riverbank filtration—fate of DBP precursors and selected microorganisms

At three drinking water utilities in the midwestern United States, significant reductions were observed in total organic carbon (TOC), dissolved organic carbon (DOC), and disinfection byproduct precursors after riverbank filtration (RBF). TOC and DOC reductions at the closer wells at the three sites ranged from 35 to 67%. Trihalomethane formation potential and haloacetic acid formation potential concentrations were reduced by 50 to 80% at the three sites. Reductions in precursors for haloacetonitriles, haloketones, chloral hydrate, and chloropicrin ranged from 30 to 100% following RBF. Reductions in the concentrations of Clostridiumwere observed in excess of 3 logs. Log reductions in the rivers and wells ranged from >2.6 to >3.3 for E.coli C bacteriophage and from >1.9 to >2.3 for E. coli F-amp bacteriophage. Limited occurrence of Giardia and Cryptosporidium in the river and well waters prevented the establishment of firm conclusions for the removal of these organisms.