AWWA JAW48559

This article describes the effect of backwashing strategies and hydraulic transients on filtration performance of biological filters. Filtration performance was assessed in terms of filter effluent turbidity, head loss, nonpurgeable organic carbon (NPOC), assimilable organic carbon (AOC), and microbial counts. The work reported here is part of a major long-term pilot-plant investigation of biological filters, with several parallel components by various investigators. The objectives of this study were to: evaluate the effect of backwash strategies -- air scour, chlorinated water wash, various bed expansions, collapse-pulsing air, and water flow rates -- on the performance of biological filters; and, investigate the effect of sudden changes in hydraulic loading on filter run length, backwash frequency, and water quality in terms of AOC, turbidity, and microbial counts. Includes 24 references, tables, figures.