AWWA JAW48094

The objective of the study described in this article was to determine the effect of backwashing on the efficiency of first-stage sand-biological activated carbon (BAC) filters. Specifically, study procedures: compared ammonia, biodegradable dissolved organic carbon (BDOC), aldehyde, and oxalate concentration profiles in first-stage sand-BAC filters before and after filter backwash, and they assessed possible changes in rates of removal throughout the filtration run; compared the efficiencies of a first-stage sand-BAC filter and a first-stage sand-anthracite filter operated under similar hydraulic conditions, both of which achieved low effluent turbities below 0.5 ntu; and, evaluated how efficiently first-stage sand-BAC filters removed biodegradable compounds by comparing concentration profiles in first-stage sand-BAC filters and second-stage BAC filters. Includes 29 references, tables, figures.