预氯化及常规工艺对消毒副产物的影响

以天津市某给水厂的水源水为实验对象,通过在实验室规模上模拟的给水处理厂工艺流程,比较了3种不同工艺流程中各单元出水的三卤甲烷(THMs)、卤乙酸(HAAs)和总有机物(TOC)浓度变化,分析了水处理单元工艺和TOC浓度对消毒副产物的影响。结果表明,预氯化生成的三卤甲烷和卤乙酸分别占最终出水中三卤甲烷和卤乙酸浓度的55.7%和66.7%,说明预氯化对出厂水中消毒副产物的产生有显著影响;混凝沉淀和过滤对三卤甲烷的去除率分别为17.2%和19.6%,而卤乙酸在水处理过程中变化不大,仅在过滤之后降低了3.32μg/L,说明过滤对三卤甲烷和卤乙酸均有一定的去除作用,而混凝沉淀仅对三卤甲烷有一定的去除作用;TOC浓度经过水处理工艺后整体呈下降趋势,但分析表明,其浓度对三卤甲烷和卤乙酸的生成影响很小,而氯则是三卤甲烷和卤乙酸生成的重要限制因素。

Effects of pre-chlorination and conventional process on disinfection by-products

The water treatment plant process was simulated on a laboratory scale, comparing the concentration changes of trihalomethanes(THMs),haloacetic acids(HAAs) and total organic carbon(TOC) in each unit of water in three different processes,and the influences of the water treatment unit processes and TOC concentrations on disinfection byproducts were analyzed in the source water in a waterworks of Tianjin. The results show that the THMs and HAAs produced in pre-chlorination process account respectively for 55.7% and 66.7% of their concentration in the finished water,indicating that pre-chlorination has a significant influence on the disinfection byproducts of finished water. The removal rates of THMs are 17.2% and 19.6%, respectively by coagulating-sedimentation and filtration,while HAAs has little change in the treatment process and its concentration reduces only 3.32μg/L after filtration,indicating that the filtration can remove THMs and HAAs,while the coagulating-sedimentation only remove THMs. TOC concentration presents a downward trend in the water treatment,but its concentration has little impact on the generation of THMs and HAAs,and chlorine is the important limiting factor.