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In the treatment of surface water for the preparation of municipal drinking water,chlorine-containing disinfectants can react with natural organic matter (NOM) and sourcewater bromide to form harmful disinfection byproducts (DBPs). Trihalomethanes(THMs) and haloacetic acids (HAAs) are currently the only carcinogenic organic DBPsregulated in tap water by the United States Environmental Protection Agency. Whilethese DBPs are important to monitor, unregulated MX (3-Chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone) and its brominated analogues present a larger potential healthrisk than HAAs and THMs due to their enhanced mutagenicity. Recently, halogenatedfuranones were included in a DBP survey of U.S. drinking water treatment plants, wherethey followed similar formation and removal trends with THMs and HAAs.Small ketone components of fulvic acid have been proposed as commonprecursors to THMs and di- and trihalogenated HAAs. This hypothesis is supported byconcurrent formation of THMs and HAAs observed after chlorination of NOM fractionsor model compounds. On the other hand 3,5-dihydroxybenzaldehyde has been citedas the simplest model of the base structure for humic substances, and some researchershave focused on the significance of the aldehyde group in the meta position to twohydroxyl groups on the benzene ring in the formation of MX-analogues via a THM andHAA formation pathway. Clearly, much remains to be learned about themechanisms of formation of these 3 groups of DBPs.In this study, the mechanisms of formation for the THMs, HAAs, and halogenatedfuranones (MX-analogues) were investigated using Uniform Formation Conditions (UFC)for chlorination of three different, well-characterized natural organic matter (NOM)isolates. UFC chlorination was chosen to simulate conditions in drinking water treatmentplants and to target the DBP precursors encountered under these conditions, with andwithout the addition of bromide. Includes 15 references, figures.

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Edition: Vol. - No. Published: 11/02/2003 Number of Pages: 5File Size: 1 file , 260 KB