshops, seminars or discussions. We will also offer to 

arrange special workshops on communications during IWA 

conferences. 

A member of the Marketing and Communications Specialist 

Group writes: 

‘A personal diagnosis of the current situation could be 

summarized by saying that marketing and communication 

development is not keeping up pace with the 

technological modernization of the water sector. The 

general trend … such as general management strategies, 

technological novelties, modernization investments 

required for better quality etc. – representing 

the primary interest themes in the major international 

water sector related events, often took precedence 

over themes related to better communication, awareness 

and customer relations. 

The general discussion trends within the water sector 

today are shaped by technical specialists, leading 

to a perception that the main stakeholder in effectively 

performing this vital public service – the end user, the 

customer, the community – is left out. Although the 

results of the efforts made by technical people in the 

water sector often remain invisible/unseen to the general 

public: most of the networks are below ground, 

water and waste water treatment facilities are outside 

cities etc. A simple motto for the PR activity could be 

“Make a very good job and then talk about it”.’ 

Another Specialist Group member says ‘we must use communications 

to make technology really work.’ 

Learn from the successful 

Communications are necessary management components 

to help reach business goals; create support for utility 

operations; make technology really work; build environmental 

awareness; build customer and consumer trust; 

obtain and keep the confi dence of owners, politicians and 

investors; build good media relations. 

Journalists, blogs and Facebook form your customers’ opinions. 

It is necessary to meet them on their own terms. 

Our common goal is to make water visible, interesting and 

accepted. As a monopoly we have to choose our own competitors. 

We can learn from model enterprises that communicate 

well: 

‘Tap water in New York has been handled, 

treated and developed with the greatest care both 


technically, environmentally and communicatively 

into ‘the best drinking water in the world’. NY is one of 

fi ve large US cities that don’t have to fi lter the drinking 

water. 

The Vienna Waterworks arrange smart campaigns 

and have built such a good reputation that the drinking 

water is considered one of the things a Viennese 

would miss when being away from town. They arrange 

excursions for you to enjoy water ... and like in NY they 

tend their Facebook relations.’ 

There are many open and communicative utilities that 

engage in campaigns to infl uence society. 

The Specialist Group recognises outstanding work of 

professionals in the water sector through its bi-annual 

communications award which is now included in the 

IWA Project Innovation Award (PIA) as its sixth category: 

Marketing and Communications. The fi rst winners will be 

presented in 2012. 

Recruiting competent personnel 

Times are changing, the world is changing, attitudes are 

changing and we the water people must learn and adapt 

to these changes. We have to face higher demands on performance. 

Risks are greater now than only a few decades 

ago. We must attract and recruit personnel with the right 

competence. 

A colleague writes: Is it so that the changes that the water 

sector has started lead to a very heavy work load? Is it so 

that the challenges we face make it clear that we don’t 

have the personnel resources needed? The amount of 

work and the stress are increasing as we are facing great 

challenges as for water catchment protection, security, big 

investment needs. Do other businesses have the same 

situation? 

Successful recruitment is diffi cult unless the water utilities 

and organisations are known and respected, considered 

interesting and attractive. Effective communications are 

necessary. 

The student recruitment campaign ‘Istudywater’ by the 

Dutch consultancy fi rm DHV was the Overall Winner of the 

IWA Marketing and Communications Award 2010. 

Conclusions 

The communication experts, the ‘specialist generalists’, 

have a key role in complementing water managers and 

water experts when building more communicative organisations 

for a successful future in closer relationship with 

water users/stakeholders on all levels in society. 

43

44 


Membrane Technology 

Written by Roger Ben Aim, Corinne Cabassud, Val Frenkel, How Yong NG, Vigneswaren, 

Masaru Kurihara, Jan Hofman, Ismail Koyuncu, Xia Huang, Mark Wiesner, 

Chunghak Lee on behalf of the Specialist Group 

Introduction 

In recent years membrane technologies have started to play 

a vital role in solving water scarcity on the planet, which 

is in close association with global climate change. The 

major reasons are that membranes allow not only effective 

separation of various contaminants from water sources to 

achieve the required quality, but also exploration of water 

resources from non-traditional sources such as wastewater 

and seawater for direct or indirect portable reuse. 

The objective of the Membrane Technology Specialist Group 

(MTSG) is to educate professionals and public around the 

globe without barriers about membrane technologies and 

to promote and exchange knowledge on membrane technology. 

Special attention is paid to the young professionals 

who will increasingly encounter membrane technologies in 

their professional life. 

The group consists of a vast spectrum of active members 

(scientists, researchers, engineers, membrane industry 

professionals and end-users.) in academic, industrial and 

public sectors. The group has grown to be one of the largest 

Specialist Groups within IWA. As of July 2011, it has 

1,652 members from 88 countries. 

The MTSG holds the international and regional bi-annual 

conferences and special workshops on specifi c topics 

relevant to membrane technologies for water/wastewater 

treatment, water reuse and desalination. The following 

MTSG international and regional conferences have been 

held and will be held with the sponsorship of IWA : 

• the International MTSG conference (1st) in Tokyo, Japan 

(1999); 

• the International MTSG conference (2nd) in Tel Aviv, 

Israel (2001); 

• the International MTSG conference (3rd) in Seoul, Korea 

(2004); 

• the International MTSG conference (4th) in Harrogate, 

UK (2007); 

• the Regional MTSG conference (1st) in Moscow, Russia 

(2008); 

• the International MTSG conference (5th) in Beijing, 

China (2009); 

• the Regional MTSG conference (2nd) in Istanbul, Turkey 

(2010); 

• the International MTSG conference (6th) will be held in 

Aachen, Germany (2011); 

• the International MTSG conference will be held (7th) in 

Toronto, Canada (2013). 

The MTSG is led by its management committee. The current 

chair is Professor Chung-Hak Lee (Seoul National University, 

Korea), the vice-chairs are Professor Franz-Bernd 

Frechen (University of Kassel, Germany) and Professor 

Vigid S. Vigneswaran (University of Technology, Sydney, 

Australia), the secretary is Dr Val Frenkel (Kennedy/Jenks 

Consultants, USA), and the treasurer is Professor Xia 

Huang (Tsinghua University, China). 

Information about MTSG members and group activity 

can be found on the Group’s website (http://www. 

iwa-membrane.org) or the IWA website (http://www. 

iwahq.org). 

Existing MTSG knowledge 

Membrane Market 

Membrane technologies have infi ltrated every corner of 

water and wastewater treatment such as municipal and 

industrial water, advanced wastewater treatment and 

reuse, sea and brackish water desalination (Frenkel 2010). 

The major reasons are the unique features of membranes 

in providing complete treatment and solving the water 

shortage problems that are in close association with global 

climate change. This has helped in accelerating the growing 

rate of membrane market. 

Membrane Market: Current Situation 

During the past 10 years, the annual growth rate of 

reverse osmosis (RO) desalination, microfi ltration (MF)/ 

ultrafi ltration (UF) membranes for drinking water treatment, 

and membrane bioreactors (MBRs) for wastewater 

treatment and reuse has been 17, 20 and 15% respectively. 

The reasons for this have been the similar capital, 

operation and maintenance costs as that of conventional 

treatment processes, a smaller footprint, fewer chemical 

requirements and much better pollutant removals. The 

energy requirement has been relatively high, although this 

is reducing with the rapid advance in R&D activities in 

this fi eld. 

The membrane market was strong in 2010 while it was 

quite different between market sectors and particular 

places, regions and countries around the globe. In general 

in 2010 the strongest membrane markets were sea water 

desalination by reverse osmosis (SWRO) and MBR technologies. 

A similar trend can be expected in 2011–2016, 

as shown in the Table 1.

Table 1. Forecast on membrane market (billions US$) for 

2011–2016 (Kwok et al. 2010) 

Market sectors using membranes 2011 2016 

Desalination pretreatment 0.05 0.13 

Membrane bioreactors 0.53 0.90 

Drinking water 0.17 0.33 

Tertiary wastewater treatment 0.16 0.39 

Industrial applications 0.16 0.30 

Subtotal MF/UF membranes 1.07 2.05 

RO/NF (nanofi ltration) 

Industrial applications 

0.33 0.51 

RO/NF Desalination 0.42 0.67 

Subtotal NF/RO membranes 0.75 1.18 

Total MF/UF/NF/RO membranes 1.81 3.25 

The membrane market in 2011 is forecasted to be US$1.8 

billion, but it is estimated to increase to US$ 3.25 billion 

over the next 5 years (about 80% growth), taking into 

account only the MF/UF/NF/RO membranes. However, it 

is worth noting that the estimation of membrane market 

has great fl uctuation depending on the data sources. For 

example, global world market of membranes for water and 

wastewater treatment in 2011 is also evaluated at about 4 

billion dollars (http://www.oecdrccseoul.org/article/globalmembrane-market-for-water-and-wastewater-treatment). 

In addition, MBR world market in 2011 is also estimated 

at about US$380 million (http://bccresearch.blogspot. 

com/2011/07/global-membrane-bioreactors-mbr-market. 

html). 

The growth rate of the SWRO market has been driven by 

the needs of the recent water supplies in places that are 

in the reasonable proximity to the ocean. Recent SWRO 

plants are large, with a capacity of 100,000 m 3 /day or 

more. For example, currently the largest operating membrane 

desalination plant in the USA is the Tampa Bay 

SWRO, with a capacity of 95,000 m 3 /day (with provision 

for up to 130,000 m 3 /day expansion). The largest SWRO 

plant in the world under construction currently is the 

Magta plant in Algeria, with a capacity of 500,000 m 3 /day 

(Kurihara 2011). 

The MBR market has been driven by needs for recycled 

water, upgrading of ageing facilities with challenged acquisition 

of the additional land and by the need for additional 

water by the industrial sector. In Europe, GE Water Technologies-Zenon 

(hollow-fi bre) and Kubota (fl at-sheet) have 

supplied most membrane equipment for the large MBR 

plants. However, new companies with novel concepts 

of membrane module design are slowly penetrating into 

municipal and industrial MBR markets. Therefore fi erce 

competition in the MBR membrane and equipment market 

supply can be expected in the coming years and exponential 

growth of the MBR market as a result (Lesjean 

et al. 2011). 


There is important growth in MBR plant sizes around the 

world, as shown in Table 2 (Simon Judd). The nine largest 

MBRs constructed or under construction have a peak 

daily fl ow of more than 100,000 m 3 /day. 

Membrane Market: Current Barriers 

In general, much current R&D on membrane technologies 

is related to analysis and control of membrane fouling, 

which is a chronic trouble for the operation of all membrane 

types. The reason is that the reduction of the relatively 

high energy demand to operate membrane plants 

still remains one of the key considerations for membrane 

processes over conventional treatment technologies, and 

the higher energy consumption is in close association with 

membrane fouling. In the coming years, many efforts will 

be dedicated to managing membrane fouling and reducing 

operational energy. 

Disposal of membrane concentrate is another challenge 

of membrane processes, especially if high pressure NF 

and/or RO membrane systems are used for salty and high 

concentrated industrial effl uents. Recently, many studies 

on membrane distillation/crystallization, forward osmosis 

and pressure-retarded osmosis have started to address 

the disposal of membrane concentrate. 

Membrane Market: Current Drivers 

There are also many factors infl uencing membrane market. 

These are decreasing investment and operational 

costs, new and more stringent legislations on effl uent 

discharges, local water scarcity, increasing confi dence in 

membrane technologies, compact footprint of membrane 

plants compared with other technologies, and high effi - 

ciency of salt removals, which will accelerate penetration 

of membrane technology to several market areas in the 

near future. 

Membrane Standardization 

The high pressure membranes such as RO and NF become 

commodities items well standardized across the industry 

and the most common high pressure element sized 8 

inches × 40 inches (200 mm × 1,000 mm) can be found 

in any RO/NF facility around the world. As RO/NF facilities 

becoming larger in size the high diameter RO sized 16 

inches (400 mm) diameter or 18¼ inches (450 mm) found 

their place in the design of the new desalination plants. 

Low-pressure membranes are still not standardized across 

the industry and this situation complicates the development 

of the MF/UF projects including MBR. More time 

is required to develop and procure MF/UF projects than 

is otherwise possible, resulting in more costly projects. 

However, there are numerous signs of the standardization 

of low-pressure membranes with MF/UF as membrane 

manufacturers are following up the after-sale market offering 

membrane replacement to the operational MF/UF and 

MBR facilities (Frenkel 2010). 

As part of the Amedeus European research project, a 

report about MBR standardization including recommendations 

has been recently published (De Wilde et al. 2007, 

www.mbr-network.eu) 

45

46 


Table 2. The 20 largest MBRs in the world? (Simon Judd, http://www.thembrsite.com/features.php) (ML/day) 

Installation Supplier Date PDF ADF 

Brightwater, WA, USA GE 2011 170 117 

Qinghe, China OW/MRC 2011 150 150 

North Las Vegas, NV, USA GE 2011 133 95 

Yellow River, GA, USA GE 2011 111 69 

Shiyan Shendinghe, China OW/MRC 2009 110 110 

Aquaviva, Cannes, France GE 2012 106 59 

Bus an City, Korea GE 2012 100 100 

Guangzhou, China Memstar 2010 100 – 

Wenyuhe, Beijing, China OW/Asahi Kasei 2007 100 100 

Johns Creek, GA, USA GE 2009 94 42 

Awaza, Turkmenistan GE 2011 87 69 

Jordan Basin WRF, UT, USA GE 2012 79 53 

Beixiaohe, China Siemens 2008 78 – 

Al Ansab, Muscat, Oman Kubota 2010 77 55 

Cleveland Bay, Australia GE 2009 75 29 

Broad Run WRF, VA, USA GE 2008 71 38 

Christies Beach, Australia GE 2011 68 27 

Incheon, Korea Econity 2012 65 – 

Lusail, Oatar GE 2011 61 61 

Ecosama, Sao Paulo, Brazil Koch 2012 61 57 

MRC, Mitsubishi Rayon Corporation; OW, Origin Water; PDF, peak daily fl ow; ADF, average daily fl ow. 


Membrane Fouling 

In general, much current R&D on membrane technologies 

is related to analysis and control of membrane fouling, 

which is the chronic challenge for operation of all membrane 

types. The reason is that the reduction of the relatively high 

energy demand to operate membrane plants still remains 

one of the drawbacks of membrane processes over conventional 

treatment technologies, and higher energy consumption 

is closely associated with membrane fouling. 

Much research is underway to mitigate membrane fouling, 

thereby to reduce energy demand to operate low (MF, 

UF) and high pressure (NF, RO) membranes. Some newer 

membrane technologies are ‘knocking the door’. 

In 2010, two particularly instructive review articles addressing 

biofouling in MBR were published by Drews (2010) 

and Xiong et al. (2010). 

Drews pointed out that many contradictory conclusions 

on membrane fouling in MBR that have been reported 

up to now in worldwide research should be re-examined, 

because a large variety of non-standardized fouling characterization 

methods were used. 

Xiong reviewed and emphasized various biological methods 

that have great potential in controlling membrane 

biofouling, because they have the advantages of high effi - 

ciency, low toxicity, and less bacterial resistance development 

over traditional physicochemical methods. As one 

example of the biological method, the recent study by 

Yeon et al. (2009) showed that the quorum sensing inhibition 

method, for example the addition of an enzyme to 

inactivate signal molecules, has advantages of non-toxicity 

and high antibiofouling effi ciency. Further study is needed 

to confi rm such a quorum quenching effect on the control 

of biofouling in full-scale MBR plants. 

Enhancing membrane performance with 

nanomaterials 

Next-generation membranes are being developed that 

incorporate nanomaterials, such as zeolites, carbon nanotubes, 

silver nanoparticles and others to improve membrane

properties and performance. These membranes have 

higher fl uxes, resist breakage to a much greater extent, 

and/or exhibit reduced biofouling. Membrane processes 

based on even more advanced nanoscale control of membrane 

architecture may ultimately allow for multi-functional 

membranes that not only separate water from contaminants, 

but also actively clean themselves and check for 

damage, detect contaminants, or combine detection, reaction 

and separation. 

Several nanomaterials are used for the formation of organic–inorganic 

porous composite membranes such as Al 2 O 3 , 

TiO 2 , SiO 2 , nAg (silver nanoparticles), CNT (carbon nanotube), 

chitosan and others. These nanomaterials improve 

membrane properties, such as (1) increased skin layer 

thickness, (2) higher surface porosity of the skin, (3) suppressed 

macrovoid formation, and (4) higher permeability 

of the membrane (Taurozzi et al. 2008). 

The very effi cient transport of water through CNT membranes 

seems promising for energy reduction in seawater 

desalination. However, the road to useful industrial applications 

of CNT membranes may be yet a long and arduous 

one owing to the selectivity and cost requirements (Verweij 

2007). Maximous et al. (2009) prepared PES ultrafi ltration 

membrane with entrapping Al 2 O 3 nanoparticles and used 

this membrane at the activated sludge fi ltration. Al 2 O 3 

nanoparticles decreased the adhesion or the adsorption 

of the EPS on the membrane surface and increased the 

fi ltration performance of membrane. 

In particular, incorporation of quorum quenching nanomaterials 

makes the membranes ‘reactive’ instead of a simple 

physical barrier. Kim et al. (2011) prepared an acylaseimmobilized 

nanofi ltration membrane with quorum 

quenching activity. This membrane prohibited biofouling, 

namely the formation of mature biofi lm on the membrane 

surface owing to the reduced secretion of EPS. 

Overall, these nanomaterials could contribute to the development 

of specifi c membranes in many desired ways. One 

challenge in the future will be to use these developments 

to tailor membranes for processes that rely on driving 

forces other than pressure, such as forward osmosis or 

membrane distillation. 

Forward Osmosis (FO) and Membrane 

Distillation (MD) 

In the context of climate change, the environmental and 

energy issues become essential and must be taken into 

account in the design of membrane systems and in their 

mode of operation, so that membrane processes remain 

or become competitive. The relatively high energy demand 

to operate conventional pressure driven membrane processes 

(MF, UF, NF, RO) still remains a challenge to be managed. 

As alternatives to reverse osmosis (RO), membrane 

distillation (MD) and forward osmosis (FO) are being considered 

for low-energy seawater desalination and wastewater 

reuse 

Forward Osmosis (FO) 

FO, a novel low-energy and natural process, has been signifi 

cantly developed in the past few years as an alternative 

membrane technology for desalination. Many studies 


on the use of FO for industrial and domestic applications 

can be found in literature. During the past decade, FO has 

been studied in wastewater treatment, seawater desalination, 

the food industry for stream concentration, as well as 

for purifying water in emergency situations. New and high 

performance FO membranes are being researched (Chou 

et al. 2010; Wang et al. 2010). 

In September 2008, Modern Water (Guildford, UK) built 

the world’s fi rst FO desalination plant in Gibraltar on the 

Mediterranean Sea. This local plant successfully completed 

testing procedures of the product water and, since 

May 2009, water has been supplied to the local community. 

A year later, in September 2009, a larger desalination 

plant was commissioned in the Sultanate of Oman at 

Al Khaluf. This new plant shares pre-treatment facilities 

with an existing RO desalination plant, providing a good 

opportunity to compare both technologies. Results were 

better than expectations, especially on resistance to fouling 

and product water quality. Moreover, despite the very 

bad quality of the source seawater, the FO membranes 

have not been cleaned or replaced over the year of operation. 

In contrast, RO membranes from the other desalination 

plant had to be cleaned every two to four weeks and 

had been replaced over the one year operation time. This 

clearly demonstrates the low fouling propensity of the FO 

process compared with the RO membrane process. 

Other key advantages of the FO desalination process 

are (1) the energy consumption is lower by more than 

30% compared with conventional RO, (2) chlorine tolerance 

and compatibility with a variety of biocides with FO 

membranes, (3) inherently low product boron levels, and 

(4) higher availability than conventional RO plant owing to 

low fouling and simple cleaning when required. 

The success of the FO process at the industrial level 

depends on how to prepare an effi cient FO membrane 

having minimal internal and external concentration polarizations 

as well as how to separate salt free water effectively 

from the draw solution (Ng et al. 2006). 

Membrane Distillation (MD) 

MD uses hydrophobic porous membranes as supports for 

a liquid/vapour interface and the vapour is transported in 

the membrane pores by diffusion. Indeed MD is particularly 

interesting because the principle itself of the transfer 

and selectivity of these membranes does not depend 

on the osmotic pressure of the solution as for the RO or 

the FO. 

Recent work has shown the use of the MD process for 

the over-concentration of brines up to very high salt concentrations 

and thus for improving the recovery of RO 

plants (Méricq et al. 2010), for the crystallization of salts 

for their valorization (Ji 2010). Another interesting application 

is when coupling the MD process with solar energies 

(Méricq et al. 2011; Guillén-Burrieza et al. 2011) or the 

recovery of heat, which can make MD become a sustainable 

process. The work in progress on this topic throughout 

the world relates to the design and development of new 

membrane modules (Winter et al. 2011) and integrated 

systems, and on the characterization and long-term control 

of membrane fouling and its properties (Krivorot et al. 

2011). Some platforms with long-term testing of the MD 

system coupled with solar energy or waste heat recovery 

47

48 


are under operation in many countries such as the Netherlands, 

Spain, Tunisia and Singapore. 

Conclusions and outlook 

Membrane fouling and energy consumption when operating 

membrane processes are still important challenges 

that need to be optimized and improved using innovative 

tools and technologies, as well as best operational practices. 

Nevertheless, for a wide range of applications in 

several areas, membrane treatment is becoming a competitive 

and economically viable option. 

The main factors infl uencing the rapid growth of membrane 

technology are the following: 

(1) multiple global challenges such as energy/resource 

shortage, climate change and rapid population 

growth; 

(2) improvement in membrane materials and modules; 

and 

(3) operational stability such as better antifouling, integrity 

testing of membrane processes. 

The key drawbacks of membrane technologies are high 

energy consumption and relatively high cost. In addition, 

questions still remain about the durability and lifespan of 

the membranes: the 20-year lifespan claimed by manufacturers 

in continuous MBRs has yet to be proved through 

operational experience. 

Owing to its aforementioned intrinsic properties, membrane 

technology will be the centre of one of the core 

technologies for us to face multiple challenges in the 

future. Membrane technology will provide great help to 

meet fi ve of the fi fteen Global Challenges (TMP 2011) 

for Humanity, namely sustainable development and climate 

change, water scarcity and water quality, balance 

population and resources, health issues and reduction of 

diseases and immune microbes, renewable energy and 

energy conversion. 

References 

Chou S., Shi L., Wang R., Tang C.Y, Qiu C. and Fane A.G. 

(2010) Characteristics and potential applications of a novel 

forward osmosis hollow fi ber membrane. Desalination 

261(3), 365–372. 

Drews A. (2010), Membrane fouling in membrane bioreactorscharacterisation, 

contradictions, cause and cures. Journal 

of Membrane Science 363, 1–28. 

Frenkel, V. (2010) Membrane technologies for water and wastewater 

treatment. International Water Association Conference 

IWA-2010, June 2–4, 2010, Moscow, Russia. 

Guillén-Burrieza E. et al. (2011) Experimental analysis of an air 

gap membrane distillation solar desalination pilot system. 

Journal of Membrane Science 379(1–2), 386–396. 

Ji X., Curcio E., Obaidani S.A., Profi o G.D., Fontananova E. and 

Drioli E. (2010) Membrane distillation-crystallization of 

seawater reverse osmosis brines. Separation and Purifi cation 

Technology 71(1), 76–82. 

Judd, S., the MBR site, http://www.thembrsite.com/features. 

php. 

Kim J.H., Choi D.C., Yeon K.M., Kim S.R. and Lee, C.H. (2011) 

Enzyme-immobilized nanofi ltration membrane to mitigate 

biofouling based on quorum quenching. Environmental 

Science and Technology 45, 1601–1607. 

.Krivorot M., Kushmaro A., Oren Y. and Gilron J. (2011) Factors 

affecting biofi lm formation and biofouling in membrane 

distillation of seawater. Journal of Membrane Science 

376 (1–2), 15-24. 

Kwok S.C., Lang H. and O’Callaghan P. (2010) Water Technology 

Markets 2010: key opportunities and emerging trends. 

Global Water Intelligence. 

Kurihara M. (2011) International Conference on Seawater Desalination 

& Wastewater Reuse, Quingdao, China, June 21. 

Lesjean B., Tazi-Pain A., Thaure D., Moeslang H. and Buisson H., 

(2011) Ten persistent myths and the realities of membrane 

bioreactor technology for municipal applications. Water 


Maximous, N., Nakhla, G., Wan, W. and Wong, K. (2009) Preparation, 

characterization and performance of Al 2 O 3 /PES 

membrane for wastewater fi ltration. Journal of Membrane 

Science 341, 67–75. 

Méricq, J.P., Laborie, S. and Cabassud, C., (2010) Vacuum 

membrane distillation of seawater reverse osmosis brines. 

Water Research 44(18), 5260–5273. 

Méricq JP., Laborie S. and Cabassud C., (2011) Evaluation of 

systems coupling vacuum membrane distillation and solar 

energy for seawater desalination. Chemical Engineering 

Journal 166(2), 596–606. 

Ng, H.Y., Tang, W. and Wong, W.S. (2006) Performance of 

forward (direct) osmosis process: membrane structure 

and transport phenomenon. Environmental Science and 

Technology 40, 2408–2413. 

Taurozzi, J.S., Arul, H., Bosak, V. Z., Burban, A.F., Voice, T.C., 

Bruening, M.L. and Tarabara, V.V. (2008) Effect of fi ller 

incorporation route on the properties of polysulfone–silver 

nanocomposite membranes of different porosities. Journal 

of Membrane Science 325, 58–68. 

TMP (The Millennium Project) (2001) Global challenges for 

humanity, Available at (assessed July, 2011). 

Verweij, H., Schillo M. and Li J. (2007) Fast mass transport 

through carbon nanotube membranes. Small 3, 1996– 

2004. 

Wang, R., Shi, L., Tang, C.Y., Chou, S., Qiu, C. and Fane, A.G. 

(2010) Characterization of novel forward osmosis hollow 

fi ber membranes. Journal of Membrane Science 355(1–2), 

158–167. 

Winter, D., Koschikowski, J. and Wieghaus, M., (2011) Desalination 

using membrane desalination; experimental studies on full 

scale spiral wound modules. Journal of Membrane Science 

375(1–2), 104–112. 

Xiong, Y. and Liu, Y. (2010) Biological control of microbial 

attachment: a promising alternative for mitigating 

membrane biofouling. Applied Microbiology and Bio technology 

86, 825–837. 

Yeon, K.M., Lee, C.H. and Kim J. (2009) Magnetic enzyme carrier 

for effective biofouling control in the membrane bioreactor 

based on enzymatic quorum quenching. Environmental 

Science and Technology 43, 7403–7409.

Metals and related substances 

in drinking water 

Written by Colin R. Hayes on behalf of the Specialist Group 

Introduction 

Contamination of drinking water by metals and metalloids 

can occur throughout the supply chain from ‘source to tap’ 

due to industrial effl uents, natural sources, water treatment 

chemicals, water mains and domestic pipe-work 

systems. 

The metals and metalloids most commonly associated with 

drinking water are listed in Table 1 together with the World 

Health Organization (WHO) guidelines, European Union 

Table 1. Metals and metalloids in drinking water 

Metal or 

metalloid 

WHO 

Guideline 

(µg/l) 

EU 

standard 

(µg/l) 


(EU) and US standards that apply, their main signifi cance 

and the principal control options. 

All water supply systems in the world, particularly piped 

supplies, are susceptible to problems arising from one 

or more metals or metalloids, many of which are health 

related. The impact in economic terms is likely measurable 

in trillions of US dollars/ EU euros and yet, all too often, 

problems with metals and metalloids are not fully appreciated, 

if at all, due to monitoring defi ciencies. Three major 

issues are described in the sections that follow. 

US 

standard 

(µg/l) H A MB Control 

Aluminium 100 – 200 200 50 – 200 Source treatment and process control 

Antimony 20 5 6 Source treatment (rare) 

Arsenic 10 10 10 Source treatment (common) 

Barium 700 – 2000 Source treatment (rare) 

Boron 2400 1000 – Source treatment (rare) 

Cadmium 3 5 5 Source protection (industry) 

Calcium – – – Source and point-of-use treatment 

Chromium 50 50 100 Source protection (industry) 

Copper 2000 2000 1300 Restrict use and corrosion control 

Iron – 200 300 Source treatment and pipe rehabilitation 

Lead 10 25 (10) 15 Pipe removal and corrosion control 

Magnesium – – – Source and point-of-use treatment 

Manganese – 50 50 Source treatment 

Mercury 6 1 2 Source protection (industry) 

Molybdenum – – – Source treatment (rare) 

Nickel 70 20 – Restrict use and corrosion control 

Selenium 40 10 – Source treatment (rare) 

Sodium – 200,000 – Source treatment or blending 

Uranium 30 – 30 Source treatment (rare) 

Zinc – – – Restrict use and corrosion control 

H, health; A, aesthetic; MB, mineral balance. 

49

50 

Arsenic 


Arsenic is present in the Earth’s crust and sediments, particularly 

in volcanic regions and sediments in the deltaic 

regions. Groundwater in contact with arsenic bearing rock 

strata or sediments can become contaminated to levels 

many times those considered safe for human ingestion. 

Potential health effects include skin damage, problems 

with circulatory systems, and increased risks of getting 

bladder cancer or diabetes. 

In Bangladesh, around half the population are suffering 

from chronic arsenic poisoning as a consequence of ingestion 

from drinking water (1) . In Europe, numerous groundwater 

abstractions are affected in countries such as Italy, 

Hungary and Serbia. Corrective treatment technologies 

are well developed, such as fi ltration through activated iron 

oxide, but relatively costly. The development of absorption 

methods using bone char, chitin or coconut husks offer 

more affordable solutions in developing nations. Some 

European countries are seeking temporary derogations 

from the legal standard, to give more time for the implementation 

of major improvement programmes. 

Problems with arsenic in drinking water are probably not 

fully appreciated. Even with the larger municipal scale systems, 

the extent of monitoring varies. Small and very small 

water supply systems, many of which are privately owned, 

are a cause for concern because monitoring is often not 

undertaken at all and expertise is lacking to do meaningful 

risk assessments. Over 10% of the European population 

and about 15% of the US population get their drinking 

water from small and very small supply systems. Other 

regions of the World will have a similar or worse position. 

Lead 

Since the early 1970s, standards for lead in drinking water 

have tightened considerably as health effects became 

clearer, particularly reductions in the IQ of children. The 

World Health Organization (2) , in its booklet in 2010 on 

Childhood Lead Poisoning has drawn attention to the 

following: 

• recent research that indicates that lead is associated 

with neurobehavioural damage at blood levels of 5 µg/dl 

and even lower, and that there appears to be no threshold 

level below which lead causes no injury to the developing 

human brain; 

• an increase in blood lead level from less than 1 to 10 

µg/dl has been associated with an IQ loss of 6 points 

and further IQ losses of between 2.5 and 5 have been 

associated with an increase in blood level over the range 

10 to 20 µg/dl. 

The Joint FAO/WHO Expert Committee on Food Additives 

re-evaluated lead in June 2010 and withdrew the provisional 

tolerable weekly intake guideline value for lead on 

the grounds that it was inadequate to protect against IQ 

loss (2) . This guideline value had been used as part of the 

basis for determining WHO’s guideline value for lead in 

drinking water of 10 µg/l, that was published in the third 

edition of Guidelines for Drinking Water Quality in 2004 

and 2008 (3) . To put this into perspective, epidemiological 

studies (4) suggest, as a general relationship, that 20 µg/l 

lead in drinking water (as an average) can be associated 

with a blood lead level of between 10 and 15 µg/dl. WHO 

has just published its 4th Edition of Guidelines for Drinking 

Water Quality (5) and retained the guideline value for lead 

of 10 µg/l, but as a provisional guideline on the basis of 

treatment performance and analytical achievability. The 

current WHO guideline value therefore offers little or no 

safety margin for children and a further tightening might 

be justifi ed in the future. 

