Water treatment
ecame formally established as WS enterprises and do not have reliable databases on these costs. Cinara, on the other hand, is also starting to promote some undergraduate and MSc dissertations to assess in a systematic and more critical way actual practical experience in the region. In spite of these limitations, the following sections present a preliminary cost analysis of MSF technology considering both initial and running costs 5.3 Cost Characteristics 5.3.1 Initial capital investment cost Factors that have an important effect on the initial investment cost in a water treatment system include: • Plant capacity • Type of plant (type of technology) • Cost of equipment (local and imported) • Design criteria and cost • Land prices • Cost of materials (local and imported) • Cost of labour • Geographic location • Transport • Climatic conditions • Level of competence and profit of constructing firms Taking the main factors as starting point, a cost model can be developed for pre-determined region, date and treatment technology. In general, the model has the following composition: C = aQ b (5.7) Ln C = Ln a + b Ln Q (5.8) In which C is cost of construction; Q is plant capacity; and a, b are coefficients. The value of the coefficient “a” corresponds to the cost of a plant with a unit capacity. The coefficient b, usually smaller than 1, indicates the economy of scale. If the value of b is closer to 1, the economy of scale is low, and as a consequence, cost efficiency will not be obtained with the increase of the size of the system. 5.3.2. Operation, maintenance and administration costs Factors that have an important effect on operation, maintenance and administration costs in a water treatment system, include: • Labour cost • Cost of consumables (local and imported) • Maintenance requirements • Energy cost • Prevailing water quality regulations • Number of users 179
Based on the practical experience with full-scale MSF plants operating by gravity in the Andean Cauca Valley, the running costs of this technology are mainly labour costs. Based on observations made during training activities and some information collected from caretakers and community based organisations, a preliminary estimation can be made of time requirements for Operation and Maintenance (O&M). Time requirements for administration seem to vary significantly between communities (Cinara, 1998). It is expected that the gradual development of more formal small enterprises for small WS systems in Colombia will contribute to improving time management and to reduce the time necessary to administer the systems, including conflict resolution inside or outside the community-based organisation. In this preliminary analysis, time required for administration is estimated as a percentage of the time required for O&M. Having an estimation of time requirement for OM&A and representative labour costs, the running cost of MSF technology in a given programme development area can be calculated. 5.4 Objectives This chapter aims to analyse and summarise information concerning the following points, although some of them are still at an exploratory stage. • To develop construction requirement models of MSF alternatives including DyGF (dynamic gravel filtration), upflow CGF (coarse gravel filtration) and SSF (slow sand filtration) stages. • To develop construction cost models of MSF alternatives, considering construction cost values of 1999 in the context of the Andean Cauca Valley. • To present preliminary information on time requirements for OM&A of MSF alternatives and to estimate OM&A costs based on labour costs in the context of the Andean Cauca Valley. • To compare initial and life cycle costs of MSF alternatives and conventional RF treatment plants. • To analyse and compare economy of scale of MSF and conventional RF plants. 5.5 Methodology 5.5.1 Initial investment cost A review of MSF systems constructed in different regions of Colombia showed that the greatest construction costs included reinforced concrete, gravel, sand, land, soil excavation, and the building including facilities for storing sand, water disinfection, and operator’s basic needs (Galvis et al, 1989; Cinara-Mindesarrollo, 1996 and 1998). Together these components represent approximately 80 percent of the direct construction cost (without including costs for administration, profits and contingencies). The remaining 20 percent is distributed between the cost of valves, fencing, illumination, accessories and pipes. Consequently, an estimate can be made of the main construction cost by relating the plant flow to the construction quantities of the different items with the greatest construction costs and multiplying these quantities by the unit cost for these items. This main direct construction cost can be then be affected by a factor (1.25) to take into account also the other (minor) direct construction costs. 180
Development and Evaluation of Multi
ACKNOWLEDGEMENTS To my supervisor,
ABBREVIATIONS ABNT: Acuavalle: ACV:
SOCs: Synthetic Organic Chemicals S
u c V V f Vs uniformity coefficient
TABLE OF CONTENTS 1. INTRODUCTION 1
4 MULTISTAGE FILTRATION EXPERIENCIE
1 INTRODUCTION Water is essential f
Table 1.2 Access to WS&S in Colombi
Table 1.5 Safe drinking water cover
1.2 Multiple Barriers Strategy and
2 OVERCOMING THE LIMITATIONS OF SLO
adjustment, are among the technolog
On January 14, 1829, Simpson’s on
With increasing life expectancy, en
Table 2.2 Treatments steps recommen
In table 2.3, WHO guideline values
2.5 The Slow Sand Filtration Proces
When the particles are very close t
in which p 0 is the clean media por
Yao et al (1971) related the remova
compensate for the increase in the
can be applied, but intermittent op
Table 2.4 Comparison of design crit
Although accepted as indirect indic
50% when the temperature falls from
Figure 2.9 Flow diagram of the wate
ut higher running costs, since more
Headloss and flow control. Final he
Figure 2.13 Influence of flow condi
Operation and maintenance (O & M).
in parallel (Galvis, 1983; Smet et
cleaning simple, DyGF should behave
case of Dortmund (Germany), the HGF
Table 2.9 Data about three experien
Some points of discussion about HGF
and 600-800 NTU) and different filt
the HGF units of Aesch (see table 2
in spite of the low removal efficie
order to overcome the water quality
full-scale units. In this research,
3 MULTISTAGE FILTRATION STUDIES WIT
in the case of UGFL. Initially, it
• Bigger and better-instrumented
l Figure 3.7 Plan view of Cinara's
The present research work was divid
Table 3.1. Design parameters, grave
Figure 3.9. Piezometer distribution
were used to collect samples for DO
were poured into a funnel using fil
H 0 : H a : Treatment levels workin
3.2 Results and Specific Discussion
3.2.2 Dynamic gravel filtration (Dy
Mean faecal coliform removal effici
Table 3.10 Comparative analysis of
DyGF-A had flow reductions in the r
The experimental data used to produ
Previous observations were further
ates (figure 3.17 B). However, at t
Longer “initial-ripening” perio
Table 3.17. Descriptive statistics
100 Filtration rate = 0.3 mh -1 100
After the present experience, faeca
nature of the organic matter and th
Table 3.24 Comparative analyses of
3.2.4.3. Filtration run lengths and
deep bed filter (data not included
and operational considerations Pard
than in sand samples from other SSF
Step dose tracer tests were made at
for HGFS and from 3 to 5 for HGF. T
Constant and declining filtration r
ANNEXES Annex 1: Accessories for Mu
aw water. The red colour is used fo
Annex 2: Design of Manifolds Manifo
+ q 2 Q1 (1.2 qn + qn) (2.2 qn) = =
R 1 = (total orifice area / lateral
0.30 0.25 0.20 0.15 0.10 0.05 0.00
Table A.4-2 General notation for th
Box A4-3. Sum of Square Error (SSE)
Annex 5: Residence times in coarse
Table A5-1 Percentage of incoming w
Annex 6 Number and Type of Valves N
Table A7-1. Descriptive statistics
Tables A7-3 Removal efficiencies of
Tables A7-5 Removal efficiencies of
Construction quantities of DyGF com
Net present value (US$) of MSF and
Change language