Undersøkelse og optimalisering av Den Nye Oset Vannbehandlingsanlegg

Abstract

The repeated occurrence of particle breakthrough hinders the practicability of hygienic barrier function of the filter plant, and the media loss also contributes to the failure. Filtering, the most important process in water treatment plant, acts as a physical barrier to pathogenic organisms, including resistant microorganisms. The assessment was carried out on the current problem of filter media loss and the repeated occurrence of particle breakthrough followed by turbidity value > 0.2 NTU. The filter run often terminated due to particle breakthrough which arises usually during an increase in hydraulic loading rate. The assessment was performed from January 2010 to June 2010 and started from the confirmation of filter media loss, searching the cause and the extent of the loss. The method of approach was studying backwash performance for all filters; measuring filter media depth, trend picture analysis, and taking grab sample and laboratory analysis. During the assessment the location of sample and depth measurement taking place was restricted to one place and finding a representative sample was one of the limitations which had an impact on quantifying the results obtained. Filter media loss occurred during the final water wash of the filter backwash cycle. One of the reasons for filter media loss was the leakage between the trough and the concrete filter wall and is already repaired. The last measurement of filter media depth shows losses of filter media. Even if filter media loss is decreasing, particle breakthrough also needs further assessment including filter media grains, support gravel and under drain.