The full extent of problems with lead in drinking water is 

unclear due to a range of monitoring defi ciencies (6) . In 

Europe, the EU Member States failed to agree a harmonised 

monitoring method for lead, copper and nickel at 

consumers’ taps. In consequence some countries are not 

monitoring at all for regulatory purposes, some take samples 

from the distribution network (where there is normally 

no lead present) and others take samples from consumers’ 

taps but only after fl ushing the pipe-work (any lead is 

fl ushed away before sampling). However, case studies (6) 

based on random daytime sampling of water supply systems 

in several EU countries have found non-compliance 

with the WHO guideline value ranging from less than 10% 

to over 50%, with around half having non-compliance 

between 20 and 30%. There is an obvious need for many 

European countries to clarify the extent of compliance of 

their water supply systems with the WHO guideline value 

of 10 µg/l. In the US, the stagnation sampling protocol 

used by the Lead Copper Rule is susceptible to a range of 

variables, particularly distortion from water stood in nonlead 

pipe-work, and problems may also have been underestimated 

although this has yet to be quantifi ed. 

Most lead in drinking water comes from the lead pipes 

that were used to connect a home to the water main in the 

street and are still in service. In Europe, it seems possible 

that up to 25% of homes still have lead pipes, putting 1 

in 4 children at risk. In the US and Canada it is estimated 

that about 3% of homes have lead pipes. In some circumstances, 

lead leaching from brass and galvanic corrosion 

of leaded solder can also cause problems. One obvious 

solution is to take out all the lead pipes but there are 

problems, including: (1) high cost; (2) disruption; (3) split 

owner-ship; and (4) the refusal of consumers to cooperate. 

Just taking out the lead pipes owned by the water 

company does not solve the problem and can even make 

matters worse in the short term with increased lead concentrations 

caused by physical disturbance of the pipework. 

Recognising the possible extent of problems, there 

is a need for water companies to operate corrosion control 

in their supply systems. Optimal plumbosolvency control 

will likely entail pH elevation (to between 8 and 9) and/or 

the dosing of a corrosion inhibitor, the most effective being 

orthophosphate at typical doses of 1 to 1.5 mg/l (as P). 

In the UK, 95% of water supplies are dosed with orthophosphate, 

at an optimum concentration, and over 99% 

of random daytime samples now comply with the WHO 

guideline value of 10 µg/l. 

General corrosion control 

The corrosive potential of drinking water has long been 

under-estimated. Corrosion of cast iron water mains has 

resulted in poor pressure, increased bursts, higher levels 

of leakage and signifi cant discolouration problems. The

cost of replacing corroded iron mains, or their refurbishment, 

is very high and at the national level can total many 

billions of US dollars/EU euros. Silicate and polyphosphate 

based corrosion inhibitors can partly ameliorate problems 

with old iron mains, but are no substitute for mains rehabilitation. 

Systems with slightly acidic water supplies and 

very low alkalinity, as commonly derived in mountainous 

areas, are particularly corrosive, made worse by the presence 

of fulvic and humic acids (organic acids that leach 

from bog-land). 

Corrosion problems can also be signifi cant when drinking 

water passes through domestic pipe-work and, additional 

to problems with lead (see above), include: (1) 

failure of copper pipe-work as a consequence of pitting 

corrosion; (2) failure of brass fi ttings due to dezincifi cation; 

(3) leaching of nickel from nickel-chrome plated 

components; (4) leaching of cadmium from galvanised 

iron pipe-work; and (5) failure of galvanised iron pipes 

once the protective zinc layer has dissipated. In various 

ways, the quality of the drinking water strongly infl uences 

these corrosion problems, examples being pH (both high 

and low), chloride and natural organic matter. This implies 

a close link with source water quality and the extent and 

reliability of its treatment. In this context, the fi nal water 

quality after desalination requires careful consideration. 

Looking to the future 

At the prompting of the World Health Organization (3, 5) , 

the global water supply sector is increasingly implementing 

a risk managed approach to operations, through 

Drinking Water Safety Plans, on a ‘source to tap’ basis. 

It is important that corrosion control needs are properly 

identifi ed through adequate awareness, appropriate 

monitoring and any other investigations that might be 

necessary, such as water corrosivity testing. A major and 

immediate priority must be to optimise corrosion control 

to reduce lead in drinking water. Concurrently, it will be 

important for the defi ciencies in the regulation of metals 

in drinking water quality to be rectifi ed, and for regulatory 

and testing systems that control the use of metal materials 

to be effective. 

The prospect of a future possible tightening of WHO’s 

guideline value for lead in drinking water is very daunting 

as it seems likely that even optimised corrosion control 

will not be capable of securing compliance. As a matter of 

priority, policy makers should be developing strategies for 

total lead pipe replacement, which could include legislation 

to force owners to certify their homes as ‘lead pipe 

free’ at the time of sale or letting. There is also a need to 

understand better, through further research, the extent of 


potentially remaining problems from legacy leaded brass 

and solder, and the ability of corrosion control to contain 

such problems. 

Ultimately the key to all the problems associated with metals 

and metalloids in drinking water is knowledge. The 

Specialist Group is therefore committed to initiating and 

promoting knowledge exchange through a series of Best 

Practice Guides, review publications and associated training. 

Updates on these initiatives are available from IWA’s 

Water Wiki. 

Conclusions 

Metals and related substances in drinking water have an 

immense signifi cance, not always appreciated, spanning 

human health, the management and refurbishment of 

water supply infrastructure and the use of metal components 

in domestic pipe-work systems. 

There is scope for the improvement of regulatory systems, 

particularly in over-coming sampling problems, so that 

monitoring data can reliably identify the situations requiring 

corrective attention. Effective regulation is also required 

to ensure that the metal components used in water supply 

systems are safe and do not cause problems for drinking 

water consumers. There is also scope to extend the use of 

risk assessment in water supply management, including the 

problems associated with domestic pipe-work systems. 

Multi-disciplinary research must be encouraged in the 

fi eld of metals and related substances in drinking water, 

especially in relation to potential health impacts. 

References 

1. Mukherjee, A.B. and Bhattacharya, P. (2001) Arsenic in 

groundwater in the Bengal Delta Plain: slow poisoning in 

Bangladesh. Environmental Reviews 9(3): 189–220. 

2. World Health Organization (2010) Booklet on Childhood Lead 

Poisoning. 

3. World Health Organization (2008) Guidelines for Drinkingwater 

Quality: Third Edition incorporating 1st and 2nd 

addenda, Vol. 1, Recommendations, WHO, Geneva. 

4. Quinn, M.J. and Sherlock, J.C. (1990) The correspondence 

between U.K. ‘action levels’ for lead in blood and in water. 

Food Additives and Contaminates 7, 387-424. 

5. World Health Organization (2011) Guidelines for Drinkingwater 

Quality: Fourth Edition. WHO, Geneva. 

6. International Water Association (2010) Best Practice Guide 

on the Control of Lead in Drinking Water. IWA Publishing, 

London. 

51

52 


Microbial Ecology and 

Water Engineering 

Written by Per Halkjær Nielsen, Katherine McMahon, Adrian Oehmen and Mark van Loosdrecht 

on behalf of the Specialist Group 

Introduction 

The overall aim of the Microbial Ecology and Water Engineering 

Specialist Group is to establish effective sciencebased 

approaches for identifying and solving practical 

problems and develop innovative processes in biological 

wastewater treatment and resource recovery. The Specialist 

Group deals with many biological systems, aerobic 

as well as anaerobic, such as activated sludge, biofi lms, 

granules, and membrane bioreactors. The scientifi c focus 

encompasses identity, physiology, ecology, and population 

dynamics of relevant microbial populations (including 

viruses, bacteria, archaea and higher organisms) and 

many of the tools, concepts, theories and challenges of 

our work are common to all engineered biological water 

treatment processes. 

Microbes and thus microbial ecology is an inherent part 

also of the water cycle in many other systems in water 

engineering. Examples are drinking water production 

and distribution systems, biofouling and biocorrosion of 

pipelines or reverse osmosis systems for conversion of 

seawater to drinking water. Some of these topics are also 

health-related and are as such treated in other SGs, but 

the methodologies and the fundamental understanding 

of microbial ecosystems are in common. Studying fundamental 

aspects of microbial biology, e.g. cell-to-cell communication 

in biofi lms, may reveal knowledge that can 

directly be applied in any of the microbial ecosystems in 

the engineered water systems. 

Microbial ecology recently got a big boost due to the fantastic 

development in novel molecular technologies, particularly 

related to DNA/RNA sequencing technologies and 

proteomics, developed by microbial ecologists and biotechnologists 

during the past 5–10 years. Most engineers have 

not been exposed to this exciting development and even 

fewer can foresee how this can be used in water engineering. 

We have selected a few hot topics where these technologies 

are already signifi cantly changing our capabilities 

to design, control and apply microbial communities in water 

engineering, and we hope this can inspire many researchers, 

developers, consultants and other persons involved in 

water engineering to join us in this exciting new era. 

Existing Specialist Group knowledge 

The Activated Sludge Population Dynamics (ASPD) Specialist 

Group changed its name to ‘Microbial Ecology and Water 

Engineering’ in 2009 so most of the present knowledge in 

the Specialist Group was developed in ASPD over the past 

15 years. ASPD had primarily focussed on the activated 

sludge process (and more recently also other systems). The 

severe operational problems with bulking and foaming were 

major drivers in these activities and as a SG, we have been 

successful in revealing the identity and function of many 

of these fi lamentous organisms and giving recommendations 

to control their growth. Also, the microbiology behind 

biological nutrient removal (N and P) has been intensively 

studied and resulted in improved understanding and better 

operation of full-scale plants, the development of recovery 

processes, and the production of high-value products 

such as bioplastics from wastewater. The microbiology of 

the activated sludge process is described in several IWA 

publications (see, for example, Tandoi et al., 2005; Nielsen 

et al., 2009a; Seviour and Nielsen, 2010). The Specialist 

Group has been an important forum for exchange of the 

many new methods and approaches in microbial ecology, 

modelling and treatment plant design and operation that 

have developed during the past 15 years. 


A. Wastewater as (part of) a biorefinery 

concept 

There is a growing need to regard wastewater treatment 

plants (WWTPs) as resource recovery systems, rather than 

purely for preventing pollutant releases to the environment. 

Recovering valuable products and energy from wastewater 

maximises the full potential of the WWTP from an economic 

and environmental standpoint. Optimising pollutant removal 

can therefore become economically benefi cial, since it 

simultaneously leads to greater product recovery. Wastewater 

can thus be viewed as a viable feedstock that can be 

integrated with other biomass feedstocks into the biorefi nery 

concept, producing value-added chemicals, fuels and 

energy from renewable resources (see Fig. 1). In addition 

to increasing resource recovery, it is also highly desirable 

to minimise the addition of chemical and energy inputs to 

WWTPs, in order to improve the environmental and costeffectiveness 

of the system as well as its sustainability. 

One important such example is the removal and recovery of 

phosphorus (P), since global P reserves are being depleted 

rapidly. The production of fertiliser such as magnesium 

ammonium phosphate (struvite) can generate revenue 

and simultaneously minimises struvite scaling problems in 

sludge handling units. The enhanced biological phosphorus 

removal (EBPR) process is most commonly combined with 

P and nitrogen (N) recovery while e.g. struvite or calcium 

phosphates can be recovered after the pre-concentration


Figure 1. Organic carbon sources in wastewater can be viewed as a viable feedstock that can be integrated with other biomass 

feedstocks into the biorefi nery concept, producing value-added chemicals, fuels and energy from renewable resources 

and also used for recovery of resources, e.g. phosphorus. 

of P and N in EBPR biomass. Optimising N and P removal 

effi ciency in WWTPs simultaneously reduces the need for 

supplemental addition of carbon sources and chemical 

precipitants and reduces oxygen demand, thereby lowering 

operational costs. Microbial ecology has an important role 

in this context since increasing our knowledge on the identity 

and metabolism of the microbial communities responsible 

for biological nutrient removal aid the development of 

novel processes, optimise existing processes and improve 

mathematical models. Some examples therein include the 

anaerobic ammonium oxidation (anammox) process (Strous 

et al., 1999), minimising greenhouse gas emissions (e.g. 

N 2 O) (Kampschreur et al., 2009; Yu et al., 2010), methanedriven 

denitrifi cation (Raghoebarsing et al., 2006) and 

maximising the growth of polyphosphate accumulating 

organisms (PAOs) over their competitors, the glycogen 

accumulating organisms (GAOs) (Oehmen et al., 2010a,b). 

Technologies for organic matter conversion into bioenergy 

sources such as methane through anaerobic digestion and 

recovery of the biogas are widely implemented at WWTPs, 

substantially lowering the energy budget required to operate 

the plant. Methods of further increasing the energetic productivity 

are being actively researched, particularly through 

bioelectrochemical systems (e.g. microbial fuel cells) and 

biohydrogen production (Logan et al., 2006; Kleerebezem 

and van Loosdrecht, 2007). These technologies can also 

be combined to generate hydrogen via microbial electrolysis 

cells (Rozendal et al., 2008). The microbial ecology of 

these systems is not well understood at present, and can be 

quite complex considering the wide variety of organic substrates 

present in wastewater. Further research could yield 

ways of optimising bioenergy production through minimising 

energetic losses via competing metabolic pathways. 

Another attractive alternative for organic matter recovery 

from wastewater is the generation of carbon-based bioproducts. 

Biodegradable plastics such as polyhydroxyalkanoates 

(PHA) are increasing in demand compared with 

petroleum-based plastics, since they can be produced 

from renewable resources, including wastewater (Fig. 2). 

PHA production through mixed microbial cultures has 

been recently shown to be competitive with traditional pure 

culture approaches, and has the potential to become more 

widely applied (Dias et al., 2008; Johnson et al., 2008). 

Other value-added chemicals that can be produced from 

wastewater include alcohols, organic acids and lipids, 

which are used as fuels or for the synthesis of bioplastics/ 

biopolymers (Kleerebezem and van Loosdrecht, 2007). 

Most of these compounds are produced through anaerobic 

fermentation, which is also critical for achieving PHA production 

and EBPR, since volatile fatty acids produced via 

fermentation are the key compounds taken up during each 

process. The microbial communities responsible for fermentation 

processes have been rarely studied (e.g. Kong 

et al., 2008), and improved knowledge is needed here in 

order to better manage the often-limiting carbon sources 

and optimise the processes that consume them; namely, 

denitrifi cation, EBPR and bioenergy/bioproduct formation. 

B. Understanding stability of microbial 

populations 

The applicability of any microbiological treatment system 

strongly depends on the stability of the microbial ecosystem, 

e.g. in relation to N-removal, settling properties of 

activated or granular sludge, or methane production. Poor 

functional stability may result in process break down and 

53

54 


Figure 2. Bacteria with large amounts of intracellular ‘bioplastic’, poly-hydroxy-alkanoates (PHA) as they use as storage 

polymers. 

poor reliability and performance of the system. Such instability 

of wastewater treatment operation has often been 

reported but it is not always known whether it is due to variation 

in the microbial populations or their function. Thus, to 

ensure effi ciency and stability in future treatment systems 

we need better knowledge about the identity of the key 

microbes, their functions, interactions, and factors regulating 

their presence. Furthermore, more general principles 

governing the stability of such microbial ecosystems should 

be developed and founded on proper theories in microbial 

ecology, thus providing a more generic and comprehensive 

approach to establish and control communities. 

Interestingly, new research has shown that microbial 

ecosystems in very similar treatment processes seem to 

have a common core community of ‘species’ or ecotypes 

shared among different plants. The most recent example 

is microbial communities in 25 Danish treatment plants 

performing EBPR, where most of the bacterial types were 

present in all plants despite signifi cant differences in plant 

design, operation and wastewater type (Nielsen et al., 

2010). Digesters treating surplus sludge from treatment 

plants (Rivie`re et al., 2009) and even the human gut (Qui 

et al., 2010) also seem to have such core communities, 

suggesting this is a general feature of similar ecosystems. 

This is extremely interesting and indicates we only need to 

deal with a limited number of core microbes for a certain 

type of treatment process, almost independently of the 

variations in plant design and operation. It is possible to 

study these core organisms by advanced single cell techniques 

alone or in combination with the -omics approach 

(see below) to reveal details in their metabolism and fi nd 

selective principles for control of certain populations and 

management of the community. Good examples are control 

of fi lamentous microorganisms involved in foaming and 

bulking (Nielsen et al., 2009b, Fig. 3). Little is known about 

the stability of the populations in such treatment systems. 

Some studies show a relatively high community stability 

whereas others show only minimal stability although the 

functional stability may be higher. More detailed studies 

with modern molecular methods are strongly needed to 

enlighten this important issue. 

The fi rst steps have been taken to form general concepts 

and theories for management of microbial communities, e.g. 

by ‘Microbial resource management’ (Curtis et al., 2003; 

McMahon et al., 2007; Verstraete et al., 2007). However, 

we need more comprehensive studies of selected highly


Figure 3. Filamentous microorganisms in activated sludge system. If present in large numbers, they cause foaming or poor 

settling properties and a deteriorated solid-liquid separation (bulking). Control of these organisms is now possible in most 

cases due to an increased knowledge about their identity and ecology. 

relevant communities in water engineering for studies by 

the novel comprehensive approaches in microbial ecology. 

Furthermore, the new knowledge should be transferred to 

a better understanding and practical recommendations for 

full-scale plants in the entire water cycle. This Specialist 

Group will take on this important future task. 

C. The use of the new-omics technologies 

in water engineering (what is it and what 

can it do?) 

There is no doubt that molecular tools have provided an 

unprecedented window into the structure and dynamics of 

microbial communities in water engineering systems. However, 

recent advances in the application of systems-level 

molecular biology to microbial ecosystems have opened 

doors about which we previously could only dream (Raes 

and Bork, 2008). Metagenomics, metatranscriptomics, 

and metaproteomics are three techniques that apply tools 

developed to study sub-cellular systems (DNA, RNA, and 

protein, respectively) of single organisms to multi-species 

assemblages (Wilmes et al., 2009). Together they describe 

the genetic blueprint of a microbial community (metagenomics), 

the genes within the community that have been 

recently transcribed into messenger RNA (metatranscriptomics), 

and those genes that have been translated into 

protein (metaproteomics). A meta-‘omics-driven approach 

treats the community as a system, within which are 

embedded the sub-cellular systems normally studied by 

microbiologists. The three techniques have the potential 

to be extremely powerful when employed on the same 

samples, providing a data-rich snapshot of both genetic 

potential and gene expression at two different levels (i.e. 

mRNA and protein). 

Metagenomics is already being used extensively to 

assess the metabolic potential of microbial communities 

in diverse habitats ranging from the oceans to soil to 

the human gut (Vieites et al., 2009; Wooley et al., 2010; 

55

56 


Gilbert and Dupont, 2011). Conceptually the technology is 

simple: sequence all of the DNA present in a sample. New 

so-called ‘next-generation’ sequencing chemistries such 

as those employed by 454 pyrosequencing and Illumina/ 

Solexa platforms have enabled massive parallelisation that 

produces thousands to millions of individual sequences 

per reaction. DNA extracted from water, sludge, or biofi lms 

can be sequenced directly, often without any amplifi cation 

or cloning, reducing biases that complicated the interpretation 

of results and confounded early metagenomics studies. 

Similarly, the metatranscriptome can be sequenced 

following removal of ribosomal RNAs and subsequent 

reverse transcription to convert mRNA into DNA (Poretsky 

et al., 2009). Metaproteomics requires separation of proteins 

in gels or by liquid chromatography, fragmentation 

into peptides, and analysis by tandem mass-spectrometry 

(Wilmes et al., 2008). Importantly, successful identifi cation 

of parent proteins from peptide mass spectra requires 

the sequence of reference genomes (or a metagenome) 

sharing extremely high identity (>90%) with the target 

organism(s). Generally, this requires that metagenomes be 

determined from the same sample (or subsample) used to 

interrogate the metaproteome. 

The promise of meta-‘omics approaches for studying the 

microbial ecology of water engineering systems has the 

potential to revolutionise our understanding of microbial 

behavior and interactions. Molecular tools based on 16S 

rRNA and other single genetic loci have taught us much 

about drivers of microbial community change in systems 

such as activated sludge, anaerobic digesters, and drinking 

water biofi lms. However, most of these studies have 

fallen short of directly linking community structure to 

process performance. A full assessment of community 

function is needed to make this link. For example, Candidatus 

Accumulibacter phosphatis is one well studied 

polyphosphate accumulating organism in activated sludge 

operated to achieve EBPR (He and McMahon, 2011). The 

abundance of Accumulibacter cells and the species-level 

diversity within the genus have been documented across 

activated sludge systems and over time within systems, 

but neither has taught us much about the metabolic 

mechanisms that control phosphorus removal. It was not 

until the metagenome of Accumulibacter-enriched sludge 

became available (Martin et al., 2006) that we could begin 

to reconstruct most biochemical pathways involved in the 

carbon and phosphorus cycling so characteristic of EBPR, 

and to track expression of genes expected to be key to the 

process. The expression of genes detected at either the 

mRNA or protein level provides an extremely convincing 

piece of evidence for operation of corresponding biochemical 

pathways, fi nally confi rming proposed metabolic models 

based on bulk metabolite measurements. Observed 

dynamics in mRNA and protein levels in for instance the 

nitrifi cation and denitrifi cation pathways are currently 

helping to rapidly understand the mechanism for net N 2 O 

production in wastewater treatment plants. This will help 

to develop process adaptations that further minimise the 

environmental impact of wastewater treatment processes 

(Kampschreur et al., 2009; Yu et al., 2010). 

Although simple in concept, in practice meta-‘omics 

approaches face signifi cant technical challenges. These 

include nucleic acid or protein extraction limitations, errors 

introduced by next-generation sequencing technologies, 

and interpretation of enormous complex datasets. However, 

many of these challenges are being tackled by the 

microbial ecology research community at large, and the 

fi eld is advancing rapidly. This is particularly true for computational 

methods for analysing meta-‘omics datasets 

(Metzger et al., 2011). Some of the most exciting advances 

relate to building predictive models of metabolite fl ux 

through communities based on comparative time series 

analysis (Stolyar et al., 2007; Zhuang et al., 2010). Still, 

most such efforts are limited to relatively simple systems 

with only a few community members. Much work remains 

to be done before we can ‘scale-up’ and apply these techniques 

to the signifi cantly more complex and dynamic realworld 

systems relevant to water engineering. The potential 

for linking ‘omics-based intra-cellular-scale metabolite fl ux 

models to system-scale process-based models is exciting 

and certainly justifi es the required effort. 

Conclusions 

Microbial ecology is an integrated part of water engineering, 

and the fascinating development in technologies to 

study microbial communities that has taken place the past 

5–10 years will make a revolution in the way we can analyse, 

understand and manipulate microbial communities in 

all aspects of water engineering systems. Most engineers 

have not been exposed to this exciting development and 

even fewer can foresee how this can be used in water engineering. 

We demonstrate with a few hot topics these new 

capabilities and perspectives and hope this can inspire 

many researchers, developers, consultants and other persons 

involved in water engineering to take actively part in 

this exciting new era. 

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58 


Off Flavours in the Aquatic 

Environment: a Global Issue 

Written by Tsair-Fuh Lin, Sue Watson, Ricard Devesa Garriga, Auguste Bruchet, Gary Burlingame, 

Andrea Dietrich, and Mel Suffet on behalf of the Specialist group 

Introduction 

Off fl avours in the aquatic environment have remained 

important over the last few years. Unpalatable taste and 

odour (T&O) in water may not be directly linked to health 

risks; nevertheless it has major, negative impacts on drinking 

water, recreational waters, and aquaculture. People 

instinctively link unpleasant T&O with toxins, disease and 

decay. Consumers may question the fundamental safety 

of municipal drinking water supplies which deliver bad 

taste to the tap, resulting in use of less regulated, alternative 

sources, such as bottled, vended, and tanker-trucked 

water. Ironically, bottled water consumption is highest - and 

increasing - in developed countries where there is the greatest 

collective access to treated water. Unpleasant odours 

in recreational water or along beaches and shorelines may 

deter public use and impact tourist and hospitality industries. 

Aquaculture industries experience signifi cant costs in 

mitigation and lost revenue as a result of tainted fi sh and 

shellfi sh. Unlike many other drinking water attributes, there 

are no standards or quantitative guidelines for T&O. Many 

of the volatile organic compounds (VOCs) that cause T&O 

are detectable to humans at trace levels, and their chemical 

identifi cation requires sophisticated analytical techniques 

not available to smaller utilities. But even with the primary 

focus on removal, proactive utility managers also recognize 

the importance of T&O as a diagnostic tool. Odours can 

indicate immediate problems with treatment or distribution 

systems or anthropogenic pollutants in source water. 

Importantly, T&O can also signal far reaching and longterm 

changes in the health and integrity of source waters. 

Raw water is literally a chemical “soup”. Its odour is 

caused the more potent, not necessarily the most abundant, 

compounds, which differ considerably in odour 

threshold concentrations (OTCs), stability and response 

to treatment. T&O outbreaks are inherently unpredictable, 

and their origins often remain untraced (Bruchet 1999). 

They can be caused by VOCs originating from one or 

more biological and/or anthropogenic sources (e.g. mineral, 

industrial, agricultural/urban runoff, accidental spills, 

or even water treatment itself). Biological activity in the 

watershed, source water and treatment plant/distribution 

systems produce a vast array of highly potent olfactants 

(Watson 2003) including the earthy-musty terpenoids, 

trans-1,10-dimethyl-trans-9-decalol (geosmin) and 

2-methylisoborneol (2-MIB), which are detectable at the 

ng/L concentration level and account for the majority of 

reported events (see below). In addition, VOCs generated 

from chemical and biological reactions in distribution systems 

and storage tanks, industrial discharges, and pipeline 

release from are also problematic. The latter are generally 

less well characterised and continue to be a major drinking 

water issue in many countries. In the last 10 years, 

methyl tert-butyl ether (MTBE), a gasoline additive that 

contaminates groundwater from leaking underground 

storage tanks has a sweet solvent odour. In this case, the 

odor of MTBE is causing T & O problems below its toxicity 

level, in the microgram/litre level. For emerging countries, 

water utilities consider odour problems to be one of their 

top issues, primarily due to growing economy, increasing 

water demand, and inappropriate environment (nutrient) 

management. It is predicted that as more countries establish 

safe supplies of drinking water (drinking water that 

meets World Health Organization standards), the issue of 

off fl avours will become more important. 

This report summarizes the current state of knowledge and 

advances of off fl avour issues and focuses on monitoring, 

biological sources and control. Three major challenges and 

future directions for the off fl avours in the aquatic environments 

are identifi ed; notably impact of climate change, 

emergency management and response, and emerging 

methods of analysis and treatment. 

Advances in Off Flavours in the 

Aquatic Environment 

Analytical and Monitoring Methods for 

Off-flavours 

Taste and odour episodes are classically monitored using 

a combination of sensory and chemical analytical techniques. 

Flavour Profi le Analysis (FPA) remains the gold 

standard for sensory analysis as it provides an accurate 

determination of the fl avour descriptors, which in turn 

helps select the most appropriate analytical techniques. 

FPA is the reference method to investigate T&O events. 

The odours, tastes and feeling factors are described in the 

well-known taste-and-odour wheel, which has been incorporating 

new descriptors and compounds as they have 

been identifi ed in real events (Suffet et al. 1999). FPA 

also describes how to establish intensity scales and how to 

train taste and odour panelists. 

Unfortunately, the drinking water industry holds on to outdated 

methods, such as the Threshold Odour Number 

method. Today, a toolbox of methods exist by which to 

screen waters for off fl avours as well as describe those 

fl avours in detail and conduct treatment studies. One area 

that needs more work is the establishment of methods for 

determining taste and odour threshold concentrations of

the chemicals of concern, taking into consideration the 

background effects of different waters, differing cultural 

preferences, and differing past experiences. 

Classical sensory analysis techniques, mainly coming 

from the food industry, have been used to characterize 

the background taste of water as a result of mineral 

content. It has been particularly useful for studies which 

investigate on the blending of conventional resources and 

demineralised water obtained by membrane technologies. 

Some recent interesting papers have recently addressed 

the metallic sensation such as from iron species, and its 

orthonasal and retronasal perception: it has a signifi cant 

odour component and therefore should be considered as 

a fl avour (Dietrich 2009). 

A wide array of techniques are available to detect trace 

organic chemicals responsible for the most common types 

of odours including geosmin, 2-MIB, haloanisoles (earthymusty), 

halophenols and iodoforms (medicinal) and MTBE 

(sweet solvent). Headspace solid phase micro-extraction 

(HSPME) and spinning bar solvent extraction (SBSE) combined 

with gas chromatography and mass spectrometry 

(GC/MS) are among the most effi cient methods for terpenoids, 

unsaturated and aromatic hydrocarbons, biogenic 

sulphides and sweet solvent odours, but closed loop stripping 

(CLSA) – GC/MS in combination with large volume 

injection or selected ion monitoring is still quite useful to 

scan environmental samples for a variety of analytes, or 

detect haloanisoles at their extremely low odour thresholds 

(about 30 picograms per litre). 

Biological Sources and Molecular 

Methods 

Biologically derived VOCs produced by algae, cyanobacteria, 

heterotrophic bacteria (notably some actinomycetes) and 


moulds are among the most frequently reported causes of 

T&O in source and treated waters (Watson 2010). VOCs 

fall in two broad biosynthetic groups, those produced at 

cell disintegration, which tend to occur in more episodic 

events (e.g. pigment and lipid derivatives), and those synthesized 

throughout growth which tend to generate protracted 

odour dynamics (e.g. terpenoids and thiols). No 

single VOC is exclusive to one species (i.e. a ‘chemical 

fi ngerprint’), while most organisms produce a number of 

these compounds. Nevertheless among algae and cyanobacteria 

there are broad differences in the most important 

VOCs produced by individual taxonomic groups and therefore, 

in the timing and nature of their impacts on source 

water odour. The most common sources of T&O are cyanobacteria, 

renowned for potent terpenoids (Geosmin and 

MIB), biogenic sulphides (isopropyl thiols) and carotene 

derivatives (β-carotene and β-ionone) and golden brown 

algae (diatoms, Chrysophyceae and Synurophyceae) 

which produce rancid/fi shy/cucumber smelling oxylipins 

(polyunsaturated fatty acid derivatives). Less commonly 

reported sources are green algae (Chlorophyta; noted 

for thiols and fatty acid derivatives), dinofl agellates and 

cryptophytes (also produce oxylipins and carbonyl compounds). 

Actinomycetes were traditionally also considered 

a major source of T&O (notably geosmin and/or MIB); more 

recently their importance relative to other biota has been 

questioned (Zaitlin and Watson 2006; Jüttner and Watson 

2007). In addition, it should be noted that all organisms 

indirectly contribute to T&O during the decomposition of 

their cells by heterotrophic bacteria; this is a major source 

of malodours along shorelines and beaches. The following 

sections enlarge on two of the most common types of 

biological T&O. 

To date, 2-MIB and geosmin are the two most widely 

reported and studied T&O compounds in water environment 

(Figure 1). Numerous studies have focused on the 

occurrence, sources, analysis, and control of these two 

Figure 1. Global reported occurrence of geosmin and 2-MIB in water environment (Prepared by De-Wei Chang) 1 

1 Prepared based on 107 articles relevant to the occurrence of geosmin and 2-MIB published between 1983 and 2011 

59

60 


chemicals in drinking water and aquaculture industries. 

These VOCs have an extremely important infl uence on 

human behaviour. On the one hand, they undermine 

consumer confi dence in supplies, but in some cases, 

they may be indirectly benefi cial. They are not known to 

be toxic to humans at levels encountered in even hypereutrophic 

systems. However, they are produced by some 

of the cyanobacteria that also produce toxins, and the 

low incidence of human poisonings by cyanotoxins may 

be partly attributable to the avoidance of water with 

signifi cant odour (Jardine and Hrudey 1999) (although it 

should be noted that there is no consistent relationship 

and these VOCs should not be used to diagnose cyanobacterial 

toxins). In addition, geosmin is an important food 

fl avourant (e.g. Camembert cheese, beetroot, coffee and 

Shiitake mushrooms). 

