Treatment stage associated changes in cellular and molecular microbial markers during the production of drinking water at the Vansjø water works


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IWA Publishing

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The production of a drinking water that meets current aesthetic, microbiological and chemical standards, generally requires a combination of mechanical puri fi cation and disinfection in a multi-component treatment chain. Treatment choices and optimisation of water processing is best informed by using markers (including microbiological parameters) which indicate how each stage contributes to the pro- duction of the potable water. The present study combines culture-based and a number of culture- independent analyses to indicate what is happening at each stage of a state-of-the-art water treat- ment chain at Vansjø near the city of Moss in Norway. We show that particularly clari fi cation with fl otation and post-chlorination have profound and positive effects on water quality with respect to the removal and inactivation of microbes. Post-chlorination achieved better disinfection of the water than UV-treatment and was of paramount importance, as the penultimate step fi ltration through granular activated shed microbes to the water. Cloning and sequencing showed that some clones present in the raw water were detected at all stages in the treatment process, perhaps providing examples of microbes breaching physically all barriers in the treatment process. Results from the study should be useful in the improvement and maintenance of the treatment process at the Vansjø plant and others.


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