Formation of DBPs from EfOM under UV365 and solar irradiation and the variation of their toxicity
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 UV365 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 UV365 and solar irradiation.Their photolysis rates were 0.0072 and 0.0523h-1,respectively,under UV365irradiation,while they were 0.0293 and 0.1551h,respectively,under solar irradiation.Their photolysis rate under solar irradiation was greater than that under UV365 irradiation.In the mixed DBPs solution,the coexisting DBPs showed promoting/inhibiting effects under UV365 and solar irradiation.Under UV365 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.
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