Traditionally, identifi cation of biological odour sources has 

used a combination of chemical analysis together with 

microscope and/or culture methods. This is problematic; 

not all species are culturable, they may change lose the 

capacity for production under certain culture conditions 

and morphologically identical strains recognised using 

a microscope may differ in VOC production. Recently, 

molecular methods such as denaturing gradient gel electrophoresis 

(DGGE), polymerase chain reaction (PCR), 

and quantitative PCR (qPCR), have been employed to 

identify the presence of potential odorant producing genes 

in environmental samples. Initially, 16S ribosomal RNA 

(16S rRNA) combined with DGGE, PCR, or qPCR has been 

used to identify and/or quantify geosmin-producing cyanobacteria, 

such as Anabaena. Similar methods have also 

been employed to construct the bacterial communities in 

water treatment processes involving biodegradation, such 

as sand fi lters, and to identify the bacteria responsible for 

the destruction of odorants. Recently, signifi cant advances 

have been made in the understanding of the biosynthesis 

of geosmin and 2-MIB by both cyanobacteria and actinomycetes, 

and providing the basis for the development of 

molecular methods to quantify the genes responsible for 

their biosynthesis (Giglio et al. 2011). The method has 

been tested in Myponga Reservoir, South Australia, which 

has frequent blooms of a geosmin producing cyanobacteria 

Anabaena circinalis. Comparison of results from qPCR, cell 

counts and geosmin measures showed that the approach 

might provide reasonably good estimates of geosminproducing 

cyanobacteria in source waters. However, the 

method still requires more validation on fi eld samples, and 

extrapolation to other cyanobacteria before this approach 

can be fully incorporated into monitoring programs. 

Lipid degradation products (oxylipins; notably 2,4heptadienal, 

2,6-nonadienal, 2,4-decadienal and 2,4,7decatrienal) 

are common causes of odour in surface 

waters (and many oily foods), responsible, for example, 

for fi shy smells associated with spring plankton blooms, 

rock biofi lms and nets. Oxylipins are produced by algae 

with high cell content of omega-3 and omega-6 fatty 

acids such as linolenic, linoleic and eicosapentaenoic acid 

(EPA), particularly golden brown algae (chrysophytes, synurophytes, 

diatoms), dinofl agellates and other fl agellates. 

Because production is triggered by enzymes released at 

cell disruption, these VOCs are generated at the end of 

an algal population cycle, or during disruptive processes 

such as grazing or treatment. However, some release also 

occurs during growth: there is now strong evidence that 

some unsaturated PUFA derivatives serve active roles 

as sexual pheromones, or in chemical defence against 

micrograzers—analogous to the wound-induced response 

in higher plants (Watson 2003). 

The complicated nature of odorants and producers also 

requires more study to further elucidate the biochemical 

pathways for different odorants in different organisms. In 

addition, more research is needed in the area of mitigation 

and treatment, and the biota and pathways involved in 

the biodegradation of odorants in natural and engineered 

environments. Progress has been slow, for a number of 

reasons. (1) At any given time, there is a diversity of VOCs 

in a water body, one or more of which may cause T&O. (2) 

Most biological communities are also highly diverse, and 

it is often diffi cult to link specifi c VOCs and species. (3) 

The major odour source may not necessarily be the most 

abundant species: VOC production per unit cell varies over 

orders of magnitude (e.g. Jüttner and Watson 2007). (4) 

Benthic and epiphytic algal populations can be signifi cant 

‘invisible sources of T&O in source water. (5) VOC production 

and detection sites can be spatially distinct due to VOC 

diffusion or transport with water masses, or active/passive 

movement of the biota. (6) VOC production may be intra- 

or extracellular, and vary over population cycles with environmental 

conditions. (7) Most water quality studies have 

focused on processes within aquatic systems, although it 

is clear that the watershed can make a signifi cant contribution 

to surface water odour. 

Treatment Methods 

The primary objective of the water treatment is its disinfection 

and to obtain a product with a suitable chemical 

purity for human consumption. However, it is important to 

also consider the important of the organoleptic properties 

of fi nished water. The effects of treatment on the T&O of 

water can be driven by three mechanisms: fi rst, the typical 

residual disinfectant fl avour, which is the main characteristic 

of tap water for consumers, as opposed to bottled 

water; secondly, the disinfection by-products, which are 

produced by chemical reaction between the disinfectant 

and the organic matter present in water; and third, the 

change in the saline content, which is relevant when membrane 

techniques are used. 

The typical disinfectant fl avour has been studied especially 

for chlorine and chloramines. Signifi cant knowledge 

has been achieved about several aspects of its perception, 

such as detection thresholds and masking or synergetic 

effects with compounds present in water. It is also well 

known that perception is dependent on persons and also 

between populations with different consumption habits. 

Concerning the disinfection by-products, notable fi ndings 

have been obtained about their identifi cation and effects, 

such as the fruity fl avours in ozonated waters due to aldehydes 

formation (Anselme et al. 1988). And third, the 

membrane technology improves the fl avour of waters by 

reducing the concentration of organic compounds. But, 

on the other hand, these processes notably reduce the 

saline content of the water and alter the proportions of 

the ions. These changes in the mineralization modify the 

taste of the water and can infl uence the perception of the 

consumer. 

Some processes (e.g. chlorination, ozonation) exacerbate 

T&O by releasing cell-bound VOCs, and/or producing

odorous disinfection by-products, as is seen, for example, 

with odorous polyunsaturated aldehydes. Conventional 

processes which trap particle-bound material (e.g. sedimentation, 

sand fi ltration) are ineffective at removing 

many dissolved VOCs. This can be achieved by activated 

carbon and membrane fi lters, but these are costly and 

their capacity reduced by raw water natural organic matter 

(NOM) - which can increase signifi cantly during high 

T&O risk periods (spring runoff, summer blooms). Bank 

fi ltration, widely established in Europe, is an effective pretreatment 

for many VOCs (and other contaminants). 

The Challenges and Future 

Research Directions 

Impact of Climate Change 

Climate change may affect freshwater quality and T&O production 

in a number of ways. Average and maximal water 

temperatures may rise slightly (~1–2 °C) in many waterbodies, 

increasing biological activity (including VOC production, 

and O 2 -requiring heterotrophic processes). This may 

also favour warm-water adapted species, including some 

(but not all 2 ) cyanobacteria. Changes in the length and timing 

of the growing season, UV irradiance/light spectrum, 

the mixing regime, fl ushing and water levels of lakes and 

fl owing waters, reservoir drawdown, severe storm events, 

ice-cover and scouring are all also likely to have a major 

effect on the distribution and success of noxious biota and 

associated VOC production. The impact is especially signifi 

cant to important odorant producers, such as cyanobacteria, 

potentially increasing odour episodes in drinking 

water resources (e.g. Paerl and Huisman 2008). 

In addition to the impact on the growth of cyanobacteria, 

the generation, fate, and transport of odorants in water 

may also be affected. Increase of water temperature may 

change both the production and loss rates of odorants. 

For example, the rate of biodegradation by bacteria and 

that of volatilization from water surface are expected to 

increase as temperature increases. Changing temperature 

may also affect the adsorption/partition of odour compounds 

among water, air, and sediments/suspended solids, 

shifting the fate of the odorants in different phases. In 

addition, increasing temperature may change water usage 

pattern for communities, and thus change the residence 

time and storage volume of reservoirs and distribution systems. 

These may also affect the budget of odorants in the 

reservoirs. 

Droughts and forest fi res have been shown to affect the 

fl avour quality of the water resource. Droughts often result 

in algal blooms as well as a greater portion of the water 

resource comprising of wastewater discharge. Forest 

fi res load different minerals and organic chemicals into a 

watershed during and after the fi res. These changes have 

impacted drinking water and have required changes in 

drinking water treatment. To date, the impact of climate 

change on off-fl avours relevant water quality has not been 

systematically analyzed, and more research relevant to this 

topic is needed. 

Analytical Methods 


New methods need to be developed for a better understanding 

of specifi c types of odours such as chlorinous 

odours that are not due to the disinfectant residual and 

are possibly caused by chloro-aldimines or other types of 

organic chloramines. Plastic and related odours caused by 

the use of synthetic organic materials in distribution systems 

are still poorly understood and also deserve investigation. 

Concerning sulphidy odours, a single simplifi ed 

method capable of simultaneously measuring hydrogen 

sulphide, merthyl mercaptan, dimethylsulphide, dimethyldisulphide 

and dimethyltrisulphide would be quite useful. 

Analytical methods need to be able to separate increasingly 

complex matrices that result from algal blooms 

(caused by climate change) and anthropogenic pressures 

on source waters. Two-dimensional gas chromatographic 

methods which have already demonstrated their ability to 

separate a few thousand compounds from a single wastewater 

extract remain to be applied for the identifi cation 

of odorants in such complex matrices. Finally, the miniaturization 

of GC/MS instruments coupled with specifi c 

interfaces such as a submersible purge and trap probe 

will in the near future offer the possibility of carrying out 

on-line analysis of specifi c odorants in diverse types of 

waters. Identifi cation of new odorants has been practically 

restricted to non polar and semi-polar compounds amenable 

to gas chromatography. In the near future, new high 

resolution liquid chromatography with mass spectrometry 

(LC/MS) instruments will likely allow identifi cation of 

unknowns, including more polar compounds contributing 

to off fl avours. 

Emergency Management and Response 

to Off flavour Events 

Although geosmin and 2-MIB continue to be important 

problems in many parts of the world, off fl avour episodes 

other than earthy-musty have been reported. Anthropogenic 

pollution in source water becomes an important 

concern, especially in developing countries. Discharge of 

waste and wastewater intentionally and un-intentionally 

into water sources are occasionally encountered. Methods 

to rapidly identify and monitor the chemicals and fl avours 

responsible for the episodes are increasingly demanded. 

While FPA remains to be one of the analytical tools to 

identify the fl avours in polluted water sources, the risk 

associated with exposure to unknown pollutants requires 

more attention when applying the method. In addition to 

the chemical methods mentioned in section 3.2, on-line 

instrumentation, such as LC/MS and GC/MS, can provide 

reliable information on micro-pollutants in near to 

real time (Storey et al. 2011), and may have the potential 

to be applied to monitor the odorants. This is needed for 

early warning as well as for the management of emergency 

events. 

Biological monitors, such as bacterial bioluminescence, 

Daphnia, algal cell and fi sh monitoring, although not 

designed for T&O episodes, may be able to provide some 

useful information to capture changes in water quality as 

well as incidental discharge of waste into source waters. 

2 

It should be noted, however, that some species of cyanobacteria (and algae) can bloom under a climate regimes ranging from arctic 

to tropical. 

61

62 


Emerging biological sensors, including adenosine triphosphate 

(ATP), immunoassay and molecular techniques, and 

fl uorescence-based methods may also provide information 

about bacteria/algae/cyanobacteria in water, potentially 

allowing for rapid interpretation of off fl avours in water. 

However, studies are required to test and validate these 

on-line sensors during off fl avour episodes. 

Methods to characterize the odorants for algal blooms are 

urgently required, as the issues are increasingly observed. 

The chemicals may be different from conventional geosmin 

and 2-MIB. For example, an important group of the 

compounds include sulphur-related compounds, which 

has been reported in Wuxi, China in 2008, where water 

supply for the city was interrupted due to sulphide relevant 

compounds (Yang et al. 2008). 

Finally, as the fi eld of risk communication grows, the communication 

to the public about the taste and odour quality 

of water needs more attention. The public has become 

more knowledgeable, or more accessible to information on 

water quality. The Internet is loaded with good and bad 

information that the public uses to make judgements about 

the safety of water. Water suppliers need to be primary 

sources of information about their water, especially when 

off fl avours occur. This requires training of water suppliers 

in risk communication and in the tools the public uses to 

obtain information, such as social networking. Fortunately, 

we can take advantage of the advances being made in 

other fi elds, such as crisis management, to guide developments 

for better public communication and education on 

taste and odour. 

Compound/Odour Specific Treatment 

Methods 

Drinking water supplies have traditionally focussed their 

efforts on providing a product with health guarantees. 

However, the consumer does not evaluate the water by 

taking into account the regulations but rather in terms of 

its aesthetic properties. For this reason, the water suppliers 

are making a noteworthy effort to improve the odour 

and taste of water by developing better treatment technologies. 

Traditionally, taste and odour issues have become relevant 

when the supplier faces a T&O event. Although sometimes 

the causative agent has been anthropogenic, the most 

common episodes have been produced by natural agents 

like geosmin and 2-MIB, which are produced by certain 

cyanobacterial blooms. For the compounds other than 

geosmin and 2-MIB, selection of treatment depends on 

the nature of the chemicals. The control of different combinations 

of odorants and treatment processes requires 

further investigation. 

Granular and powdered activated carbon have been 

shown to be very effective at reducing the concentrations 

of undesired compounds, but they are not able to remove 

certain compounds, such as some sulphur-related compounds 

from anaerobic reactions. Other choices should 

be made, including oxidation and advanced oxidation 

processes in this case. It is necessary to investigate alternatives 

such as ozonation combined with UV irradiation or 

hydrogen peroxide. 

Membranes have been a revolution in the water treatment 

sector. In the future, more effi cient materials will be available, 

and it will be possible to achieve better removal of 

undesired compounds. 

Conclusions 

Although off fl avours in the aquatic environment continue 

to be a major drinking water issue in many countries, the 

different nature of the issues found in particular regions 

substantiates the importance of the problems. Monitoring 

and analytical methods for off fl avour chemicals require 

further studies, in particular for on-line and/or near real 

time analytical capacities, and also an enrichment of the 

taste-and-odour wheel from the FPA method with new 

descriptors and compounds. Sensory analysis is a useful 

complementary tool to chemical analysis for understanding 

taste-and-odour events. It is being used to understand perception 

of the water consumers, for example about disinfectants 

or blending of conventional and membrane treated 

waters. Further study of odour threshold concentrations 

and how to set aesthetic-based drinking water standards 

for water supply is an area of future research as well. 

The genes responsible for the biosynthesis of geosmin and 

2-MIB have been decoded and more studies are needed 

to verify the approach for quantifi cation of odorant producing 

genes as well as to fi nd their correlation with odorant 

concentrations. Extrapolating the approach to other species 

and genera of cyanobacteria and odorant degrading 

bacteria will certainly establish a foundation for better 

monitoring techniques. Climate change obviously may 

have the potential to signifi cantly infl uence water quality. 

Its impact on the growth of cyanobacteria, the generation, 

fate, and transport of odorants in water deserves a systematic 

analysis and more research. 

As anthropogenic pollution in source water becomes an 

important concern, methods to rapidly identify and monitor 

the chemicals and fl avours responsible for episodes 

are increasingly demanded. On-line instrumentations and 

biological monitors may have the potential to be applied 

directly and indirectly to monitor for odorants, although 

method development and validation are required. Treatment 

of the most common episodes caused by geosmin 

and 2-MIB has been standardized. However, for other 

emerging chemicals, selection of treatment trains depends 

on the nature of the chemicals. The effectiveness for the 

control of different combinations of odorants and treatment 

processes requires further investigation. 

References 

Anselme, C., Duguet, J.P. , Mallevialle, J. and Suffet, I.H. (1988) 

Removal of taste and odors by ozonation. Journal American 

Water Works Association 80(10), 45–51. 

Bruchet, A. (1999) Solved and unsolved cases of taste and odor 

episodes in the fi les of Inspector Cluzeau. Water Science 

and Technology 40(6), 15–21 

Dietrich, A. (2009) The sense of smell: contribution of orthonasal 

and retronasal perception applied to metallic fl avour of 

drinking water. J. Water Supply: AQUA 58(8), 562–570. 

Giglio, S., Chou, W.K.W., Ikeda, H., Cane, D.E. and Monis, P.T. 

(2011) Biosynthesis of 2-Methylisoborneol in Cyanobacteria. 

Environ. Sci. Technol. 45, 992–998

Jardine, C.G, Gibson, N. and Hrudey S.E. (1999) Detection of 

odour and health risk perception of drinking water. Water 


Jüttner, F. and Watson S.B. (2007). Biochemical and ecological 

control of geosmin and 2-methylisoborneol in source waters. 

Appl. Environ. Microbiol. 73(14), 4395–4406. 

Paerl, H.W. and Huisman J. (2008) Blooms like it hot. Science 

320, 57. 

Storey, M.V., van der Gaag, B. and Burns, B.P. (2011) Advances 

in on-line drinking water quality monitoring and early 

warning systems, Water Research 5, 741–747. 

Suffet, I.E., Khiari, D. and Bruchet, G. (1999) The drinking water 

taste and odor wheel for the millennium: beyond geosmin 

and 2-methylisoborneol, Water Science and Technology 

40(6), 1–14. 


Watson, S.B. (2003). Chemical communication or chemical 

waste? A review of the chemical ecology of algal odour. 

Phycologia 42: 333–350. 

Watson, S.B. (2010) Algal taste and odour. Chapter 9 in Algae: 

Source to Treatment. AWWA Manual of Water Supply 

Practice, M57, ISBN 978-1-58321-787-0. 

Yang, M., Yu, J.W., Li, Z.L., Guo, Z.L., Burch, M. and Lin, T.F. 

(2008) Taihu Lake Not to Blame for Wuxi’s Woes. Science 

319, 158. 

Zaitlin B. and Watson, S.B. (2006). Actinomycetes in relation to 

taste and odour in drinking water: myths, tenets and truths. 

Water Research 40:1741–1753. 

63

64 


Resources-oriented sanitation 

Written by Ebba af Petersens, Marika Palmér Rivera, Tove Larsen, Grietje Zeeman, Günter Langergraber 

and Elisabeth Kvarnström on behalf of the Specialist Group 

Context 

Although the services of urban water management are 

vital for urban societies, experience shows that wastewater 

management does not have a high priority when 

resources are scarce. In a world with increasing scarcity 

not only of economic, but also of physical and environmental 

resources, resource effi ciency of wastewater management 

becomes more urgent than ever. A holistic view of 

resource effi ciency will encompass at the same time the 

management of resources in wastewater (e.g. water and 

nutrients), the physical resources spent on treatment and 

transport (most importantly energy), the natural resources 

to protect (e.g. the receiving waters, but also increasingly 

the atmosphere), and the anthropogenic resources (e.g. 

capital). Today, many up-coming problems are solved 

incrementally without considering the problems associated 

with the solution of the immediate problem. The 

most prominent examples are the solutions for water scarcity, 

where for instance desalination leads to high energy 

consumption. 

In view of the immense problems arising from global population 

growth, urban development and climate change on a 

global scale, a paradigm change of urban water management 

is necessary. Source diversion is a promising concept 

for more resource effi ciency in wastewater management, 

and will facilitate also for the application of resourcesoriented 

sanitation. 

The IWA Specialist Group (SG) on 

Resources-Oriented Sanitation 

The IWA Specialist Group (SG) on Resources-Oriented 

Sanitation focuses on resource effi ciency in wastewater 

management as well as beyond the wastewater system. 

For resources-oriented sanitation systems to be sustainable 

from more perspectives than resource-effi ciency they 

should comply to the protecting and promoting of human 

health by i) providing a clean environment and breaking 

the cycle of disease, ii) be economically viable, socially 

acceptable, and iv) technically as well as institutionally 

appropriate. For sustainable implementation of sanitation 

systems it is of utmost importance to take into account the 

whole system and not only single technologies. 

This chapter outline some of the trends and challenges for 

resources-oriented sanitation, as observed by members of 

the Specialist Group. 

Existing knowledge, experience and 

practice 

In order to give an idea of the global development of 

resources-oriented sanitation systems, examples from 

several different countries are given below. 

Burkina Faso 

Pilot projects of urine-diverting toilets to provide urine and 

composted faeces for agricultural use have met with great 

success in Burkina Faso. Local fi eld studies calculated 

that each person excretes approximately 2.8 kg of nitrogen, 

0.45 kg of phosphorus and 1.3 kg of potassium per 

year, which is the equivalent of about 10 kg of commercial 

fertiliser. This is enough fertiliser to support growth of crops 

on 300–400 m 2 of land. These numbers have convinced 

many farmers to use these “new” fertilisers. Policy regarding 

reuse has lagged behind, but the success of the technique 

has led to the inclusion of urine-diverting toilets and 

subsequent use of their products as accepted technologies 

in the national sanitation policy. The cities of Ouagadougou 

and Banfora have also signed offi cial decrees allowing for 

reuse. In Ouagadougou, municipalities have agreed to 

partly fi nance the collection system (household contribution 

is too low to run the whole system), and monitoring the 

whole system. The Ministry of Agriculture has also agreed 

to monitor extension workers and train farmers. Furthermore, 

the Ministry of Health has agreed to use its health 

workers for quality control and will monitor and assess any 

health risks associated with the system. 

Figure 1. Urine collection tanks in Ouagadougou, Burkina 

Faso (picture provided by Günter Langergraber).

Philippines 

In the Philippines, a bottom-up process facilitated the 

incorporation of reuse into national legislation. The 

Philippine Clean Water Act of 2004 aims to protect the 

country’s water bodies from pollution from land-based 

sources. Several studies show that domestic wastewater 

is the principal cause of organic pollution of water bodies 

in the Philippines. The Act was silent on nutrient recycling, 

but when public consultations on the Act’s Implementing 

Rules and Regulations (IRR) were held, the Philippine 

Ecosan Network advocated for the incorporation of the 

ecosan concept into the IRR. Thus, reuse is now legally 

supported in the Philippines. 

Niger 

The International Fund for Agricultural Development (IFAD) 

supported a productive sanitation project in Niger during 

2009 which was implemented by CREPA (Le Centre 

Régional pour l’Eau Potable et l’Assainissement à faible 

coût) and PPILDA (Project for the Promotion of Local Initiative 

for Development in Agui). A policy study from that 

project recommended to work on three levels: (i) stakeholder 

level, (ii) framing of productive sanitation in existing 

strategies and programs, (iii) to promote resources-oriented 

sanitation , for widespread of productive sanitation in Niger. 

On the issue of stakeholders it was recommended to work 

with farmer-to-farmer visits, inter-village groups, women 

organisations and locally active NGOs. Stakeholders important 

on regional level in Niger are the de-concentrated state 

technical services, other on-going projects and the coordinating 

body of water and sanitation actors on regional 

level: CREPA. The regional level actors are important in 

Niger, where the decentralisation process is not yet fully 

functional. Thus, the technical capacity available with the 

de-concentrated state technical services is very important. 

The interaction with other projects could be to try and introduce 

the concept of urinals in CLTS (Community-Led Total 

Sanitation) projects. This would be a simple way to build 

upon the CLTS method and allowing for simple reuse without 

compromising the CLTS goal of zero open defecation. 

Sweden 

Since the beginning of the 1990s, there has been an 

on-going debate in Sweden about the sustainability of the 

current wastewater systems in terms of nutrient recovery. 

This debate led to the development of sanitation systems 

with urine-diversion and by now, there are approximately 

ten thousand porcelain urine-diverting toilets installed in 

Sweden and at least 10–15 larger systems for reuse of 

human urine, of which most are managed by municipalities. 

Although these systems have proven to have great 

potential, the technology needs to be further developed 

(especially urine-diversion toilets) in order to be more convenient 

and user-friendly. 

Due to initial problems with urine-diversion in pilot projects, 

there was a backlash against source-separating sanitation 

systems in the early 2000s. However, lately there has 

been an increased interest in resources-oriented sanitation, 

mainly for on-site sanitation solutions in rural areas. 

New guidelines for on-site sanitation from 2006 set very 


high demands on reduction of phosphorous, but also state 

that recycling of nutrients ought to be achieved. The prime 

driving force for resources-oriented solutions for on-site 

systems is not necessarily always nutrient recycling, but 

pathogen removals (through collection of blackwater) and 

of phosphorus and nitrogen from the immediate environment. 

There is a long tradition of source-diversion systems 

and approximately 150 thousand summer houses have dry 

toilets, with or without urine diversion. There is also about 

75 thousand houses with separate collection of blackwater 

in closed tanks. To reduce transports of collected 

blackwater and to facilitate the use of sanitised blackwater 

as fertiliser on arable land, vacuum toilets are installed in 

increasing numbers and there is even one municipality 

that requires all home owners with on-site sanitation to 

install vacuum toilets and closed tanks for collection of 

blackwater. 

Sweden has national environmental objectives where one 

of the targets is that by 2015 at least 60% of the phosphorus 

in wastewater should be reused on productive land; 

half of which arable land. Since most of the wastewater is 

treated in conventional wastewater treatment plants, the 

focus for this target has been the reuse of sludge from 

wastewater treatment plants as fertiliser. There is however 

and on-going debate about the pollutants in sludge. The 

national organisation for co-operation between water and 

wastewater utilities has launched a system for control of 

sludge quality for reuse in agriculture, and the Swedish 

national farmers’ association is positive regarding the 

use of quality controlled sludge as fertiliser. However, the 

farmers’ association has stated that they prefer sourceseparated 

urine and blackwater, and that Sweden should 

adopt a long term strategy for the conversion of conventional 

wastewater systems to source-separating systems. 

Figure 2. Toilet seat with urine-diversion (Sweden, picture 

provided by Ebba af Petersens). 

65

66 


The Netherlands 

Since early 2000’s several “new sanitation” projects 

have been demonstrated in The Netherlands. Projects 

comprise both urine diversion and separation of black 

water and grey water. Projects are in general community 

(building)-on-site. An overview of different projects is presented 

at http://themas.stowa.nl/Themas/New_sanitation. 

aspx?rID=1002 and http://www.desah.nl/. 

Demonstration and research go hand in hand from the 

beginning and Wageningen University and other universities, 

the Centre of Excellence for Sustainable Water 

Technology (WETSUS), various companies, municipalities, 

water boards and the Dutch umbrella organisation 

for the Water Boards (STOWA), are strongly involved in 

research, demonstration and implementation. The cooperation 

between organisations with different expertise and 

the successful demonstration at a relevant scale resulted 

in an increasing interest in ‘new sanitation’ from the various 

stakeholders. 

Nowadays new housing developments adopt one of two 

approaches to sanitation. These approaches include 

either community–on-site collection, transport, treatment/ 

recovery and reuse of black water and grey water based 

on vacuum technology for black water (also referred to as 

DeSaR= Decentralised Sanitation and Reuse) or community-on–site 

collection of urine, combined with centralised 

treatment of the remaining wastewater stream and (semi)centralised 

recovery of nutrients and removal of pharmaceuticals 

from urine. The DeSaR concept is demonstrated 

at a scale of 32 houses since June 2006 and now applied 

in Wageningen in a new offi ce building of the Institute 

for Ecology (NIOO) and is under construction in a housing 

estate of 250 houses in Sneek. The same concept is 

also applied in a school in the Ukraine. Within the DeSaR 

concept, biogas is produced from black water. The liquid 

anaerobic effl uent contains the major part of the nutrients. 

Phosphate is recovered as struvite and nitrogen is 

removed with anammox processes. In the NIOO building, 

nitrogen and phosphorus will be recovered with the growth 

of algae. 

In the beginning of 2011, the fi rst full scale Saniphos unit 

for recovery of nitrogen (ammonium sulphate) and phosphorus 

(struvite) from urine was opened. In addition, urine 

from large festivals is collected and treated for resource 

recovery. 

Several aspects can be indicated as driving force for “new 

sanitation” in The Netherlands: (i) Water boards agreed 

on an energy reduction for wastewater treatment of 30% 

in the period 2005-2020. (ii) Phosphate is increasingly 

recognised as a limiting nutrient. Recently the Nutrient 

Platform was established with a focus on increasing the 

attention for the Phosphate problems. (iii) Sewers have to 

be renewed in the coming future; and (iv) Pharmaceutical, 

hormones and personal care products in domestic wastewater 

are increasingly recognised as a potential problem 

for the environment and human health. 

Germany 

In 2002, the German Water Association (DWA, formerly 

ATV-DVWK) established a working group on new 

sanitation concepts (in German also referred to as Neuartige 

Sanitärsysteme or NASS). NASS concepts are defi ned 

as those that go beyond traditional water-borne sanitation 

with the main aim to recover and reuse resources. The 

working group has the goal to systematically summarise 

technologies and experiences with different NASS concepts. 

As part of the work a guideline on planning and 

implementation of NASS concepts was prepared and will 

be published soon as “DWA Arbeitsblatt”. It is expected 

that the new guideline will allow easier implementation 

of resources-oriented sanitation concepts especially in 

German speaking countries. 

Figure 3. Design for the technical building of the 250 

houses under construction in Sneek, The Netherlands, 

picture provided by Grietje Zeeman). 


It is diffi cult to give a general global view on the trends 

and challenges for resources-oriented sanitation, since 

drivers and technologies differ throughout the world. In 

parts of the world where artifi cial fertilisers are excessively 

expensive, nutrient recovery from sanitation systems is an 

important driver for the development of resources-oriented 

sanitation systems and also a driver for investment in 

improved sanitation (as shown by examples above). However, 

there is a great need to spread the knowledge about 

resources-oriented sanitation solutions, which will create 

a demand among users for these systems. It is generally 

agreed that resources-oriented sanitation benefi ts food 

security and that there is a monetary value of reuse. This 

economic argument could then be used to lobby decisionmakers. 

It is often forgotten that with a safe handling system 

including sanitation for all recycled products, then far 

less pathogens will be spread in the environment than with 

the present system. 

In Europe, where artifi cial fertilisers are still cheap and 

readily available, the economic incentives for reuse of 

nutrients from wastewater are low and the development 

of resources-oriented sanitation solutions is driven by 

a consciousness that conventional wastewater systems 

may not be sustainable in the long term. Regulations 

on wastewater management and fertiliser use in many 

countries, as well as on a European Union level, are not 

adapted to resources-oriented sanitation and thus make 

it diffi cult to implement these systems. If EU-regulations 

on fertilisers for organic farming would allow sanitised 

urine and black water, there would be a great interest 

among organic farmers for these fractions. In Sweden 

a new regulation on handling of wastewater fractions,

including urine and blackwater, is under way, which sets 

requirements regarding hygenisation, heavy metal content, 

etc., and facilitates the use of these fractions on 

arable land. 

A lot of knowledge on how to install and manage urine 

diversion and blackwater separation systems has been 

gained in research and pilot projects, but this knowledge 

needs to be transferred to implementers, technicians, 

municipalities, etc. Toilet design needs improvement, but 

the market today is far too small for the manufactures to 

invest in product development, and without a better toilet 

design it is diffi cult to attract a bigger market. There is also 

a lack of economic incentives for home owners, farmers 

and other stakeholders. 

If existing infrastructure for conventional water-borne sanitation 

exists an abrupt change to resources-oriented sanitation 

is not realistic. Therefore a strategy for a gradual (50 

years) transition from conventional to resources-oriented 

sanitation should be developed. New settlements and 

those parts of the old system that have to be renewed can 

be converted to resources-oriented concepts more easily. 

Additionally, the development of guidelines on planning 

and implementation of resources-oriented sanitation 

concepts from an organisation well-accepted among engineers 

(such as the DWA in Germany) shall contribute to 

more widespread implementation of resources-oriented 

systems. 

Conclusions (and outlook) 

In view of the immense problems arising from global population 

growth, urban development and climate change 

on a global scale, a paradigm change of sanitation and 

excreta management is necessary. Source diversion is 

a promising concept for achieving resource effi ciency in 

wastewater management, but it will take a large effort of 

research and technical development in order to develop 

competitive technologies. For rural areas, a large number 

of technologies are available, but compact, attractive technologies 

for urban areas are missing. One main challenge 

of source diverting technologies is the requirement for 

decentralised, complete solutions. With more wastewater 

fractions, the transport issue becomes critical and at the 

same time, several technologies must be implemented. At 


the moment, most practical research takes place in rural 

areas of developing countries, because there is a huge 

demand on implementation of sanitation systems. Besides 

technological challenges, e.g. lack of attractive source 

diverting toilets for urban areas, the importance of including 

soft factors (e.g. operation and maintenance) already 

in the planning process for a sustainable implementation 

has to be stressed. 

Another important factor for achieving a paradigm shift, 

for designing the new wastewater systems for the 21st 

century and beyond including resource-effi ciency, is 

an urgent need for the wastewater sector to think about 

problem-solving and product-adapting in both ends of the 

waste water chain. There is a consumer also at the end, 

the farmer, and her/his demands on the nutrients from the 

society, its quality and availability should lead the development 

of new, innovative resources-oriented sanitation 

systems. An increased understanding of the farmer as 

a client rather than an alternative to a landfi ll for today’s 

sludge would create a new platform where it is more likely 

that resources from the society can be reused safely in 

agriculture with a high acceptance. It makes all the sense 

in the world for the wastewater sector to look at the waste 

sector where source diverting and composting of organic 

household waste is quite commonplace these days, where 

large-scale trials to create a compost from mixed household 

waste seem out-dated. If the toilet fraction of the 

wastewater, the blackwater or urine and faeces separately, 

would be kept separately it is logical that the equivalent 

development of an accepted reuse of the high nutrientcontaining 

wastewater fractions could be achieved. 

