Water Treatment Technologies and Their Costs - Global Drinking Water Management and Conservation - page 46

Class 3 treatments MF-UF and UV seem to be cheaper than HRC for plants which
produce less than 100 m 3 of water per day and all the way up to 500 m 3 /day, even
though HRC is a Class 2 water treatment process. But in general Fig. 3.4 suggests
that the higher the Class of water treatment is, the higher will be the average costs
per cubic meter for the sample of small systems in BC.
We observe that the average cost per cubic meter of the statistically estimated
equations given above do not conform exactly to the hypothetical Fig. 3.1 , but
exhibit the nonlinearities that we expected. Another nonlinearity may be the cost of
moving from one technology to another, especially when there has been a long-term
commitment to a particular technology.
It is possible that older small systems continue to use higher cost older tech-
nologies as there is no incentive to modernize in the public sector. In other words,
there are technologies currently available in the market that can provide higher
contaminant removal at a much lower cost per cubic meter. Hence, we

nd that a
technology, which can provide Class 3 and 4 water treatment, shows lower average
cost per cubic meter than a small system, which is only providing Class 1 and 2
water treatments. Another possible reason is that there are site-speci c costs that

can contribute to the gap in the costs functions between technology and actual
existing systems that are in the same class. For example, many of the small systems
in BC mentioned above have higher transportation costs due to remoteness and the
handling of hazardous materials such as chlorine. However, site-specific costs alone
cannot account for this very large gap. We observe that some treatment classes at
lower

flow rates dominate in terms of cost-effectiveness. Class 3 MF-UF and UV
provide water treatment at a much lower cost per cubic meter than BC small
systems Classes 1 and 2 between output flow rates of 50 to 200 m 3 per day; but at

higher flow rates this gap tends to decrease. Finally, the cost per unit for these

existing BC small systems is high compared to the rated costs because the systems
are privately owned and costs include a markup for pro t.

Before we summarize the conclusions, we need to distinguish between systems
that use groundwater as the source and systems that use surface water as the source.
Most of the above analysis is concerned with surface water as the source for water
treatment plants.
Based on Figs. 3.3 and 3.4 and the results presented in the previous sections, we
provide the following tentative conclusions:

1. The estimated cost curves show that small systems could achieve a higher
removal of contaminants at a lower cost than their currently used technology;
2. A small publicly owned system could get Class 2 and 3 water treatment if they
use HRC or MF-UF for about 9 to 11 cents respectively, provided the

ow rate

is 100 m 3 per day;
3. For systems using surface water, UV appears to be the least expensive for small
systems at only 7 cents 9 per m 3 for a plant with capacity of 100 m 3 for Class 3,
which shows that the competitive advantage remains even when costs of

9

Includes 5 cents for sand filtration or sediment removal.