Potable water production
In Roetgen, the decision to build a membrane-based water treatment plant was based on economics and performance. Dautzenberg: ‘Our plant started operating in December 2005. Before that we had a normal, two-stage open rapid filtration plant, a classic sand filtration operation as is typically used in Germany to produce drinking water from reservoir water. At the time our plant had already been in operation for over 30 years, and we were considering how best to renew it. When the planning calculations with conventional and membrane technology showed about the same economics, we decided in favour of membrane technology because it appeared to be more future-proof and because the cleaning performance is significantly better”. The Dreilägerbach reservoir is not the only one the Roetgen water plant can depend on.
Every year, millions of cubic metres of raw water come from up to four other reservoirs. An ingenious system system of tunnels, pumping stations,transfer and bypass pipes allows WAG Nordeifel to choose from which storage lake to take water. The water quality in an open reservoir can be compromised, for example by weather effects, or an oil or fuel spill from a road accident. In order to keep the plant running and the region supplied with drinking water at all times,the filter systems can be divided and a reservoir can be taken “offline” if it needs time to recover. Compared to traditional systems, membrane-based treatment is also much better able to deal with variations in raw water quality, making operations much more stable and reliable.
According to Dautzenberg, the Xiga 40 membranes have far exceeded expectations. “We wanted a skid designin which you could use membranes fromdifferent manufacturers. The idea was to keep our options open in case there are developments in price and quality, and to retain the ability to make the best choice when the time for replacement has come. Meanwhile it has become clear that the service life of the Xiga 40 is much better than we had expected. We counted on eight years, we hoped for ten years, and they have worked well for over twelve years. We have never used chlorine to clean the membranes, which contributes to a longer life. The number of leaks in the membranes was also much lower than expected, averaging four per month”.
From WAG Nordeifel’s point of view, there is not much to say about energy consumption, production and quality. The system works with dam pressure, so onlythe backwashing requires energy input. Production follows demand and quality is prescribed by the German Drinking Water Ordinance. Walter Dautzenberg: “The filtrate quality in the microbiological sense was always inconspicuous, which was not always the case with sand filtration in the past. This plant has significantly improved the stability of the treatment process and particle retention. We have therefore recommended membrane technology in general and these membranes in particular to colleagues who also treat dam water. We also feel well looked after by Pentair’s customer service over the years. Together we were able to determine the right time to replace the membranes.”
12 blocks with Xiga 40.
UF membrane elements installed in December 2005 and replaced in 2018-2019.
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