Occurrence of by-products of strong oxidants reacting with drinking water contaminants--scope of the problem.

Abstract

This paper describes results of a detailed literature review of the organic and inorganic by-products that have been identified as being formed in aqueous solution with four of the strong oxidizing/disinfecting agents commonly employed in drinking water treatment. These agents are: chlorine, chlorine dioxide, chloramine, and ozone. Significant findings include the production of similar nonchlorinated organic oxidation products from chlorine, chlorine dioxide, and ozone. In addition, all three chlorinous oxidants/disinfectants can produce chlorinated by-products under certain conditions. The presence of chloronitrile compounds in drinking waters is indicated to arise from reactions of chlorine or chloramine to amine/amide functions in amino acids or proteinaceous materials, followed by dehydrohalogenation. These nitriles could hydrolyze to produce the corresponding chloroacetic acids. It is concluded that to minimize the presence of oxidation by-products in drinking waters, the concentrations of oxidizable organic/inorganic impurities should be lowered before any oxidizing agent is added.

Chlorine Dioxide Inactivation of Cryptosporidium parvum Oocysts and Bacterial Spore Indicators

“…Among the other advantages attributed to chlorine dioxide is the fact that it does not form many halogenated, and potentially carcinogenic, disinfection by-products typically associated with free chlorine. Chlorine dioxide does, however, react to form chlorite and chlorate (8,20,21,23,29,33). The U.S. Environmental Protection Agency maximum contaminant level for chlorite is 1.0 mg/liter.…”

“…Few studies have been published concerning the inactivation of protozoan parasites in water when chlorine dioxide is used; however, enough data have been collected so far to suggest that chlorine dioxide is a stronger oxidant than free chlorine. Chlorine dioxide does not form halogenated by-products typically associated with chlorine, including trihalomethanes and haloacetic acids; it does, however react to form chlorite and chlorate, which may be toxic at high concentrations (8,20,21,23,29,33).…”

Health Risk Assessment for Bromate (BrO<sub>3</sub><sup>–</sup>) Traces in Ozonated Indian Bottled Water

“…Bromide is not oxidized by chlorine dioxide, so the use of chlorine dioxide will not generate hypobromous acid, hypobromite ion or bromate [7]. Although bromate can be formed on simultaneous exposure to chlorine dioxide and light, the reaction is thermodynamically unfavourable and bromate is unlikely to be formed under water treatment conditions [8,9]. Bromate can also be formed in electrolytically generated hypochlorous acid solutions when bromide is present in the brine [10].…”

La production de trihalomethanes dans les systemes de distribution d eau potable au Quebec

“…Le reste (10 %) opère une substitution ou une oxydation incomplète des composés organiques (Rice et Gomez-Taylor, 1986). Il s'associe donc à d'autres éléments pour former des produits, dont la plupart sont indéfinis ou ne peuvent être clairement identifiés en raison de la stabilité des structures et des facteurs de solubilité.…”