Analysis Of The Degradation And Biological Toxicity Reduction Of EDCs In Landfill Leachate Membrane Concentrates

Treatment of municipal solid waste in landfills would lead to the production of landfill leachate.In order to meet the discharge standard,membrane-based processes,such as nanofiltration,were widely used in the treatment of landfill leachate,resulting in the production of landfill leachate membrane concentrates?MCs?.Due to its poor biodegradability,high content of endocrine disrupting chemicals?EDCs?and toxicity,MCs were considered as refractory and toxic wastewater.With the improvement of living standards,diseases induced by EDCs become more and more common.Migration and transformation of EDCs in environment were investigated in previous researches,but little was known about EDCs in MCs.And most of the researchers focused on improving the removal efficiency or developing new treatment technologies,ignoring the toxic assessment of EDCs in landfill leachate.Gaining insight into the biotoxicity of MCs could promote the development of innovative and efficient treatment technologies and provide guidance for parameter design in treatment processes.In this paper,typical EDCs in MCs from a landfill in Guangzhou were detected by GC-MS.Treatment efficiency of typical EDCs in MCs using ultraviolet catalytic wet oxidation process?UV-CWOP?,dynamic analysis and the formation of intermediates during UV-CWOP were also discussed in detail.Extensive toxic assessments about MCs,including inhibitory effect on Chlorella vulgaris,acute toxicity on zebrafish and estrogenic toxicity on MCF-7 cells,were also performed.Comprehensively estimated the biotoxicity of MCs and the performance of UV-CWOP for biological detoxification.Following is the main results:?1?In this study,typical endocrine disruptors in membrane concentrate was analyzed,and the result indicated the contents of PAEs were as the followings DMP:127?g/L?DBP:215?g/L?DEHP:197?g/L.While DEP,BBP and DnoP were not detected.In addition,the contents of other endocrine disruptors were BPA:8.6?g/L?NP:6.8?g/L?BaP:18.4?g/L?Cr:114.0?g/L?HA:965.0 mg/L,etc;?2?The degradation of phthalic acid esters endocrine disruptors in the leachate membrane concentrate by UV-CWOP was accorded with the first-order kinetics model.The removal efficiencies were DMP:98.7%,DBP:93.6%,DEHP:89.4%and the half-life were DMP:6.372min,DBP:8.571 min,DEHP:9.846 min respectively;?3?Through the proliferation toxicity experiment of humic acid,bisphenol A,nonylphenol,butyl phthalate and Cr⁶⁺on MCF-7 in the leachate membrane concentrate,it showed that the butyl phthalate was the major contributors to cell proliferation toxicity in membrane concentrate;?4?The EC₅₀0 of the leachate membrane concentrate was 48%for chlorella and the LC₅₀0 was5%?v/v?for the zebrafish.After the treatment,the growth status of chlorella was close to that of the control group and the zebrafish mortality was reduced to 0%.The proliferation effect of MCF-7 cells showed that the toxicity of 5%?v/v?concentration of landfill leachate was 93%,and it increased to 119%after degradation for 10 min.Concentration experiments showed that the maximum cell proliferation was 10^-22 mg/L and the toxicity rule was:mixture of PAEs>DEHP>DBP>DMP.During UV-CWOP degradation process,the toxicity was first increased,slowly decreased and reach biological safety afterwards.