Distribution Of Antibiotics And Antibiotic Resistance Genes In A~2/O-MBR Treatment Process

In recent years,Antibiotics and ARGs known as"emerging pollutants"have become a global environmental pollution problem.The sewage treatment system is considered to be a huge reservoir of antibiotics and ARGs,and has received extensive attention from many scholars.There are few studies on the distribution and removal of antibiotics and ARGs during the upgrading of sewage treatment plants.Based on USE/SPE-UPLC-MS/MS technology and real-time fluorescent quantitative PCR technology,this study optimized the detection methods of typical antibiotics and ARGs in sewage treatment systems.On this basis,the distribution characteristics of antibiotics and ARGs in sewage and activated sludge of each treatment unit during the commissioning period and the stable operation period of the A²/O-MBR treatment system were studied.Analyzed the response law of the microbial community in the system during the commissioning period and the stable operation period,and constructed the relationship between antibiotics,ARGs and the microbial community structure in terms of water quality parameters,microbial community structure and pollutant removal effect,and the main conclusions obtained are as follows:（1）Established a simultaneous determination method for 4 categories of15 typical antibiotics in sewage and sludge of sewage treatment system.The detection limit and quantification limit of the method are 0.01～2.97μg/L and0.06～9.90μg/L,respectively.The sludge spiked recovery rates were 57.02～156.79%and 36.98～143.76%respectively.The q PCR quantitative method of ARGs was optimized,the standard curve was linear,R² was greater than0.995,and the amplification efficiency was between 89.41%and 102.1%,meet the quantitative requirements.（2）During the commissioning period and the stable operation period,10and 7 target antibiotics were detected in the influent and effluent of A²/O-MBR treatment system,and 10 target antibiotics were detected in the sludge.The total removal rate of antibiotics by the system is 50.73%and 61.22%respectively.The residual antibiotics in the water phase are mainly OFL,SCP and NOR,while the residual antibiotics in the mud phase are mainly OFL,NOR,ENR,CIP,TC,OTC and AZM.RDA analysis found that COD,TN and NH₄⁺-N in the A²/O-MBR treatment system were positively correlated with SDZ,SMM,OTC and NOR（P<0.05）.（3）During the commissioning period and the stable operation period,the absolute abundance of target ARGs in the influent of the A²/O-MBR treatment system varies from 1.52E+05 to 4.70E+07 copies/m L and 6.69E+06 to1.41E+08 copies/m L,respectively.The absolute abundance of ARGs in the effluent varies from 1.05E+04 to 1.47E+06 copies/m L and 9.99E+02 to3.92E+05 copies/m L,respectively.The variation range of the absolute abundance of target ARGs in the sludge of each treatment unit is 3.80E+08～7.92E+10 copies/g and 6.14E+08～6.26E+10 copies/g,respectively.The reduction of the absolute abundance of each target ARGs by the A²/O-MBR treatment system was 1.1～2.47 log and 2.26～4.55 log,respectively.（4）Spearman correlation analysis shows that for water samples,COD,NH₃-N,TP are positively correlated with ARGs and int I 1,while DO and NO₃-N are negatively correlated with ARGs and int I 1.At the same time,only NOR and OTC antibiotics are positively correlated with ARGs and int I 1.For sludge samples,OFL,CIP and OTC are positively correlated with sul1,p H,MLSS are positively correlated with tet W and int I 1,tet W is negatively correlated with AZM,and int I 1 is negatively correlated with ROX.（5）During the commissioning period and stable operation period,the microbial community structure in the A²/O-MBR treatment system is significantly affected by a variety of water quality parameters and antibiotics.Among them,p H and MLSS affect the water quality parameters with the most significant changes in the microbial community.At the same time,6antibiotics（OTC,NOR,OFL,ENR,AZM,ROX）are extremely significantly related to 21 genera.（6）Co-occurrence network analysis identified 17 genera as potential hosts for ARGs,among which 13 genera including Rhodobacter,Thermomonas,Defluviicoccus,Caldilineaceae,Kouleothrix,Nitrospira,Trichococcus and Terrimonas were identified as potential host common to sul2,tet W and tet A.Candidatus＿Competibacter and Lactobacillus were identified as potential host common to sul 2 and tet W.Tetrasphaera was identified as a potential hosts for tet W and tet A,and the potential host of sul1 is unclassified＿Patescibacteria.