Study On Edcs Removal And Microorganism In Soil Wastewater Treatment System

Bisphenol A(BPA) and steroid estrogen(E1,E2,E3,EE2) as typical endocrine disrupting chemicals which widely existed in the environment threaten animals and human. Their fate in sewage treatment process caught people's increasing attention. Soil treatment is a popular method applied in rural nonpoint pollution watershed, and then the removal of BPA and steroid estrogen in soil treatment system deserves intensive study.Typical EDCs including bisphenol A, estrone, 17β-estradiol, 17α-ethynylestradiol, and estriol were selected as the target compounds. Solid phase extraction(SPE) and gas chromatography(GC)coupled with mass spectra(MS) analysis was applied to detect the concentration of EDCs.Firstly, this paper selected Luoshi River, a river in typical rural nonpoint pollution watershed in Dali erhai lake as the study object. Distribution characteristics of EDCs in river and sediment were discussed.The results indicated that EDCs widely existed in Luoshi River. The concentrations of bisphenol A (BPA), ethinyl estradiol (EE2), estrone (E1), estradiol (E2) and estriol (E3) were 1.01～43.64ng/L and 1.16～13.74ng/L, 2.54～20.53ng/L, nd～23.18ng/L and nd～26.55ng/L, respectively. Considering the total amount of EDCs pollution, it was proved that two major towns, Yousuo and Dengchuan, contributed the largest amount of EDCs, then EDCs reduced as a result of wetland intercept and stream's self-purification. Luoshi River imported EDCs into Erhai Lake at the rate of 1.35～3.70μg/s. The highest enrichment of E1 and E3 occured in the downstream area of urban, which showed consistency with the total amount. The analysis indicated that EDCs were deposited nearby rather than carried downstream. Among all the detected EDCs in sediment, E3 had the largest amount (1.48～28.44μg/kg), followed by E1(0.36～2.95μg/kg). And E2 would not be easily enriched because of rapid degradation.Experiment for EDCs and other pollutant removal was carried in soil treatment device through making up simulated wastewater. After a period of time for stable running, treatment system was able to remove EDCs and other pollutant to some degrees. Soluble phosphate and COD removal effect in devices was relatively good, while total nitrogen poor. Among five kinds of EDCs, BPA, E1, E2 and EE2 were obliterated better than E3. Water jam caused the treatment column working unstably and poor processing ability. The lab experiments showed that it was beneficial for the devices to remove conventional pollutants and EDCs by reducing hydraulic load and providing appropriate C/N ratio. In condition, that the nitrification and the EDCs removal is relevant was proved by the counting of nitrobacteria.A bacterial strain(numbered as B-01) that was isolated from soil treatment devices, which can degrade BPA very effectively and grow well in nutrient solution of high BPA concentration. During the early 24 hours for degradation, bacteria consumed BPA rapidly, and then consumption rate slowed down. And increasing carbon source could promote BPA degradation to a certain degree. The superior BPA degradation bacterial strain was identified as Pseudonomas sp.