D10: Impact of Contaminants - Hydromod

Integrated Water Resource Management for Important Deep European Lakes and their Catchment Areas
EUROLAKES
D10: Impact of Contaminants
FP5_Contract No.: EVK1-CT1999-00004
Version: 4.0
Date: 25/07/01
File: D10-vers.4.0.doc
Page 106 of 136
The aim of any water treatment is defined in Mutschmann et Stimmelmayer (1999) as:
1. To change natural parameters of the water so that water is hygienically harmless for
human consumption and suitable for technical use. This includes softening of water,
iron and manganese removal, modifying of carbonate balance, aeration of water,
etc..
2. To remove anthropogeneous substances. Originally this mainly meant removal of
bacteria and viruses by disinfection. However since intensivation of agriculture and
industrialisation it means removal of nitrates, pesticides, heavy metals, organic chlorine
compounds, and others
For the removal of anthropogeneous substances extremely cost intensive treatment
processes exist, like reverse osmosis, ultra filtration, ion exchange, biological treatment,
etc...which would also be suitable for the removal of endocrine substances.
That means technically each substance can be removed. With membrane processes
for example (ultra filtration, nano-filtration, reverse osmosis, electro dialysis) it is possible
to remove any molecules desired, but this would undoubtedly double or triple present
water tariffs what is economically and also politically very difficult.
On the other hand the effect of conventionally applied processes on endocrine substances
is not known at all, and there are no publication available on this matter. So the
effect of these processes on endocrine substances must be investigated prior to deciding
to go for high tech processes, supposed this approach is considered reasonable
at all.
Protection of the natural water sources by avoiding the contamination with anthropogeneous
substances must be given priority to investing into end of pipe technology.
Commonly applied processes for treating of drinking water
Since water quality is individual for each source of drinking water each source required
individual treatment to render it into drinkable water complying with national and European
directives.
Water treatment engineering and chemistry is a science for itself, and the following
shall only give a rough overview about commonly applied processes.
Figure 11-5 illustrates the main treatment lines commonly found, which may be supplemented
by additional special treatment lines made necessary by the presence of
specific undesirable substances in the raw water (e.g. fluorine, nitrates, calcium)
Line 1 is designed to treat clean, unpolluted raw water requiring only disinfection to
achieve the required microbiological quality. Line 2 is designed to treat water with no
pollutants, except SS, and requiring simple filtration prior to disinfection. Where the
water contains a small quantity of colloids, or has a more pronounced colour, in-line coagulation
will solve the problem (Line 3). If the quantity of coagulant required to remove
the colloids or reduce the colour is too high, the floc formed will be large and will rapidly