The technical part of the system needs to be functioning 

fl awlessly in order for complete acceptance in the long run 

and there is a need for client thinking also in the end of 

the chain. However, a fully functional technical system is 

not the only key to full acceptance of resources-oriented 

sanitation. Nothing will happen on a larger scale without 

political buy-in and active steering in the sector. The wastewater 

sector, being heavy on infrastructure, is conservative 

and to achieve a paradigm shift in such a sector some 

fi rm, high-level political decision-making is necessary. 

Thus what is ultimately needed for achieving the paradigm 

shift is political boldness to lead and push for the shift, as 

well as technological, innovative and managerial boldness 

within the wastewater sector. 

67

68 


Decentralised wastewater 

management: an overview 

Prepared by the Specialist Group on Sanitation and Water Management in Developing Countries 

of the International Water Association 

Introduction 

Wastewater management (WWM) is important for minimisation 

of health and environmental risks. However, there 

is lack of adequate WWM services and inadequacies in 

institutions, particularly in developing countries, which 

often exposes populations to water related diseases and 

environmental pollution. As WWM requires substantial 

fi nancial resources it is important to fi nd cost-effective 

solutions, and decentralised WWM may thereby be such a 

cost-effective solution. 

This document discusses the basic concept and rational 

of decentralised WWM, the different technical options for 

it and gives suggestions on how to identify and assess 

whether a decentralised system is favorable over a 

centralised one. 

Definition 

In contrast to centralised wastewater treatment, characterised 

by the use of one centralised wastewater treatment 

plant (WWTP) for the largest possible confi ned catchment 

area in a region, decentralised wastewater management 

usually refers to dividing the largest possible catchment 

area into smaller regions having separate wastewater 

treatment plants. The terms “centralised” and “decentralised” 

do not therefore necessarily correspond to the 

terms “large” and “small”, but to “larger” and “smaller”, 

as illustrated in Figure 1. The smallest possible decentralised 

system would be on-site systems serving individual 

households. 

Rational for decentralised WWM 

The choice between centralised or decentralised WWM 

is usually determined by site-specifi c conditions concerning 

whether there are any restrictions for the centralised 

solution or whether constructing several smaller WWTP 

has any advantages over constructing the largest possible 

(centralised) WWTP. 

Possible restrictions for centralised WWM 

• Higher costs in areas of low population density and /or 

scattered settlement and/or under certain topographic 

conditions. 

• Public opposition or resistance. 

• Financial limitations. 

• Institutional limitations. 

Possible advantages for 

decentralised WWM 

Figure 1. Centralised and decentralised WWM (WWTP: Wastewater Treatment Plant) 

• Economic advantages for areas with low population density 

and/or scattered settlement and/or under certain 

topographic conditions. 

• Better public participation and acceptance. 

• More appropriate to the local context and needs. 

• Less restrictions for piloting innovative technologies. 

• Better utilisation of “value-products” of wastewater (e.g. 

nutrients, energy or reuse of treated wastewater). 

• Potential for lower energy use/carbon footprint due to 

reduced need for pumping. 

• Better adaptation to rapid urban growth.

Technological options for 

decentralised wastewater 

management 

Concepts 

A decentralised wastewater management system consists 

of either a collection and a storage/disposal system, or a 

collection and a wastewater treatment system. The former 

is usually applied at on-site (household) level, and the latter 

is usually applied at the off-site (communal) level. At 

the communal level two cases can be distinguished: either 

a public toilet system with a (on-site) wastewater treatment 

plant, or a sewerage system which collects the wastewater 

from several households and conveys the wastewater 

to a wastewater treatment plant. There are several household 

and communal sanitation options available and a 

basic classifi cation based upon on-site, off-site and water 

demand is shown in Table 1 below. 

Sewerage system 

Four types of sewerage systems can be identifi ed as 

options for a decentralised wastewater collection system: 

• Conventional sewerage system. 

• Simplifi ed sewerage system. 

• Pressure sewerage system. 

• Vacuum sewerage system. 

For developing countries the simplifi ed sewerage system is 

likely to be most appropriate. 

Wastewater treatment system 

For those concepts that require a waste water treatment 

system several options are available. A wastewater treatment 

system usually comprises primary, secondary and 

tertiary treatment steps, depending on the required effl uent 

quality. Individual treatment systems may be classifi ed 

as follows: 

Table 1. Overview of household and communal sanitation options 

On-site 

Toilet 


• Natural Treatment Systems: This covers treatment 

systems that are based on natural systems such as 

constructed wetlands or wastewater treatment ponds. 

• Built Treatment Systems: These systems can basically 

be divided into aerobic and anaerobic systems. Aerobic 

systems include conventional activated sludge systems, 

trickling fi lters, oxidation ditch, rotating bed reactors 

and membrane bioreactors. Anaerobic systems include 

anaerobic fi lters, biogas-plants, anaerobic baffl ed 

reactors (ABRs) and upfl ow anaerobic sludge blanket 

reactors (UASBs). 

• Physical/Chemical treatment systems: These systems 

include primary sedimentation, chemical coagulation/ 

precipitation and fi ltration. 

• Combined Treatment Systems: Usually a combination of 

different treatment systems has to be applied to achieve 

the required effl uent quality. 

The selection of appropriate treatment systems depends 

on the one hand on the type of wastewater to be treated 

(eg blackwater, greywater, or both) and on the other on the 

required effl uent treatment quality. Further, several other 

aspects, in particular land requirements, energy demand 

and operation and maintenance requirements need to be 

considered when selecting a treatment system. 

Assessment 

Decentralised wastewater management options are favourable 

if topographic conditions determine that no centralised 

system is feasible, or if a decentralised system shows 

any of the following advantages that outweigh any advantages 

of a centralised system as indicated earlier. 

Hence, if it is not obvious that a decentralised option 

is clearly preferable, then a feasibility study should (a) 

compare both centralised and decentralised options and 

(b) identify the optimal level of decentralisation (i.e. if 

the largest or the smallest possible decentralised options 

should be selected or any options in between) and the 

type of most suitable decentralised wastewater management 

system. 

Water demand 

Low Medium High 

Pit latrines Pour fl ush toilets + pit latrines Flush toilets + septic tanks 

Composting toilets Pour fl ush toilets + septic tanks Aqua privy 

Dry urine separation toilets + 

storage units 

Wet urine separation toilets + 

treatment system 

Greywater Soak pit and infi ltration 

Septic tank 

Off-site Most above options but with public toilets (off-site with respect to the households) 

Flush toilets/Greywater + 

sewerage system + 

treatment system 

69

70 


Content of a good feasibility study 

A good feasibility study for comparing centralised with 

decentralised wastewater management options should 

investigate the following aspects: 

• Technical feasibility. 

• Costs. 

• Environmental aspects. 

• Social, socio-economic and fi nancial aspects. 

• Institutional aspects. 

Technical feasibility 

Topographical and other local factors will need to be surveyed 

in order to clarify which concepts and technologies 

are technically feasible and can be maintained sustainably 

at the local level. 

Costs 

A cost estimation should encompass the investment and 

the O&M costs for at least 10–15 years. Capital investment, 

re-investment, annual recurring costs (O&M), and 

benefi ts should be quantifi ed to select economically viable 

technologies. The O& M cost may include the personnel 

and material cost for regular operation, repair and maintenance 

work, costs for energy and other consumables. 

The economic benefi ts associated with the technology 

such as biogas, fertilisers or water for reuse should also 

be calculated. At the feasibility stage, the various options 

for sanitation technology can be compared with the total 

net present value (NPV). A NPV calculates future investment 

and operation costs for a certain time span using a 

discount rate, which trades off present capital and future 

running costs and benefi ts (a shorter time span and 

higher discount rate give less weight to future costs and 

benefi ts). 

Environmental aspects 

What is the required effl uent quality of the treated wastewater? 

Where can effl uents be discharged? Are there any 

hygienic concerns? Benefi ts of side products such as 

biogas, fertiliser or reused water shall be considered under 

the cost calculation. Note, however, that those aspects 

may also be considered under environmental aspects if 

required (e.g. if saving of water is an environmental goal). 

Social, socio-economic and financial 

aspects 

Involvement of the future users and stakeholders is a key for 

successful planning. Further the affordability and options 

for fi nancing of the system should be investigated and a 

fi nancing plan prepared. Thereby, the full range of public 

and private fi nancing sources should be considered. 

Institutional aspects 

Arrangements for O&M as well as any arrangement for 

public-private partnerships (PPPs) should be investigated 

in the light of the required capacity for operating 

and fi nancing the system. Issues of monitoring and control 

should be considered. 

Conclusions 

Decentralised wastewater management can be a viable and 

cost-effective solution and should be considered whenever 

possible. It covers a large variety of options and also 

includes mixed approaches such as partly decentralisation 

or decentralisation of some elements and at the same time 

centralisation of others. As an example, whereas certain 

wastewater fractions may be collected locally they may be 

treated centrally (e.g. centralised sludge treatment). 

Various options should be considered and a comprehensive 

feasibility study should identify which is the best 

level or mix of decentralised and centralised wastewater 

management. 

Acknowledgements 

The following members of the Specialist Group have contributed 

to and/or reviewed this document: 

Dr. David Baguma, United Nations University 

Dr. Walter Betancourt, Instituto Venezolano de Investigaciones 

Cientifi cas 

Mr. Jaime L. Garcia-Heras, CEIT, Spain 

Ms. Ayesha I. Davis, The Luis Berger Group, Panama 

Dr. Vikram M. Pattarkine, PEACE USA, USA 

Mr. Bill Peacock, Halcrow, India 

Dr. Michael D. Smith, WEDC, Loughborough University, 

UK 

Mr. S. Vishwanath, independent consultant, India 

Dr. Juliet Willets, University of Technology Sydney, 

Australia 

Prof. Zukifl i Yosop, University Technology Malaysia, 

Malaysia 

+ Markus, Hamanth, Jonathan


Sludges, residuals and biosolids: 

global trends and challenges 

Written by S. Dentel on behalf of the Specialist Group 

Introduction 

Sludges are the result of water and wastewater treatment, 

including industrial wastewater. The accumulated sludges 

can essentially be considered as the materials removed 

from the water in a more concentrated form, with the exception 

of biomass grown in biological processes intended to 

biodegrade pollutants. Quantities and associated costs 

can be considerable. For example, wastewater plants in 

the USA treat about 120 million cubic meters of wastewater 

per day, at a cost exceeding $13 billion per year. 

The cost of managing the resulting sludges is 30–50% 

of this amount. US wastewater treatment also requires 

an estimated 21 billion kilowatt hours of energy per year, 

and again the sludge processing requires 30–50% of this 

amount. Thus sludge represents both an economic and 

environmental concern of considerable importance. Properly 

managed, it may also be a signifi cant resource. 

Existing Knowledge 

The above estimate of sludge amounts in the USA comes 

from a survey conducted by the North East Biosolids and 

Residuals Association (NEBRA 2007). It is believed to be 

more accurate than previous estimates, which were primarily 

based on calculations from wastewater fl ows rather 

than actual solids amounts. These numbers are thus 

reported here as the most accurate available, and from the 

country generating the largest amount of sludge. However, 

estimates have recently provided for many other countries 

as well (LeBlanc et al. 2008; Spinosa 2011). 

The NEBRA survey estimated that about 55% of US biosolids 

are put to “benefi cial use”, meaning any intentional 

use in order to improve soil characteristics, such as nutrient, 

organic, or structural properties (Figure 2.1). This 

includes agricultural use on farmlands; distribution to the 

public as biosolids qualifying for landscaping; horticulture 

and agriculture; and other uses, such as land restoration 

in surface-mined areas) or in silviculture (woodlands). In 

the “non-benefi cial” (disposal) categories were disposal in 

municipal solid waste landfi lls or as landfi ll cover, dedicated 

surface disposal sites, and incineration. These amounts are 

mainly refl ective of practices at larger treatment facilities 

(>0.044 m 3 /s), which comprise under 20% of all installations 

but over 92% of treated fl ow. Minor facilities are more 

likely to store biosolids in lagoons for long periods before 

land application, or use less elaborate or expensive methods, 

such as landfi lling. They may also transport their untreated 

solids to larger treatment facilities for management. 

Land application of biosolids is also widely practised in 

Australia, Brazil, some provinces of Canada, and some of 

the less densely populated countries of Europe. The substantial 

masses of biosolids being applied to land globally 

lead to ongoing questions about health and ecological 

risks associated with this practice, as described later. 

Figure 1. Breakdown of biosolids use in the USA according to 2007 NEBRA study. Illustration from Dentel (2011). 

71

72 


In more populated regions of the developed world, various 

types of thermal oxidation are more commonly practised 

(Spinosa 2011). In this case, the energy value from the 

sludge can be recovered, but this is only signifi cant if the 

sludge has been well dewatered. Thermal oxidation may 

offer the opportunity to recover phosphorus for use as a 

fertiliser, although the technology is unproven to date. It 

would also preclude co-incineration with less P-rich materials 

such as solids waste. 

Quantifi ed surveys on stabilisation and dewatering practices 

are not available for most countries. In the USA, 

data are available from the 2007 NEBRA survey, shown in 

Figures 2 and 3. Percentages based on numbers of installations 

differ from those according to biosolids amount, 

because smaller facilities are more likely to use less complex 

processes such as aerobic digestion and belt fi lter 

press dewatering. Larger treatment plants are more likely 

to utilise anaerobic digestion, centrifugation and composting. 

Thus, even though many facilities employ aerobic 

digestion, larger facilities use anaerobic digestion and 

composting. Likewise, only 11% of the facilities dewater by 

centrifugation, but this method is applied to roughly half 

of all biosolids that are dewatered. By number or by mass, 

over 90% of all dewatering is by centrifugation, belt fi lter 

press or drying beds. Dewatering is a key step in economic 

sludge processing if drying, incineration or signifi cant 

transportation are to be practised. 

Outside the USA, mesophilic anaerobic digestion appears 

to be the main type of biological stabilisation for large 

treatment facilities. The exception is China, which has 

not included digestion in its programme for development 

of large treatment facilities (Xu 2011). For dewatering, it 

appears that fi lter presses and belt fi lters are more frequently 

utilised than are centrifuges (e.g. Cisneros 2011; 

Snyman 2011). Drying beds are more common in the 

developing world. Composting and landfi lling are also 

favoured in countries where more complex processes are 

impractical. 

Future trends in sludge processing are tied to economic 

development. The most rapid growth in sludge quantities 

and management is expected in China (Xu 2011), with 

growth also in South Korea as ocean disposal is eliminated, 

and in Turkey as it works toward EEC environmental 

standards. 

General trends and Challenges 

Concerns with land application 

In regions using land application, there is widespread concern 

(e.g. NRC 2002) about “emerging contaminants” in 

sewage sludge. Improved risk assessment methodologies 

are sought to better establish standards for these constituents. 

Studies (Viau et al. 2011) also suggest that risks from 

“emerging pathogens,” such as norovirus, may be much 

greater than estimated based on the commonly monitored 

bacterial indicators such as faecal coliform. This will lead 

Figure 2. Dewatering operations by type (NEBRA 2007). Number of operations based on responses from 50% of states, 

sludge masses based on 25% of all states. 

Figure 3. Stabilisation operations by type (NEBRA 2007). Number of operations based on responses from 50% of states, 

sludge masses based on 25% of all states.

to inclusion of new or emerging contaminants or pathogens, 

or different indicator organisms for monitoring pathogen 

levels. 

The controversy regarding contaminants in land-applied 

biosolids is unlikely to end regardless of specifi c limitations 

on contaminant levels. The presence of contaminants at 

any detectable levels has been used to support the term 

“toxic sludge” (e.g. SourceWatch.org 2010). Detection of 

synthetic organic contaminants in sludge-derived compost 

at ppb and low ppm levels (PRWatch.org 2010) was also 

used to support the “toxic sludge” label (e.g. PBDEs at 

731 ng/g; triclosan 1312 ng/g; nonylphenol 7065 ng/g). 

Numerous web sites can be located devoted solely, and 

vociferously, to the prohibition of land application of biosolids, 

declaring that “sewage sludge is poison”. 

Careful and comprehensive characterisations of organics 

in sludge have been completed recently. The US EPA 

conducted a “Targeted National Sewage Sludge Survey” 

(2009) of 84 different samples, measuring for metals, 

polyaromatic hydrocarbons and other semi-volatile organics, 

inorganic anions, polybrominated diphenyl ethers, 

and 97 pharmaceuticals, steroids, and hormones. Bis 

(2-ethylhexyl) phthalate was found in all samples, in concentrations 

up to hundreds of mg/kg. Some PBDE congeners 

were in the mg/kg range. Twenty seven metals 

were found in virtually every sample. Three pharmaceuticals 

(cyprofl oxacin, diphenhydramine and triclocarban) 

were found in all 84 samples, and nine were found in 

at least 80 of the samples. Three steroids (campesterol, 

cholestanol and coprostanol) were found in all samples, 

and six steroids were found in at least 80 of the 

84 samples. However, these results refl ect not only the 

number of chemical constituents in sludges, but also the 

acute sensitivity of contemporary analytical methods and 

equipment. 

Another study (McClellan and Halden 2010) used 110 

archived EPA biosolids samples, combined to create fi ve 

“mega-composites” from which to obtain an averaged 

value of 72 sludge constituents. Triclocarban and triclosan 

were found at the highest concentrations, 36±8 and 

12.6±3.8 mg/kg, respectively. The study concluded that 

biosolids recycling is a “signifi cant mechanism” for the 

environmental release of pharmaceuticals and personal 

care products. 

In the USA, incineration of sewage solids will fall under 

more stringent Clean Air Act standards if the EPA’s proposed 

classifi cation as a solid waste is approved (USEPA 

2010). This will not eliminate thermal oxidation as an 

option, but will increase costs where outdated furnaces 

may be in use. The same trend may ensue elsewhere. 

Process trends and challenges 

Technology development worldwide has focused mainly on 

reducing sludge masses and/or producing biosolids with 

Class A or equivalent properties. Traditional composting is 

waning as a stabilisation option for larger US cities, in part 

due to operating costs, and also to odours. Aerobic thermophilic 

digestion processes have been of interest, but 

poor dewaterability and an unfavourable energy balance 

may limit further implementation. Thermophilic digestion 

processes are gaining attention because they can also 


produce well stabilised biosolids. The mechanisms of 

pathogen destruction in these processes are undergoing 

increasing scrutiny in order to assure reliability and prevent 

regrowth. 

Drying and pelletising technologies are of increasing interest 

in providing a usable product without the operating 

complexities of composting. Drying can be based on either 

direct or indirect heating methods, and the processes are 

often of a proprietary nature (e.g. microwave heating). Pelletising 

offers the aesthetic qualities of composted sludge 

with a more controlled production process. The process 

reliability and fl exibility are combined with a lower process 

“footprint”. Potential drawbacks are the varying sise, nutrient 

quality, odour and other properties of different pellet 

types. The costs of drying and pellet production are, of 

course, linked more closely to energy expenses than in the 

case of composting. 

Technology trends and challenges 

Many emerging technologies for sludge management were 

reviewed by the EPA (USEPA 2006). The technologies 

were classifi ed as “established,” innovative” (new, but with 

some pilot or full scale experience), or “embryonic” (in the 

development or lab stage in the USA). Table 9.1 lists the 

innovative technologies and the potential benefi ts. The 

greatest number of these is in the categories of stabilisation 

and dewatering. 

Of these processes, one of signifi cant interest is the 

Cambi TM thermal hydrolysis process, because the Blue 

Plains wastewater treatment plant in Washington, D.C. is 

currently constructing four of these process trains with a 

410 dry tonne per day total average capacity. The system 

will be augmented by burning digester gas in turbines to 

provide both power and heat, the latter being used for the 

Cambi process. Completion is scheduled for 2014. 

One process, called SlurryCarb®, was indicated in the 

EPA study to be “embryonic”, but would now be classifi ed 

as innovative. This process, developed by Atlanta-based 

Enertech Environmental, pressurises sludge above its 

saturated steam pressure and raises the temperature to 

effect oxidation of organic material. Most water is maintained 

in the liquid state to avoid energy expenditures 

of evaporation (Dickinson et al. 2006). The processed 

sludge is amenable for use as a fuel, and it is claimed that 

overall process produces about twice as much energy as 

it consumes (Enertech 2008). Supported by Mitsubishi, a 

demonstration plant was successfully operated in Japan, 

and a full scale plant commissioned in Rialto, California 

in 2009. 

Another management option being explored in the USA 

is deep well injection of sludge, currently being studied 

in Los Angeles, injecting 400 wet tons per day to a depth 

of 1700 m (Sanin et al. 2011). The sludge generates 

methane through thermophilic anaerobic digestion, which 

is then to be recovered as a fuel. The gas composition, 

according to lab tests, should be over 90% methane due 

to solubilisation of the carbon dioxide at the high pressure 

(150 atm), yielding over 90% methane in the collected 

gas. Because the nondegradable carbon and the 

CO 2 remain underground, the practice is also viewed as 

carbon sequestration. 

73

74 


Innovative Technology and Advancement 

Conditioning 

Microsludge TM Conditioning 

(chemical destruction of cells) 

Ultrasonic 

Thickening 

Flotation thickening – anoxic gas 

Membrane thickening 

Recuperative thickening 

Stabilisation 

Aerobic/anoxic 

Anaerobic baffl ed reactor (ABR) 

Columbia biosolids fl ow-through thermophilic ttmnt 

High rate plug fl ow (BioTerminator 24/85) 

Temperature phased anaerobic digestion (TPAND) 

Thermal hydrolysis (CAMBI TM Process) 

Thermophilic fermentation (ThermoTech TM ) 

Three-phase anaerobic digestion 

Two-phase-acid/gas anaerobic digestion 

Vermicomposting 

Dewatering 

Quick dry fi lter beds 

Electrodewatering 

Metal screen fi ltration - inclined screw press 

Bucher hydraulic press 

DAB TM system 

Geotube® container 

Thermal Conversion 

Reheat and oxidise (RHOX) 

Supercritical water oxidation 

Minergy - vitrifi cation 

Drying 

Belt drying 

Direct microwave drying 

Flash drying 

Fluidised bed drying 

Other 

Cannibal TM process 

Lystek 

Injection into cement kiln 

Potential PotentialBenefitRelativetoEstablishedTechnologies 

Benefi t Relative to Established Technologies 

Low L Capital Cost 

Low L Annual 

Costs C 

Reduces R Solids 

or o Thickens 

Produces P Class A 

Biosolids B 

Reduces R Odour 

Benefi B cial Use 

(non ( Agriculture)

Research trends and challenges 

As indicated above, concerns with sludge/biosolids constituents 

are ongoing in the USA. Controversies have included 

the possible risks from dioxins, furans, and co-planar 

PCBs, which the EPA decided not to regulate after a reassessment 

completed in 2003. Antimicrobials, ibuprofen, 

caffeine, plasticisers, fl ame retardant chemicals, endocrine 

disruptors and antibiotics are nearly ubiquitous in 

biosolids. The decision to include many additional sludge 

constituents in the Targeted National Sewage Sludge 

Survey (USEPA 2009) provides additional knowledge of 

concentrations, but not of exposure or risk levels. 

Pathogen reactivation and regrowth are questions of growing 

concern, although this has been based on indicator 

organism (faecal coliform) measurements to date. The 

reactivation can occur when sludge is processed through 

thermophilic digesters and dewatered by high-speed centrifuge. 

Research also indicates that centrifugal dewatering 

can exacerbate faecal coliform regrowth following stabilisation, 

e.g. during storage or transportation, which means 

that the densities determined after stabilisation do not 

refl ect levels when the material is released of plant custody 

(Qi et al. 2004). For the many plants using PSRP (process 

to signifi cantly reduce pathogens), faecal coliform measurement 

is not required but the discrepancy still underlies 

the use of PSRP. The regrowth/reactivation phenomenon 

is being studied so that its implications can be addressed 

in future regulations and practices. Additional indicator 

organisms are clearly needed to refl ect the diverse levels of 

pathogen resistance to treatment processes (Viau 2011). 

Studies of odour sources and mechanisms are also 

ongoing. Standardised methods of quantifying odours will 

be needed if any limits are to be added to biosolids regulations. 

However, odours have yet to be clearly correlated 

with health or ecological harms (Viau 2011). 

Selected “hot topics” 

Near-term challenges in sludge management will centre 

around topics such as the following: 

Dewatering of wastewater sludges: Approximately 50% of 

the energy content in wastewater is still contained in the 

sludges that have been generated in purifying the water. 

In addition, the sludge contains much less water relative 

to the combustible or biodegradable matter. However, for 

thermal treatment to extract this energy, even more water 

must be removed so that its heat of vaporisation does 

not negate the heat of combustion of the organic matter. 

Effi cient dewatering is thus cost effective, and this is the 

case for other treatment options, e.g. when transportation 

of the sludge solids (and water) are necessary. However, 

current dewatering processes cannot easily exceed 35% 

solids except with prohibitive process times or energy 

input. Research into improved dewatering processes, or 

into pretreatment processes that signifi cantly improve 

dewaterability, is economically attractive. A gamut of physical, 

chemical, and biological processes are being trialled 

globally; many of these are listed in Table 8.1. 

Energy extraction from liquid sludges: An alternative to 

high-level dewatering is the development of methods for 

energy extraction from the liquid sludge before thicken- 


ing or dewatering. Methods for signifi cantly enhancing 

anaerobic digestion effi cacy are being sought worldwide to 

increase the yield of methane as an energy-rich product. 

A recently developed technology known as the microbial 

fuel cell is another means, which could produce signifi cant 

amounts of electricity directly from sludge (Dentel et al. 

2004). Research is currently focused on using this process 

for wastewater treatment, but its use on sludge would 

avoid meeting of effl uent standards while still having signifi 

cant energy potential. 

Sustainability and sludge treatment: Some municipalities 

are initiating greenhouse gas inventories (e.g. Willis 2010) 

which help establish a “triple bottom line” basis for design 

and operational decisions in wastewater treatment facilities, 

including sludge and biosolids management. Operationally, 

this means that the nutrient value, energy value, and greenhouse 

gas contributions of sludges must all be balanced, 

or counterbalanced, in determining the most environmentally 

conscionable management scheme. Important future 

decisions on sludges will be made on this basis, but the 

methodologies for doing so are yet to be established and 

commonly accepted. In principle, even the environmental 

risks from emerging pathogens and contaminants must be 

incorporated in any such methodology. 

Concluding remarks 

Two trends in sludge management are countervailing: 

greater concern about its potentially harmful constituents, 

but greater awareness of its nutrient and energy values. 

How these are reconciled will depend on public and governmental 

prioritisations, but also on whether suitable 

technologies are developed and accepted to meet these 

issues with acceptable solutions. 

References 

Cisneros, B.J. (2011) Mexico. In Wastewater sludge: a global 

overview of the current and future prospects. 2nd ed. IWA 


Dentel, S.K. (2011) United States. In Wastewater sludge: a global 



Dentel, S.K., Strogen, B., and Chiu, P.C. (2004) Direct generation 

of electricity from sludges and other liquid wastes. Water 

Sci. Technol. 50(9), 161–168. 

Dickinson N.L., Bolin K.M., Overstreet E. and Dooley B. (2006). 

Slurry dewatering and conversion of biosolids to a renewable 

fuel, U.S. Patent application 20060096163. 

EnerTech Environmental (2008). The Slurry-Carb Process, 

Renewable Energy from Biosolids, http://www.enertech. 

com/downloads/SlurryCarbOverview.pdf. 

LeBlanc, R., Matthews, P. and Richard, R.P. (2008) Global Atlas 

of Excreta, Wastewater Sludge, and Biosolids Management: 

Moving Forward the Sustainable and Welcome Uses of a 

Global Resource. UN Human Settlements Programme (UN- 

HABITAT). 

McClellan, K. and Halden, R.U. (2010). Pharmaceuticals and 

personal care products in archived US biosolids from the 

2001 EPA national sewage sludge survey. Water Research 

44(2), 658–668. 

National Research Council (2002). Biosolids Applied to Land. 

Advancing Standards and Practices. National Academies 

Press: Washington, D.C. 

NEBRA - North East Biosolids and Residuals Association (2007). 

A National Biosolids Regulation, Quality, End Use & Disposal 

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Survey. NEBRA, Tamworth NH, USA. www.nebiosolids.org/ 

uploads/pdf/NtlBiosolidsReport-20July07.pdf. 

NEBRA - North East Biosolids and Residuals Association (2010). 

Information Update: US EPA Defi nes Sewage Sludge as 

Solid Waste. www.nebiosolids.org/uploads/pdf/Info-EPA- 

Defi nesSludge-May10.pdf. 

PRWatch.org (2010). San Francisco’s Free Organic Biosolids 

Compost is Toxic Sludge, and Not Good For You!. www. 

prwatch.org/taxonomy/term/106. 

Qi Y.N., Gillow S., Herson D.S. and Dentel S.K. (2004) Reactivation 

and/or growth of fecal coliform bacteria during centrifugal 

dewatering of anaerobically digested biosolids. Wat. Sci. 

Tech. 50(9), 115–120. 

Sanin, F.D., Clarkson, W.W., and Vesilind, P.A. (2011) Sludge 

Engineering. DEStech Publications, Lancaster PA-USA. 

SourceWatch.org (2010), Breaking News on Toxic Sludge. www. 

sourcewatch.org/ index.php?title=Portal:Toxic_Sludge. 

Snyman, H.G. (2011) Africa. In Wastewater sludge: a global 



Spinosa, L., ed. Wastewater sludge: a global overview of the current 

and future prospects. 2nd ed. IWA Publishing, London. 

USEPA (2006). Emerging Technologies for Biosolids Management, 

Washington, D.C., EPA-832-R-06–005. 

USEPA (2009). Targeted National Sewage Sludge Survey, 

Washington, D.C., EPA-822-R-08–014. 

USEPA (2010). Identifi cation of Non-Hazardous Materials That 

Are Solid Waste: Proposed Rule, www.epa.gov/epawaste/ 

nonhaz/defi ne/index.htm#proposed. 

Viau, E., Bibby, K., Paez-Rubio, T. and Peccia, J. (2011) Toward a 

consensus view on the infectious risks associated with land 

application of sewage sludge. Environ. Sci. Technol. 45(13), 

5459–5469. 

Willis J. (2010). Example Using the Local Governments 

Operations Protocol at DCWASA, MABA Workshop on 

Greenhouse Gas Accounting for Wastewater Treatment & 

Biosolids Management, Eatontown, N.J., www.mabiosolids. 

org/ uploads/pdf/conferenceproceedings. 

Xu, G. (2011) China. In Wastewater sludge: a global overview of 

the current and future prospects. 2nd ed. IWA Publishing, 

London.

Statistics and Economics 


Water pricing policies in situation of water scarcity and in maintaining 

access to water - improving and enlarging statistical information 

Written by Ed Smeets on behalf of the Specialist Group 

Introduction 

One of the dimensions of the water crisis is the rarefaction 

of available resources in comparison with needs. In this 

context, well-designed pricing policies are major regulatory 

tools to induce water savings behaviour and to preserve 

fi nite freshwater resources. 

A complementary aspect of this issue refers to 

waste water recycling and seawater desalination. In a 

context of growing scarcity, alternative resources have 

an enormous potential: on a global scale, it is forecasted 

that within the next decade, installed capacity for reuse 

will triple and installed capacity for desalination will 

double. 

Human beings have been freely exploiting natural resources 

for many centuries. However, the era of abundance is over. 

Could pricing policies reduce or prevent exposure to future 

water shortages? 

For the international community, 2015 will be a critical 

year. It is the year prescribed by the United Nations for 

achieving the Millennium Development Goals for Water 

and Sanitation and, in so doing, reducing poverty in the 

world. 

