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EVALUATION OF NANOFILTRATION PRETREATMENTS FOR FLUX LOSS CONTROL
Citation:
Speth*, T F., A. M. Gusses, AND R. S. Summers. EVALUATION OF NANOFILTRATION PRETREATMENTS FOR FLUX LOSS CONTROL. AWWA Membrane Technology Conference Proceedings, American Water Works Association, 1999, 23 p, Long Beach, CA, 2/28-3/3/99.
Description:
Differing nanofiltration pretreatment approaches for Ohio River water were evaluated withthe intent of producing systems with varying degrees of biological fouling. The membrane feed water was alum-coagulated, settled, and filtered Ohio River water (SF-ORW). Five 1.8" x 12" NF-90 Film Tec spiral-wound membrane elements were used. One element was fed SF-ORW. The other elements were fed ozonated SF-ORW, ozonated/biofiltered SF-ORW, ozonated/biofiltered SF-ORW, and chloraminated SF-ORW. After two months of continuous operation, the membranes were autopsied to determine what was present in the foulant. Heterotrophic plate count (HPC) analysis was used to enumerate microorganisms, pyrolysis-GC/MS was used to classify types of organic materials, sludge digestion was used to quantify inorganics, confocal microscopy was used to determine the depth of the foulant layer, and dried weights were used to determine the amount of total dried foulant. Contrary to the original premise, the results showed that the systems with the greatest biological growth showed the greatest flux after two months of operation. Therefore, the biological growth lessened the impact of fouling due to inorganics, organics, or particulates presumably by creating a foulant layer with diffuse properties.