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The algal toxin microcystin-LR has been identified in source and treated drinkingwaters in the US (Carmichael, 2001; Karner et al., 2001). Chlorination has been shownto inactivate microcystin-LR in several cases (Nicholson et al., 1994; Tsuji et al., 1997;Hart et al., 1998; Bruchet et al., 1998). Since chlorination is extensively used in mediumand large water utilities in the US it is important to establish CT (contact time chlorineconcentration) values for the chlorination of microcystin-LR. The objective of this projectwas to conduct an evaluation of the inactivation kinetics of extracellular microcystin-LRby free chlorine. The analysis provided estimation of inactivation rate constants and CTvalues needed for inactivation of the toxin.Twenty-seven batch chlorine inactivation experiments of extracellularmicrocystin-LR were performed. The chlorination experiments were run with threedifferent initial toxin concentrations (1, 3, and 10 ug/L), three different chlorine doses (1,3, and 10 mg/L), and three different pH values (6.0, 7.5, and 9.0), at a temperature of11C. All experiments were performed at five chlorination contact times, up to 100minutes. Ascorbic acid was added as the chlorine quenching agent at the end of thechlorination time. Microcystin-LR was quantified with enzyme linked immunosorbentassay. For 19% of the samples, microcystin-LR was also quantified with highperformance liquid chromatography to provide additional confidence in the laboratoryresults. The results of the two methods were correlated with an R2 of 0.904. Includes 6 references.

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Edition: Vol. - No. Published: 11/02/2003 Number of Pages: 3File Size: 1 file , 220 KB