Removal Efficiency Of Resistant Bacterial And Resistant Genes From Wastewater By UV Activated Persulfate

Antibiotics play an important role in disease control.Thus,antibiotics are widely used and exist in the environment,which causes selection pressure on the microorganisms in the environment and spread of antibiotic resistant bacteria(ARB)and antibiotic resistant genes(ARGs).These will pollute the environment and endanger human health.As the wastewater treatment plants(WWTPs)are considered to be the repository of ARB and ARGs and become the main source of ARB and ARGs transmission.Therefore,it is significant to remove and control ARB and ARGs in the WWTPs to protect human health.Ultraviolet Activated Persulfate(UV/PS)technology is a kind of advanced oxidation technology with broad application prospect.Persulfate can be activated to produce free radicals with high oxidation potential,and can degrade a variety of environmental pollutants,so it has been widely concerned.Based on this,this study proposed a new method using UV/PS to remove ARB and ARGs from secondary effluent of WWTPs and explore the mechanism of UV/PS treatment to remove ARGs and ARB.The main achievements of this study include the following aspects:Compared with the treatment of ultraviolet(UV)and persulfate(PS),UV/PS can inactivate ARB more effectively and quickly.After 10 min treatment,the inactivation rates of erythromycin resistant bacteria(ERB),sulfadiazine resistant bacteria(SRB),tetracycline resistant bacteria(TRB)and ciprofloxacin resistant bacteria(CRB)by UV/PS were 96.6%,94.7%,98.0% and 99.9%,respectively.UV/PS also has obvious removal effect on ARGs.The removal of total ARGs by UV/PS treatment reached 2.08 orders of magnitude,which is 0.41 and 1.38 orders of magnitude higher than that of UV and PS treatment alone.The removal rates of erm B,sul1,sul2,tet O and qnr S by UV/PS were 83.35%,58.54%,42.35%,43.19% and 63.54%,respectively,which were higher than those of UV and PS alone.In addition,UV/PS also has a high removal rate for mobile gene elements.The removal rates of int I1 and int I2 were 75.98% and 92.74%,respectively,which helps to reduce the horizontal transfer of ARGs.The results of high-throughput sequencing showed that the community structure of bacteria changed significantly after UV/PS treatment.At the level of phylum,the relative abundances of Proteobacteria and Actinobacteria increased,while those of Bacteroidetes and Firmicutes decreased.At the level of genus,the relative abundance of Rhodoferax and Aquabacterium decreased,while the relative abundance of Pseudomonas and Nitrosomonas increased.Particularly,the relative abundance of Pseudomonas,the potential pathogens was increased,which indicates that the environmental hazards caused by Pseudomonas should be paid attentioned.The results of correlation analysis indicate that there are multiple antibiotic resistant bacteria and potential pathogens carrying ARGs in the wastewater,and the removal of ARGs may be related to the removal of potential ARB.The results of free radical quenching showed that in UV/PS system,hydroxyl radicals(·OH)and sulfate radicals(SO4–·)all contribute to the removal of ARGs and ·OH plays a major role.The results show that UV/PS system combines UV radiation and free radical oxidation,which synergistically promote the removal of ARB and ARGs.This study provides a new idea and method for the removal of ARGs and ARB in wastewater.