Annual report Chair on Drinking Water Engineering 2008 - TU Delft

ehaviour and reMoval of natural organic Matter (noM) in
treatMent Processes
Research objectives
The objective of this research is to understand the behaviour of different natural organic matter (NOM) fractions
in drinking water treatment processes and to improve the drinking water quality at the consumers tap by
extending the treatment with an ion exchange process. Removing NOM before the existing treatment train will
have a positive effect on following treatment steps, leading to cost effective alternative treatment strategies.
Also the biofilm formation in the distribution network will be limited by NOM removal with ion exchange.
Project outline
Introduction
The presence of NOM in drinking water influences both the efficiency of treatment steps, and processes in the
distribution network such as the formation of biofilms. With a combination of technologies different fractions of
NOM can be determined, which gives more insight in the effects of NOM in the treatment and distribution network.
Fluidized ion exchange is a new treatment step for NOM removal. The behaviour of ion exchange resin in
a fluidized column will be investigated. Also the water quality improvement of this new step will be researched.
Research will be carried out at Weesperkarspel (WPK) treatment plan of Waternet, Amsterdam.
Approach
A new treatment step, ion exchange, is being used for removing specific NOM fractions. The effect of this new
treatment step on other treatment steps on the water quality at the consumers tap has been investigated in
batch experiments and on pilot scale. Those processes can then be optimised. First, different IEX resins were
tested on specific NOM fraction removal by batch experiments. Second, the batch experiments results have
been verified with pilot plant research. Finally, the effect of NOM removal on following treatments steps will
be investigated with batch experiments and on pilot scale, as well as the effect on the biofilm formation in the
distribution network.
Results
WPK water was used for batch experiments with 3 different IEX resins
and 1 sorbent resin. WPK water consists of mainly humic NOM fractions.
Lewatit VP OC 1071 and MIEX DOC resin were the best performing
resins. By first removing NOM with these resins, the life times of the
following GAC filters will increase by a factor 10 for DOC removal. The
results had to be verified by pilot research, which started in October
2008. Ion exchange is the first step in this pilot plant (Figure 1), followed
by ozonation, pellet softening, biological activated carbon filtration and
slow sand filtration. Beside this train, there is a reference train without
ion exchange for comparison. To investigate the effect of NOM removal
by ion exchange on biological stability, biofilm monitors are placed after
the slow sand filters. First results of this pilot experiment are expected
in March 2009.
48 <strong>Annual</strong> <strong>report</strong> DWE 2008
Figure1 - Ion exchange column at
pilot plant Weesperkarspel