Pollution Of Estrogen In Water Supply And The Photocatalytic Removed Technology Coupled With Ultrafiltration

Environmental estrogens(EES)are "new" chemical pollutants,and widely concerned by the public and academia.Though they are presented in the environment at trace concentration level,it is difficult to be biological degraded effectively in environment,which is harmful for human health through food chain biomagnification for their high biological activity and polarity.The environmental behavior and effect removal of EES have become a hot research topic in recent years.Shandong Province is located in lower reaches in the eastern route of South-to-North Water Transfer Project,with high risk of water pollution.Multiple water sources coexisted in this area,including mountainous reservoirs,Yellow River reservoirs and groundwater.Since the implementation of the eastern route of South-to-North Water Transfer Project,Yangtze River has been another new water supply source.In this context,pollution risk of EES in drinking water sources could beincreased.In Shandong Province,mostly water works were dominated by conventional treatment processes,always with low and limited EES removal capacity mainly by the process of "coagulation-sedimentation-Filtration-disinfection?.Therefore,how to effectively identify and control EES in water is a serious problem to be solved in urban water supply industry.In this study,we developed a pollution characteristics assessment system of EES including component and total determination,and health risk assessment,and systematically evaluated pollution characteristics of EES in 19 drinking water sources and water plants of 13 cities in eastern route of South-to-North Water Transfer Project.Results showed that17?-estradiol,estrone and triclocarban were found in Yangtze River,triclosan and triclocarban were found in Shandong water sources,and triclocarban were found in water plants.From the compre hensive toxicity of water from different processes of different water plants,the conventional processes for EES removal were limited,ozone-activated carbon treatment process and ultrafiltration membrane treatment process had better removal effect on EES.The average year health physical health risk caused by drinking water way was evaluated by health risk assessment model.Human exposure risk index of triclocarban was low.Human exposure risk index of oestrone was higher than non-carcinogenic risk values caused harm to human health.Human exposure risk index of 17?-estradiol was low,but its main degradation product in the transformation process was estrone.Therefore,systematic research of water treatment technology and the removal mechanism is very important for estrone and 17?-estradiol.Preparation method of modified ultrafiltration membrane was studied.3 factors and 3 levels orthogonal experiments were carried out with PVDF quality,PVP quality and nano-Ti O2 mass as the main factors in the design of modified PVDF ultrafiltration membrane.Based on the membrane flux,retention rate,anti-pollution ability and comprehensive index of PVDF-Ti O2 modified ultrafiltration membrane,the experimental results of ultrafiltration membrane were analyzed.The optim al scheme and its variance analysis were compared,and the optimal scheme of variance analysis was selected,that is,the mass of PVDF is 25.0g,the mass of PVP is 3.0g,and the quality of nano-Ti O2 is 1.0g.The properties and adsorption capacity of modified ultrafiltration membranes were characterized.The result was shown that the ultrafiltration membranes have good matrix properties,and the static adsorption process for estrone and 17?-estradiol fit Freundlich adsorption isotherm.PVDF-PVP-Ti O2 membranes had adsorption effect on estrone and 17?-estradiol,but the adsorption capacity was poor and easy saturation,that is to say,the effect was not ideal.Therefore,a systematic study of the modified membranes for estrone and 17?-estradiol removal performance were carried out.Under dark reaction conditions,removal rates of PVDF-PVP-Ti O2 membrances to estrone and 17?-estradiol were unstable and only 36.1% and 11.4% respectively,while they were up to 93.4% and 73.1% when under UV illumination respectively,suggesting an obviously improved removal efficiency.However,there was an aging risk of membrane materials.The reaction process was related to UV light,p H,and dissolved organic carbon.The removal of estrone and 17?-estradiol by PVDF-PVP-Ti O2 membrances was adsorption and photocatalysis coupling,and ultraviolet catalysis play a leading role.At the same time,the product and reaction mechanism of PVDF-PVP-Ti O2 for estrone and 17?-estradiol removal in pure water were investigated.The removal of E1 and E2 was in accord with the first order reaction kinetics model.Carbonyl group and phenolic hydroxyl of benzene ring in estrone is the active site,forming series products of hydroxylation,methylation,oxidation,and hydrolysis.Tertiary carbon and phenolic hydroxyl of benzene ring in 17?-estradiol is the active site,forming series products of hydroxylation,methylation,hydrolysis and oxidation.Phenolic hydroxyl on the benzene ring may be estrone and 17?-estradiol common active site.The strone degradation by modified PVDF membrane on the photocatalytic conditionsmay disturbs the removal of endocrine activity and reduces the biological toxicity.Finally,modified PVDF-PVP-Ti O2 membrane was applied to the treatment of the source water in the Shandong reservoir of the south to North Water Transfer Project.Results showed that compared with conventional water treatment process,the PVDF-PVP-Ti O2 membrane had good removal efficiency for E1 and E2,as well as on turbidity,oxygen consumption(CODMn)and total organic carbon(TOC)in water.The modified membrane material has a good prospect in practical engineering application.