再生水臭氧氧化的新型有机溴代副产物及其DNA损伤效应控制原理

For the byproducts formed from ozonation of reclaimed water, bromate are generally concerned in current researches. However, due to the presence of dissolved organic matter in reclaimed water, ozonation also produces organo-brominated byproducts, which may be much more toxic than bromate. At present, a large number of organo-brominated byproducts have not been identified, and their toxicity characteristics have not been clarified. Only focusing on the bromate formation may seriously underestimate the risk of byproducts! The risk of byproducts during ozonation of reclaimed water can be fully recognized and controlled only by understanding the organo-brominated byproducts and their toxicity characteristics..Considering the toxic effects of organo-brominated byproducts from ozonation of reclaimed water, this study aims to isolate and identify the novel organo-brominated byproducts, understand the effects of byproducts on DNA base modification, base deletion and DNA strand breakage in human hepatocytes, grasp the toxic mechanism of byproducts, and indentify the preferentially controlled byproducts. Grasping the characteristics of electron donating groups and electron donating capacity of dissolved organic matter during ozonation and its relationship with the formation of organo-brominated byproducts. Identifying the key intermediates affecting the formation of organo-brominated byproducts and to elucidate the formation mechanism of byproducts. Optimizing the ozone/hydrogen peroxide synergistic process for co-control of byproducts and DNA damage effects. Providing theoretical basis and technical support for ensuring the water quality safety of reclaimed water.

针对再生水臭氧氧化的副产物，现有研究普遍关注溴酸盐的生成和控制。由于再生水含有溶解性有机物，臭氧氧化也会生成有机溴代副产物，其毒性远高于溴酸盐。目前大量有机溴代副产物未被识别，其毒性特性也未被掌握。因此，仅关注溴酸盐生成可能严重低估副产物的风险！掌握新型有机溴代副产物及其毒性特性，才能全面认识和控制再生水臭氧氧化过程中副产物的风险。.本研究针对再生水臭氧氧化的有机溴代副产物的毒性效应，分离鉴定新型有机溴代副产物，掌握副产物对人肝细胞DNA碱基修饰、碱基缺失和DNA链断裂的影响特性及有机物的致毒机制，识别优先控制的有机溴代副产物。掌握臭氧氧化过程中溶解性有机物供电子基团和供电子能力的变化特性及其与有机溴代副产物生成的关联。识别影响有机溴代副产物生成的关键中间产物，阐明副产物的生成机制。优化联控溴代副产物及其DNA损伤效应的臭氧/过氧化氢协同工艺，为保障再生水的水质安全提供理论依据和技术支撑。

臭氧氧化广泛应用于污水再生处理，但会生成毒害副产物。当前研究普遍关注溴酸盐的危害及其控制，忽视了次溴酸与污水中溶解性有机物反应生成的有机副产物。本研究的目的是掌握臭氧氧化对污水厂二级出水毒性的影响特性。阐明溴离子存在条件下，臭氧氧化过程中副产物的生成特性及毒性特性。提出面向溴酸盐、有机副产物及毒性同步控制的臭氧氧化工艺，为保障水质安全提供理论依据和技术支撑。.发现臭氧氧化能有效去除二级出水的细胞毒性和遗传毒性，臭氧投加量为10 mg/L时，细胞毒性当量可被去除53%-66%，遗传毒性当量可被去除51%-76%。臭氧氧化难以去除溶解性有机碳（DOC），但可部分去除紫外吸收和荧光强度。臭氧氧化降低了溶解性有机物各分子量组分的荧光信号（240/360 nm）和紫外吸收（UV254）值，但增加了100-500 Da组分的DOC含量。臭氧氧化过程中，UV254的去除率与细胞毒性和遗传毒性的去除率显著相关，推荐UV254作为臭氧氧化过程中毒性去除的替代指标。.发现溴离子导致污水臭氧氧化后有机副产物的毒性显著增加。与不含溴离子的臭氧氧化水样相比， 100 μg/L的溴离子即可显著增加细胞毒性和遗传毒性。二级出水中溴离子浓度的增加可导致臭氧氧化过程中总有机溴（TOBr）和溴酸盐的增加。细胞毒性和遗传毒性随着TOBr的生成而增加。尽管溴酸盐也会在一定程度上增加毒性，但毒性增加幅度十分有限。TOBr是导致毒性增加的主要原因。.发现臭氧/氨氮/溴离子体系中二级出水的细胞毒性和遗传毒性进一步增加。氨氮抑制了溴酸盐和总有机溴生成，但是导致了氮元素与有机物结合生成有机氮。氨氮抑制了溴代乙腈生成，但生成了更多溴代乙酰胺和溴代硝基甲烷。含氮副产物尤其是高毒性溴代含氮副产物的生成可能是氨氮导致毒性升高的原因。.发现臭氧/过氧化氢协同氧化工艺可同时抑制溴酸盐、有机溴代副产物、细胞毒性和遗传毒性的生成。投加过氧化氢是理想的控制再生水臭氧氧化副产物和毒性的方式。