AWWA JAW17913

This article discusses the effects of chemical treatment, activated carbon adsorption, and combinations of chemical treatment and adsorption on the formation of trihalomethanes (THMs), specifically on THM formation potential (THMFP). Removal of total organic carbon (TOC) from humic solutions by adsorption, alum coagulation, lime softening, or a combination of chemical treatment and adsorption generally resulted in a reduction in the formation of THMs. Although high levels of TOC removal by adsorption were found to increase incremental THM reduction, high levels of TOC removal by alum coagulation or lime softening generally decreased the incremental reduction of THM formation, as reflected by the THMFP. Because greater removal of TOC does not necessarily produce greater reduction of THMFP, it is suggested that water treatment systems intended to remove THMs should be optimized specifically to control that parameter rather than to maximize TOC removal. Includes 10 references, tables, figures.