AWWA WQTC55166

A nationwide survey of 12 full-scale treatment plants was initiated in the US in 2000. Approximately 50 disinfection byproducts (DBPs) that rated a high priority for potential toxicity and were not included in the Information Collection Rule (ICR) are being studied. Some of the halogenated DBPs detected in this study have included mono-, di-, tri-, and/or tetra- species of halomethanes (HMs) (including iodinated species); haloacetonitriles (HANs); haloketones (HKs); haloacetaldehydes (HAs); and, halonitromethanes (HNMs). As the presence of bromide resulted in a shift in speciation for the trihalomethanes (THMs) and haloacetic acids (HAAs), brominated DBPs for other classes of DBPs (HANs, HKs, HAs, HNMs) were detected that were not in the ICR. Chloramination formed certain dihalogen-substituted DBPs (HAAs, HAs) preferentially over related trihalogenated species. In addition, chlorine dioxide produced dihalogenated HAAs. Although the use of alternative disinfectants minimized the formation of THMs, certain dihalogenated DBPs formed at significant concentrations. Biologically active granular activated carbon (GAC) removed a wide range of halogenated DBPs. A number of DBPs (e.g., certain HAs) were not stable at alkaline pH levels, probably because of base-catalyzed hydrolysis. Includes 29 references, tables, figures.