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RESEARCH & DEVELOPMENT
Gatze Lettinga: urging uptake of UASB technology
● Professor Gatze Lettinga was awarded the Lee Kuan Yew Water Prize at this year’s Singapore
International Water Week for his contribution to wastewater treatment through the development of
Upflow Anaerobic Sludge Blanket (UASB) technology. BILL McCANN spoke with him about his research
and his continued work surrounding UASB uptake.
This year’s Lee KuanYew
Water Prize was awarded
to Professor Gatze Lettinga
for his pioneering work in
the development of Upflow
Anaerobic Sludge Blanket
(UASB) technology for
wastewater treatment.
First awarded in 2008,the
prize,sponsored by the Singapore
Millennium Foundation,was
presented during Singapore
InternationalWaterWeek in
late June.
Much of Professor Lettinga’s
research and development was
centred onWageningen
University in the Netherlands
where he spent some 30 years,
retiring in 2001 after some 13
years as Professor in Anaerobic
TreatmentTechnology and
Reuse in the Department of
EnvironmentalTechnology.
When joiningWageningen as
an associate professor in 1970
Gatze Lettinga describes himself
as‘a layman in biological wastewater
treatment’and says his early
years there were characterised by
attempts to incorporate physicalchemical
methods into his studies
on anaerobic treatment,post
treatment and resource recovery.
The physical-chemical
approach recommended itself,he
says,because he had studied and
obtained his PhD in that field
during his education in chemical
engineering at theTechnical
University of Delft.
The development of UASB
He feels that this background has
been invaluable in pursuing his long
term interests in environmental
protection and sustainability,
especially the knowledge gained
on heavy metals,humic acids,
chelating agents,chlorination and
chemical precipitation.Also
influential in those early years was
an article by Professor Perry
McCarty of Stanford University,
USA,himself awarded the
StockholmWater Prize in 2007
for advancing understanding of
the chemical and biological
processes involved in
wastewater treatment.
As Lettinga explains:‘The very
first article I read about anaerobic
wastewater treatment,in my first
weeks after starting atWageningen,
was by Perry McCarty.It outlined
the big benefits of anaerobic
processes for both primary
and secondary treatment of
wastes and wastewater.I was
immediately convinced that
this should be the field to work
in,not especially for academic
reasons,but particularly because
it looked to offer enormous
potential to protect the environment
in a really sustainable way.’
With great modesty and
generosity he goes on to credit
McCarty with much of the initial
advancement in this area and says
that,but for a lack of research
funding in USA at the time,the
latter would undoubtedly have
gone on to develop the UASB
system.Events turned out differently,
with the initial focus on
UASB research atWageningen
directed towards high organic
content industrial effluents.This
was partly because 1970 Dutch
legislation on pollution control
was forcing industry to seek
affordable treatment methods
and,says Lettinga,he hoped and
believed that would encourage
interest in the anaerobic approach.
At the same time the
Netherlands,as elsewhere,
continued to put all the emphasis
on conventional aeration treatment
where public sector sanitation
was concerned.Research on
UASB pre-treatment for municipal
effluents did not begin until
about 1976,initially at laboratory
scale and looking at applications
in optimal temperature conditions.
Lettinga says these comprehensive
investigations are still
ongoing but,by 1981,Dutch
government funding supported a
larger scale – 64m 3 – demonstration
plant in Cali,Colombia,as
well as pilot plant research on
post-treatment systems.
Since then UASB technology
resulting from theWageningen
breakthrough has been increasingly
applied – demonstration
plants followed by full scale
operational units initially in
Colombia,Brazil and India,but
more recently also in Egypt,
Ghana and elsewhere.
Today there are said to be over
3000 UASB plants operating
worldwide.Brazil,Mexico and
Colombia are amongst the several
countries where the technology
is particularly favoured,with
Brazil being at the fore in diversifying
application from industry
into the public sanitation sector.
For Professor Lettinga the
affordability and low energy
demands of the technique have
always advertised it as the way
‘The NBM-concept undoubtedly will become
widespread; it cannot be prevented, obstructed
or ignored anymore.’
Professor Gatze Lettinga
forward in the developing
countries.In the developed
world it has always been harder
to overcome entrenched views
and the priority accorded to
investment in conventional
aerobic treatments.
But that domination,he
believes,is coming to an end,
driven by the increasing recognition
of his own long-held view
that the environment has to be
protected in a sustainable way.