However, once poor people are connected to the public 

networks, what happens? Are low-income people 

capable to pay their bills regularly? Will they keep on 

benefi ting from the water services? It depends of many 

factors such as their revenues, the price of water and 

the tariffs structure, which are all essential elements for 

making the service affordable. But also the accompanying 

measures implemented by operators and public 

authorities when people are connected are important 

and also the cost of connection to the network and if 

this cost is charged separately or recuperated by overall 

service revenues. 

Discussion on topics like water scarcity, access to 

water and on many other topics in the water sector 

often has to be supported by statistical data in form of 

tables, graphs, etc. Therefore, it is very important that 

these data are gathered, checked and transformed into 

understandable fi gures so that policy makers, political 

leaders, managers, etc. are supported in making their 

decisions. 

Existing knowledge 

In the past several workshops and conferences were 

organised by our Specialist Group around the topic of water 

pricing in general or more in detail dealing with specifi c 

aspects of water pricing. In addition, many presentations 

by members of our Specialist group took place on several 

World Water Congresses and articles were published in 

Water Utility Management International. 

Some of the present, active members of our Specialist 

Group have extended knowledge of water pricing and thus 

have the capacity to make important contributions to the 

discussion of this topic. Besides that it is worthwhile to 

mention that some of them are working in countries facing 

water scarcity, like Spain and Cyprus. This will facilitate 

case study elaboration on this topic. For instance, for seasonal 

tariffs, it should be easier to know, at least in these 

countries, to what extent they are being used and they have 

proved to be effective. Since the early 1990s the Specialist 

Group – in particular the Working Group on Statistics – has 

carried out International Surveys to collect data on water 

production, water use and water charges and on water 

regulation. The information is published as a leafl et at the 

biennial IWA World Water Congress. This means that the 

Specialist Group has a lot of knowledge about these kinds 

of data and is able to produce tables, graphs, time series 

about different countries and different cities. 

However, like always, manpower, time and resources are 

subject to restrictions. Hopefully, it is possible to mobilise 

enough efforts to realise our objectives as written below. 

Planned activities 

To answer questions on water pricing in situations of water 

scarcity, we would like to explore in the next few years 

the following issues (keeping in mind, that in all countries, 

pricing policies and the price of water are decided by public 

authorities and/or the regulatory body, not by utilities). 

• How generalised water under pricing and unaccepted 

pricing policies (e.g. when municipal consumption is 

not charged or not paid) contributed to move, in some 

regions, from water abundance to water scarcity; 

• The way ahead towards a coherent water resource strategy, 

with effi cient tariff and non-tariff solutions (such 

77

78 


as two part tariffs, promotion of change in consumer 

behavior to foster water use effi ciency, etc.); 

• The measures to be taken in term of regulation, responsibilities 

breakdown or evolution of economic models of 

utilities, in order to prevent confl ict of interest among 

water utilities (which are paid according to the number 

of cubic meters sold and should, at the same time, 

encourage water savings among consumers) 

• The growing resort to non conventional resources and 

the way to design adapted tariffs for using alternative 

water resources. 

From a concrete perspective we plan the following 

activities. 

• To organise a workshop on these topics during the 2012 

IWA Congress; 

• To make a presentation on these topics in 2013, either 

during the Stockholm Water Week which is organised 

each year in August or during the Singapore Water Week 

which importance is increasing. The latter occasion 

would also help in networking with Asian institutions. 

Many institutions are already dealing with the Millennium 

Development Goals. As a Specialist Group we don’t 

have the means to organise worldwide and comprehensive 

surveys to check if these goals are achieved like 

United Nations Agencies are doing. However, the issue 

of how people are maintaining access to water services 

once they got their connections is less observed and 

analysed. 

Therefore we would like to point out two specifi c topics. 

• In developing countries. What pricing policies and social 

policies have to be implemented to help people recently 

connected to public networks to pay their bills and then 

to keep on benefi ting from the water services? There are 

many possible and complementary solutions: extension 

of fi nancial solidarity, education programme to prevent 

overconsumption among new subscribers, twinning 

electricity and water services in Africa (for the fi rst one 

to subsidised the second one) 

• In developed countries. It is sure that the Millennium 

Development Goals concern above all the developing 

countries. However, poverty also extends into the 

developed countries, and is forcing them to fi nd solutions 

to maintain access to water for poor people already connected. 

For them, the challenge is not to create new service 

lines as in the developing countries. Thus we will present 

experiences, mainly from European countries, to illustrate 

how combining affordable water pricing, tariff structures, 

cross-subsidisation mechanisms (between water service 

subscribers and taxpayers, between domestic and no 

domestic users) and social policies, in order to maintain 

access to water and sanitation services. 

From a concrete perspective, and to extend linkage with 

other water institutions, we plan to organise, in 2014, one 

workshop on this topic during one major Conference (such 

as the 2014 IWA Congress, the Singapore Water Week, the 

Stockholm Water Week). Being organised one year before 

the deadline to achieve the Millennium Development 

Goals, the results of this workshop could be used in 2015 

by other organisations when they assess the situation. 

To support topics like the above we are planning to extend 

our activities on the international surveys and statistical 

data we produce every two years. 

We would like to enlarge the gathering and analysis of data, 

so that we can turn data into knowledge. Examples of new 

approaches could be cross relation analysis, more use of 

time series, etc. 

Data on customer behaviour are more or less lacking in the 

information that we collect. So we are planning to gather 

more information on topics like bad payments, willingness 

to pay for intelligent metering, consumption levels and to 

compare and analyse for instance the results of different 

countries and different cities. 

Furthermore, we would like to enlarge the database more 

with data of continents and countries which are missing for 

the most part, like Africa, South America and Asia. 

Conclusion 

Within the IWA community, the Statistics and Economics 

Specialist Group is the central group for elaborating economic 

topics like water pricing policies. 

Although in the past many activities in this respect were 

developed by the Group, there is still a lot to discuss. That 

is why we will be dealing more in detail with this topic in 

the coming years, mainly focusing on water pricing policies 

in situations of water scarcity, on maintaining access to 

water services once people are connected, and improving 

and enlarging our statistical information.


Sustainability in the Water Sector 

Written by M. B. Beck, C. Davis, S. J. Kenway, J. Porro, S. Matsui, G. Crawford, H. Hilger and H. Zhang 


Introduction 

The challenge in the notion of sustainability lies in this 

complex compound of issues: 

• The desire to associate the word “sustainability” with 

whatever one is doing is nigh on universal. It is liberally 

evident in the mission and goals of the Association. It is 

somehow intuitively grasped by all. 

• However, holding steady in one’s mind this massively 

multi-disciplinary notion, and long enough and suffi - 

ciently completely to defi ne it “operationally” — as is the 

wont of engineers — seems as elusive as ever. 

• At bottom, the role of sustainability is akin to that of the 

catalyst. It is working (and crucially so) when yet it is not 

prominent either in the prior circumstances of what is to 

be changed — about the stewardship of water and other 

resources — or in any successful (posterior) engineered 

outcomes. It is as the changes wrought by the systems 

thinking suffused into the Yarra Valley Water company, 

as recorded in Crittenden et al. (2010). 

If one likens defi ning sustainability to the task of producing 

a “Manual of Practice for the Whole of Life”, then that is a 

measure of the challenge. 

Mindful of this, the Group has been working: 

To embrace and express in a comprehensive and 

rounded sense what sustainability might amount to 

when realised as Integrated Urban Water Management 

(IUWM) nested within Integrated Water Resources Management 

(IWRM) — hence the Sustainability Concepts 

Paper, begun in 2002 and now published in 2011 (Beck 

2011). 

To raise the profi le of sustainability within the Association, 

through the installation of the IWA Sustainability 

Prizes (fi rst awarded at the Vienna Congress, 2008) and 

the hosting of Workshops on Triple Bottom Line accounting 

(Beijing Congress, 2006; Kenway et al. 2007). 

To experiment in and with the learning microcosm of the 

Sustainability Agora (Beijing Congress, 2006; Vienna 

Congress, 2008), as a means of moving towards forms 

of governance for enabling (as opposed to disabling) the 

practice of sustainability in the water sector (Beck and 

Jeffrey 2007). 

To develop the Global Water Platform — “Bringing the 

World’s Water Information to Everyone” — to enhance 

best practices in sustainable water management in 

those places around the world least easily reached by 

the Association’s meetings and customary publications. 

The Platform’s website (www.globalwaterplatform.org) 

is designed to help people share the information they 

have, get the information they need in a form they can 

use, and collaborate to build new solutions. 

To launch (in 2010) the cross-disciplinary Task Group 

on “Wastewater Utility Greenhouse Gas Footprints” 

(www.iwataskgroupghg.com), with its remit of minimising 

energy consumption, operational costs, and greenhouse 

gas emissions, while yet maximising performance 

in maintaining aquatic environmental quality. 

Existing knowledge: Concepts Paper 

The Sustainability Concepts Paper (Beck 2011) is the integral 

of essentially all that this Group has participated in 

over the period of 2002 through 2011, in pondering and 

promoting sustainability within IWA. It began as a background 

discussion paper for the First Leading Edge Sustainability 

(LES) Conference (Venice, 2002); was advanced 

through the Second LES Conference (Sydney, 2004); is 

organised around the accountancy of the Triple Bottom 

Line (TBL); embraces the best of the IWA Sustainability 

Prizes (Ashley et al. 2008; Sharma et al. 2009; Starkl et al. 

2009; Crittenden et al. 2010; Willis et al. 2010); and is 

fundamentally defi ned by the plurality of perspectives on 

the Man-Environment relationship — itself the cornerstone 

of the designs for the Sustainability Agora. 

“Intuitively grasped by all” may sustainability be, but not 

in any agreed manner, when more than mere intuition is 

needed. There is no one “right way” about sustainability, 

except always to acknowledge this plurality of opposed 

outlooks on how to steward the Man-Environment relationship, 

and to seek to harness constructive contestation and 

disagreement amongst them (Thompson 2002). For IWA’s 

water professionals, moreover, the discomforting stance of 

the Sustainability Concepts Paper is that there is also no 

one “right” school of engineering thought on sustainability 

for IUWM nested with IWRM (Gyawali 2001; Dixit 2002). 

In sum, the very essence of sustainability is this: 

Always Learning; Never Getting it Right 

For all the many pages of the Sustainability Concepts Paper, 

or the changes catalysed in the practices of Yarra Valley 

Water (Crittenden et al. 2010), continuing transformation 

is defi ning for sustainability at the institutional and personal 

levels: in the form of learning organisations (Senge 

et al. 2008); and in availing ourselves (as individuals) 

79

80 


of what psychologists Kegan and Lahey (2009) call the 

higher mental complexity of “leading to learn”. 

Organised according to the Triple Bottom Line, the Sustainability 

Concepts Paper describes the “state-of-the-art” 

as follows: 

• On environmental benignity: Things are in transition, 

from a sole focus on eco-effi ciency — from being 

“less bad” in lowering the water metabolism of cities 

to an absolute minimum — towards including the complementary 

focus on eco-effectiveness (Dyllick and 

Hockerts 2002; McDonough and Braungart 2002), i.e., 

pursuit of the environmental “good” of cities and their 

water infrastructures as net contributors to ecosystem 

services in their surrounding watersheds (Beck et al. 

2010). The work of The Natural Step (www.naturalstep. 

org) and DHV (www.dhv.nl) in re-engineering the Soerendonk 

wastewater treatment plant in The Netherlands 

is exemplary. It stands (with others) at the frontiers of 

practice. 

• On economic feasibility: Grand economic theory about 

our environmental bequests of natural capital to future 

generations (Solow 1993; Sumaila and Walters 2005; 

Farley and Daly 2006) has for the moment markedly 

outstripped contemporary practice in counting the cost 

of what it might take, for example, to stimulate the recovery 

of nutrients as resources from wastewater (becoming 

“more good”) instead of seeking to be utterly rid of 

them as pollutants (becoming “less bad”). 

• On social legitimacy: Water scientists and engineers 

are leaders, amongst other policy and social scientists 

(Gatzweiler 2006; Boulanger 2008; Thompson 2008; 

Ney 2009; Romer 2010), in bringing the equally lofty 

notion of a “refurbished pluralist democracy” to work on 

the ground (Beck et al. 2011): in demonstrating practical 

paths towards more desirable governance (and away 

from failing governance); and in resolving some of the 

most intractable and widespread challenges of sustainable 

environmental stewardship (Gyawali 2004). These 

are challenges, for instance, of rapidly urbanising watersheds, 

with burgeoning populations, who have spiritual 

associations with water (Davis 2008), yet who are not 

served by classical systems of water and wastewater 

infrastructure (Gyawali 2004). At the frontiers of practice 

can be found the work of the Nepal Water Conservation 

Foundation on the Kathmandu-Bagmati city-watershed 

couple (NWCF 2009). 

We are urged to “Think Globally, Act Locally”. In the Sustainability 

Concepts Paper we advocate its complement, 

as in: 

Engineers “Acting Most Locally” to engender a community 

eager to engage in “Thinking Globally” 

Trends and challenges 

Global water platform: seeing sustainability 

in practice 

The over-arching challenge for the Group remains that of 

“getting the message out” with regard to sustainability. As 

IWA turns its strategic intentions towards Lower and Middle 

Income Countries (LAMICs), the Specialist Group on 

Sustainability sees Information Technologies (IT) and the 

web as central in supporting this Association-wide mission. 

Populations in many LAMICs are young; young water professionals 

in these countries have ready access to cell 

phones, computers, and the internet; these are, above all, 

“their” technologies and their means of communication. 

Yet language, income, and geography often bar the access 

of these young water professionals to IWA meetings and 

publications. What form of Global Water Platform — what 

further development of www.globalwaterplatform.org; what 

genuinely relevant and effective innovations in internet 

technologies — will place the assets of IWA knowledge at 

the disposal of these LAMIC water professionals? How will 

they in their turn change and enhance IWA’s knowledge 

assets? How, at bottom, is the IWA Sustainability Specialist 

Group to serve under-served audiences in promoting best 

practices in sustainability and to see their practices shape 

the evolving concepts of sustainability? 

There is more, however, to the current trends and challenges 

guiding the work of the Specialist Group than the 

vital task of serving the needs of global communication 

around the water sector. Since the Group’s inception in 

2006, its policy has deliberately been one of not hosting 

research symposia every 2–3 years. It is now time for this 

policy to be changed. There are issues much in need of 

research and enquiry, such as the following. 

Sustainability in the language of 

business & economics: making 

resource recovery happen 

There has been time enough over the past two decades for 

water professionals to think their way out of the mind-set 

of holding up the classical water-based paradigm of urban 

wastewater infrastructure as the single, most environmentally 

benign form of IUWM within IWRM. Niemczynowicz 

(1993) has disabused us of any wish we might have to 

cling to this orthodoxy alone. There has been time enough 

also for policy and social scientists to think about the 

socially legitimate options for engineering our way out of 

the attaching state of institutional and technological “lock 

in”. We have become quite inventive about what might be 

put in its place: separation at source of domestic, municipal, 

and industrial material fl ows; decentralisation; systems 

of dry sanitation; low-impact development; “smart water”; 

ecological engineering; green chemistry; and so on. 

Computational assessments suggest that extending the 

(conventional) wastewater infrastructure of a city such 

as Metro Atlanta, Georgia, USA, to eliminate a further 50 

tonnes of “polluting” phosphorus beyond current performance 

levels, might easily cost around $2-4M (on an annualised 

basis). Yet with source separation, enabled through 

the installation of urine-separating toilets (USTs) (Larsen 

et al. 2009), there could be as much as 1,700 tonnes of 

“resourceful” phosphorus to be recovered each year in 

the city’s raw wastewater, along with 16,600 tonnes of 

nitrogen, with a combined market value of $22M as fertiliser. 

Indeed, these nutrients might alternatively be used 

to produce biofuels from algae, or dispensed to rivers in 

a carefully controlled manner as “nutrient supplements” 

for restoring and enhancing watershed ecosystem services 

(Beck et al. 2010).

The crucial question, however, is what — having to do with 

money, economics, and entrepreneurship — might spark 

the transition from such a current “unsustainable cost 

stream” to a future “sustainable benefi t stream”? If we can 

have a global carbon-trading market, to reduce carbon 

emissions to the atmosphere, how can we yet re-orient its 

counterpart: of watershed pollutant-discharge trading and, 

conspicuously, nutrient pollutant trading? When might this 

be overturned: from a focus on environmental bads to 

environmental goods, such that we shall see trading in a 

“watershed recovered-resources market”? 

What could be the practical engineering outcomes from 

working with the fi nancial calculus of “natural capital” 

(Hawken et al. 1998) and “ecosystem services” (Aronson 

et al. 2006), together with the capex and opex of engineering 

economics (with which we are already well familiar)? 

Can we conceive of the hard, unsentimental business 

cases for sustaining the enterprises of watershed “ecosystem 

service providers”, without risking their “service 

failure” through the loss of biodiversity (Kremen 2005; 

Graham and Smith 2004)? 

Tracking sustainability in the city — not Just 

the nation or the utility 

Relative to nations and utilities little has been formally 

observed and tracked of the city’s metabolisms — water, 

nutrients, energy, and so on (Kennedy et al. 2007). Determining 

progress away from unsustainability and towards 

“water-sensitive” cities is currently almost impossible to 

evaluate. When Rees and Wackernagel (1996) famously 

introduced their concept of the urban ecological footprint, 

they invited us to imagine the city as a “large animal 

grazing in its pasture”. From this, one did not acquire a 

favorable impression of the environmental conduct of the 

“large animal”. How indeed do cities interact with their surrounding 

watersheds, thereby altering water, nutrient, and 

energy cycles in the wider picture (Kenway et al. 2011a,b)? 

What do we need to measure to track and to benchmark 

progress in city policies and to discriminate between leading 

sustainability policies and infrastructures, as opposed 

to those that are lagging behind? 

According to the biological metaphor: 

how might we measure not only the appetite (footprint) 

of the city, i.e., the environmental consequences of 

importing its voluminous inputs and exporting its equally 

voluminous outputs; but also 

its metabolism, i.e., the environmental consequences of 

how those urban inputs are transformed into the urban 

outputs; and 

its pulse-rate, i.e., the environmental consequences of 

tuning the social and economic life of the city to just the 

narrow and environmentally impoverished bandwidth 

of merely the 24-7 frequencies alone in the spectrum 

(Beck et al. 2010; Beck 2011)? 

What arrangements of the technologies of urban water 

infrastructure will bestow ecological resilience (sensu 

Holling 1996) upon the behaviour of the city — and how 

would we track this? 

Conclusions 

Seen from today, we conjecture: 


• That sustainability in the water sector will be driven 

not only by the principles of eco-effi ciency — lowering 

the material-energy metabolisms of the city-watershed 

couple — but also by eco-effectiveness, whereby the 

built environment should nourish (not deplete) the natural 

environment; 

• That the economic calculi of sustainability should enable 

a decision about re-engineering an urban wastewater 

infrastructure, for example, for the recovery of a “perfect 

fertiliser”, to be based demonstrably on monetary tradeoffs 

amongst inter alia the benefi ts to the agricultural 

sector, the energy sector, and the ecosystem-services 

sector; 

• That socially legitimate policy will emerge not merely 

from seeking some measure of agreement (as in consensus), 

but from harnessing the creativity of properly 

orchestrated, robust disputation and disagreement 

amongst the interested parties, each with its passionate 

commitment to what it believes is the only right way to 

go about sustainability. 

We fully expect this assertion to be shown to be inadequate, 

in some way, in the event. It is entirely in the spirit 

of sustainability for this to be welcomed, even sought out 

by design. 

References 

Ashley, R., Blackwood, D., Butler, D., Jowitt, P., Davies, J., Smith, 

H., Gilmour, D. and Oltean-Dumbrava, C. (2008) Making asset 

investment decisions for wastewater systems that include 

sustainability. J Environmental Engineering 134(3), 200– 

209, DOI: 10.1061/(ASCE)0733-9372(2008)134:3(200). 

Beck, M.B. (2011) Cities as Forces for Good in the Environment: 

Sustainability in the Water Sector, Warnell School of Forestry 

& Natural Resources, University of Georgia, Athens (ISBN: 

978-1-61584-248-4) (also available from www.cfgnet.org). 

Beck, M.B. and Jeffrey, P. (2007) Sustainable standpoints — 

embracing diversity of opinion. Water21 August, 13–14. 

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Boulanger, P.-M. (2008) Sustainable development indicators: 

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Crittenden, P., Benn, S. and Dunphy, D. (2010) Learning and 

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Farley, J. and Daly, H. (2006) Natural capital: the limiting 

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Rainfall extremes and urban drainage 

Written by P. Willems and T. Einfalt on behalf of the Urban Drainage Specialist Group 

Introduction 

Urban drainage is a system of man-made and natural elements 

serving to protect human population and the environment 

against adverse effects of wet-weather fl ows and 

wastewater effl uents in urban areas. Although wastewater 

effl uents are hardly affected by rainfall, wet-weather fl ows 

(i.e. stormwater runoff and combined sewer overfl ows) are 

directly driven by rainfall, and the capacity of urban drainage 

to provide effective service depends directly on the 

characteristics of rainfall and their variation in time and 

space. Extreme rain storm events cause sewer surcharging 

and surface fl ooding, or water ponding, and in areas 

served by combined sewers they also cause extensive 

discharges of polluted combined sewer overfl ows (CSOs) 

into receiving waters. Consequently, these events severely 

impact the life of people and the quality of the aquatic 

environment in urban areas, and the urban population 

therefore pays attention to the quality and lead-time of 

rainfall forecasts, the risk of fl ooding, fl ood damages, and 

impacts of climate change on such phenomena. Critical 

questions are raised with respect to the accuracy and reliability 

of rainfall forecasts or simulations, the propagation 

of uncertainty, and the range of consequences for daily 

life. These great challenges are faced by environmental 

scientists, municipal practitioners and managers, and 

political decision makers alike. 

In this context, the International Working Group on Urban 

Rainfall (IGUR) of the IWA Urban Drainage Specialist 

Group (www.jcud.org), operated jointly by IWA and IAHR 

(the International Association for Hydro-Environment 

and Research) closely follows and disseminates the latest 

developments in knowledge, technology and existing 

procedures concerning rainfall measurement, analysis and 

modelling for urban stormwater management (see http:// 

www.kuleuven.be/hydr/gurweb/index.html). The IGUR 

reported that strong advancements were recently made in 

the measurement and analysis of the spatial variability of 

urban rainfall. Another particular focus point of the Group 

is climate change. Major worldwide attention is currently 

given to the study of changes in rainfall extremes due to 

global warming and the corresponding urban drainage 

impacts. Concerning both issues, major advances are 

expected in the next 5–10 years. 

Advances in measurement and 

analysis of local urban rainfall 

Urban drainage experts face major challenges regarding 

urban rainfall extremes. Owing to the relatively small spatial 

and temporal scales of the relevant hydrological processes 

of sewer and urban drainage systems, rainfall data are 

required also at these scales. The density of existing rain 

gauge networks is, however, still very limited in most urban 

areas. Owing to this and other reasons for limited availability 

of local and short-interval urban rainfall data, rainfall 

estimates are still one of the main sources of uncertainty 

in urban drainage studies, particularly in applications that 

focus on rainfall extremes. 

Recent advances in the measurement of precipitation 

include various types of radars and spatial rainfall 

processing techniques. Precipitation measurement by 

radar is currently considered a reliable means of obtaining 

precipitation data with a spatial scale of 1 km² or less 

and a temporal resolution of 5 minutes or less. Since the 

use of radar measured precipitation data requires a different 

knowledge than the traditional use of rain gauges, 

numerous efforts have been made to encourage the use 

of more complex data in urban and small-scale hydrology 

(e.g. Einfalt et al. 2004; Michelson et al. 2005). Radar 

technologies that are currently extensively tested for measuring 

rainfall with high spatial resolution are the Local Area 

Weather Radars (LAWRs) or X-band polarimetric radars 

(e.g. Thorndahl and Rasmussen 2011). These can be 

seen as an alternative to C-band and S-band radar for 

local urban areas. Another promising technology under 

development is microwave technology in commercial wireless 

links (e.g. Leijnse et al. 2010). More details on these 

advances can be found in the forthcoming Special Issue 

of Atmospheric Research on “precipitation in urban areas” 

(see section 2.4). 

Climate change and urban rainfall 

extremes 

A particular focus point in the context of climate change 

is on non-stationarities in rainfall time series, which may 

have signifi cant consequences for estimation of extreme 

rainfall statistics (Willems et al. 2011). There is strong 

evidence that due to the global warming the frequency 

of extreme rain storms, and as a consequence the probabilities 

and risks of sewer surcharge and fl ooding, are 

changing. In their Fourth Assessment Report (AR4) the 

Intergovernmental Panel on Climate Change (IPCC 2007) 

indeed reported, for the late 20th century, a worldwide 

increase in the frequency of extreme precipitation intensities 

as a result of global warming. Based on climate model 

simulations with different future greenhouse gas emission 

scenarios, IPCC (2007) furthermore concluded that it is 

very likely that this trend will continue in the 21st century. 

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The consequences of these regionally varying changes 

have to be assessed in a perspective of sustainable 

development. Water managers have to anticipate these 

changes, to limit the fl ood risks, to which the inhabitants 

are exposed. In addition, the insurance industry, as well as 

the different water users and policy makers, need quantifi 

cation of these risks to develop and adopt the appropriate 

policies. Consequently, the number of hydrological 

impact studies of climate change has strongly increased 

in recent years. These studies, however, most often 

focus on river discharge extremes and low-fl ow risks. The 

number of climate change studies dealing with urban 

drainage impacts is still rather limited, partly because 

they require a specifi c focus on small urban catchment 

scales (usually few kilometres) and short-duration rainfall 

extremes (at time scales as short as 5 minutes). Despite 

the signifi cant increase in computational power in recent 

years, climate models still remain relatively coarse in 

space and time and are therefore unable to resolve signifi 

cant climate features relevant to the fi ne scales of 

urban drainage systems. The models also have limitations 

in the accuracy of describing precipitation extremes 

(e.g. high intensity convective storms leading to sewer 

surcharge and fl ooding). This is due to the poor description 

of the non-stationary phenomena during convective 

storms resulting in the most extreme events at a local 

scale. Climate models are derived from weather forecast 

models, which currently are not able to describe small 

scale convective activities with a good accuracy. As such, 

the climate models are thus still not satisfactory for providing 

an adequate assessment of the impacts of future 

climate change scenarios at the local scale of individual 

cities. The models cannot provide data at the appropriate 

spatial and temporal resolutions for these impact assessment 

studies, which are usually done through simulation 

with urban hydrological and sewer system models 

(Willems et al. 2011). 

Current research on climate change and urban drainage 

therefore mainly focuses on statistical downscaling 

techniques. By means of these techniques, information 

provided by large-scale global or regional climate models 

is downscaled to information of very high spatial and temporal 

resolutions that is appropriate for urban runoff studies. 

Consequently, the expected results from such impact 

studies could be highly uncertain, depending strongly on 

the feasibility and reliability of the downscaling process. 

This problem becomes even more challenging when dealing 

with the extreme rainfall events. 

The IGUR is currently fi nalising a state-of-the-art review 

report on “Climate change and urban rainfall extremes 

and drainage”. The report will provide an overview of 

existing methodologies and relevant results related 

to the assessment of the climate change impacts on 

urban rainfall extremes as well as on urban hydrology 

and hydraulics. In particular, the overview focuses on 

several diffi culties and limitations regarding the current 

methods and will discuss various issues and challenges 

facing the research community in dealing with the 

climate change impact assessment and adaptation for 

urban drainage infrastructure design and management. 

For more information on this forthcoming review report, 

please contact the IGUR Chair (Patrick.Willems@bwk. 

kuleuven.be). 

Forthcoming: Special Issue of 

Atmospheric Research on precipitation 

in urban areas 

A Special Issue of Atmospheric Research on “precipitation 

in urban areas” is about to appear. The Special 

Issue presents peer-reviewed selected papers from the 

“8th International Workshop on Precipitation in Urban 

Areas”, which was held in St Moritz, Switzerland, 10–13 

December 2009 (http://www.ifu.ethz.ch/stmoritz) and was 

co-organised by the IGUR. The workshop had four focus 

themes: (a) the accuracy of rainfall measurements - radar, 

microwave, rain gauges; (b) the propagation of uncertainty 

from atmospheric data to models; (c) the use of simulation 

and uncertainty concepts in urban hydrology; and (d) the 

use of advanced statistical tools and methods for studying 

climate change impacts on extreme rainfall. The forthcoming 

issue will be the seventh Special Issue prepared in 

collaboration with the IGUR, following the earlier special 

issues of 1991 (Niemczynowicz and Sevruk 1991), 1996 

(Sevruk and Niemczynowicz 1996), 1998 (Einfalt et al 

1998), 2002 (Burlando 2002), 2005 (Einfalt et al 2005) 

and 2009 (Burlando 2009). 

References 

Burlando, P. (Ed.) (2002). Rainfall in urban areas. Water Science 

and Technology, 45(2), 1–152 (Special Issue “5th International 

Workshop on Precipitation in Urban Areas, Pontresina, 

Switzerland, 10–13 December 2000”). 

Burlando, P. (Ed.) (2009). Atmospheric Research, 92(3), 

281–380 (Special Issue “7th International Workshop on 

Precipitation in Urban Areas, St Moritz, Switzerland, 07–10 

December 2006”). 

Einfalt, T., Arnbjerg-Nielsen, K., Fankhauser, R., Rauch, W., 

Schilling, W., Nguyen, V., and Despotovic, J. (1998). Use of 

historical rainfall series for hydrological modelling - workshop 

summary. Water Science and Technology, 37(11), 1–6 

(Special Issue “4th International Workshop on Precipitation 

in Urban Areas, Pontresina, Switzerland, 04–07 December 

1997”). 

Einfalt, T., Molnar, P., Schmid, W. (Ed.) (2005). Atmospheric 

Research, 77(1–4), 1–422 (Special Issue “6th International 

Workshop on Precipitation in Urban Areas, Pontresina, 

Switzerland, 04–07 December 2003”). 

Einfalt, T., Arnbjerg-Nielsen, K., Golz, C., Jensen, N.E., Quirmbach, 

M., Vaes, G., Vieux, B. (2004). Towards a roadmap for 

use of radar rainfall data use in urban drainage. Journal of 

Hydrology 299, 186–202. 

IPCC (2007). Climate Change 2007: The Physical Science Basis, 

Summary for Policymakers, Contribution of Working Group 

I to the Fourth Assessment Report of the Intergovernmental 

Panel on Climate Change, IPCC Secretariat, Geneva, 

Switzerland. 

Leijnse, H., Uijlenhoet, R., Berne, A. (2010). Errors and uncertainties 

in microwave link rainfall estimation explored using 

drop size measurements and high-resolution radar data. 

Journal of Hydrometeorology 11, 1330–1344. 

Michelson, D., Einfalt, T., Holleman, I., Gjertsen, U., Friedrich, K., 

Haase, G., Lindskog, M., Jurczyk, A. (2005). Weather radar 

data quality in Europe – quality control and characterization. 

Review. COST Action 717, Luxembourg. 

Niemczynowicz, J., Sevruk, B. (Ed.) (1991). Atmospheric 

Research 27(1–3), 1–229 (Special Issue “International 

Workshop on Urban Rainfall and Meteorology, St. Moritz, 

Switzerland, December 1990”).

Sevruk, B., Niemczynowicz, J. (Ed.) (1996). Atmospheric 

Research 42(1–4), 1–292 (Special Issue “Closing the gap 

between theory and practice in urban rainfall applications, 

St. Moritz, Switzerland, 30 November – 4 December 

1994”). 

Thorndahl, S., Rasmussen, M.R. (2011). Marine X-band weather 

radar data calibration. Atmospheric Research, doi:10.1016/j. 

atmosres.2011.04.023. 


Willems, P., Arnbjerg-Nielsen, K., Olsson, J., Nguyen, V.T.V. 

(2011) Climate change impact assessment on urban rainfall 

extremes and urban drainage: methods and shortcomings. 

Atmospheric Research, 10.1016/j.atmosres.2011.04.003. 

