Study On The Contamination Characteristics Of Antibiotic Bacteria And Antibiotic Resistant Genes In Municipal Wastewater Treatment Plants

At present,the pollution of antibiotic resistant bacteria（ARB）and antibiotic resistance genes（ARGs）has attracted widespread attention.Sewage containing ARB and ARGs generated in the process of human life,medical treatment and industrial production will eventually flow into the sewage treatment plant through the pipeline network,which makes the sewage treatment plant become the repository of ARB and args and the main source of environmental pollution.The effective removal of ARB and ARGs in sewage treatment plants plays an important role in preventing the spread of antibiotic resistance.In order to study the effect of wastewater treatment process on the removal of ARB and ARGs,this study used plate counting method and fluorescence quantitative PCR technology to comprehensively analyze the spatial distribution characteristics of ARB and ARGs in wastewater treatment plants,and discussed the influence of seasonal factors on the distribution of ARB and ARGs.Clarify the effect of different treatment processes on the removal of ARB and ARGs.Research indicates:（1）Pollution characteristics of ARB and ARGs in different seasonsSix kinds of ARB can be detected in the influent and effluent water of the municipal sewage treatment plant.The abundance of ARB in the influent was 10⁷-10⁹CFU·L^-1,and the abundance of ARB in the effluent was 4-7 lower than that in the influent.The abundance of influent in summer was higher than that in winter,and the abundance of effluent in summer was lower than that in winter.whether it is total heterotrophic bacteria or ARB.In winter,20 kinds of ARGs can be detected in the influent and effluent of municipal wastewater treatment plant,but only 18 kinds of ARGs can be detected in summer.Intl I and intl II cannot be detected,and the average absolute abundance of ARGs in summer is 0.1-0.5 orders of magnitude lower than that in winter.The removal efficiency of ARB and ARGs by biological treatment process was less affected by season,while the removal efficiency of ARB and ARGs by physical separation process and ultraviolet disinfection process was more affected by season.The removal rate of ARB and ARGs by physical separation process in winter was 0.05-0.42 log and 0.2-0.3 log higher than that in summer,respectively.The removal rate of ARB and ARGs by ultraviolet disinfection process in winter was 2-3 log and 0.4log lower than that in summer.（2）Pollution characteristics of ARB and ARGs in different raw waterThe absolute abundance of ARB and ARGs in different raw water was different,the abundance of ARB in black water>the abundance of ARB in pure domestic sewage>the abundance of ARB in mixed sewage system of industrial wastewater and domestic sewage,the abundance of ARB in black water was about 1 order of magnitude higher than that in domestic sewage,and about 2 orders of magnitude higher than that in mixed sewage system of industrial wastewater and domestic sewage;the absolute abundance of ARGs in a sewage system with 50%industrial wastewater and 50%domestic sewage is>Absolute abundance of ARGs in a sewage system mixed with 10-20%industrial wastewater and the rest of domestic sewage>Absolute abundance of ARGs in a sewage system mixed with 30%industrial wastewater and 70%domestic sewage>Absolute abundance of ARGs in pure domestic sewage The absolute abundance of ARGs in a sewage treatment system where industrial wastewater and domestic sewage are mixed is about one order of magnitude higher than the absolute abundance of ARGs in pure domestic sewage.（3）Removal efficiency of ARB and ARGs by different treatment processesIn the wastewater treatment process,the removal rates of ARB by biological treatment,disinfection and filtration units were 2.7 log,2.22 log and 2.5 log,respectively,with little difference;but the removal rates of ARGs by biological treatment,disinfection and filtration units were 1.5 log,0.73 log and 0.21 log,respectively,with great difference.The removal efficiency of ARB and ARGs by IFAS process combined with sludge membrane is the best,followed by activated sludge process,and the treatment efficiency of MBBR Process with pure biofilm is poor.In addition,most ARB will eventually enter into sludge instead of sewage,and the abundance of ARB in activated sludge of aerobic tank is 1 to 2 orders of magnitude higher than that on biofilm.But most ARB proportion of biofilms in a proportion higher than in the activated sludge.From anaerobic stage to anoxic stage and then to aerobic stage,the absolute abundance and relative abundance of ARGs showed a downward trend,and the relative abundance and absolute abundance of ARGs on biofilm were higher than those in activated sludge.The removal rate of ARB and ARGs by sodium hypochlorite disinfection is 1-2orders of magnitude higher than that by ultraviolet disinfection;the removal rate of ARB by membrane filtration is 2.5 log,while the removal rate of ARB by filter cloth filter and continuous flow sand filter is only 0.7 log and 0.3 log;the removal rate of ARGs by continuous flow sand filter is about 0.1 log higher than that by filter cloth filter.