Microcystin-LR degradation kinetics during chlorination: Role of water quality conditions.

摘要: Abstract Microcystin-LR (MCLR) produced during certain cyanobacteria blooms can contaminate drinking water sources and pose a threat to public health. Previous studies of MCLR degradation by free chlorine may have artifacts from using strong reducing agents quench chlorination reactions, they also not explored the influence quality characteristics such as pH, alkalinity, temperature dissolved organic matter (DOM). Using novel quencher, 1,3,5-trimethoxybenzene (TMB), apparent rate constants were found be higher than those obtained with thiosulfate (S2O32−), traditionally used quencher. Thiosulfate converted N-chlorinated products back parent MCLR, thereby underestimating loss over time. The second-order for HOCl (kHOCl) OCl− (kOCl-) determined 72 ± 13 28 ± 1.8 M−1s−1, respectively, allowing determination (kapp,MCLR) any known pH condition. reaction was strongly affected presence DOM, while changes in ionic strength alkalinity had little effect. Free originating both terrestrial microbial sources, exhibited two-stage decay. initial demand first 15 s carbon (DOC) concentration (initial demand = 1.8 × DOC), later slower decay correlated well SUVA254 (kapp,DOM = 0.73 × SUVA254 - 0.41). results yielded practical model predict waters varied characteristics.