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THE OCCURRENCE OF A NEW GENERATION OF DBPS (BEYOND THE ICR)
Citation:
Krasner, S. W., S. Pastor, R. Chinn, M. J. Sclimenti, H. S. Weinberg, S D. Richardson, AND A D. Thruston Jr. THE OCCURRENCE OF A NEW GENERATION OF DBPS (BEYOND THE ICR). Presented at American Water Works Association Water Quality Technical Conference, Nashville, TN, November 11-15, 2001.
Impact/Purpose:
Determine the actual concentrations of suspected health-impacting DBPs produced using non-chlorine disinfectants, how often they occur, under what conditions they are formed, and their fate and transport in the distribution system.
Description:
A nationwide survey of 12 full-scale treatment plants for disinfection by-products (DBPs) was initiated in the U.S. in 2000. Approximately 50DBPs that rated a high priority for potential toxicity and were not included in the Information Collection Rule (ICR) are being quantified. 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, THMs, HAAs, HANs, HKs, HAs, and 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 (ozone, chlorine dioxide, chloramines) 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.