贵阳市典型污水处理厂新污染物的赋存、去除及归趋

Occurrence,removal and fate of emerging pollutants in typical wastewater treatment plants in Guiyang

抗生素和内分泌干扰物(Endocrine Disrupting Compounds,EDCs)是污水中常见的新污染物,而污水处理厂出水中残留的新污染物因对生态系统和人体健康存在潜在威胁而备受关注.目前关于污水处理厂中新污染物的迁移转化及归趋研究存在差异,为调查不同污水处理工艺同时对抗生素和EDCs的去除效果,本研究选取了贵阳市4座典型污水处理厂,研究了10种抗生素和10种EDCs的赋存情况、去除效果及迁移规律,并评估了对受纳水体造成的生态风险.结果表明:在进出水及污泥中抗生素和EDCs均有不同程度检出,其中,氧氟沙星(OFX)和邻苯二甲酸二(2-乙基己)酯(DEHP)为主要贡献者,进出水中抗生素总浓度分别为569.78~781.63和14.43~458.78 ng·L^(-1),进出水中EDCs总浓度分别为3297.98~4454.72和669.27~1884.00 ng·L^(-1),抗生素和EDCs在处理工艺流程中的去除率分别为-85.65%~95.22%和3.51%~65.44%.不同污水处理单元对新污染物的去除效果差异较大,除个别处理工艺对磺胺类(SAs)抗生素、四环素类(TCs)抗生素存在负去除现象以外,抗生素和EDCs去除效果最佳的单元分别集中在三级处理和二级处理;二级处理中SBR工艺较氧化沟、CAST和A2/O处理工艺对抗生素的去除效果更佳,而A2/O工艺对EDCs去除效果最好.质量平衡分析表明,生物降解主要是SAs抗生素和低分子量的EDCs的去除,而污泥吸附是OFX、DEHP和DNOP(邻苯二甲酸二正辛酯)的主要去除途径.生态风险评估表明,OFX具有最大的风险商值,对水生生物造成高风险,其他目标新污染物对水生生物造成中风险或低风险.本研究结果可为污水处理厂现有工艺运行参数调控和新污染物去除工艺设计提供支撑,也可为我国污水中抗生素和内分泌干扰物的排放标准制定提供数据参考.

Antibiotics and Endocrine Disrupting Compounds(EDCs)are common emerging pollutants in municipal sewage.However,the potential threat of the emerging pollutants to the ecosystem and human health in the effluent from wastewater treatment plants has attracted much attention.At present,there are still differences in the studies on the migration,transformation and regression of emerging pollutants in wastewater treatment plants.In order to investigate the removal effects of antibiotics and EDCs in different treatment processes,this study selected four typical wastewater treatment plants in Guiyang,studied the occurrence,removal and migration regularity of 10 antibiotics and 10 EDCs,and assessed the ecological risks to the receiving water bodies.The results showed that antibiotics and EDCs were detected in the influent,effluent and sludge,of which ofloxacin(OFX)and di-(2-ethylhexyl)phthalate(DEHP)were the main contributors.The total concentrations of antibiotics in the influent and effluent ranged from 569.78 to 781.63 ng·L^(-1) and 14.43 to 458.78 ng·L^(-1),respectively.EDCs in the influent and effluent ranged from 3297.98 to 4454.72 ng·L^(-1) and 669.27 to 1884.00 ng·L^(-1),respectively.The emerging pollutants removal efficiency of different wastewater treatment units varied greatly.The removal rates of antibiotics and EDCs in the treatment process were-85.65% to 95.22% and 3.51%to 65.44%,respectively.In addition to the negative removal phenomenon of sulfonamides(SAs)and tetracycline(TCs)antibiotics by individual treatment processes,the best removal efficiency of antibiotics and EDCs was concentrated in the tertiary treatment and secondary treatment,respectively.In the secondary treatment,SBR process had better removal on antibiotics than Oxidation Ditch,CAST and A2/O processes,while A2/O process had the best removal on EDCs.Mass balance analysis showed that the removal of SAs antibiotics and low molecular weight EDCs was mainly biodegradation.While the removal of OFX,DEHP and DNOP(di-n-octyl phthalate)were mainly sludge adsorption.Ecological risk assessments indicate that OFX has the greatest risk quotient,posing a high risk to aquatic organism,and other targeted emerging pollutants pose a moderate or low risk to aquatic organism.This study provided support for the control of existing process parameters in wastewater treatment plants and the design of emerging pollutants removal process,and also provided data reference for the establishment of the discharge standard of antibiotics and EDCs in wastewater.