Closing the water and
solids loops
He describes anaerobic treatment
as the first step in what he calls
the‘Natural Biological
Mineralization’(NBM) concept
of wastewater treatment,in his
view offering,when completed
with physical/chemical treatment,
a robust and affordable
route to the end objective‘for
everybody,everywhere.’
Elaborating on the theme he
says:‘When combined with
proper wastewater collection
systems and when transport is
kept to a minimum,the concept
can enable the closing of water
and solids loops.It can be applied
at almost any scale,does not suffer
from excess sludge problems and
takes half the space of a conventional
treatment plant,making it
an ideal technology for the
growing trend towards decentralized
treatment and reuse.
‘The NBM-concept undoubtedly
will become widespread;it
cannot be prevented,obstructed
or ignored anymore.The
achievements in the industrial
sector will become better
known,as will the achievements
in the public sanitation sector
in Brazil.Progress will come
too in the prosperous regions,
despite the huge investments
made there in super-centralized
conventional plants.
‘The transition may take
decades,but that is okay;we need
a step by step implementation,
each time when a suitable
opportunity arises.It all depends
on visionary and independent
leadership and decision making.’
Professor Lettinga continues to
play a very active part in making
all that happen.Retirement from
Wageningen in 2001 was in
reality no more than a transfer of
activities to the Lettinga
Associates Foundation (LeAF),an
independent knowledge centre
founded at roughly the same time
to transfer know-how and offer
training in all aspects of UASB
implementation and operation.
With close ties toWageningen,
LeAF aims to bridge the gap
between research and practical
application.Professor Lettinga
continues as a member of the
Board and speaks enthusiastically
of many ongoing LeAF projects,
including a training and capacity
building scheme in the Balkans
and UASB designs for plants
in France,Mexico,Morocco
and theYemen.
All this,he says,leaves little
time at the moment for some
planned book writing. ‘My
intention always has been to
work on but in an independent
way,free of links to business,but
time goes away so quickly.’ ●
WATER21 •• OCTOBER MONTH 20XX 2009 00 63

RESEARCH & DEVELOPMENT
Carbon neutral sewer repairs
UK company Wessex
Water has reported on
the successful trial use of a
carbon emissions calculator
developed in Canada.
Developed by Dr Mark Knight
ofWaterloo University,Canada,
the calculator and its capabilities
were introduced to the company
through the International Society
forTrenchlessTechnology (ISTT)
and were initially tested on a
contract for trenchless repair of a
1000m length of sewer in Bristol,
south-west England.
WessexWater Project
Engineer,Julian Britton,said this
first use of the calculator in the
UK had indicated that the
trenchless relining of the sewer
had saved 97% of the carbon
emissions that would have been
attracted by the conventional
open cut method.
Britton believed this to be
the only tool currently available
for such calculations and said
it operated on the basis of
input data that included not
only,in this case,the length
and diameter of the sewer
concerned,but also the duration
of the contract and details of
traffic volumes.This latter
enabled the output result to
include an allowance for
emission savings from reduced
traffic congestion.
With over 7000m of sewers
repaired by trenchless methods
during the past yearWessex is
constantly searching for advances
in this area and is,at the same
time,working to make it’s
trenchless operations as nearly
possible‘carbon neutral.’
In both these objectives
Britton says the company
derives great benefit from
sharing ideas with ISTT.
In the Bristol contract use of
Saving carbon with variable speed
In a study of the carbon
emissions savings to be
made from use of variable
speed drives industrial motor
manufacturer ABB claims to
show that variable speed
control on a 250kW motor
can compensate for the
emissions from manufacture
and disposal in just half of
one operating day.
Made in conjunction with
Finland’sTampere University of
Technology the study was based
on three motor sizes – 0.75kW,
7.5kW and 250kW – and showed
that payback time reduced in
inverse proportion to motor size.
Estimated time to overcome
manufacture and disposal
emissions was put at 1.1 days for
the medium sized motor and six
days for the smallest unit.
In the context of reducing
carbon footprint ABB make the
point that a positive contribution
to the environment comes only
after the early savings from
variable speed control have
reached the total emissions
arising from manufacture and
disposal of the unit.
Once that point is reached the
motor will make continuous
savings,and the operator will
have a reduced carbon footprint,
throughout the operating life of
the unit.In the case of the
Dealing with diffuse nitrates
Anew approach to dealing
with diffuse nitrate
pollution from agriculture
has been successfully tested at
a site in Northern Ireland
where it proved able to
reduce the nitrate
concentration of shallow
groundwater by over 90%.
