AWWA JAW39326

A phospholipid analytical technique was used to measure the amount of biomass attached to the surfaces of drinking water filter media. The method was reproducible and able to detect significant differences in biomass concentrations in different filters and at various depths within filters. The amount of attached biomass decreased as filter depth increased, suggesting that most removal of natural organic matter occurred at the top of the biofilters. The results show that granular activated carbon media were able to hold more biomass than were anthracite and sand media and that concentrations of biomass in anthracite-sand filters were lower with chlorine in the backwash water. Includes 32 references, tables, figures.