Water Treatment Technologies and Their Costs - Global Drinking Water Management and Conservation - page 36

In Germany, roughly 74 percent of drinking water is drawn from ground and
spring water, and the remainder is drawn from surface water sources, such as lakes
and rivers (Althoff 2007 ). By 2010, 63 percent of the groundwater bodies in
Germany had achieved a rating of

(BMU 2014 ). Of the total
1,000 groundwater bodies, only 4 percent have not achieved a

“ good chemical status ”

“ good quantitative

status, i.e. 4 percent of the aquifers did not have enough water. The status of

surface water is such that 88 percent of water bodies achieved a

”

chemical
status, while only 10 percent of all surface water bodies had obtained at least a
“

“ good ”

ecological status (BMU 2014). Given the quality of groundwater, practi-
cally no disinfection is needed. The 2011 Pro

good ”

le of the German Water Sector states:

The quality of drinking water is so good that the use of disinfectants in water treatment can
even be forgone in many places without [compromising] the high hygienic drinking water
standard.

Since there is no chlorine, there are no DBPs; in areas where the source is
groundwater, there are no chemical residues in the water and of course no salinity.
Thus, for the groundwater sources we can conclude that German drinking water
from the water treatment plants is equivalent to Class 5. In North Rhine-Westphalia,
in the City of Cologne, they use groundwater as the source, which is then filtered

through activated carbon, producing a very high quality of water. To quote from the
City of Cologne website (RheinEnergie 2013 ):

Some waterworks in Cologne used disinfectant to prevent an increase in the number of
germs, and thus hygienic deterioration of the drinking water quality on the way to the
customer. Our water lab proved, however, that the perfect hygienic quality of drinking
water can be guaranteed even without the use of chlorine dioxide or chlorine.
Where surface water is used in North Rhine-Westphalia, they detected per

u-

orooctanoate (PFOA) in drinking water at concentrations up to 0.64 /L in Arns-

berg, Sauerland, Germany. In response, the German Drinking Water Commission
(TWK) assessed per

µ

uorinated compounds (PFCs) in drinking water and in June

2006 became the first in the world to set a health-based guideline value for safe

lifelong exposure at 0.3 uorooctanesulfonate, PFOS).

PFOA and PFOS can be effectively removed from drinking water by percolation
over granular activated carbon.
For each treatment class, we also hypothesize the shape of the cost curves.
Average costs per volume of water treated will vary with (a) source water quality,
(b)

µ /L (sum of PFOA and per

flow rate, and (c) target water quality. We expect that for a given type of source
water quality, average costs per cubic meter depend on economies of scale. For a
given source water quality, Fig. 3.1 below shows the hypothesized (theoretical)
average costs as a function of the flow rate for different treatment classes. This

graph assumes that contaminants are additively separable and linear.
In reality, that assumption of linearity and additive separability would not hold as
some technologies can have an overlap in their functions. For example, technologies
that can remove suspended solids (Class 2) can also remove some pathogens (Class 3)
and possibly some DBP precursors (Class 4), if used in conjunction with coagulation.