在UV_(365)和太阳光辐照下EfOM生成DBPs及其毒性的变化

Formation of DBPs from EfOM under UV_(365) and solar irradiation and the variation of their toxicity

为了探究污水厂出水中溶解性有机物(EfOM)经氯化消毒处理后生成的消毒副产物(DBPs)暴露在太阳光下的变化规律,探究了单一及混合DBPs在UV_(365)和太阳光辐照下的光解和水解特性,从而揭示氯化EfOM过程生成的DBPs的增衰规律以及伴随的两种生物毒性的变化.结果表明,氯化EfOM生成的6种DBPs中,一氯二溴甲烷和1,1,1-三氯丙酮在UV_(365)和太阳光辐照下均可降解,在UV_(365)辐照下的光解速率分别为0.0072和0.0523h~(-1),而在太阳光下光解速率分别为0.0293和0.1551h^(-1),其在太阳光下的光解速率大于UV_(365).混合DBPs体系中,在UV_(365)或者太阳光的辐照下,共存的DBPs之间可产生促进/抑制降解现象.在UV_(365)辐照下,Ef OM生成的DBPs(除了三氯甲烷)基本随着时间的延长而增加了16.5%~231.1%,并且氯化EfOM溶液的急性毒性和遗传毒性分别升高了17.0%和降低了5.6%.但是,在太阳光辐照下,三氯乙酸和1,1,1-三氯丙酮则下降了36.2%和82.2%,其它DBPs基本保持稳定,且氯化EfOM溶液的急性毒性和遗传毒性降低了35.8%和37.7%.这将为污水厂尾水排放到开放性水体受太阳光辐照后的生态安全保障提供了一定的依据.

This study investigated the variation of the disinfection by-products(DBPs)under solar irradiation which formed from chlorination process of dissolved organic matter in wastewater treatment plant effluent(EfOM).Firstly,the photolysis and hydrolysis properties of individual and mixed DBPs under UV_(365) and solar irradiation were identified,and then the variation of DBPs formed from EfOM chlorination and associated biotoxicities were revealed.The results showed that among the six DBPs formed from EfOM chlorination,bromodichloromethane and 1,1,1-trichloroacetone could be degraded under UV_(365) and solar irradiation.Their photolysis rates were 0.0072 and 0.0523h-1,respectively,under UV_(365)irradiation,while they were 0.0293 and 0.1551h-1,respectively,under solar irradiation.Their photolysis rate under solar irradiation was greater than that under UV_(365) irradiation.In the mixed DBPs solution,the coexisting DBPs showed promoting/inhibiting effects under UV_(365) and solar irradiation.Under UV_(365) irradiation,the concentration of DBPs(except chloroform)formed from EfOM increased by 16.5%~231.1%along the irradiation time,and the acute toxicity and genotoxicity of chlorinated EfOM increased by 17.0%and decreased by 5.6%,respectively.However,under solar irradiation,the concentrations of trichloroacetic acid and 1,1,1-trichloroacetone decreased by 36.2%and 82.2%,respectively,while other DBPs remained stable.Moreover,the acute toxicity and genotoxicity of chlorinated EfOM decreased by 35.8%and 37.7%,respectively.This provides a certain basis for guaranteeing the ecological safety of wastewater treatment plant effluent after discharging into the open water bodies and exposing into the sunlight.