纳米铁活化过硫酸盐与超滤组合对二级出水中污染物的去除效能及影响因素

Removal of pollutants in the secondary effluent by nano-iron activated persulfate and ultrafiltration combined process and its influencing factors

针对污水处理厂二级出水开展深度处理研究,采用纳米铁(nFe)活化过硫酸盐(PS)-超滤(UF)组合工艺去除二级出水中抗生素抗性基因(ARGs)和有机物,并探究pH值和温度对ARGs去除率的影响。结果表明,与直接UF和PS-UF工艺相比,nFe/PS-UF组合工艺对二级出水中ARGs、int I1及16S rRNA的去除效果最佳,对数削减量为2.51~3.52;二级出水中游离态ARGs比细胞态ARGs含量高,nFe/PS-UF组合工艺对细胞态和游离态ARGs去除效果优于直接UF和PS-UF组合工艺,其对细胞态和游离态ARGs的对数削减量分别为2.91~3.82和2.35~3.42;组合工艺对溶解性有机碳(DOC)和不同类型有机物的去除效果最好。其中DOC的去除率为30.0%,酪氨酸类、色氨酸类、富里酸类和腐殖酸类有机物去除率分别为84.5%、81.3%、81.1%和45.5%,且水中DOC含量与不同种类ARGs浓度有显著相关性。pH值和温度对组合工艺去除二级出水中ARGs有显著影响,pH值降低和温度升高有利于提高组合工艺对ARGs的去除效果。

This article carries out advanced treatment research on the secondary effluent of urban wastewater treatment plants,using iron nanoparticles(nFe)to activate persulfate(PS).Then,this study combines with ultrafiltration(UF)to remove antibiotic-resistant genes(ARGs)and organic compounds in the secondary effluent of wastewater treatment and explores the effect of initial pH value and temperature on the removal efficiency of ARGs.The results showed that PS and nFe/PS pre-oxidation could effectively improve the removal efficiency of four kinds of ARGs(tetA、tetC、sulⅠand sulⅡ),intⅠ1 and 16 S rRNA in the secondary effluent.The optimal dosages of PS and nFe were determined to be 4 mmol/L and 2 mmol/L,respectively.At this time,the PS-UF and nFe/PS-UF combined process could reduce the ARGs mentioned above the most,and the concentration dropped from 10^(5.10)-10^(8.24) copies/mlto 10^(4.38)-10^(6.82) copies/mL and 10^(4.02)-10^(5.97) copies/mL,respectively,which showed that the activation of nFe could enhance the reduction effect on ARGs.The removal efficiency of these ARGs,intⅠ1 and 16 S rRNA by nFe/PS-UF combined process,was higher than the direct UF and PS-UF combined process.The reduction was 10^(2.51)-10^(3.52) copies/mL.The ARGs mainly exists in the form of a free state and cellular state in the secondary effluent.The content of free state ARGs was higher than that of cellular state ARGs,and the concentrations were 10^(4.37)-10^(6.01) copies/ml and 10^(4.86)-10^(6.28) copies/mL,respectively.Compared with the direct UF and PS-UF combined processes,the removal efficiency of cell state and free state ARGs of the nFe/PS-UF combined process was superior.The lograithmic removal amount of those different states ARGs was 2.91-3.82 and 2.35-3.42,respectively.The nFe/PS-UF combined process had better removal efficiency for dissolved organic carbon(DOC)and various organic compounds.The DOC removal rate was 30%,and the removal rates of tyrosine,tryptophan,fulvic acid,and humic acid organic matters were 84.5%,81.3%,81.1%,and 45.5%,respectively.Research by the linear fitting method analysis showed a positive correlation between the contents of DOC and the different total concentrations of ARGs,which implied that the reduction of ARGs could benefit from the enhanced removal of the contents of DOC.What’s more,the pH value and temperature had a significant effect on the ARGs removal in the secondary effluent by the combined process.The decrease in pH value and the increase in temperature improved the removal effect of ARGs by the nFe/PS-UF combined process.