85

86 


Wastewater Pond Technology 

Written by Marcos von Sperling on behalf of the Specialist Group 

Introduction 

Waste stabilisation ponds are widely used natural processes 

for domestic and industrial wastewater treatment 

around the world. The main variants of stabilisation ponds 

are anaerobic and facultative ponds, which aim primarily 

at organic matter removal, and maturation ponds, whose 

main target is the removal of pathogenic organisms. Facultative 

and maturation ponds rely basically on the production 

of oxygen by algae during photosynthesis, and the 

utilisation of the surplus oxygen by the bacteria responsible 

for the major pollutant conversion processes. There 

are also mechanised variants, such as aerated lagoons 

and high-rate ponds, with different treatment objectives. 

This chapter deals mainly with the non-mechanised ponds 

(anaerobic, facultative and maturation). 

Unmechanised ponds are notoriously known for being 

simple wastewater treatment processes. They are simple 

to design, build and operate. Their dimensioning usually 

uses reasonably well-known recommended organic loading 

rates, hydraulic retention times and fi rst-order kinetics. 

Their detailed design has traditionally concentrated mainly 

on the confi guration of inlet and outlet structures and on 

protection and sealing of embankments and pond bottom. 

Their construction is simple, comprising mainly earth 

movement. Routine operation is indeed trouble free, and 

is more related to maintenance practices than to proper 

operational control measures. Ponds do not involve electromechanical 

equipment and do not consume energy. 

When comparing with the performance of other treatment 

processes, facultative ponds produce effl uents with intermediate 

levels (but in many cases satisfactory) of organic 

matter content, somewhat high suspended solids concentrations 

(owing to the presence of algae) and very low 

or null counts of protozoan cysts and helminth eggs. If a 

series of maturation ponds is included, a very high level 

of pathogenic bacteria and viruses removal is achieved. 

Owing to their high hydraulic retention times, ponds are 

usually robust to withstand variations in infl uent quantity 

and quality, and even careless operation. 

As a result of these points, there are thousands of ponds 

applied on a worldwide basis. Although these attributes 

make them a very important choice for wastewater treatment 

at developing countries, ponds are also widely used 

in developed regions, especially at small communities. 

However, similarly to other treatment processes, there 

are challenges that need to be faced to enhance pond’s 

applicability and performance. These challenges have 

been separated into the following topics: 

Practical challenges: 

• Reduce land requirements. 

• Reduce suspended solids (algae) in the effl uent. 

• Reduce risks of malodours in anaerobic ponds. 

• Increase effl uent use for irrigation. 

Scientifi c challenges: 

• Understand the mechanisms of pathogen removal. 

• Understand the mechanisms of nutrient removal. 

• Develop reliable hydraulic and kinetic mathematical 

models. 

Challenges in expanding pond applicability 

and sustainability: 

• Explore energy and carbon management opportunities. 

Practical challenges 

Reduction of land requirements 

In warm-climate regions, facultative ponds usually require 

between 2 and 4 m 2 per inhabitant. In temperate climates, 

approximately double the area is required and in cold climates 

(where surprisingly they are also used), larger land 

requirements are observed. If a series of maturation ponds 

are included in the treatment line, the total area may double. 

This poses a practical limitation, because in many 

cases there will not be a large area, somewhat fl at and 

with reasonably good soil in the vicinity of the community. 

Although there are no formal size limitations for ponds 

(there are pond systems with 400 ha), in many cases land 

restriction will confi ne ponds to small or medium-sized 

communities. 

To increase ponds applicability, a reduction of land requirements 

is obviously welcome. The inclusion of anaerobic 

ponds ahead of the facultative ponds may reduce the area 

to around 2/3 of that needed for facultative ponds only. 

In some warm-climate countries, UASB (upfl ow anaerobic 

sludge blanket) reactors are replacing the anaerobic and 

facultative ponds, and the overall system of UASB reactors 

+ maturation ponds becomes smaller (but still land 

intensive).

Reduction of suspended solids in the 

effluent 

Well operating facultative and maturation ponds rely on a 

good production of microalgae, which are responsible for 

photosynthesis. However, a large amount of these algae 

leave with the fi nal effl uent, and are responsible for the 

increase of suspended solids and particulate BOD in the 

wastewater discharged to water bodies. If the effl uent 

from a pond needs to have its quality improved in terms of 

organic matter and suspended solids, then algae removal 

is a good choice. 

Some of the possibilities are: (a) intermittent sand fi lters, 

(b) rock fi lters, (c) microsieves, (d) ponds with fl oating 

macrophytes, (e) land application, (f) wetlands, (g) coagulation 

and clarifi cation processes, (h) fl otation, (i) aerated 

biofi lters and (j) trickling fi lters. 

Sand fi ltration produces an effl uent with excellent quality, 

but tend to clog very quickly. Coarse rock fi ltration is not 

so effi cient, but gives a good contribution and is much 

less prone to clogging (they can run for years without 

cleaning). Recent experiments with aerated rock fi lters 

have shown good removal of other constituents, such as 

coliforms. Floating macrophytes, such as duckweed, are 

used in several ponds in order to reduce sunlight penetration 

and thus decrease algal growth. These ponds give the 

possibility of using the high-protein content duckweed for 

fi sh ponds, but require a good strategy for their removal 

from the pond surface. 

The inclusion of any of these processes, especially the 

mechanised ones, should naturally fi nd a justifi cation from 

the point of view of the needs of the receiving water body 

(and not only as a safeguard in terms of compliance to 

discharge standards), since they imply an elevation of the 

treatment costs and operational complexity. Wastewater 

treatment by ponds must remain simple, and the challenge 

here is to improve their effl uent quality without deviating 

from the primary characteristic of conceptual simplicity. 

Reduction of risks of malodours from 

anaerobic ponds 

Anaerobic ponds are open anaerobic reactors, and thus 

may be subject to the release of malodorous gases, especially 

hydrogen sulphide. Substantial experience exists on 

how to reduce these risks, based on the implementation of 

ponds far away from houses, adoption of suitable organic 

loading rates, a good knowledge of the infl uent characteristics 

(amount of sulphate in the wastewater) and the 

utilisation of inlet pipes close to the pond bottom, to allow 

good contact between organic matter and biomass. However, 

because a natural treatment process is being used, 

there is always the risk that during a certain period something 

will not go on as planned, and obnoxious odours may 

be emanated. 

Some anaerobic ponds are being covered to capture the 

gas and thus control their release into the atmosphere. 

This also creates the opportunity of biogas utilisation and 

carbon credits compensation. However, in many cases the 

anaerobic ponds are very large, and the challenge is to reliably 

cover a large surface area without allowing gases to 

escape, and still keeping simplicity as a key element. 


Increase of the effluent use for agricultural 

irrigation 

Effl uents from facultative ponds are usually suitable for 

restricted irrigation (good helminth eggs removal), and 

effl uents from maturation ponds may be fi t for unrestricted 

irrigation (irrigation of crops that are eaten uncooked or 

unpeeled), since these ponds are able to remove coliforms 

to low counts and comply with the World Health Organization 

guidelines. 

This widens up considerably the applicability of ponds, 

because they become not only a good wastewater treatment 

process, but also a technology that is able to lead to a 

productive use of the fi nal effl uent. Pond effl uents contain 

water, organic matter and nutrients, which are required by 

soil and crops. Irrigation with pond effl uents is successfully 

done in several countries around the world, especially 

those located in arid or semi-arid regions. However, it is 

felt that much more could be done on this respect in many 

other countries. A suitable effl uent is being generated, 

but there is no managerial structure to link treated effl uent 

producers (sanitation companies) and farmers. The 

challenge here is more institutional than technical, but is 

certainly an issue that needs to be well looked in many 

countries. 

Scientific challenges 

Understanding the mechanisms of pathogen 

removal 

Ponds are very important treatment systems for the 

removal of pathogenic organisms. Protozoan cysts and 

helminth eggs are removed by sedimentation, while bacteria 

and viruses are mainly removed by inactivation mechanisms, 

especially in maturation ponds. Molecular biology 

detection methods are being more widely applied in ponds 

research, allowing the qualitative or quantitative identifi - 

cation of the actual pathogen species, instead of relying 

only on traditional indicators, such as coliforms. More and 

more PCR (polymerase chain reaction), FISH (fl uorescence 

in situ hybridisation) and quantitative PCR methods 

are being applied in ponds research, opening up a new 

road of important discoveries. 

A lot is already known about the removal of pathogens in 

ponds, including sedimentation and inactivation. However, 

the mechanisms involved in the inactivation of bacteria and 

viruses are receiving more attention. From these mechanisms, 

elucidation of steps involved with sunlight inactivation 

have been achieved, involving direct damage of DNA 

structures by UVB and indirect damage by endogenous 

and exogenous sensitizers. These mechanisms are infl uenced 

by environmental conditions in the ponds, such as 

dissolved oxygen, algae, humic substances and pH, and 

affect in a different way bacteria and viruses. Inactivation 

in the dark also deserves attention, and involves predation, 

high pH, algal toxins and stress. 

However, the prediction of pathogen removal effi ciency 

involves not only the kinetic aspects of inactivation, but 

also the hydraulic behaviour of the ponds, which are infl uenced 

by the presence of baffl es, the length-to-width ratio 

87

88 


and the placement of inlet and outlet structures. Advancements 

in this fi eld have been achieved, as discussed further 

below. 

Understanding the mechanisms of nutrient 

removal 

Stabilisations ponds are not very effi cient in the removal 

of nutrients (nitrogen and phosphorus). However, specifi c 

confi gurations, such as maturation ponds and high-rate 

algal ponds are able to achieve high nitrogen removals. 

In the literature, always cited classical mechanisms for N 

removal are: assimilation of ammonia and nitrate by algal 

biomass, conventional nitrifi cation-denitrifi cation, sedimentation 

of dead biomass and accumulation on sludge 

layer after partial hydrolysis and ammonia volatilisation. 

Amongst those, ammonia volatilisation due to high pH 

induced by photosynthesis has been frequently referred 

to as the main mechanism. However, recent researches 

are pointing out that this may not be the case. Tracer 

experiments with 15 N-stable isotopes and fi eld measurements 

of actual ammonia lost by volatilisation have shown 

that the fraction of N removed by this mechanism may 

be small and have only a minor infl uence on the overall 

removal. Nitrifi cation has been observed in some ponds 

and not in others – a possibility is that the presence of 

ammonia in the form of free ammonia (NH 3 ) due to high 

pH values may inhibit the growth of nitrifying organisms. 

Organisms responsible for anaerobic ammonia oxidation 

(anammox) are also being investigated, using molecular 

biology mechanisms, in order to see if they play an important 

role in nitrogen removal. Anyway, nitrogen removal 

in shallow ponds seems to be greater than in deeper 

ponds. 

Regarding phosphorus, a major removal mechanism 

could be the precipitation of the phosphates in the form 

of hydroxyapatite or struvite under high pH conditions. In 

the case of phosphorus removal, the dependence of high 

pH values is larger than with nitrogen: the pH should be at 

least 9 so that there is a signifi cant phosphorus precipitation. 

Such high pH values are not consistently maintained, 

night and day, in most ponds, and this could be the reason 

why phosphorus removal effi ciencies are not large in most 

ponds. Recent research has identifi ed the possibility that 

algae can also develop a mechanism of luxury P uptake, 

like phosphate accumulating bacteria do in activated 

sludge. If this in indeed the case, and one is able to control 

the environmental conditions that favour this mechanism, 

an important possibility for phosphorus removal in ponds 

may be obtained. 

The road is still open for more fundamental research that 

can widen the understanding of mechanisms, thus allowing 

ponds to be more effective in nutrient removal, enhancing 

their applicability in situations in which the effl uent needs 

to be discharged to sensitive water bodies. 

Development of reliable hydraulic and 

kinetic mathematical models 

During many years, stabilisation ponds were only modelled 

assuming ideal complete-mix and plug-fl ow reactors. 

Although this still holds true owing to the simplicity 

of both models, later on designers started to incorporate 

the dispersed-fl ow model, which accommodates fl uid dispersion 

in the equations for prediction of effl uent quality, 

thus approximating more to the reality of actual reactors. 

Experimental determination of the dispersion number 

using tracers has been done at several sites, leading to 

empirical equations for their simple estimation, based on 

physical characteristics of the pond. 

More recently, computational fl uid dynamics (CFD) models 

have been used, allowing the study of the best arrangement 

for inlet and outlet structures and for the placement of 

baffl es, aiming at increasing pollutant removal effi ciencies. 

This better representation of the specifi c hydraulic behaviour 

of each pond is of course associated with a higher 

degree of complexity, but the increase in the availability 

and use of CFD software may result in its more systematic 

use by consulting companies in the design of ponds. 

Traditional kinetic models for the prediction of effl uent concentrations 

from stabilisation ponds have used fi rst-order 

reactions, but recent approaches focus on the representation 

of biomass growth rates and the resulting uptake or 

release of constituents. Structures similar to the IWA activated 

sludge model (ASM) are being developed for ponds, 

with the added degree of diffi culty that not only bacterial 

growth and decay need to be modelled, but also algal biomass. 

At a higher level are recent models that jointly incorporate 

CFD and ASM models, being thus hopefully able to 

provide a better representation of the hydrodynamics and 

reaction kinetics at stabilisation ponds. 

With the development of more advanced and reliable 

mathematical models, designers will hopefully have better 

tools to tailor each pond to the particular infl uent and site 

characteristics, as well as effl uent quality requirements. 

Challenges in expanding pond’s 

applicability and sustainability 

As with other wastewater treatment processes, sustainability 

issues are now a matter of considerable concern 

and research focus. Ponds are inherently sustainable in 

the sense that they are a natural process, simple, without 

energy demand, robust and able to operate within the 

expected removal effi ciency even under some unfavourable 

operational conditions. However, sustainability nowadays 

also incorporates other aspects, such as green-house 

gas emissions and the possibility of producing energy. 

Methane emission, which could be a concern in terms of 

greenhouse effect, is important only in anaerobic ponds. 

Besides the fact that not all pond systems use anaerobic 

ponds, some of these ponds are now being covered, with 

gas capture and burning or treatment and recovery. Credit 

carbon analysis is currently being undertaken in several 

pond systems. 

The potential of generating green energy/biofuel through 

algal biomass is nowadays a matter of considerable interest. 

Successful pilot-scale studies have been made, and 

the challenge now is how to produce and harvest algae 

from such large reactors as ponds. Some full-scale applications 

are already in place, and this is a topic in which 

much development is expected.

Concluding remarks 

The inherent simplicity of a natural wastewater treatment 

process is one of the fi rst concepts that come to mind 

when one thinks on stabilisation ponds. For some practitioners, 

there may be an impression that everything that 

is needed is already known in this relatively old treatment 

process. 

However, as was seen in this text, this does not mean that 

everything that relates to ponds is really simple: in the fi eld 

of wastewater treatment, it is one of the most complex systems 

to understand, describe and model. From the biological 

point of view, the simultaneous interaction of different 

groups of bacteria with different algae species leads to a 

very complex ecological system, with mutualistic relationships 

between heterotrophs and autotrophs. The understanding, 

quantifi cation and mathematical representation 

of the several different resulting biochemical reactions and 

the growth rates of the various organisms involved are a 

challenge for pond’s researchers. In addition, because 


ponds are large open reactors, their hydraulic behaviour 

is very much infl uenced by temperature, wind and placement 

of inlet and outlet structures. The representation of 

pond’s hydrodynamics represents another challenge. 

Fortunately, with the advancement of fi eld and laboratorial 

detection techniques and mathematical modelling tools, 

scientists are now coming somewhat closer in the understanding 

and representation of the mechanisms involved 

in ponds behaviour. The expectation is that this will assist 

in a better prediction of the removal effi ciency of key pollutants 

under different environmental conditions, leading 

to better designs, tailored to each situation. 

This text presented many challenges that need to be 

faced on a short or medium term. It is diffi cult to specify 

which of those will prevail and be more embraced by the 

technical community. What is defi nitely known is that 

pond´s research will continue in depth around the world, 

and that the future is open for pond’s researchers and 

practitioners! 

89

90 


Water and Wastewater in 

Ancient Civilisations 

Written by A. N. Angelakis, L. W. Mays, G. De Feo, M. Salgot, P. Laureano, and N. Paranychianakis 


Prolegomena 

The rapid technological progress in the twentieth century 

created a disdain for the past achievements. Past 

water technologies, were regarded to be far behind the 

present ones; signifi ed major advances achieved in the 

20th century. There was a great deal of unresolved problems 

related to the management principles, such as the 

decentralisation of the processes, the durability of the 

water projects, the cost effectiveness, and sustainability 

issues such as protection from fl oods and droughts. In 

the developing world, such problems were intensifi ed to 

an unprecedented degree. Moreover, new problems have 

arisen such as the contamination of surface and groundwater. 

Naturally, intensifi cation of unresolved problems 

led societies to revisit the past and to reinvestigate the 

successful past achievements. To their surprise, those 

who attempted this retrospect, based on archaeological, 

historical, and technical evidence were impressed by two 

things: the similarity of principles with present ones and 

the advanced level of water engineering and management 

practices in ancient times (Koutsoyuannis et al. 2008; 

Mays 2008 and 2010). 

Modern day water technological principles have a foundation 

dating back three to four thousand years ago. These 

achievements include technologies such as dams, wells, 

cisterns, aqueducts, baths, recreational structures, and 

even water reuse. These hydraulic works and features 

refl ect also advanced scientifi c knowledge, which for 

instance allowed the construction of tunnels from two 

openings and the transportation of water both by open 

channels and closed conduits under pressure. Certainly, 

technological developments were driven by the necessities 

for effi cient use of natural water resources in order to 

make civilisations more resistant to destructive natural elements, 

and to improve the standards of life. With respect 

to the latter, certain civilisations developed an advanced, 

comfortable and hygienic lifestyle, as manifested from 

public and private bathrooms and fl ushing toilets, which 

can only be compared to our modern facilities which were 

re- established in Europe and North America in the beginning 

of the last century (Angelakis et al. 2005). 

With the increasing worldwide awareness of the importance 

of water resources management in the ancient civilisations, 

the IWA SG on WWAC was established in 2005 

and so far two IWA International Symposia on Water and 

Wastewater Technologies in Ancient Civilisations has been 

organised in 2006 and 2009, in Iraklion, Greece and in 

Bari, Italy, respectively. Also, a 3rd IWA Symposium will 

be organised in Istanbul, Turkey, 22–24 March 2012. With 

the experience gained from these Symposia, it is to note 

that the participants are from several disciplines, with a 

dominant number from the water sciences, history and 

archaeology; but also including engineering, life, environmental, 

and health sciences, biology, geosciences, and 

others. The geographical coverage of the exposed features 

and facilities, is very wide, with the prominence in the 

Mediterranean world. However, several other civilisations 

from other parts of the world such as the southwestern 

United States, South America and Asia are included. The 

themes are from prehistoric to medieval and modern times 

and are presented in a coherent and critical way. 

The principles and practices in water management of 

ancient civilisations are not well known as well as other 

achievements of ancient civilisations, such as poetry, 

philosophy, science, politics and visual arts. A lot is to 

be learned from ancient technologies and practices so 

the SG on WWAC is also focused on the development of 

water technologies through centuries in various parts of 

the world. Specifi c case studies are considered. To put 

in perspective the ancient water management principles 

and practices, it is important to examine their relevance to 

modern times and to harvest some lessons. Furthermore, 

the relevance of ancient works are examined in terms of 

the evolution of technology, the technological advances, 

homeland security, and management principles. Finally, 

a comparative assessment of the various technologies 

among civilisations should be considered. 

Ancient water and wastewater 

technology 

Humans have spent most of their history as hunting and 

food gathering beings. Only in the last 9,000 to 10,000 

years they discovered how to grow agricultural crops and 

tame animals. Such revolution probably fi rst took place in 

the hills to the north of Mesopotamia. From there the agricultural 

revolution spread to the Nile and Indus Valleys. 

During this agricultural revolution, permanent villages, 

anticipated from experiences of sedentary life without 

agriculture, replaced a wandering existence. About 6,000 

to 7,000 years ago, farming villages of the Near East 

and Middle East became cities. During the Neolithic age 

(ca. 5,700–3,200 BC), the fi rst successful efforts to 

control the water fl ow were driven (such as dams and 

irrigation systems), owing to the food needs and were 

implemented in Mesopotamia and Egypt. Urban water 

supply and sanitation systems were dated at a later stage, 

in the Bronze Age (ca. 3,200–1,100 BC).

Hassan (1998) stated that ‘the secret of Egyptian civilisation 

was that it never lost sight of the past’; because of the 

unpredictability of the Nile River fl oods and the production 

of grains suggest order and stability. The ancient Egyptians 

depended upon the Nile not only for their livelihoods, but 

they also considered the Nile to be a deifi c force of the 

universe, to be respected and honoured if they wanted it 

to treat them favourably. The river annual rise and fall were 

likened to the rise and fall of the sun, each cycle being 

equally important to their lives, though both remaining a 

mystery. Since the Nile sources were unknown up until the 

19th century, the Ancient Egyptians believed the watercourse 

to be a part of the great celestial ocean, or the sea 

that surrounds the whole world. 

The fi rst actual recorded evidence of water management 

was the mace head of King Scorpion (ca. 2725–2671 BC), 

the last of the predynastic kings, which has been interpreted 

as the tool to initiate a ceremonial start to breaching 

the fi rst dyke to allow water to inundate the fi elds or the 

ceremonial opening of a new canal. Mohenjo-Daro was a 

major urban centre of the Indus civilisation during the early 

Bronze Age, located about 400 km north of present-day 

Karachi, Pakistan. This planned city, built around 2450 BC 

received water from at least 700 wells and had bathrooms 

in houses and sewers in streets as well as thermal baths 

(Jalter 1983). The Mesopotamians were not far behind. 

The Sumerians, during the Bronze Age, and other ancients 

that inhabited Ancient Mesopotamia provided an enormous 

amount of information about themselves through 

cuneiform tablets. Water provided by the Euphrates and 

Tigris Rivers shaped their societies. Elaborate irrigation 

systems were developed requiring continuous canal maintenance 

and construction of waterworks. Sedimentation in 

many canals was such a critical problem, that it was easier 

to abandon these canals and build new ones. One Sumerian 

epic indicates that humans were created specifi cally to 

dig irrigation ditches. The Sumerian epics also referred to 

the effect of uncontrolled human activity on the soil and 

environment, being interpreted as God’s curses, what we 

now understand as the environmental effects of intense 

irrigation (Mays 2008 and 2010). 

Meanwhile, on the periphery of these areas (e.g. in Arabia 

and in the deserts of Iran, Pakistan and India), food production 

through farming and nomadic pastoralism, hunting 

and fi shing, intensifi ed as the various capacities of 

the desert environment came to be used more effi ciently. 

It’s the creation of the oases: humankind’s most important 

realisation to survive in arid areas of the planet. An 

oasis is never a natural or casual creation. It is formed by 

small-scale local communities possessing environmental 

understanding specifi c to sites made habitable by applying 

techniques whose invention and preservation require considerable 

effort. The oases associate different skills and 

elements that already exist by using them in a new way. It 

is the fruit of the union of the environmental know-how of 

nomadic hunter-gatherers and herdsmen, with the water 

techniques of farmers (Laureano 2000). 

The creation of the oases depends on the possession of 

hydraulic qualifi ed expertise and the combined use of animals 

and plants suitable for the purpose, conditions that 

were fi rst met in the early age of metals, around the third 

millennium BC. In this period nomadic populations that had 

remained on the margins of the age’s great city-building 


processes chose an agro-pastoral lifestyle and, driven by 

motives and pressures related to that choice, interacted, 

allied, established symbiosis with or assimilated other 

groups, opening to all the package of specifi c concepts 

that will lead to a leap in complexity and establish the oasis 

as a complete system for the support of lives and livelihoods. 

Through oases, these groups ensured physical and 

economic survival in hostile but mineral-rich areas that 

had become strategic in the Chalcolithic Period and Iron 

Age. It is in this context that was introduced the technology 

of catchment’s tunnels a factor that allows the enormous 

spread of oases. They are known in Iran as qanat or kareez, 

in Morocco as khettara and in Algeria as foggara. This 

technique has been in use for thousands of years, over a 

vast area extending from China to Persia, Spain, and even 

Latin America. As it is well known, catchment’s tunnels are 

underground channels consisting of verticals shafts connected 

at their bottom with a sub-horizontal tunnel bringing 

water from an aquiferous stratum. The underground 

tunnel has a slight downward slope useful for the water 

tapped to run down it and into the open air by gravity. That 

these techniques are not the result of an imposition by a 

central power, but expressions of the knowledge of local 

populations, is demonstrated by their extreme variety and 

environmental adaptability, and by the diverse terminology 

used in each countries. 

Other great civilisations such as the Minoans, located on 

modern-day Crete, fl ourished during the Bronze Age (ca. 

3200–1100 BC). They had wonderful water and wastewater 

systems, such as those found in Knossos, Malia, 

Phaistos, Zakros, and other sites. These systems included 

aqueducts, cisterns, fi ltering systems, sedimentation 

basins, rainfall-harvesting systems, terracota pipes for 

water supply and sewage, and sewerage and drainage systems. 

As the Minoans developed trade relations with the 

Greek mainland, they came to infl uence the Myceneans 

(ca. 1,600–1,100 BC). The contact of Mycenaean’s with 

Minoan Crete played a decisive role in the shaping and 

development of Mycenaean culture and the dissemination 

of Minoan water and wastewater technologies in the central 

Greece and other parts of Europe. While the two civilisations 

were almost opposites culturally, Mycenean and 

Minoan art and technology showed signs of cultural diffusion. 

The strong bond of Minoans with Myceneans ended 

when the Myceneans decided to invade Crete. After a brief 

period of Mycenean control the Minoan civilisation disappeared. 

The Myceneans were the most direct ancestors 

to the later Greeks. Mycenean culture and power reached 

its peak around 1300 BC. Then the cultural diffusion that 

resulted from trade contacts with the Hittite Empire and 

Egypt started to deteriorate. All these remarkable civilisations 

had one thing in common, even with the advanced 

capabilities to provide water supply, these civilisations 

all collapsed. The interesting question is whether water 

resources sustainability was a signifi cant component for 

their failure (Mays et al. 2007). 

In the later archaic (750–500 BC) and classical (500–336 

BC) periods, both historical sources and archaeological 

excavations provide evidence that water and wastewater 

technologies were advanced and widespread in Greece. 

Greeks built on the previous knowledge of hydraulics and 

water resources, but yet they also failed. The advancement 

of urban water technology and management is illustrated 

by the aqueduct of Samos (known as tunnel of Eupalinos) 

91

92 


and the Peisistratean for Athens (Koutsoyiannis et al. 

2008). 

The Romans replaced the Greek rule in most locations, 

inherited the technologies and developed them further. In 

addition, the Romans substantially increased the application 

scale and implemented water projects in almost every 

large city (De Feo et al. 2011). The Greek and Roman water 

technologies are not only a cultural heritage but are the 

underpinning of modern achievements in water engineering 

and management practices. A few examples are the 

Hadrianic aqueduct in Athens and that in ancient Olympia 

known as Nymphaion of Herodes of Atticus which were 

constructed in the 2nd century A.D. Apparent characteristics 

of technologies and practices not only by the Greeks 

and Romans, but in many other ancient civilisations are 

durability and sustainability (De Feo et al. 2011). Nowadays, 

the popular but inaccurate image is that Roman 

aqueducts were elevated throughout their entire length 

on lines of arches, called arcades. Roman engineers, as 

their Greek predecessors, were very practical and therefore 

whenever possible the aqueduct followed a steady 

downhill course at or below ground level (Hansen 2006). 

As a matter of fact, on average 87% of the length of the 

Rome’s aqueduct system was underground (De Feo et al. 

2011). The longest aqueduct in the Roman world was constructed 

in the Campania Region, in Southern Italy. It is the 

Augustan Aqueduct Serino-Naples-Miseno, which is not 

well known owing to there being no remains of spectacular 

bridges, but it was a masterpiece of engineering (De Feo 

and Napoli 2007). 

Also, management practices were integrated, combining 

both large-scale and small-scale systems that have 

allowed cities to sustain for millennia. The durability of 

some of the systems that operated up to present times, 

as well as the support of the technologies and their scientifi 

c background by written documents enabled these 

technologies to be inherited by present societies despite 

regressions that have occurred through the centuries 

(e.g. in the Dark Ages). For instance, the spectacular 

ruins of Pompeii provides a clearer understanding of a 

Roman urban water distribution system, with similarities 

to a modern water distribution system. In fact, the 

ending point of a Roman aqueduct was the castellum 

divisorium which had the double function of serving as 

a disconnection between the aqueduct and the urban 

distribution network as well as dividing the water fl ow to 

various uses and/or geographical areas of the city. From 

the castellum divisorium, the three pipes conveyed the 

water to different parts of the city fi lling water towers: 

the castellum secondarium or castellum privatum (De 

Feo et al. 2011). It happened e.g. after the fall of the 

Roman Empire, when water sanitation and public health 

declined in Europe. Historical accounts tell of incredibly 

unsanitary conditions – heavily polluted water, human 

and animal wastes in the streets, and water thrown out 

of windows onto people in the streets. Consequently various 

epidemics ravaged Europe. During the same period, 

Islamic cultures, on the periphery of Europe, had religiously 

mandated high levels of personal hygiene, along 

with highly developed water supplies and adequate sanitation 

systems, which in several cases were the same old 

Greek and Roman facilities, preserved along the centuries 

(Mays 2008 and 2010). 

There is no doubt that the ancient societies in Mesoamerica 

and the Southwestern United States did fail partially from 

the depletion of natural resources and climate change, 

at least particularly as related to water (Mays 2007). The 

period from about 150 AD to 900 AD, was the most remarkable 

in the development of Mesoamerica. During the Classic 

period the people of Mexico and the Maya area built 

civilisations comparable with the advanced civilisations in 

other parts of the world. In Mesoamerica those ancient 

urban civilisations developed in arid highlands where 

irrigation (hydraulic) agriculture allowed high population 

densities. In the tropical lowlands, however, there was a 

dependence on slash-and-burn (milpa) agriculture which 

kept the bulk of the population scattered in small hamlets. 

The non-urban lowland civilisation possibly resulted from 

responses to pressures set up by the hydraulic, urban 

civilisation. Teotihuacan (City of the Gods) in Mexico is the 

earliest example of highland urbanism (Mays 2010). 

Different water and wastewater techniques were applied 

according to local conditions. For example, water supply 

in some Minoan settlements was dependent on springs 

and in others on a surface runoff or groundwater systems. 

Despite this diversity, common construction mastery 

seems to have been applied in several places in a 

relatively reduced time span. It can be suggested that a 

group of people living in prehistoric sites were aware of 

the principles of water relevant technologies. This suggests 

the existence of master craftsmen responsible for 

constructing and maintaining the water supply system of a 

community. They should also be in charge for the solution 

of some water related problems and were able to provide 

palaces and settlements with effi cient, decentralised, environmental 

friendly and even sophisticated water supply 

and wastewater systems (Angelakis et al. 2011). 

The link between traditional 

knowledge and water resources 

sustainability 

At the beginning of this new millennium a water crisis which 

threatens human’s existence in many parts of the world is 

being experienced. One might ask, how sustainable is it 

to live in a world where approximately 1.1 billion people 

lack safe drinking water, approximately 2.6 billion people 

lack adequate sanitation, and between 2 million and 

5 million people die annually from water-related diseases? 

In the attempt to solve this water crisis the concepts of 

water resources sustainability is creating concern. Water 

resources sustainability is the ability to use water in suffi 

cient quantity and quality from the local to the global 

scale to meet the needs of humans and ecosystems for 

the present and the future to sustain life, and to protect 

humans from the damages brought about by natural and 

human-caused disasters that affect sustaining life (Mays 

2007). The overall goal of water resources management 

must be water resources sustainability. 

A component of water resources sustainability is the use of 

traditional knowledge, which constitutes the ancient knowledge 

of humanity (www.tkwb.org). The United Nations 

Convention to Combat Desertifi cation (UNCCD) provided 

the following defi nition of it: ‘Traditional knowledge consists

of practical (instrumental) and normative knowledge concerning 

the ecological, socio-economic and cultural environment. 

Traditional knowledge originates from people 

and is transmitted to people by recognisable and experienced 

actors. It is systematic (inter-sector and holistic), 

experimental (empirical and practical), handed down from 

generation to generation and culturally enhanced. Such a 

kind of knowledge supports diversity and enhances and 

reproduces local resources.’ 

