AWWA JAW59118

During riverbank filtration (RBF), surface water is subjected to ground passage and a combination of physical, chemical, and biological processes (e.g., filtration, dilution, sorption, and biodegradation) that can significantly improve the raw water quality. This study of three drinking water utilities in the midwestern United States compared RBF with bench-scale conventional treatment for reduction of disinfection byproduct (DBP) precursors. A companion article published in the October 2003 JOURNAL discussed the fate of DBP precursors and selected microorganisms during RBF. River waters from the three sites were subjected to a treatment train consisting of coagulation, flocculation, sedimentation, filtration, and ozonation. Data indicated that RBF performed as well as or better than bench-scale conventional treatment with respect to DBP precursor removal. Bench-scale treatment reduced total and dissolved organic carbon concentrations by 20 to 50%, whereas the water's subsurface travel to the closer wells at the three sites resulted in reductions between 30 and 70%. Reductions in precursor material for trihalomethanes, haloacetic acids, haloacetonitriles, haloketones, chloral hydrate, and chloropicrin were in the range of 40 to 80% with bench-scale treatment and 50 to 100% with RBF. With respect to removal of natural organic matter and DBP precursors, RBF has the potential to provide significant benefits, comparable to those offered by conventional unit processes. As RBF continues to gain popularity in the United States, one potential major role for the process may be as a pretreatment step for DBP precursor control. Includes 38 references, tables, figures.