AWWA WQTC58990

The City of Philadelphia has long-term goals of looking for strategies to reduce the formation of disinfection byproducts. One of the strategies involves getting a better understanding of the make-up of source waters in order to determine the best treatment technology. Using XAD-4 and XAD-8 resins, natural organic matter (NOM) in Philadelphia's sources of drinking water (Wissahickon River, Schuylkill River, and Delaware River) was fractionated based on the selectivity of the resin towards different functional groups. The filtered source waters and fractions were reacted with chlorine to determine their contribution to the formation of disinfection byproducts (THM4, HAA6, TOX, haloacetonitriles, haloketones, chloral hydrate, and chloropicrin). The isolated fractions were humic/fulvic acid, fulvic acid, non-humic, and non-acid hydrophilic. From the isolated fractions, characteristics were determined by calculation for the fractions of humic, humic acid, hydrophobic neutrals, and hydrophilic acid. The fulvic acid and non-acid hydrophilic fractions made up most of the composition of the NOM. The humic fraction, composed mostly of fulvic acid, exhibited the highest reactivity (measured as specific formation potential, or SFP) with chlorine. The NOM from the Delaware River was found to be the most reactive in terms of TOX and HAA6 formation. The reactivities were sometimes highly variable over time for each location and some fractions exhibited a gradual decline in reactivity. SUVA-254 showed good agreement in terms of the relationship of reactivity to predicted fraction composition. Includes 7 references, tables, figures.