饮用水中典型微生物消毒过程中消毒副产物的生成规律

以饮用水中典型微生物--大肠杆菌（Escherichia coli）为试验对象，研究pH值、氯化时间、氯投量及细菌浓度对大肠杆菌在氯化消毒过程中生成消毒副产物（DBPs）的影响，并分析何种氯化条件下，DBPs控制效果最佳.研究表明：随氯投量增加，二氯乙腈（DCAN）呈先上升后下降趋势；随氯化时间延长，三氯丙酮（1，1，1-TCP）和DCAN先增加后减少；在pH值从5升高到9时，1，1，1-DCP、三氯硝基甲烷（TCNM）、二氯乙酸（DCAA）和三氯乙酸（TCAA）持续降低；细菌污染水源事件在近年常有报道，当水源水中细菌浓度增加时，饮用水中三氯甲烷（TCM）、TCNM、DCAA和TCAA浓度增加，但DCAN、三氯乙腈（TCAN）、二氯丙酮（1，1-DCP）和1，1，1-TCP不一定增加.为了达到低毒性的目的，氯投量浓度不宜太高，同时控制氯化时间为6h和pH>8.

Formation of major disinfection by-products from representative microorganisms during drinking water chlorination

Formation of disinfection by-products (DBPs) from chlorination of Escherichia coli, a bacterial strain which was commonly found in drinking water as a representative of aquatic microorganism, was investigated under selected conditions. Evaluated factors included contact time, chlorine dosages, pH and bacterial concentrations. These factors potentially influence the DBPs formation in the disinfection systems, which could be optimized for minimization of DBPs formation during chlorination of drinking water. Results showed that the formation of DCAN from the bacterial suspension initially increased and then decreased with increased chlorine dose. The formation of 1,1,1-TCP and DCAN followed a similar pattern of increase and then decrease with prolonged reaction time. At the same time, the concentrations of DCAA, TCAA, TCNM and 1,1,1-DCP decreased when pH was increased from 5 to 9. Bacterial contamination in aquatic environments has been extensively reported in recent years. Increased bacterial concentration in the raw water may lead to a higher formation of TCM, TCNM, DCAA and TCAA, but not for DCAN, TCAN, 1,1-DCP and 1,1,1-TCP. To achieve a low toxicity in drinking water, it is suggested from this study that chlorine concentration should be kept low, under disinfection contact time of 6h and alkaline condition (pH>8).