Study On The Removal Rules Of EDCs In Oxidation Ditch Sewage Treatment Process

In recent years, related reports about environmental pollution be caused by endocrine distrupting compounds (EDCs) reveal that steriod sex hormones and related synthetic compounds, e.g. those used in contraceptive pills, have been shown to be present in the aquatic environment, mainly as a result of inefficient removal in sewage treatment plants (STPs). Studies in North America, Europe, Japan and Australia have reported the presence of endocrine disrupting compounds (EDCs) in wastewater treatment plant (WWTPs) effluent could affect physiological and reproductive function in exposed wildlife organisms consistent with exposure to hormonally active chemicals. The modern municipal sewage treatment plants are mainly to remove nutrient pollutant and microorganic contaminant from sewage, but cannot effectively remove persistent organic pollutants (POPs) such as EDCs. Therefore, the occurrence of EDCs in rivers and receiving environments situated near STPs raises concern over the removal efficacy of these compounds by conventional treatment processes.Due to the trace concentration of EDCs in aquatic environment from ng/L toμg/L, the methods of solid phase extraction (SPE) and high performance liquid chromatography (HPLC) for determination of target EDCs in sewage were established in this research firstly. By this way, the concentrations of target EDCs in the second sewage treatment plant in Huainan were investigated in sewage during sewage treatment process in detail. We discussed the efficiency to remove target EDCs of oxidation ditch sewage treatment process and studied the removal rules of target EDCs in oxidation ditch sewage treatment process.Conclusion presented in this thesis can be summarized as follows:—The solid phase extraction method and HPLC analysis were developed to detect the trace concentration of estrone(E1),17a-ethynylestradiol(EE2),4-nonylphenol(NP),bisphenol A(BPA),Dimethyl Phthalate(DMP),Diethyl Phthalate(DEP). Dibutyl phthalate(DBP) and Butylbenzyl Phthalate(BBP) in sewage. Spike recovery of target chemicals for ultrapure water shows between 93 percentages to 102 percentages.—In the treating process, the contents of TOC,TN and UV254 are decreasing. The concentrations of TOC,TN and UV254 in secondary effluent from STP are 7.89mg/L,12 mg/L and 0.052 cm-1 respectively. The total removal rates of TOC,TN and UV254 are 80.8%,65.5% and 48.5%,respectively.—The concentrations of E1,EE2,BPA,NP,DMP,DEP,DBP and BBP in the treating processes of STP in Huainan were also quantitatively determined by SPE-HPLC. The concentrations of E1,EE2,BPA,NP,DMP,DEP,DBP and BBP were in the range of 23.8～254.9 ng/L.6.4～29.23 ng/L 0.03～3.49μg/L,0.04～6.3μg/L,n.d.～59.23μg/L,n.d.～2.25μg/L 0.48～4.43μg/L and 2.31～17.6μg/L respectively.The result shows that the anaerobic stage can efficiently remove E1 in wastewater and the aerobic stage can efficiently remove EE2. In the whole process, the total removal rates of E1 and EE2 are 82.4% and 78%, respectively.The primary treatment has certain removal effect for BPA and NP, which appears to be primarily associated with the adsorption of sludge. The removal rates of NP and BPA in the oxidation ditch process are 25.3% and 44.9%, respectively. In the whole process, the total removal rates of NP and BPA are 67.3% and 79.5%, respectively.The primary treatment has a higher effect on DMP and DEP, with the removal rates of DMP and DEP are 92.4% and 92% respectively. In the whole process, the DBP and BBP were reduced 69% and 23.8% respectively and the DEP was removed by about 92.4%.The concentrations of E1,EE2,NP,BPA,DEP,DBP and BBP in secondary effluent from STP are 23.8ng/L,6.4ng/L,1.19μg/L,0.09μg/L,0.17μg/L,0.86μg/L and 12.28μg/L respectively. The DMP in secondary effluent from STP has not been detected.