Supported by the European
Commission’s LIFE financial
instrument,the NITRABAR
process is,in effect,a cut-off
trench that intercepts the shallow
groundwater as it flows towards
the river or other water body.
The trench and its fill material
form what is described as a
permeable reactive barrier in
which iron or other metals or
minerals are mixed with readily
available carbon substrates such
as tree bark,wood chippings or
leaf compost.This creates an
environment in which the
micro-organisms naturally
present in the soil and groundwater
can flourish to speed the
denitrification process,reducing
the dissolved nitrate in the
groundwater to gaseous nitrogen.
In practical application the
reactive barrier is preceded with
a permeable gravel chamber to
aid the collection and passage of
water from field drains and near
surface layers.
While many management
options now assist the farmer in
reducing the adverse environmental
impacts of current applications of
fertiliser or manure the unique
attribute of NITRABAR is that
it will deal with the nitrates
leaching slowly into water bodies
from surface applications made
possibly as long as 20 or 30 years ago.
The 46-month project started
in December 2005.Professor
Robert Kalin of the UK’s
250kW motor studied here the
lifetime savings were put at
7500MWh or 3800 tonnes of
carbon dioxide emissions.
Speaking about the findings,
Steve Ruddell,ABB General
Manager in the UK,said he
believed that purchaser investment
decisions currently based
purely on financial considerations
would,within the next five years,
have to give equal consideration
to the emissions factor.‘There
will be a sea change in the way
companies look at investment
decisions and they will be just as
keen to save carbon dioxide as
they are saving money today,’he
said.‘Our study shows that using
Strathclyde University designed
the system and led the research
team,which included partners
from Belgium,Malta and Poland.
Monitoring and data collection at
the Northern Ireland test site
began in early 2008.
The tests showed that the
method is cost-effective when
compared with other available
methods of dealing with diffuse
nitrate pollution and a significant
advantage is that it is the
only option for dealing
with historic pollution.
Another important advantage
is that,once installed,the
trench does not impede
normal field operations.
It was also concluded that
NITRABAR is an effective
means of maintaining agricultural
land in production and allowing
agriculture to continue,particularly
in high nitrate areas.
heat cured liners contributed to
the saving of harmful emissions
and he believes even greater
savings will become apparent
when the most recent
methods of curing linings
are brought into play.
These include‘melt in place’
thermoplastic liners and UV light
curing – the latter a technique
thatWessexWater is planning to
introduce during 2010.●
Further information: Press
Officer, Wessex Water
Email: Clare-Marie.Dobing@
wessexwater.co.uk
variable speed drives is one of
the most cost-effective measures
to achieve rapid and radical
CO 2 reductions.’
The study noted that nearly
70% of all industrial electricity
consumption is in motor
drives and an estimated 20%
of that is wasted by use of
external throttling devices to
control flow of air or liquids
in pipes or ducts rather than
variable speed drives to
control the motors. ●
Further information: Steve
Ruddell, ABB Limited,
Warrington, Cheshire, UK.
Email: energy@gb.abb.com
Amongst the perceived
limitations of the system are
the limited residence time
within the permeable barrier
and the unknown time limit
on sustaining effective
denitrification before the
carbon source needs replenishing.
In the project closing report
it is noted that,although this
study centred on nitrate
pollution in agriculture the
system might equally be
applied in a number of other
roles,including dealing with
diffuse phosphate or
pesticide pollution or
acting as a protective barrier
to treat contaminated
groundwater emanating
from industrial sites.●
Further information:
Professor Robert Kalin.
Email: Robert.Kalin@Strath.ac.uk
64
WATER21 • OCTOBER 2009

An alternative filtration process for sludge separation
MESH, a process which uses textile
filter fabrics to separate treated water
from activated sludge, is being
investigated as part of a membrane
bioreactor development in wastewater
treatment. CHRISTIAN LODERER
explains how his new approach works
and the positive results from the pilot
study.
At the Institute for
Environmental
Biotechnology at IFA-Tulln,
an applied research centre in
Austria, a new process is
under investigation that can
bring a significant stimulus
to membrane bioreactor
(MBR) development.
