慢滤-低压纳滤对二级出水中有机物和抗生素抗性基因的去除效能研究

Removal efficiency of organic matters and antibiotic resistance genes in secondary effluent by slow filtration-low pressure nanofiltration

抗生素抗性基因(Antibiotic Resistance Genes,ARGs)作为新型环境污染物,在污水处理厂二级出水中被频繁检出,成为人类健康和生态安全的潜在威胁。本文采用慢滤-低压纳滤(Nanofiltration,NF)组合工艺去除二级出水中ARGs和溶解性有机物(Dissolved Organic Carbon,DOC),探讨该工艺对ARGs和DOC的去除机制及效能。结果表明,生物膜慢滤-NF组合工艺对二级出水中ARGs和DOC的去除效果最好,对DOC的去除率为82.5%,质量浓度降为2.0 mg/L;对富里酸类有机物和腐殖酸类有机物的去除率分别达到87.2%、85.8%,对不同分子质量区间有机物的去除率均在90%以上,其中,对>100 kDa、50~100 kDa以及10~<50 kDa区间有机物的去除率均在95%以上,出水中几乎不含有这类物质;组合工艺对4种ARGs(tet A、tet W、sulⅠ、sulⅡ)的去除量为10^(4.83)~10^(5.67)copies/mL;生物膜慢滤对水中细胞态和游离态ARGs的去除效果优于慢滤,其对细胞态和游离态ARG的削减量分别为10^(1.06)~10^(3.52)copies/mL和10^(1.73)~10^(3.07)copies/mL;水中DOC与不同类型ARGs均具有显著正相关性;生物膜表面生长的变形菌门、放线菌门、假单胞菌属及蛭弧菌属等微生物可以加强对水中ARGs和DOC的去除。综上,慢滤-NF组合工艺可以有效去除二级出水中的ARGs和DOC,可以作为二级出水深度处理的有效方式。

Antibiotic resistance genes(ARGs),as a new type of environmental pollutants,are frequently detected in the secondary effluent of wastewater treatment plants,becoming a potential threat to human health and ecological security.In this study,the combined process of slow filtration and low-pressure nanofiltration(NF)was used to deeply remove ARGs and dissolved organic carbon(DOC)in the secondary effluent.Furthermore,the removal mechanism and efficiency of this process on ARGs and DOC are discussed.The results show that the biofilm slow filtration-NF combined process can effectively reduce ARGs and DOC in the secondary effluent,the removal rate of DOC is 82.5%,and the concentration is reduced to 2.0 mg/L.The removal rates of fulvic acid and humic acid organic matter go up to 87.2%and 85.8%,respectively,as well as the removal amount of organic matter in different molecular weight ranges is more than 90%.The removal rates of organic matter in the>100 kDa,50-100 kDa,and 10-<50 kDa are above 95%.The effluent hardly contains such substances.The reduction of ARGs(tet A,tet W,sul I and sul II)by the combined process is 10^(4.83)-10^(5.67) copies/mL.Compared with the slow filtration process,the removal efficiency of cell state and free state ARGs of the biofilm slow filtration process is superior.The removal amount of those different states’ARGs is 10^(1.06)-10^(3.52) copies/mL and 10^(1.73)-10^(3.07) copies/mL,respectively.There is a significant positive correlation between the content of different types of ARGs and DOC in water.Biofilm surface growth microorganisms such as Proteobacteria,Actinobacteria,Pseudomonas,and Bdellovibrio can enhance the removal of ARGs and DOC from sewage.In conclusion,the slow filtration-NF combined process can effectively remove ARGs and DOC in the secondary effluent and can be used as an effective way for advanced treatment of the secondary effluent.