Where can traditional knowledge help in water resources 

sustainability to be implemented? Because water impacts 

so many aspects of our existence, there are many facets 

that must be considered in water resources sustainability. 

How do we overcome our modern day shortcomings and 

strive for water resources sustainability? Possibly one way 

is to study the past. The use of traditional knowledge may 

play a major role in solving some of the present day and 

future water resources sustainability issues, especially in 

developing parts of the world. 

Many civilisations, which were great canters of power and 

culture, were built in locations that could not support the 

populations that developed. Now we fi nd ourselves in similar 

situations in many places around the world. Arid zones 

cover 41.3% of the world’s land surface, corresponding 

to 34.7% of the planet’s inhabitants (2.1 billion people). 

Urban growth in these areas has been largely sustained 

by tapping remote water resources. Under the growing 

pressure of global warming, these resources are becoming 

increasingly insuffi cient and are at risk of complete 

collapse in the medium and long term. The situation of 

urban centres in arid regions is therefore critical. Only so 

much water fl ows in the world’s rivers: the concentration of 

resources in built-up areas has worked to the detriment of 

outlying lands, depriving fl ora and fauna of the water their 

vital processes require and hence triggering processes of 

soil degradation, erosion and desertifi cation. 

One might argue that if the ancient societies had our 

present day technologies, they would not have failed. However, 

even newer technologies, are not the answer for our 

present day problems; therefore, there is need to rely on 

traditional knowledge to tackle these problems. 

What relevance does the failure or collapse of ancient civilisations 

have upon modern societies? Learning from the 

past and discovering the reasons for the success and failure 

of other societies seems very logical. We certainly are 

a much more advanced society than those of the ancient 

societies, but will we be able to overcome the obstacles 

to survival before us? The collapse of some civilisations 

may have been the result of the very processes that had 

been responsible for their success (e.g. the Mayans and 

Romans and others). 

What relevance do ancient civilisations have upon modern 

day water resources sustainability? Or better yet, what can 

we learn from these ancient civilisations? Diamond (2005) 

proposed a fi ve-point framework for the collapse of societies: 

(a) damage that people inadvertently infl ict on their 

environment, (b) climate variability, (c) hostile neighbours, 

(d) decreased support by friendly neighbours, and (f) society’s 

responses to its problems. Three of these can relate 

to water resources sustainability. 


Past, present and future cities 

It is well accepted that urbanisation will continue to 

increase in the future and its impacts to the environment 

and especially to water and wastewater will continue to 

increase signifi cantly. In the food-chain, production of 

meat, fi sh and dairy products consume 2.9-fold more 

water, 2.5-fold more energy, 13-fold more fertiliser and 

1.4-fold more pesticides than the vegetarian ones. Thus, 

in the near future their production will account for more 

than 50% of the overall water consumption. 

On the other hand, the old water and wastewater technologies 

developed in ancient civilisations, which are the 

underpinning of the modern achievements, may provide 

valuable insights for sustainable water and wastewater 

engineering and management practices in the future cities. 

Lessons to be learnt from the past could be relevant 

to (a) Design philosophy of water and wastewater projects 

(e.g. construction and operation period); (b) adaptation to 

the environment; (c) management (balancing water availability 

with the demand); (d) architectural aspects of the 

cities; (e) diet habits; and (f) sustainability, as a design 

principle (Koutsoyiannis et al. 2008; Mays 2010). 

As an example, currently, engineers typically use a design 

period for structures of about 40 to 50 years as dictated 

by economic considerations. Sustainability, as a design 

principle, has entered the engineering lexicon only in the 

last decade. Naturally, it is diffi cult to estimate the design 

principles of ancient engineers but it is notable that several 

ancient works have operated for very long periods, 

some until recent times and other are still operative. For 

example, wastewater and stormwater drainage systems 

were functioning in Minoan settlements since the Bronze 

Age (Angelakis et al. 2005). These include bathrooms and 

other sanitary and purgatory facilities, as well as wastewater 

and storm sewer systems. In fact, the hydraulic and architectural 

function of sewer systems in palaces and cities are 

regarded as one of the salient characteristics of Minoan 

civilisation. They were so advanced that they can be successfully 

compared with their modern counterparts. 

Epilogue (and outlook) 

Many civilisations, which were great centres of power and 

culture, were built in locations that could not support the 

populations that developed. Now we fi nd ourselves in similar 

situations in many places around the world. How do we 

balance the mega water projects with the methods of traditional 

knowledge? Koutsoyuannis et al. (2008) explored 

the legacies and lessons on urban water management 

learned from the ancient Greeks. They summarised the 

lessons learned as follows: 

a) The meaning of sustainability in modern times should 

be re-evaluated in light of ancient public works and 

management practices. Technological developments 

based on sound engineering principles can have 

extended useful lives. 

b) Safety, with respect to water, is of critical importance in 

the sustainability of a population. 

93

94 


c) In water-short areas, development of cost-effective 

decentralised water and wastewater management program 

is essential. 

d) Traditional knowledge could play important role for sustainable 

water supply in the future cities. 

e) Climate variability is not a new phenomenon. People 

have always had to cope with the uncertainty natural 

phenomena and unpredictability of the environment. 

Precisely these conditions have shaped knowledge and 

adapted it locally to respond to adversity with appropriate 

techniques for capturing and distributing water, 

protecting soil, recycling and optimising energy use. 

These techniques constitute a great reserve of biological 

diversity and sustainable knowledge. 

The use of traditional knowledge does not directly apply 

techniques of the past but instead, attempts ‘to understand 

the logic of this model of knowledge’ (Laureano 2007). 

Traditional knowledge allowed ancient societies to keep 

ecosystems in balance, carry out outstanding technical, 

artistic, and architectural work that has been universally 

admired. The use of traditional knowledge has been able 

to renew and adapt itself. Traditional knowledge incorporates 

innovation in a dynamic fashion, subject to the test of 

a long term, achieving local and environmental sustainability. 

An important subject for the sustainability in developing 

nations of the world is to research the implementation 

of methods of traditional knowledge for water supply. Many 

of these techniques may prove to be very valuable over the 

more conventional (more sophisticated) ones. 

The ancients for the most part lived in harmony with 

nature and their environment, those that did not failed. 

Their actions should be warnings to us, in other words the 

ancients have warned us. Today we do not live in harmony 

with nature and the environment. 

Usually we defi ne ‘ancient civilisations’ as those confi ned 

far away into past and, therefore, dated as ‘very old’. However, 

compared to the time scale they were the dawn of 

civilisation, their being ancient is more properly referred to 

as being ‘young civilisations’. If we relate the evolution of 

civilisation using the human life as the time scale, rather 

than centuries, it would be more immediate to recognise 

the ‘ancient civilisations’ like ‘young’ whereas the ‘modern 

civilisation’ as ‘old’. It is well known that young people 

have a greater risk attitude, compared to the elderly and 

thus the ‘fi rst civilisations’ were more genuine, spontaneous, 

instinctive as well as they had a greater risk attitudes 

that leading them toward the construction of wonderful 

and fantastic works, better understanding the human 

needs and wishes. In the light of the water and wastewater 

technologies perspective, this is particularly true because 

water is the beginning of life as stated by (Aristotle, Metaphysics, 

983 b.). Thus, we have to recover the ability to 

‘think young’, to ‘think sustainable’! 

References 

Angelakis, A.N., Koutsoyiannis, D. and Tchobanoglous, G. 

(2005). Urban wastewater and stormwater technologies in 

the Ancient Greece. Water Research 39(1): 210–220. 

Angelakis, A.N., Dialynas, M.G. and Despotakis, V. (2011). Evolution 

of water supply technologies in Crete, Greece through 

the Centuries. In: Evolution of Water Supply Throughout Millennia. 

IWA Publishing, London, UK (in press). 

Angelakis, A.N., Salgot, M., Paranychianakis, N.V. and De Feo, 

G. (2010). 2nd Newsletter: IWA-SG on Water and Wastewater 

Technologies in Ancient Civilizations. IWA, pp. 1–24, 

http://www.iwahq.org/Home/Networks/Specialist_groups/ 

List_of_groups/Water_and_Ancient_Civilizations/. 

De Feo, G. and Napoli, R.M.A. (2007). Historical development of 

the Augustan aqueduct in Southern Italy: Twenty centuries 

of works from Serino to Naples. Water Science and Technology: 

Water Supply 7(1), 131–138. 

De Feo, G., Mays, L.W. and Angelakis, A.N. (2011). Water 

and Wastewater Management Technologies in Ancient 

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Science (P. Wilderer, ed.), vol. 1, pp. 3–22, Academic Press, 

Oxford, UK. 

Diamond, J. (2005). Collapse: How Societies Choose to Fall or 

Succeed. Viking, New York, USA. 

Hassan, F.A. (1998). Climate change. Nile fl oods and civilization. 

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Rome. http://www.waterhistory.org (accessed February 

2010). 

Jalter, M. (1983). La Santé par les Eaux. 2000 ans de thermalisme. 

S.I. l’Instant Durable, Clermont-Ferrand, France. 

Koutsoyiannis, D., Zarkadoulas, N., Angelakis, A.N. and 

Tchobanoglous, G. (2008). Urban water management in 

Ancient Greece: legacies and lessons. ASCE, Journal of 

Water Resources Planning & Management, 134(1): 45–54. 

Laureano P. (2000). The Water Atlas, Traditional Knowledge to 

Combat Desertifi cation. UNESCO, Laia Libros, Barcelona, 

Spain. 

Laureano P. (2007). Ancient water techniques for proper 

management of Mediterranean ecosystems. Water Science 

& Technology, Water Supply 7(1): 237–244. 

Mays, L.W. (ed.) 2007). Water Resources Sustainability. 

McGraw-Hill, New York, USA. 

Mays, L.W. (2008). A very brief history of hydraulic technology 

during antiquity. Environmental Fluid Mechanics 8(5): 

471–484. 

Mays, L.W. (ed.) (2010). Ancient Water Technologies. Springer, 

The Netherlands. 

Mays, L.W., Koutsoyiannis, D. and Angelakis, A.N. (2007). A brief 

history of urban water supply in antiquity. Water Science & 

Technology: Water Supply 7(1): 1–12.

Water reuse: a growing option 

to meet water needs 

Written by V. Lazarova, J. Hu and L. Sala on behalf of the Specialist Group 

Introduction 

During the past few years, water reuse is characterised by 

a major expansion, becoming thus a competitive option to 

meet water needs and to respond to the climate change 

(Jimenez and Asano 2008; GWI 2010). The growing interest 

in water reuse is observed in both developed and 

developing countries with a major trend for diversifi cation 

of water reuse practices. Recycled water is considered as 

an important element of integrated water resource management 

and, in exchange for an increase in energy consumption, 

it is making possible to close or accelerate the 

urban water cycle and preserve the natural water resources 

and biodiversity. According to the recent market study of 

GWI 2010, the growth of water reuse is expected to outpace 

desalination with a strong increase up to +300% of 

the capacity of high-quality water reuse plants owing to the 

lower energy requirements. 

Water reuse applications 

One of the most important trends of this accelerated development 

is the diversifi cation of water reuse practices. By 

2000, agricultural irrigation was, and still remains, the 

major water reuse application (Lazarova and Bahri 2005; 

Jimenez and Asano 2008). During the past decade, urban 

water reuse – mainly for landscape and golf course irrigation 

– has emerged as the application with the highest rate 

of development. Indirect potable reuse, and in particular 

aquifer recharge (Figure 2.1), have been implemented in 

many countries as an effi cient solution for the augmen- 

Figure 2.1. View of the recharge with recycled water of the 

unconfi ned dune aquifer of Torreele/St-André in Belgium. 


tation of water supply after complementary polishing and 

storage of recycled water. Other relevant and cost effi cient 

applications are also emerging such as environmental 

enhancement (replenishment of ponds, lakes, wetlands, 

rivers) and industrial use of reclaimed urban wastewater. 

Finally, direct potable reuse, practiced for over 40 years 

in Namibia, is starting to be considered in California as an 

option for the next 20 years leaving some bitter controversy 

behind (Leverenz et al. 2011). 

Water reuse terminology 

To facilitate communication among different groups associated 

with water reuse, it is important to understand the 

terminology used in this fi eld, including the glossary used 

in recent water reuse regulations. 

Water reuse is the most commonly used term for the 

benefi cial use of treated wastewater, but can also refer to 

reuse of stormwater, rainwater or greywater (used potable 

water from bath and sink). Treated wastewater suitable 

for a given reuse application is often called reclaimed or 

recycled water. According to the Oxford English Dictionary, 

these two terms are synonyms. Because the public 

is widely engaged in recycling paper, glass, plastics and 

other household wastes and clearly understands what the 

word recycling means, water recycling is the preferred 

term in several recent regulations. 

Consequently, water reuse, water recycling and water reclamation 

are synonyms used to indicate the use of properly 

treated wastewater for benefi cial purposes. The preferred 

term should be water recycling, as better accepted and 

easier to understand for the large public. 

It is important to stress that with the implementation of 

advanced membrane treatment technologies, the quality 

of recycled water is equivalent and even better than 

natural freshwater. For this reason and to improve public 

acceptance, new terms are emerging such as NEWater, 

EcoWater, etc. 

Finally, only planned water reuse projects are included 

within the terms water recycling or water reuse. The understanding 

and the acknowledgment of the non planned 

water reuse ¬ in particular, river water downstream of raw 

or treated wastewater discharge ¬ is also very important 

but have to be dissociated from the planned benefi cial 

reuse of adequately treated wastewater. 

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Technical advance in water reuse 

Over 3000 water reuse projects have been assessed by a 

survey conducted a few years ago (Bixio et al. 2005), some 

of them in an advanced planning phase. The major part of 

the water recycling schemes are located in Japan (>1,800) 

and the USA (>800), followed by Australia (>450), Europe 

(>200), the Mediterranean and Middle East area (>100), 

Latin America (>50) and Sub-Saharan Africa (>20). Nowadays, 

this number should be signifi cantly higher with the 

fast development of water reuse in China, India and the 

Middle East. As mentioned previously, agricultural and 

urban irrigation remains the major use of recycled water. 

Several mature treatment technologies enable to produce 

recycled water quality to meet the water quality requirements 

for the intended reuse applications. The major technical 

challenge is to ensure the reliability of plant operation 

to consistently meet water reuse regulations. 

Table 2.1 illustrates the most common treatment trains 

for the main water reuse applications. Non-conventional 

(extensive or natural) treatment processes are an effi cient, 

easy to operate and cost effective solution for developing 

countries and rural areas for full treatment or polishing of 

secondary effl uents. 

One of the major technical challenge of wastewater treatment 

for agricultural water reuse is to ensure the health 

safety, and at same time to conserve the fertilising value 

of wastewater. Advanced physico-chemical primary treatment, 

implemented in Mexico, achieved this objective by 

means of the combination of high-rate clarifi cation and 

disinfection, without the removal of dissolved carbon, 

nitrogen and phosphorus, the last two being the main fertilising 

elements. 

It is important to underline that even for irrigation, recycled 

water of microbiological quality identical to that of drinking 

Table 2.1. The most common wastewater treatment schemes recommended for the major water reuse applications 

Type of reuse 

1. Restricted 

irrigation 

2. Unrestricted 

irrigation, 

e.g. crops 

eaten raw 

3. Urban uses, 

e.g. irrigation of 

parks, golf 

courses 

4. Dual distribution 

in-building for 

toilet fl ushing 

5. Aquifer recharge 

via infi ltration 

basins 

6. Indirect potable 

reuse, e.g. direct 

aquifer or 

reservoir recharge 

7. Industrial uses 

(cooling or boiler 

water) 

Extensive (non-conventional) 

treatment trains Intensive treatment trains or mixed technical solutions 

E.1a. Stabilisation ponds 

in series (including 

aerated lagoons) 

E.1b. Wetlands in series 

E.1c. Others: infi ltrationpercolation, 

algae 

ponds, etc. 

E.2a. Not recommended 

E.2b. Only in special cases 

trains E.1. with a well 

designed and monitored 

polishing step such as 

maturation ponds 

I.1a. Secondary treatment by activated sludge (AS) 

I.1b. Other secondary treatment trains, e.g. trickling fi lters, 

biofi ltration 

I.1c. Advanced primary treatment (high rate clarifi cation) and 

fi ltration 

I.1d Idem as a,b,c with a disinfection step 

(chlorination or (UV) or maturation ponds) 

I.2a. Secondary treatment by activated sludge with 

tertiary fi ltration and disinfection (Cl, UV or ozone) 

I.2b. Membrane bioreactor (MBR) followed by disinfection 

(Cl or UV) 

I.2c. Secondary treatment by activated sludge 

followed by soil-aquifer treatment (SAT) 

E.3. Not recommended I.3a. Idem as I.2a,b,c 

I.3b. Secondary treatment by activated sludge followed by 

tertiary ultrafi ltration (MF or UF) with chlorination 

E. 4. Not applicable I.4. Idem as I.2a,b or I.3b with ozonation as disinfection 

step or activated carbon for colour removal 

E. 5. Not applicable I.5. Idem as I.2a,b 

E.6. Not applicable I.6a. Multibarrier conventional treatment processes, 

e.g. AS or BRM followed by ozonation, 

fi ltration, activated carbon, fi nal disinfection 

I.6b. Advanced membrane treatments, e.g. AS or 

BRM followed by MF/UF, reverse osmosis (RO) 

and advanced oxidation (UV/H 2 O 2 ) 

E.7. Not applicable I.7a. AS or BRM with nitrifi cation followed by chlorination (cooling) 

I.7b. AS followed by MF/UF and RO with a double 

pass RO for high pressure boiler water 

I.7c. BRM followed by RO with a double pass 

RO for high pressure boiler water 

Source: adapted from Lazarova 2001, Bixio et al. 2005 and Asano et al. 2007

Figure 2.2. View of maturation ponds in Jordan. 

water can be consistently produced, which is the case with 

Title 22 disinfected effl uent for unrestricted irrigation of 

crops eaten raw and public gardens and lawns. According 

to the California Water Recycling Criteria (2000), the 

Title 22 treatment includes coagulation, fl occulation, 

sedimentation, fi ltration and disinfection. A more recent 

tertiary treatment for this purpose is the combination of 

high-rate tertiary fi ltration and UV radiation. The major 

irrigation projects using such high quality recycled water 

are implemented in Monterey County, California (120,000 

m 3 /d) for irrigation of 5000 ha of farmland with vegetable 

crops; Milan, Italy (432,000 m 3 /d) for irrigation of 22,000 

ha of rice; Virginia, Adelaide in Australia (65,000 m 3 /d) for 

horticultural crops irrigation. 

Advance in science and technology greatly contributes 

to the implementation of new more effi cient wastewater 

treatment trains. Advanced technologies, especially membranes, 

enable the production of high quality recycled 

water equivalent to drinking water quality. A number of 

recent projects and/or expansions of existing reuse facilities 

have chosen membrane technologies, in particular 

for indirect potable reuse (Water Replenishment Project 

in Orange County, California; Wulpen Aquifer Recharge 

Project in Belgium; Western Corridor in Australia; 

NEWater Projects in Singapore). The high reliability of 

membrane treatment and the decreasing membrane cost 

favour the implementation of membrane tertiary treatment 

for non-potable applications such as urban uses 

for landscape irrigation, toilet fl ushing and fi re protection 

(Sydney Olympic Park and Rouse Hill, Australia), as well 

as for industrial purposes as cooling or boiler water (West 

Basin Water Recycling Project, California; Luggage Point 

Project, Australia). 

The Groundwater Replenishment (GWR) System in 

Orange County, California, is the largest water purifi cation 

project in the world for indirect potable reuse (265,000 

m 3 /d; 70 mgd). The GWR System produces high-quality 

recycled water that exceeds all state and federal drinking 

water standards and enables to meet the annual 

needs of local population. The GWR System takes highly 

treated wastewater and purifi es it using a state-of-theart, 

three-step process – microfi ltration, reverse osmosis, 

and advanced oxidation by ultraviolet (UV) radiation and 

hydrogen peroxide. The majority of the treated water is 

pumped to recharge lakes in Anaheim where the water 


Figure 2.3. View of microfi ltration units, Western Corridor 

(Australia). 

Figure 2.4. The NEWater Visitor Centre in Singapore. 

takes the natural path of rainwater as it fi lters through 

sand and gravel to the deep aquifers of the groundwater 

basin. Some of the recycled water, 21 to 57%, depending 

on the time of the year, is injected into Orange County’s 

seawater intrusion barrier. The GWR System helps 

decrease Orange County’s dependency on imported 

water from the Colorado River and Northern California. It 

takes a resource that would otherwise be wasted to the 

ocean, purifi es it and provides a new source of water. 

Additionally, the new facility uses approximately one-half 

the amount of energy required to transport the imported 

surface water. It also minimises the amount of fl ow to the 

ocean outfall during storms, preserving the county’s vital 

coast. The GWR System maintains ‘water diversity’ in an 

arid region, provides high-quality water for the groundwater 

basin and protects the environment by reusing a 

precious resource. 

Another well-known project for high-quality recycled 

water production is Singapore NEWater. In 2002, the 

fi rst NEWater plant was born. Singapore’s NEWater consists 

of polishing treated wastewater (both from domestic 

and industrial origin) by a three-stage tertiary treatment 

of ultrafi ltration, reverse osmosis and ultraviolet. The 

NEWater quality surpasses the World Health Organization 

requirements for drinking water and is used mostly by the 

industry (cooling of air conditioners) but also for indirect 

potable reuse. It is expected that NEWater will meet 30% 

of Singapore water needs by 2011, providing a secure 

alternative to the traditional water sources represented by 

importations from neighbour Malaysia and by the local 

catchments. 

97

98 


An important new concept in water reuse is the ‘fi t to 

use’ approach, which consists in the production of recycled 

water quality that meets the needs of the end users. 

When water reuse is implemented for different purposes, 

the most cost effi cient solution is to use several tertiary 

treatment trains to produce ‘designed water’ for each 

type of use. The best world example of the application of 

this concept is the West Basin Water Recycling Plant in 

California (315,000 m 3 /d), which produces fi ve quality 

recycled water: (1) disinfected tertiary effl uent for irrigation, 

(2) nitrifi ed disinfected tertiary effl uent for industrial 

cooling make-up water, (3) high-quality softened recycled 

water after microfi ltration (MF), reverse osmosis (RO) and 

advanced oxidation (UV + H 2 O 2 ) for the salt-intrusion 

barrier, (4) MF/RO disinfected water for cooling and lowpressure 

boiler feed and (5) MF and double pass RO for 

high pressure boiler feed water. 

Advanced treatment technologies and innovative analytical 

methods are making possible the production of recycled 

water similar and even better that drinking water quality. 

Nevertheless, the scientifi c evidence for the elimination 

of emerging contaminants and pathogens is not enough 

to achieve the public acceptance and political support for 

some water reuse projects. Such an example is the Western 

Corridor Recycled Water Project in Australia, which is 

intended to supplement drinking water reservoirs using a 

seven-barrier system to ensure the highest recycled water 

quality. This planned indirect potable reuse project purifi es 

the effl uent from six wastewater treatment plants by microfi 

ltration, reverse osmosis and advanced oxidation before 

supplementation of the water supply dams (an environmental 

barrier). The goals of the research are optimising 

existing processes and/or investigating alternative technologies, 

monitoring and evaluating contaminants of concern 

and, where possible, developing strategies to further minimise 

or eliminate the identifi ed risks. Research demonstrates 

that recycled water treated using the seven-barrier 

system adopted complies with all relevant standards and 

regulations for recycled water. However, conveying these 

scientifi c fi ndings successfully to the large public and 

convincing them that recycled water from this process is 

perfectly safe and valuable alternative water supply for the 

growing population is still a very challenging task. 

Owing to the emerging high demand of high quality recycled 

water, membrane technology is a hot topic in water 

reuse R&D. MBR have already been proven to sustain 

higher effl uent quality for reverse osmosis (RO) and more 

cost effective novel fi ltration methods are being investigated. 

One of them is the forward osmosis (FO) where 

separation occurs by using the osmotic pressure gradient 

between the feed solution and a highly concentrated draw 

solution. Treatment and recovery of RO brine generated 

during water reclamation is also under consideration using 

innovative technologies such as capacitive deionisation 

that uses an electric fi eld and porous electrodes to separate 

the anions from the cations and ultimately remove 

salts from the feed solution. 

Challenges of water reuse 

Despite the growing development of water reuse worldwide, 

its full-scale implementation and operation still face 

several regulatory, economic, social and institutional chal- 

lenges. Water reuse practices have to be adapted to each 

local situation in order to be safe, amenable, benefi cial and 

sustainable, both fi nancially and environmentally. Water 

reuse quality criteria shall be consistent and enforced by 

good management of recycled water quality with on-line 

control. 

The convergence of water reuse regulations is a very important 

challenge for the worldwide development of water 

reuse and its integration in urban water management. New 

regulations should be based on health protection, but also 

including treatment goals and a simple not very expensive 

water quality monitoring. A costly compliance monitoring, 

as those required by few recent regulations, could be an 

impediment to water reuse development. 

Economic viability of water reuse projects is another signifi - 

cant challenge that can be afforded by means of adequate 

water management policies. In fact, the value of recycled 

water is determined by the use to which it is put. Full cost 

recovery is a desirable objective but depends on ability to 

pay and the importance of other management objectives, 

including social and environmental criteria. Unfortunately, 

water reuse pricing is suffering from the competition 

with undervalued and/or subsidised conventional water 

resources and the lack of fi nancial incentives. 

An understanding of social and cultural aspects of water 

reuse is necessary to develop sustainable water recycling 

schemes. Reuse projects can fail for lack of social support, 

and reuse for potable purposes meets with the strongest 

opposition. Even for non-potable reuse purposes, public 

attitudes such as perception of water quality and willingness 

to pay or to accept a wastewater reuse project play 

an important part. In every country, the public’s knowledge 

and understanding of the safety and applicability of 

recycled water is a key factor for the success of any water 

reuse programme. Consistent communication and easy to 

understand messages need to be developed to the public 

and politicians explaining the benefi ts of water reuse for 

the long term water security and sustainable urban water 

cycle management. 

Energy shortage is nowadays a worldwide problem. 

Recently, alternative or renewal energy has attracted great 

attention. In the sector of wastewater treatment, energy 

consumption has been carefully examined and research 

works on energy minimisation in wastewater treatment 

and/or water reuse through novel processes are currently 

under investigation. The bottleneck for high-end water 

recycling systems, which usually involve membrane technologies 

and consume substantial amount of energy has 

been noted. In the near future, the challenges in water 

reuse would be the development of novel processes that 

consume less energy and/or enhance energy recovery. 

Conclusions 

Water recycling and reuse are rapidly growing practices 

worldwide that can be sustainable, cost competitive and 

energy saving options to increase water availability, providing 

thus a viable solution to adapt to climate change. 

Water reuse has been recognised as the solution for water 

shortage problems worldwide. Water reuse industry benefi 

ts from technology advances and innovations, but also

faces several new challenges such as concerns on health 

impacts, energy footprint and social and economic considerations. 

It is believed that there is still a long way to achieve 

the ultimate goal of sustainable water management worldwide, 

where water reuse plays a key role in establishing a 

benefi cial linkage between water, nature and human. 

References 

Asano, T., Burton, F.J., Leverenz, H.L., Tsuchihashi, R. and 

Tchobanoglous, G. (eds) (2007). Water Reuse: Issues, 

Technology, and Applications, McGraw-Hill, New York. 

Bixio, D., De Heyder, B., Cikurel, H., Muston, M., Miska, V., 

Joksimovic, D., Schäfer, A.I., Ravazzini, A., Aharoni, A., 


Savic, D. and Thoeye, C. (2005). Municipal wastewater 

reclamation: where do we stand? An overview of treatment 

technology and management practice. Water Science and 

Technology: Water Supply, 5(1) 77–85. 

Global Water Intelligence (2010). Municipal Water Reuse Markets. 

Media Analytics Ltd.,Oxford, United Kingdom. 

Jimenez, B. and Asano, T (eds) (2008). Water Reuse: An International 

Survey of Current Practice, Issues and Needs. IWA 


Lazarova, V. and Bahri, A. Eds. (2005). Irrigation with recycled 

water: agriculture, turfgrass and landscape, CRC Press, 

Boca Raton, FL, USA. 

Leverenz, H.L., Tchobanoglous, G. and Asano, T. (2011). Direct 

potable reuse: a future imperative. Journal of Water Reuse 

and Desalination, 1(1), 2–10. 

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Watershed and River 

Basin Management 

Written by Zaki Zainudin, Wendell Koning, Michael Weyand, Peter Kelderman and Bob Crabtree 


Leaps and bounds have been made in areas related to 

river basin management on a global scale, in line with various 

technological advances of the 21st century. We review 

six emerging trends related to water science, research and 

management. 

Transboundary water management 

and challenges 1 

One of the main issues, which have come under the close 

scrutiny of the W&RBM SG, is international transboundary 

water management, where a position paper was produced, 

elaborating various issues related to the subject matter and 

was presented at the IWA 2010 Young Water Professionals 

(YWP) conference in Kuala Lumpur, Malaysia. Transboundary 

water management refers to water management processes 

that straddle at least one political jurisdiction, either 

within a nation or across an international boundary. For 

example, 20 European countries depend on neighbouring 

countries for more than 10% of their water resources and 

5% draw 75% of their resources from countries upstream 

(UNECE 2009). Global water withdrawals have tripled 

over the past 50 years. At the same time, fl ood events, 

caused by climate change effects; increased impermeable 

surfaces, and anthropogenic use of fl ood plains, are 

increasing in both frequency and severity. It is estimated 

that almost half of the world’s population will be living in 

areas of high water stress by 2030 (UNESCO 2009). 

Thus, there is increased potential for confl ict over the allocation 

of water resources and the distribution of the benefi 

ts and costs associated with water use, which escalates 

when management has to be coordinated across borders. 

Political power is not equally distributed and can be used to 

maximise benefi ts to one nation rather than for the collective 

good of all nations and the environment (SIWI 2009). 

Traditionally, transboundary water management was 

focused on the four main aspects: protecting downstream 

users, equitable and effi cient allocation, planning and 

investment, and integrated monitoring and assessment. 

However, other emerging issues will require attention for 

effective transboundary water management to be achieved 

in the future. These are, amongst others, climate change 

aspects, groundwater and marine topics as well as the 

installation of adaptive and fl exible institutions. To address 

these emerging issues several recommendations for future 

transboundary water management are made. 

• Adopt guidance on climate change and update it as our 

knowledge increases. 

• Harmonise surface water, ground water, coastal and 

marine policies. 

• Ensure legal agreements are implemented and linked to 

local actions on the ground. 

• Clarify the outcomes required from cooperation and how 

the costs and benefi ts of cooperation are distributed. 

Climate change and environmental 

Impacts 2,3 

Climate change is now a common discussion item amongst 

politicians, scientists, weather experts and the public. 

However, the reality of climate change and the expected 

impacts are a challenge to defi ne. It is very diffi cult to forecast 

conditions in watersheds in 50 to 100 years, and yet, 

it is expected that water managers will set up measures 

and implement them in water systems to meet the given 

circumstances in the future. Climate change models for 

example, have predicted a reduction of 30% to infl ows 

in the Murray system. In the past twelve years, much of 

southern Australia has recorded lower than average rainfall, 

and in particular, extreme low rainfalls were recorded 

in 2006 and 2007. This weather pattern has led to 

extremely low infl ows for the Murray River and its tributaries 

and contributed to the antecedent conditions for three 

mega fi res (2003, 2007 and 2009). The recent drought 

sequence in the Murray Darling Basin may be a natural 

drought sequence exacerbated by climate change. The 

impact of these events on the farming communities, the 

irrigation industry, town water supply and environmental 

fl ows has been signifi cant. 

Looking upon climate change impacts in Europe, this region 

has to deal with two major developments. First, there may 

1 Adapted from Kirsty L. Blackstock; Perri Standish-Lee; Michael Weyand; Wendell Koning, Alan Vicorya and Peter Litheratry, “Transboundary 

waters: the role of integrated water resource management, IWA, Water 21, October 2011, pp. 22–24. 

