Water Treatment Technologies and Their Costs - Global Drinking Water Management and Conservation - page 33

3.2 Six Classes of Water Treatment Technologies
Suppose we consider a large state-of-the-art water treatment plant and use their
costs of water treatment as an initial benchmark. One such treatment plant is the
Seymour-Capilano Filtration Plant run by the Greater Vancouver Regional District
(GVRD) in Canada. This plant, which came on stream in December 2009, will give
us a perspective on costs at a large water plant. The source water for this GVRD
plant is of high quality, and is possibly free of micro-pollutants, largely because of
the source water quality. Table 3.1 gives some information on this system. Due to
economies of scale, the plant has the potential to produce drinking water at CAN
$0.40 per cubic meter. However, when the distribution costs are added, it is esti-
mated that the consumer would pay about $1 per cubic meter. This provides a
comparative benchmark of the costs at a large state-of-the-art water treatment
system and shows to what extent the costs of small water systems differ from those
at a large system.
Not all systems can produce at the cost and level of drinking water quality that
this Vancouver plant can produce. But our survey of new technologies suggests that
there are technologies for small systems with similar low average costs per cubic
meter. As stated before, in general, costs depend on the number of contaminants
removed, although there may also be other nonlinearities. Below we provide a
scheme, which would allow us to classify a given water treatment plant by the
number of contaminants removed, based on technology being utilized at the plant.
We postulate six classes of water treatment technologies in Table 3.2 .
Class 1 represents the minimum level of treatment, which is disinfection by
chlorination only. We consider chlorination the minimum disinfection treatment
level since all water treatment plants are required to produce water that is free of
pathogens. While most groundwater based systems would rely on chlorine only
(Class 1), many surface water small water systems will be Class 2, i.e. water that
has suspended solids removed and is disinfected. In a Class 3 plant, protozoa will
also be removed or inactivated, possibly with the aid of UV or ozonation. If, in
addition, all dissolved organic matter is also removed before chlorination, then that
would be water without disinfection byproducts (DBP), and we classify such
treatment technology as Class 4.
On the other hand Class 5 (i.e. Classes 5a and 5b) represents technologies that
also remove chemicals, micro-pollutants, DBPs, protozoa, and suspended solids, in
addition to disinfection. In the scheme proposed in Table 3.2 , each progressively
Table 3.1 Description of GVRD state-of-the-art water treatment plant
Parameter Description
Capital cost $1 billion
Capacity 1,900,000 m 3 /day
Break-even cost $0.40/m 3
Treatment system Sand Filtration, UV and hypochlorite
The information in Table 3.1 is from personal communication