典型医药活性物质在污水处理厂中的归趋及其风险评估

采用固相萃取、高效液相色谱/串联质谱法 (污泥样品先采用超声波萃取预处理方法提取) 检测分析了包括磺胺类、喹诺酮类、大环类酯类抗生素、心血管类、止痛剂类等8类医药活性物质在重庆某污水厂中的含量水平及其行为归趋.采用 EC/PNEC 综合评价体系评估环境中目标医药活性物质的生态风险,利用质量平衡分析的方法分析了其在水相及污泥相中的分布.结果表明,目标物质在水相中均可检出,其检出浓度在ng/L~μg/L,在污泥样品中可检测出18种目标物质,其浓度在ng/g (干重,下同).仅仅1.1%的目标物质被污泥吸附去除.污水处理厂初级处理及氯化消毒阶段对目标物质无明显去除效果,目标物质的去除主要发生在生物处理阶段,生物的降解或转化作用是目标物质的主要去除机制.EC/PNEC分析表明,磺胺嘧啶、磺胺甲恶唑、氧氟沙星与脱水红霉素在污水处理厂出水及其污泥中综合评价因子均大于1,它们的存在可能对环境产生不同程度的危害.本研究结果表明,污水处理厂并不能完全去除水相中微量的医药物质,为防止排放导致的潜在生态风险,出水及污泥中活性医药物质需采取措施进行进一步的处理.

Fate of pharmaceutically active compounds in a municipalwastewater treatment plantand risk assessment

The occurrence and fate of eight therapeutic groups, including antibiotics, analgesics, antiepileptics, antilipidemics, antihypersensitives, were studied at a municipal wastewater treatment plant in Chongqing. PhACs were detected using high performance liquid chromatography/tandem mass spectrometry after solid-phase extraction, and the sludge samples were extracted by ultrasonic-assisted extraction before solid-phase extraction. The distribution of PhACs in water and sludge phase was calculated by mass balance analysis. Risk quotients, expressed as the ratios of environmental concentrations and the predicted no-effect concentrations, were used to analyze the ecotoxicological assessment of the target PhACs in the environment. Results showed that all the target pharmaceutically active compounds (PhACs) were present in wastewater, in concentrations ranging from low ng/L to a few μg/L.Among the target PhACs, 18were detected in the sludge samples and most PhACs were found at low ng/g dry weight levels. Only about 1.1% of the total mass load of the studied PhACs was removed by sorption of sludge. The removal of PhACs was insignificant in primary and disinfection processes and was mainly achieved during the secondary treatment. The aqueous removals for the selected PhACs were mainly attributed to the biodegradation processes. Risk quotients were higher than unity for sulfadiazine, sulfamethoxazole, ofloxacinand erythromycin-H2O, in effluent and sludge samples, indicating a significant ecotoxicological risk to human health. Therefore, further removal of PhACs in effluent and sludge is required before their discharge and application to prevent their introduction into the environment.