代表性二级处理、三级处理和湿地生态修复技术对城镇污水人源干细胞毒性的削减

Reduction of Cytotoxicity in Human Stem Cells by Representative Secondary Urban Sewage Treatment,Tertiary Treatment and Wetland Ecological Restoration Technology

污水中的难降解污染物往往具有浓度低但毒性强的特点,可以通过多种暴露途径直接或间接对人体健康产生有害影响,因此有必要评估污水处理技术对健康效应的削减效果。本研究选择人骨髓间充质干细胞(human bone marrow mesenchymal stem cells,hBMSCs)体外模型,评估典型二级处理、三级处理和湿地修复技术进水、主要工艺排水的综合毒性,并与发光菌急性毒性测试结果进行比较。水样萃取物对hBMSCs的细胞毒性呈剂量依赖性关系,进水毒性单位(toxicity unit,TU)在0.03~0.22范围内,出水TU为0.02~0.03。二级处理技术对细胞毒性的削减率为59.8%。三级处理过程中经混凝、微滤和反渗透处理后,出水无显著细胞毒性,但经臭氧消毒后最终排水的细胞毒性较进水无显著变化。湿地修复技术对细胞毒性的削减率为49.9%。66.7%(14/21)水样品对于hBMSCs细胞毒性的TU值高于发光菌急性毒性的TU值。在相对富集倍数(related fold enrichment,REF)20%效应浓度(EC_(20))下,二级处理和三级处理技术对污水hBMSCs细胞毒性的削减率低于发光菌急性毒性,但湿地修复技术对细胞毒性的削减率高于发光菌急性毒性。结果提示污水处理厂排水中残留的难降解有机污染物对人源干细胞具有较强的有害效应,为再生水水质安全性评价以及城镇污水资源化技术研发提供参考依据和方法。

The refractory pollutants in the sewage wastewater usually exhibit high toxicity at low dose,which directly or indirectly pose harmful effects on human health via various exposure pathways.Therefore,it is necessary to evaluate the toxicity removal efficiency of different sewage treatment technology.In this study,human bone marrow mesenchymal stem cells(hBMSCs)was selected as an in vitro model to evaluate the integrated toxicity of the influent,the main unit process effluent from typical secondary treatment,tertiary treatment and wetland ecological restoration technology,and the final effluent,in comparison with the commonly used luminescent bacteria acute toxicity tests.The water extracts induced cytotoxicity in hBMSCs in a dose-dependent manner.The influent toxicity unit(TU)was in the range of 0.03~0.22,and the effluent TU from secondary treatment was in the range of 0.02~0.03.The toxicity was reduced by 59.8%after the secondary treatment.After coagulation,microfiltration and reverse osmosis in the tertiary treatment process,the effluent exhibited no significant cytotoxicity,but the cytotoxicity had no significant change after ozone disinfection.The cytotoxicity was reduced by 49.9%after the wetland ecological restoration treatment.The organic extracts in the sewage caused higher toxicity to hBMSCs than luminescent bacteria.Compared with the test results of the acute toxicity in luminescent bacteria,66.7%(14/21)of the water samples showed higher toxicity to hBMSCs.Under 20%effect concentration for related fold enrichment(REFEC_(20)),the reduction of cytotoxicity by secondary and tertiary treatment technology was lower than the acute toxicity of luminescent bacteria,but the reduction of wetland ecological restoration technology on the cytotoxicity of wastewater was higher.The results suggested that the residual organic pollutants in the wastewater of sewage treatment plants had detrimental effects on human stem cells.Wetland ecological restoration technology may have good prospects for reducing the cytotoxicity of sewage.The results provided referential basis and methods for the evaluation of the safety of reclaimed water quality and the development of urban sewage recycling technology.