2 Adapted from “Climate Change Impacts on River Basin and Freshwater Ecosystems: Some Observations on Challenges and Emerging 

Solutions”, Avi Ostfeld, Stefano Barchiesi, Matthijs Bonte, Carol R. Collier, Katharine Cross, Geoff Darch, Tracy A. Farrell, Mark Smith, Alan 

Vicory, Michael Weyand and Julian Wright. 

3 

Adapted from John Riddiford, “Water Management in Challenging Times – A Perspective from South-East Australia”, IWA W&RBM Newsletter, 

February 2010.

e changes in temperature conditions. It is expected that 

there is a tendency to dryer and hotter summers as well 

as wetter and milder winters. However, although different 

calculations on climate modelling have been made, there 

is still uncertainty as to what extent these changes in temperature 

will occur. Secondly, it is expected that there will 

be a change in the intensity of heavy storm events but, 

similar to the temperature changes, to what extent is still 

uncertain. To gain knowledge about possible climate conditions 

in the future, it is thus necessary to use climate 

change models in predicting impacts of climate change 

on river basin and freshwater ecosystems. The majority 

of global circulation models predict that climate change 

will result in severe changes in the water cycle leading to 

signifi cant drying in some areas of the world and wetting 

in others. More detailed modeling identifi es specifi c spatial 

and temporal complexities, such as strong changes in the 

seasonality of river fl ows. Despite uncertainty pertaining to 

methods, assumptions and input data of climate change 

models, most models point towards a trend of an increasing 

frequency of fl ooding and droughts events. 

The fourth report of the Intergovernmental Panel on 

Climate Change (Bates et al. 2008) predicted the following 

impacts on freshwater resources and ecosystems, ranging 

from likely to a high degree of confi dence in their occurrence 

based on observational records and climate change 

projections. 

• Global warming is likely to cause large-scale changes in 

the hydrologic cycle impacting timing, intensity and duration 

of water fl ows. Precipitation and average annual 

runoff will increase in high latitudes but decrease in some 


Figure 1. The Danube River Basin - covering 19 European states: Albania, Austria, Bosnia and Herzegovina, Bulgaria, Croatia, 

the Czech Republic, Germany, Hungary, Italy, Macedonia, Montenegro, Moldova, Poland, Romania, Serbia, Slovakia, Slovenia, 

Switzerland, Ukraine. 

subtropical and lower mid latitudes, especially in regions 

currently already dry; Increased intensity and variability 

in precipitation will likely increase risks of fl ooding and 

droughts (in many locations suffering extreme poverty 

like Bangladesh). 

• Water supplies from glaciers and snow cover will likely 

decline, reducing river base fl ows and increasing peak 

fl ows and consequently changing the water quality 

(Bonte and Zwolsman 2010). 

• There is a high confi dence that rising water temperatures 

and related changes in ice cover, total dissolved 

solids (TDS), oxygen levels and circulation will impact 

freshwater biological systems. 

• In addition, freshwater species often serve as excellent 

indicators of ecosystem functions. Key threat drivers 

which can be identifi ed include increasing dam 

density; river fragmentation; consumptive water losses,; 

over abstraction; increase in cropped land; increase in 

impervious surfaces; wetland non-connectivity; increases 

in invasive species and aquaculture; and, increased loadings 

of organics, pesticides, sediments, nitrogen and phosphorous 

(Vö rö smarty et al. 2010). Habitat loss and degradation 

present particular challenges to freshwater species 

that, in many cases, cannot relocate, with ecosystems often 

highly concentrated in relatively r estricted areas. 

Eventually, the combination of these factors erodes the 

resilience of ecosystems until they cease to cope with 

sudden changes. Managing rivers based on identifi cation 

and implementation of environmental fl ows can help protect 

the resilience of aquatic ecosystems. Environmental 

fl ows are based on maintenance of variable fl ows both 

within and between seasons and years to meet ecological 

101

102 


needs such as provision of healthy, diverse fi sh and riparian 

habitat, channel maintenance and water quality (Poff 

et al. 2010; Arthington et al. 2010). 

3. Water quality modelling and 

artificial neural network 4,5 

Water quality models are useful tools, which can, for 

example, be used to project and assess the effects of 

climate change in river basins. In Malaysia, water quality 

modeling is widely used to draft sustainable river basin 

management strategies. They have become an integral 

part of environmental management including for environmental 

impact assessments (EIAs) and river rehabilitation 

initiatives (Zainudin at al. 2009). Computer models enable 

pre- visualisation of impacts from proposed developmental 

activities before it actually occurs, which enables a thorough 

environmental management plan under various test 

scenarios with optimal cost and deteriorative implications. 

Models are also used as an investigative tool in relation to 

assessment and development of abatement measures that 

need to be taken to maintain or achieve a specifi c target 

quality. Once the baseline model has been developed, 

each reach (tributaries and main-stem) can be scrutinised 

to determine its Waste Assimilative Capacity (WAC). 

Depending on the current condition of the river, whether it 

is still within or beyond the desired water quality, the total 

amount of pollution load that it can still sustain or needs 

to reduce can then be determined using the water quality 

model (Mills et al. 1986). There are various types of models 

available in the market, both open source and commercial, 

and each with its own advantages and limitations, as well 

as specifi c focus areas. The input data and competency 

of the modeler are important variables for consideration to 

attain convincing and reliable model output. Nothing gives 

the modeler a better indication of the water quality characteristics 

of a water column than conducting an on-site fi eld 

survey collecting water quality and hydraulic data. 

Catchment based water quality modeling is gaining widespread 

use in the UK to understand where the greatest 

benefi t in a catchment can be achieved through ‘end 

of pipe’ and diffuse pollution reductions. Model results 

are used to target cost-effective investment by the environmental 

regulators, the water industry, and those with 

responsibilities for agriculture and urban diffuse pollution. 

SIMCAT is a mathematical model that describes the 

quality of river water throughout a catchment by using a 

Monte-Carlo simulation approach to predict the behavior 

of the summary statistics of fl ow and water quality, such as 

the mean and a range of percentiles. A key feature of SIM- 

CAT is the ability to derive quality relationships between 

points in a river based on the statistics of observed 

data. This enables SIMCAT to consider errors associated 

with sampling of data rather than errors associated with 

calibration of more detailed deterministic water quality 

process representations. Catchment scale river water 

quality modelling with the Environment Agency’s SIMCAT 

stochastic-deterministic river quality model is regarded as 

the best current approach to support decision making for 

river water quality planning in the UK. 

Water quality monitoring is performed to collect and analyse 

various water quality constituents. The data collected 

covers a wide range of parameters over a given period 

of time and is benchmarked against various standards 

to ascertain it’s benefi cial use. Currently, as mentioned 

above, there are various water quality models that are used 

to assess and project effects of climate change in river 

basins. These models have some limitations (Ali 2007), 

related to their underlying formulations and structure. Artifi 

cial Neural Networks (ANN) are used to solve complex 

engineering problems where it is diffi cult to develop models 

from the fundamental principles, particularly when dealing 

with non-linear systems. ANN is a system loosely modeled 

on the human brain. It resembles the human brain in two 

respects: the knowledge is acquired by the network through 

a learning process, and inter-neuron connection strengths 

known as synaptic weights are used to store the knowledge. 

ANN can be defi ned as a distributed computational system 

composed of several individual processing elements operating 

largely in parallel, interconnected according to some 

specifi c topology (architecture) and having the capability 

to self-modify connection strengths during the processing 

of element parameters (learning) (Haykin 1994). Some 

research has been carried out to apply ANN to water quality 

forecasting (Palani et al. 2008). It is expected that the 

ongoing global research in water science will move in the 

direction of enhanced utilisation of more robust modeling 

tools, such as ANN to become a key component in meeting 

higher level of water quality and increased demand. 

Development of decision support 

systems (DSS) 6,7 

Integration of water quality models and geographical information 

system (GIS) tools gives rise to decision support 

system (DSS) platforms that eases use for the end-user 

and enables graphical analysis of potential impacts. Such a 

system was developed for the world-famous Three Gorges 

situated on the middle reaches of the Yangtze River, that has 

a total length of 193 km. There are more than 8,500 commercial 

ships in operation, 17 cities and more than 1,700 

industrial enterprises located by the reservoir. Industrial, 

municipal and ship effl uent has become the main pollution 

source for the Yangtze River and results in, on average, 12 

water pollution accidents in the Three Gorges Reservoir 

Area (TGRA) every year. An integrated GIS based water 

pollution management information system for the TGRA, 

called WPMS_ER_TGRA, was developed. The ArcGIS 

Engine was used as the system development platform and 

Visual Basic as the programming language. The simulation 

4 Article contribution from Zaki Zainudin and Bob Crabtree from the IWA Specialist Group on Watershed and River Basin Management. 

5 

Article contribution from Mohammed Saedi Jami, Bioenvironmental Engineering Research Unit (BERU), Kulliyyah of Engineering, International 

Islamic University Malaysia (IIUM). 

6 Adapted from Zhai Jun, “An Integrated Geographic Information (GIS)- Based Water Pollution Management Information System for the 

Three Gorges Reservoir Area, P.R. China.”, IWA W&RBM Newsletter, September 2010. 

7 

Adapted from Pau Prat, Lluí s Corominas and Manel Poch, “Environmental Decision support system to select Robust operational strategies 

in Urban water Systems (ENDERUS)”. IWA W&RBM Newsletter, September 2010.

analysis of pollution incidents is mainly divided into three 

steps: add or edit the accidental pollution source; quickly 

calculate the concentration fi eld and its movement in time; 

and, analyse and visually show the simulation results. 

Subsequently, the GIS-based information system was 

applied to the emergency water pollution management 

following a shipwreck that released 10 tons of phenol into 

the Yangtze River over 2 hours. The results showed that 

WPMS_ER_TGRA can assist with emergency water pollution 

management by simulating the transfer and diffusion of 

accidental pollutants in the river. Furthermore, it can identify 

the affected area quickly and show how it will change 

over time within a few minutes of an accident occurring. 

In Spain, the Catalan Institute for Water Research (ICRA) in 

collaboration with the Laboratory of Chemical and Environmental 

Engineering (LEQUIA) are working on the project 

“Environmental Decision support system to select Robust 

operational strategies in Urban water Systems (END- 

ERUS)” that aims at developing an Environmental Decision 

Support System (EDSS) that addresses management 

problems in urban water systems, including the sewer 

system, wastewater treatment plants, storage tanks and 

the receiving water bodies. The EDSS will suggest operational 

strategies that will improve the overall performance of 

the system and, at the same time, will contribute to achieving 

the environmental standards promoted by both the 

European Water Framework Directive (WFD) (2000/60/ 

EEC) and the Spanish “Plan Nacional de Calidad de las 

Aguas” (PNCA) 2007-2015. The EDSS will include specifi c 

knowledge about: i) the physical, chemical and biological 

processes taking place in the different operational units 

comprising the UWS; ii) the complex interactions amongst 

these units, and, fi nally iii) a set of upstream actions based 

on literature, previous experiences or simulation studies 

mainly focused on the protection of the receiving water. 

ENDERUS will defi ne operating strategies to achieve different 

objectives. These strategies will be evaluated by means 

of dynamic mathematical models of the integrated urban 

water system and by using environmental legislation and 

economic and social criteria. The operating strategies will 

also be characterised using sensitivity analysis (to fi nd the 

most sensitive parameters in the urban water system) and 

estimating the robustness against changes in the wastewater 

composition, in the sewer system confi guration, and 

against toxic, hydraulic and pollutant shocks. 

Emerging contaminants in surface 

waters and drinking water production 8 

In Europe, millions of people depend for their drinking 

water on surface waters, such as the Danube, Meuse, 

Rhine, and Tagus River Basins. These surface waters are 

contaminated with thousands of chemical compounds 

originating from industry, agriculture and household uses 

and their number is still increasing. This confronts drinking 

water companies with the challenge and responsibility to 

deal with contaminants in their sources and still prepare 


safe drinking water. Classes of emerging contaminants 

now detected in the aquatic environment that are of relevance 

for drinking water production include endocrine 

disrupting compounds such as hormones and compounds 

with hormone-like properties, pharmaceuticals, illicit and 

non-controlled drugs, sweeteners, personal care products, 

complexing agents, nanoparticles, perfl uorinated compounds, 

fl ame retardants, pesticides, and fuel additives. 

The individual compounds are observed in concentrations 

that are generally considered too low to cause acute effects. 

Nevertheless, health effects due to long-term exposure to 

a mixture of low concentrations of all kinds of emerging 

contaminants cannot be excluded with current knowledge. 

Moreover, contamination of drinking water with man-made 

substances is considered to be unwanted. Drinking water 

companies use the precautionary principle to prevent the 

release of emerging contaminants into the environment as 

the preferred approach to safeguard sustainable drinking 

water production. In the mean time, they use extensive 

monitoring of their water sources; and, the development 

and application of advanced treatment techniques to prepare 

safe drinking water. 

In Canada, in addition to those contaminants previously 

identifi ed, attention is now being given to the presence of 

pharmaceuticals in the aquatic environment, that are commonly 

used in the livestock industry. There are approximately 

6.4 million head of cattle, 2.1 million pigs, 11.8 

million chickens, and 0.7 million turkeys in the province of 

Alberta (Statistics Canada 2006). Many of these animals 

receive medication; however, information regarding specifi c 

pharmaceuticals and their usage volumes in Alberta, and 

other provinces of Canada, are not routinely collected. Penicillin 

was the most commonly used antimicrobial and was 

administered in the animals’drinking water and by injection. 

In Alberta, Forrest at al. (2011), analysed 247 water samples 

from 23 watersheds during the open water season 

between, May 2005 and May 2006. Samples were analysed 

for 27 commonly used veterinary pharmaceuticals. Trace 

(ng·L-1) concentrations of antimicrobials were detected in 

51% of the samples (127 out of 247 samples). Maximum 

concentrations for the nine antimicrobials detected ranged 

between 3 and 250 ng·L-1 (Forrest at al. 2011). The antimicrobials 

detected and their concentrations were found 

to be similar to those in some recent European and North 

American livestock pharmaceutical stream surveys. 

Non-Point Source (NPS) monitoring 

and management strategies using 

constructed wetlands 9 

Wastewater treatment plants are commonly utilised to 

reduce contaminants from points-sources of pollution to 

protect water bodies. However, with regard to non-point 

sources of pollution (NPS), this approach has various 

drawbacks and practical limitations due to the potential 

volumes to be treated. In Korea, around 40% of the 

pollution load is attributed to NPS and this is expected 

8 

Adapted from Corine J. Houtman, “Emerging contaminants in surface waters and drinking water production”, IWA W&RBM Newsletter, 

March 2011. 

9 

Adapted form Joon Ha Kim, Joo-Hyon Kang and Sung Min Cha, “Non-Point Source (NPS) Monitoring and Management Strategies Using 

Constructed Wetlands”, IWA W&RBM Newsletter, February 2010. 

103

104 


to increase further, up to 50%, by 2015. Therefore, best 

management practices (BMPs) are becoming an emerging 

issue in Korea (Kim et al. 2007). 

Constructed wetlands are widely recognised as a costeffective 

method to reduce NPS pollution in both urban and 

rural area (Gunes and Tuncsiper 2009, Poe et al 2003). 

The Korean government launched a new mitigation program 

to reduce the elevated pollution contribution from 

diffuse by means of constructed wetland. Gwangju Institute 

of Science and Technology, a leading institution of 

environmental science and technology in Korea, carried 

out the research on NPS management using constructed 

wetlands since September 2008. The constructed wetland 

is located at the Yeongsan watershed in the Jeolla Province, 

the southwest part of the Korea. The results showed 

that the removal effi ciency of the wetland was highly variable 

depending on the sampling strategies, meteorological 

conditions, and operation of the wetland system. The 

characteristics of particulates, including TSS and turbidity, 

represented quite different patterns when the sampling 

frequencies increased or decreased. Clear evidence of the 

relationship between hydrograph and pollutograph further 

supported that pollutant loads could be reasonably estimated 

based on rainfall depth and soil condition. 

In the United States and Canada, Ducks Unlimited (DU) is 

an organisation committed to the conservation of wetlands 

and the development of constructed wetlands for wastewater 

treatment. Their conservation strategy is comprised 

of the following elements (DU 2011): restoring grasslands, 

replanting forests, restoring watersheds, working with 

landowners, working with partners, acquiring land, conservation 

easements, management agreements, and, the 

use of Geographic Information Systems (GIS). 

Among notable projects that they have completed is the 

construction of the 15 hectare Annapolis Royal wetland in 

2002. The wetland is being used to treat the community’s 

wastewater before it enters the Annapolis River (Ducks 

Unlimited 2011). The quality of effl uent from Annapolis 

Royal already met environmental standards, but it was 

high in phosphorous and nitrogen, which are two nutrients 

that, when abundant, reduce water quality and degrade 

habitat. The approach has improved the quality of water 

fl owing into the Annapolis River and the nutrients that fl ow 

through the wetland enrich and enhance the area for wildlife 

(Ducks Unlimited 2011). The project also consists of a 

trail system and interpretive signage to encourage the local 

community to come out and enjoy their wetland. 

References 

Ali, M.Z. (2007). The application of the artifi cial neural network 

model for river water quality classifi cation with emphasis on 

the impact of land use activities: a case study from several 

catchments in Malaysia. University Of Nottingham. PhD 

Thesis. 

Arthington, A.H., Naiman, R.J. and McClain, M. E. (2010). Preserving 

the biodiversity and ecological services of rivers: new 

challenges and research opportunities. Freshwater Biology 

55: 1–17. 

Bates, B.C., Kundzewicz, Z.W., Wu, S. and Palutikof J.P. 

(2008). Climate Change and Water. Technical Paper of the 

Intergovernmental Panel on Climate Change. Geneva, IPCC 

Secretariat. 

Bonte, M. and Zwolsman, J.J.G. (2010). Climate change induced 

salinisation of artifi cial lakes in the Netherlands and consequences 

for drinking water production. Water Research 

44(15): 4411–4424. 

Ducks Unlimited (2011). How DU conserves Wetlands and Waterfowl 

and Annapolis Royal Wetland. http://www.ducks. 

org/conservation/how-we-conserve / http://www.ducks.ca/ 

province/ns/projects/annapolis/index.html 

Forrest, F., Lorenz, K., Thompson, T., Keenliside, J., Kendall, J. 

and Charest, J. (2011). A scoping study of livestock antimicrobials 

in agricultural streams of Alberta. Canadian Water 

Resources Journal 36(1): 1–16. 

Gunes, K. and Tunsciper, B., (2009). A serially connected sand 

fi ltration and constructed wetland system for small community 

wastewater treatment. Ecological Engineering 35, 

1208–1215. 

Haykin S. (1994). Neural Networks: A Comprehensive Foundation. 

Macmillan College Publishing Company, New York, USA. 

Kim, L.H., Ko, S.O., Jeong, S. and Yoon, J. (2007). Characteristics 

of washed-off pollutants and dynamic EMCs in parking lots 

and bridges during a storm. Science of the Total Environment 

376, 178–184. 

Mills, W.B., Bowie, G.L., Grieb, T.M., Johnson, K.M. and Whittemore, 

R.C. (1986). Handbook: Stream Sampling for Waste 

Load Allocation Applications, 1st edition. Washington, DCU- 

SA: United States Environmental Protection Agency. 

Palani, S., Lionga S. and Tkalicha P. (2008). An ANN application 

for water quality forecasting. Marine Pollution Bulletin 

56(9): 1586–1597. 

Poe, A.C., Piehler, M.F., Thompson, S.P. and Paerl, H.W. (2003). 

Denitrifi cation in a constructed wetland receiving agricultural 

runoff. Wetland 23(4), 817–826. 

Poff, N.L., Richter, B.D., Arthington, A.H., Bunn, S.E., Naiman, 

R.J., Kendy, E., Acreman, M., Apse, C., Bledsoe, B.P., Freeman, 

M.C., Henriksen, J., Jacobson, R.B., Kennen, J.G., 

Merritt, D.M., O’Keefe, J.H., Olden, J.D., Rogers, K., Tharme, 

R.E. and Warner, A. (2010). The ecological limits of hydrologic 

alteration (ELOHA): a new framework for developing 

regional environmental fl ow standards. Freshwater Biology 

55(1), 147–170. 

Rajic ́, A., Reid-Smith, R., Deckert, A.E., Dewey, C.E. and McEwen, 

S.A. (2006). Reported antibiotic use in 90 swine farms in 

Alberta. Canadian Veterinary Journal 47(5), 446–452. 

SIWI (Stockholm International Water Institute) (2009). Stockholm 

Water Front – Beyond the River: A Transboundary Waters 

Special Issue [accessed 15th September, 2009] http:// 

www.siwi.org/documents/Resources/Water_Front/Water_ 

Front_1_lowres.pdf 

Statistics Canada (2006). Census of Agriculture for Alberta. 

Alberta Agriculture and Rural Development. Statistics and 

Data Development. Agdex 852-1. 

UNECE (2009) The Water Convention...at your service. 

United Nations, Geneva. http://www.unece.org/env/water/ 

publications/brochure/Water_Convention_e.pdf 

UNESCO (2009) United Nations World Water Development Report 

3: Water in a Changing World. The United Nations Educational, 

Scientifi c and Cultural Organization (UNESCO), Paris, 

and Earthscan, London. 

Wu, C.Y., Kao, C.M., Lin, C.E., Chen, C.W. and Lai, Y.C. (2010). 

Using a constructed wetland for non-point source pollution 

control and river water quality purifi cation: a case study in 

Taiwan. Water Science & Technology 61(10), 2549–2555. 

Vö rö smarty, C.J., McIntyre, P.B., Gessner, M.O., Dudgeon, D., 

Prusevich, A., Green, P., Glidden, S., Bunn, S.E., Sullivan, 

C.A., Reidy, C., Liermann and Davies, P.M. (2010). Global 

threats to human water security and river biodiversity. 

Nature 467: 555–561. 

Zainudin, Z., Rashid, Z.A. and Jaapar, J. (2009). Agricultural 

non-point source modeling in Sg. Bertam, Cameron 

Hig hlands using QUAL2E. Malaysian Journal of Analytical 

Sciences 13(2), 170–184.

Winery wastewater treatment 

in a sustainable perspective 


Written by D. Bolzonella (SG Chair), R. Chamy (SG Secretary), F. Cecchi, R. S. Chrobak, H.H. Fang, 

M. Greven, A. Grasmick, D. Jeison, J. Lema, J. Mata-Alvarez, R. Moletta, R. Mulidzi, J. Rochard 


Introduction 

Wine production is one of the leading sectors in the food 

processing industry and accounted for some 27.6 million 

tons (on average) in the years 2005–2009: 64% of the 

production originated from European countries, while the 

Americas accounted for another 20%, then Asia, Oceania 

and Africa accounted for 7%, 5% and 4%, respectively. 

Three European Countries, Italy, France and Spain, generated 

57% of the worldwide production. Figure 1 shows the 

wine production of major players of the wine market in the 

past few years. 

Unfortunately, the wine-making process has some important 

environmental drawbacks: 

• the intensive use of land, 

• the large use of water, 

• the application of pesticides, 

• the production of large amount of waste and wastewater, 

which need proper treatment to be disposed of. 

Figure 1. Wine production per annum in the main. 

Just to emphasise some key fi gures, the water footprint 

of wine is reported to be 120 litres of water for one glass 

of wine (125 ml): that is 1,000 m 3 per m 3 of wine, a level 

comparable to that of other crops requiring intensive irrigation 

(Bolzonella and Fatone 2010), while its carbon footprint 

is some 1.2 g of CO 2 equivalent per bottle (720 ml) 

(Kern and Rochard 2009). 

Because all these aspects are of fundamental importance 

for future sustainable wine production, the Specialist Group’s 

members are active researchers in all these areas, with an 

obvious particular emphasis on wastewater treatment. 

Wine and water: an overview 

When considering the environmental impacts deriving from 

wine-making, the production of wastewaters is of primary 

importance: in fact, water is used in several washing activities 

in the different steps of wine-making, like crushing and 

de-stemming, fermentation, fi ltration and bottling. 

105

106 


Produced wastewaters are characterised by variable fl ow 

rates, as they are seasonal in nature, high in organic loading 

(up to 10 gCOD/L and more during vintage) and in 

carbon-to-nitrogen ratio (C/N > 30) and sometime low in 

pH. In terms of fl ow rate, 60–70% is produced in three 

months, during vintage and wine production. Because 

of all these peculiarities, winery wastewaters need to be 

properly treated in high-effi ciency systems before their 

release in the sewerage system or the environment. 

The treatment of winery wastewater can realised using 

several biological processes based both on aerobic or 

anaerobic systems using suspended biomass or biofi lms. 

Several systems are currently offered by technology providers 

and current research envisages the availability of new 

promising technologies for winery wastewater treatment 

(Andreottola et al. 2009). When considering the main wine 

producers, France, Italy and Spain, where vineyards and 

cellars are more often part of the urban rather than rural 

environment, intensive processes with small footprints are 

preferred (Moletta et al. 2009) whereas in non-European 

contests extensive treatment processes, like ponds and 

constructed wetlands, can be preferred because of their 

low power demand and excess sludge production (Arienzo 

et al. 2009; Mulidzi 2010). 


Considering the contributions and discussions to the most 

recent conferences of the Specialist Group, some hot topics 

for the future research can be enlightened here. 

The necessity for a sustainable viticulture and winemaking 

clearly remains the main and primary concern. 

Therefore most efforts are related to the reduction of the 

environmental impacts of the wine-making industry. In 

general, the need for better waste and wastewater management, 

better control over chemical stores, as well as 

defi nite improvement in water management and increase 

in solid wastes recycling are clear targets. In fact, these will 

preserve the environment on the one hand and will cause 

long-term cost savings on the other. The following hot topics 

for future research can be considered in particular. 

High-performance wastewater treatment 

and reuse 

Considering the European situation, there is a clear necessity 

for high-performance intensive processes: in recent 

years, a vast mass of work has dealt with both the study 

and application of membrane bioreactors. These systems 

have demonstrated their capability in coping with high 

hydraulic and organic loading variability in reactors with 

a relatively small footprint (Guglielmi et al. 2009; Shah 

et al. 2008), producing an effl uent with interesting characteristics 

for reuse. Obviously, this technique is particularly 

energy-demanding (Bolzonella and Fatone 2010). 

Unfortunately, this is typically the case when the market 

overcomes research and development: a lot of work for 

a deeper understanding and optimisation of these processes 

is needed in the near future. 

Another important piece of work related to this topic is the 

research and application of anaerobic processes: in fact, 

because of their typical characteristics (that is, high organic 

content and biodegradability), they are particularly suitable 

for several different anaerobic processes, depending 

on the solids content of the waste(water) (Moletta 2005, 

2009; Chamy et al. 2007). 

Extensive treatment processes 

Beside high-performance processes, extensive processes 

also need further development. These systems are historically 

very diffuse in the southern part of the planet (see, 

for example, Arienzo et al. 2009; Mulidzi 2010). Recently, 

the use of high-performance wetlands has also found 

new application in the European context (Rochard et al. 

2010). 

Micropollutants management 

Large amounts of pesticides and chemicals are used in 

agriculture. In the light of a more sustainable viticulture, 

the management of spraying residues and water for washing 

activities should be considered with particular attention 

(Rochard et al. 2009). These waters can be treated 

by physical, chemico-physical and biological processes, 

or a combination of those, to reduce the presence of these 

harmful compounds. Although some commercial solutions 

are already available, this topic remains on the agenda for 

future improvements. 

Carbon footprint 

Wine production and winery wastewater treatment inevitably 

produce and emit greenhouse gases (GHG) such as 

CO 2 , CH 4 , N 2 O (Kerner et al 2009; Rosso et al. 2009). 

Further investigations are needed in this fi eld and the lifecycle 

assessment (LCA) to reduce the environmental activity 

of wine-production. 

In addition, in this case, the introduction of anaerobic 

processes, because of their relatively low energy demand, 

can reduce the GHG emissions. 

Conclusions 

The wine industry, from grape growing to bottling and 

delivery, determines considerable environmental impacts. 

Most of those are related to water management and wastewater 

treatment. According to the scenario illustrated 

above, notable efforts are needed to face these impacts: 

researchers in the fi elds of water management and waste 

and wastewater fi elds are called to cooperate with colleagues 

of other disciplines to reduce the wine industry 

footprint. 

References 

Andreottola G., Foladori P. and Ziglio G. (2009). Biological treatment 

of winery wastewater: an overview. Water Science & 

Technology 60(5), 1117–1125. 

Arienzo, M., Christen, E.W., Quayle, W., Di Stefano, N.. (2009). 

A wastewater treatment system for small scale Australian 

wineries. In: Proceedings of the V IWA International Specialized 

Conference on Sustainable Viticulture: winery waste and 

ecological impacts management, March 30th – April 3rd 

2009, Verona and Trento, Italy.

Bolzonella D. and Fatone F. (2010). Réduire l’empreinte du vin 

sur l’eau, un défi majeur. Revue des Oenologues et des 

Techniques Vitivinicoles et Oenologiques, 137, 7–8. 

Bolzonella D., Fatone F., Pavan P. and Cecchi F. (2010). Application 

of a membrane bioreactor for winery wastewater treatment. 

Water Science & Technology 62(12), 2754–2759. 

Cavazza A., Franciosi E., Pojer M. and Mattivi F. (2009). Washing 

grapes before crushing: effects on contaminants 

and fermentation. Proceedings of the V IWA International 

Specialized Conference on Sustainable Viticulture: winery 

waste and ecological impacts management, March 30th – 

April 3rd 2009, Verona and Trento, Italy. 

Chamy R., Pizarro C., Vivanco E., Schiappacasse MC, Jeison D., 

Poirrier P. and Ruiz-Filippi G. (2007). Selected experiences 

in Chile for the application of UASB technology for vinasse 

treatment. Water Science & Technology 56(2), 39–48. 

Guglielmi G., Andreottola G., Foladori P. and Ziglio, G. (2009). 

Membrane bioreactors for winery wastewater treatment: 

case-studies at full scale. Water Science & Technology 

60(5), 1201–1207. 

Kerner S. and Rochard J. (2009). Quantifi cation of greenhouse 

effect gas with the French method Bilan Carbone®: from 

the vine to the table. In Proceedings of the V IWA International 

Specialized Conference on Sustainable Viticulture: 

winery waste and ecological impacts management, March 

30th – April 3rd 2009, Verona and Trento, Italy. 

Méoule C., Rochard J., Kerner S. (2009). Vitimax®: Winery 

and phytosanitary effl uent treatment system. Proceedings 

of the V IWA International Specialized Conference on Sustainable 

Viticulture: winery waste and ecological impacts 


management, March 30th – April 3rd 2009, Verona and 

Trento, Italy. 

Moletta R. (2005) Winery and distillery wastewater treatment by 

anaerobic digestion. . Water Science & Technology, 51(1), 

137–144. 

Moletta R. (2009). Biological treatment of wineries and distillery 

wastewater. In Proceedings of the V IWA International Specialized 

Conference on Sustainable Viticulture: winery waste 

and ecological impacts management, March 30th – April 

3rd 2009, Verona and Trento, Italy. 

Mulidzi A.R. (2010). Winery and distillery wastewater treatment 

by constructed wetland with shorter retention time Water 

Science & Technology 61(10) 2611–2615. 

Rochard J., Grinbaum M., Codis S., Coulon T. (2009). Management 

of sprayer wash water: various treatment techniques 

and testing of a reed bed system. Proceedings of the V IWA 

International Specialized Conference on Sustainable Viticulture: 

winery waste and ecological impacts management, 

March 30th – April 3rd 2009, Verona and Trento, Italy. 

Rochard J., Oldano A., Marengo D. (2010). Environmental innovation 

in winery effl uent management: use of reed beds. 

12th International Conference on Wetland Systems for Water 

Pollution Control, Venice (Italy), 4–8 October 2010 

Rosso D., Bolzonella D. (2009). Carbon foot-print of aerobic 

winery wastewater treatment. Water Science & Technology, 

60(4), 1185–1190. 

Shah, A.; Bulleri, J.; Ross, R.; Carter, J.; Long, M. (2008). Successful 

plant scale winery wastewater treatment using 

membrane bioreactor in northern California. Proceedings of 

WEFTEC 08, Chicago, IL, October 18–23, 3408–3425. 

107

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