饮用水消毒与输配过程中卤代硝基甲烷类消毒副产物的生成与转化机制

Nitrogenous disinfection by-products (N-DBPs), due to their high genetic toxicity and mutagenic effect, have recently become one of the research hotspots regarding disinfection of drinking water. The proposed study, taking halonitromethanes (HNMs) as the target pollutants, will investigate systematically their formation and further transformation mechanisms during water disinfection as well as in water supply network. First, the impacts of various precursors, disinfectant species, addition sequences, and the presences of bromide and nitrite ions on the formation of HNMs will be examined through batch experiments. Second, this study will evaluate the individual contributions of pipeline biofilm nitrification and degradation and the catalytic and reductive reactions induced by pipeline material, pipeline scale and soluble substances to the formation and transformation of HNMs. Finally, the major influential factors controlling the formation and transformation of HNMs in water supply network will be determined through simulation tests with pipeline reactors. Overall, this study will gain insights into the formation and transformation mechanisms of highly toxic HNMs throughout the whole process of water disinfection and water distribution, and on that basis, propose effective measures for controlling the concentration levels of HNMs at the end of pipeline to ensure the safety of drinking water.

由于含氮消毒副产物的高遗传毒性和致突变特性，近年来已成为饮用水消毒领域研究热点之一。本研究以卤代硝基甲烷（HNMs）为目标污染物，研究饮用水消毒与管网输配过程中HNMs的生成与转化机制：首先，通过批次实验，考察消毒过程中不同前驱物特性、消毒剂形态、投加次序、溴离子与亚硝酸根离子存在等条件下对HNMs生成的影响；其次，分别评估管网生物膜的硝化与降解作用、管材/管垢/溶出物的催化促进与还原作用对HNMs生成与转化的贡献；最后，通过模拟管段反应器运行试验，明确管网输配过程中HNMs生成与转化的主控因子。本项目将全过程解析消毒和输配中高毒性HNMs的生成与转化机制，在此基础上，提出管网末端HNMs浓度的有效调控措施，保障饮用水安全。

卤代硝基甲烷（HNMs）是一类高细胞毒性、遗传毒性的含氮类消毒副产物。在该项目的资助下，系统考察了饮用水消毒与输配环节，HNMs生成的动力学参数、机理、路径与影响因素。首先考察了含胺基、硝基类微污染物在紫外、氯等作用下降解的动力学参数与母体物结构变化规律，初步明确了不同含氮官能团在饮用水消毒过程中的路径、因素及HNMs生成势变化的机制：与单纯氯化相比，紫外/氯可显著加速氯霉素的降解，同时促进了HNMs的生成。HNMs的即时、24h生成势的提升量与作用时间呈正向相关，并对产生的羟基自由基、氯自由基的贡献进行了定量评价。发现紫外光解含硝基类Ranitidine和Nizatidine微污染物时，其HNMs生成势同步下降，紫外光解过程中的脱硝基反应是HNMs生成势下降的关键反应，进而有针对性地提出控制HNMs生成的工艺措施。在输配环节考察了饮用水输配过程中铜管腐蚀产物CuO、Cu2O、Cu2+对DBPs生成的影响，供水管网的不同腐蚀产物对促进溴代消毒副产物（Br-DBPs）生成的机制不同，铜管管垢的金属价态是决定自由溴的歧化方向的关键因素：CuO可促进BrO3−的生成，而Cu2O和Cu2+以促进Br-DBPs的生成为主，且背景水质对铜管腐蚀产物的促进作用影响较大。