AWWA WQTC62391

Nanofiltration of surface waters has been successfully implemented at large scale facilities to improve drinking water quality. However, fouling remains one of the most important issues in membranes technologies as, on a long-term, it usually causes loss of performances. Biofouling consists of the accumulation of microorganisms and their secretions at the membrane surface. It remains one of the most difficult types of fouling to handle. Once it has appeared, curative treatment of biofouling consists in cleaning the membrane, using appropriate biocides, or combination of both. However, the best way to cope with biofouling remains to minimize its development, and therefore to choose an adequate pretreatment of waters before membrane filtration. Predicting biofouling potential of pretreated waters is uncertain by common fouling potential measurements such as Silt Density Index, or even by feed water quality analyses. The more accurate mean to conclude biofouling potential is to foul membranes, and then, proceed to an autopsy, in which biomass and organic content of the membrane deposit are quantified. In this work, in addition to bacterial enumeration and carbon dosage of the material colonizing the membranes, an original procedure was used to assess the bacterial deposit at the membrane surface which consists of measuring a potential enzymatic activity of the bacterial biomass. Includes 8 references, tables, figures.