| Water pollution has been the concern of global research. With the development of water treatment technology, traditional water pollution problems have been solved, and newly emerging water pollutants gradually draw people’s attention. Newly emerging water pollutants, such as endocrine disrupting chemicals (EDCs) and nitrogenous disinfection byproducts (N-DBPs) through chloramine disinfection processes have gained significant attention among scientists and public due to its potential environmental effect.17β-estradiol, acting as the most typical endocrine disrupting chemical, presents high activity even at extreme low concentration and shows great threat to human’s health and aquatic environment.With the widely use of oral contraceptives and hormone replacement therapy,17β-estradiol has been frequently detected in aqueous environment, but it can not be removed by traditional method. So it is of great importance to research photodegradation mechanism and estrogenic activity of 17β-estradiol to ensure safety of aqueous environment.In addition, nitrogen based disinfection byproducts (N-DBPs) occur at low concentrations, but have been determined to have high cytotoxicity and mutagenicity and therefore may represent a human health hazard. Traditional methods can not remove this kind of compounds effectively, so it is necessary to develop further water treatment technology. Advanced oxidation/reduction processes (AO/RPs) which utilize free radical reactions are new alternatives to degrade these species.The main job during my master period includes two parts:Firstly, we studied photodegradation process and estrogenic activity of 17β-estradiol in sewage effluent. Secondly, we researched advanced oxidation/reduction processes of removing haloacetamides.As far as experinments of 17β-estradiol, the main conclusions were as follows: Firstly, it was the first time to select sewage effluent as research medium rather than simulative water by adding nature organic matters (NOMs). Experinment results showed that indirect photodegradation was more important than direct photodegradation, and photodegradation rate in sewage effluent was faster than in nature organic matters solutions, which indicted that photodegradation was the main way for sewage treatment plant to remove 17β-estradiol. Secondly, we researched role of singlet oxygen (1O2), hydroxyl radical (·OH) and effluent organic matter (3EfOM*) played in photodegradation of 17β-estradiol in sewage effluent. The results indicated that singlet oxygen (1O2) and hydroxyl radical (·OH) controlled photodegradation of 17β-estradiol in sewage effluent. Thirdly, it was the first time to find that 17β-estradiol presented high photodegradation rate in acidic and alkaline sewage effluent.Besides, the second-order reaction constant of E2 with 1O2 increased with pH values. Finally, this was the first study to combine chemical analyse and estrogenic activity analyse to.research photodegradation of 17β-estradiol.As far as experinments of haloacetamides, the main conclusions were as follows: measured hydroxyl radical and hydrated electron kinetics for these 12 HAcAms species in this study demonstrated that they can be removed by further AO/RPs treatment, with the reducing hydrated electron reaction being faster than those of the oxidizing hydroxyl radical reaction. Hydroxyl radical oxidation likely occurred at C-H and iodine group, while the solvated electron was more effective and focused on the halogen group. These reaction rate constants are important for kinetic models necessary to describe the destruction of HAcAms disinfection byproducts via advanced oxidation and reduction processes. AO/RPs are likely to be feasible techniques for removal of HAcAms in full-scale water treatment processes, while the careful assessment is required. |
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