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Haloacetic acids (HAAs) are a group ofdisinfection byproducts (DBPs) resultingfrom chlorination of naturalorganic matter in drinking water.Concerns over the carcinogenic effects ofHAAs prompted the US Environmental ProtectionAgency to regulate them through theStage 1 Disinfectants/DBP Rule. The stabilityof HAAs in distribution systems and duringsample storage is not well understood, buttheir control in finished water is important towater utilities.The objectives of this study were to investigatethe stability and biodegradation ofHAAs in the presence of suspended bacteriaor biologically active carbon (BAC) in waterand evaluate the carbon adsorption capacitiesof HAAs through experiments. HAAswere not found to be stable in the presence ofbiological activity, BAC effectively removedmilligram-per-litre, level HAAs spiked indechlorinated drinking water. The degradationof HAAs coincided with an increase inheterotrophic bacteria growth, indicatingthat a certain portion of commonheterotrophic bacteria in treated water wasable to degrade HAAs. Granulated activatedcarbon (GAC) also removed HAAs, througha combination of carbon adsorption andbiodegradation.Zhou and Xie suggest that the carbonadsorption of HAAs could supplement biologicalHAA removal - when new GAC filtermedia are installed in water treatment systems,carbon adsorption could remove HAAsbefore bioactivity is fully developed. By thetime the carbon adsorption capacity isexhausted, biodegradation will be dominantin removing HAAs. This study provideswater professionals with a better understandingof the stability of HAAs in the distributionsystem and the importance of samplepreservation during HAA monitoring andanalysis. Includes 19 references, table, figures.

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Edition: Vol. 94 - No. 4 Published: 04/01/2002 Number of Pages: 7File Size: 1 file , 450 KB