The Behavior Of Antibiotic Resistance Genes In River Basin And Drinking Water Treatment

Antibiotic is one kind of the most important medical discoveries in 20_th century,used in infectious diseases control widely.However,more and more bacteria become resistant to antibiotic due to to unreasonably use or abuse of antibiotic.In the Global Risks Report,resistance to antibiotic posed threat to human.Antibiotic resistance genes(ARGs)have already been taken as emerging contaminants.The rapid human activities exacerbate spread of ARGs in surface water.But surface water is the source water of drinking water treatment plants(DWTP).We need pay attention to the effect of DWTP on ARGs controlling.Biological activated carbon(BAC)process is one kind of drinking water advanced treatments.Researches on the behavior of ARGs in BAC help protect drinking water and human health.In this study,seasonal and geographical distributions of ARGs and their host bacterial communities were characterized through the use of high-throughput quantitative PCR and 16S rRNA gene high-throughput sequencing in a peri-urban river.Combining investigation in drinking water source area,this study investigated the dynamics of ARGs and bacterial communities in BAC treatment.Based on the lab experiments’ results,this study also gave suggestions on setting technological parameters,such as kinds of activated carbon,empty bed contact times(EBCT),backwash modes.The high prevalence of ARGs downstream indicated distinct antibiotic resistance pollution in town and village,5.2-33.9 times higher than it in upstream.The pollution of ARGs was more serious in seasons with high temperature.Biomakers of ARG types and bacterial taxa were determined by visualization tools(network analysis and LEfSe).blaVEB and tetM are proposed as indicators of relevant ARGs.Correlation analysis showed bacterial communities and mobile genetic elements(MGEs)had significant correlation with ARGs and MGEs were also identified as the key-contributing factor driving ARG alteration.The promotion of ARGs was observed in BAC treatment,the number of detected ARGs and the relative abundance of beta-lactamase,fluoroquinolone-quinolone-florfenicol-chloramphenicol-amphenico(FCA),macrolide-lincosamide-streptogramin B(MLSB)more than doubled.Resistome in drinking water was influenced by biofilm on BAC based on source apportionment.29 ARGs were identified from biofilm sources,and they persisted after chlorination.Lab experiments showed,selection of activated carbon type had effect on ARGs on effluent.The ARGs pollution in coal activated carbon was less serious than it in wooden activated carbon,relevant to activated carbon pore structure.Silver loaded activated carbon can control spread of ARGs due to silver ion.The quality of effluent was also effected by EBCT while long-time running of BAC.There was break point with increase significantly of ARGs due to membrane fouling.This study suggested EBCT at 20 min and air backwash before the break point in order to protect drinking water.