MBR technology has lately
attracted significant attention as
an improved wastewater treatment
process offering significant
advantages in terms of a reduced
footprint as well as a superior
effluent quality.However the
higher energy demand compared
to standard processes is still a
major hindrance for more
widespread applications.The
innovative approach,developed
by ProfessorWerner Fuchs and
his group,uses textile filter
Water21nternet
The new interactive‘Water in Storages’
website is being updated weekly to show
water availability in public water storages
across the Murray-Darling Basin,
Australia.The Murray-Darling Basin
Authority (MDBA) developed the new
site,which includes data collated from
water management sources in the four
Basin states.Minister for Climate Change
andWater,Senator PennyWong said:
‘Water managers,irrigators,community
and environment groups,students,and
anyone else with an interest can just click
on an interactive map of the Basin for the
latest data on water held in public storage
anywhere in the Basin.They can also
check the current volume of water in
each storage facility expressed as a figure
and a percentage.And for the River
Murray,current storage levels can be
compared against historical comparisons
at the click of a mouse.Visitors will also
be able to access information on the latest
seasonal water allocations via links to each
relevant State water agency.’In response
to public interest,the water volume and
level of South Australia’s Lower Lakes will
fabrics to separate the treated
water from the activated sludge.
The concept of MESH,as the
process was termed,is based on
three important facts.
Activated sludge appears in
the form of flocs,which is a
result of physicochemical
interactions between
micro-organisms,extracellular
substances and inorganic
particles.The floc size,ranges
from 20 to more than 500 µm.
Instead of membranes with
usual pores sizes less than 0.2 µm,
coarser filter material can
be used to separate the
activated sludge from the
treated wastewater.
The retention of sludge
flocs leads to the formation
of a secondary layer or dynamic
membrane on the filter surface.
This additional filter layer retains
particles even smaller than the
nominal mesh size.
Because of their significantly
larger pore size these filters
experience almost no filter
resistance.In consequence,
much higher flow rates can
be achieved and the operational
pressure for such a system
also be viewable on the website and
updated weekly.
www.mdba.gov.au/water/waterinstorage
is much lower compared
to membranes.
A feasibility study on the
process was made within a
European Commission-funded
project by a consortium of
eight European partners
from industry and research.
A 160 population equivalent
pilot plant equipped with
two modules housing tubular
filter elements with a mesh
size of 29 µm was successfully
operated for one year.The
effective filter area was 14 m 2 .
The filtration was operated in
a cyclic mode with 30 minutes
of filtration followed by a
hydraulic cleaning step that
includes permeate backwashing
and air sparging.
Within the pilot study,it
was demonstrated that
permanent high flux rates of
90 up to 150 l/m 2 .h can be
obtained and that the effluent
quality complies well with all
European regulations.
Moreover,the energy
consumption per cubic metre
of permeate process is half that
of an MBR and at the same level
as an activated sludge process.
The European Rainwater Catchment
Systems Association (ERCSA) has
launched a new website,which details
projects being undertaken by ERCSA
worldwide,as well as information on
upcoming conferences and factsheets on
rainwater harvesting.
www.ercsa.eu
The US Environmental Protection
Agency (EPA) is now on the blogging
websiteTwitter.Recent additions to the
EPA website can be followed at:
http://twitter.com/EPAweb
Available for download fromWater
SavingWeek’s website is a water footprint
assessor which allows you to calculate not
just how much clean water per day you
use,but also the amount of water involved
in the production of everyday items and
the food and drink we consume.The
Water SavingWeek,which was held 17-
The MESH filter bioreactor
has considerable potential as
a wastewater treatment
process where a small area
requirement is of high priority.
It provides similar advantages
as membrane bioreactors
with regard to elevated sludge
concentration and volumetric
loading rates resulting in a
reduced area requirement.At
the same time an effluent quality
equal to well operated standard
activated sludge systems can
be achieved. ●
About the author
Christian Loderer, University of
Natural Resources and Applied
Life Sciences (BOKU), Vienna,
Austria. Email: christian.
loderer@boku.ac.at
Study pilot plant.
23 July 2009,highlighted the fact that we
each,on average,use 3400 litres through
agricultural crops,1095 litres through
manufactured products and 150 litres in
the home.
www.watersavingweek.org.uk
UN-Water has added a new page onto its
website which brings together educational
materials produced by UN-Water
members and partners in order to
communicate the importance of water to
children and young people.
www.unwater.org/kids
If your organisation has a web homepage
or if you know of any interesting sites,let
us know the address.Send details to Keith
Hayward,Editor Water21,to:
khayward@iwap.co.uk
And don’t forget the Association’s linked
websites:
www.iwahq.org
www.iwapublishing.com
www.my-water-career.com
www.the-water-resource.com
WATER21 •• OCTOBER MONTH 20XX 2009 00 65