Effects Of Oxytetracycline On Performence And Resistance Genes Of Anaerobic Digestion With Chicken Manure As Substrate

Anaerobic biotechnology treatment of chicken manure has the advantages of low energy consumption,low pollution and recoverable biomass energy?biogas?.Therefore,it is widely concerned.However,antibiotics are commonly add during modern intensive farming,lead to antibiotic residues in chicken manure,higher concentrations of antibiotics will have a certain degree of inhibition on the anaerobic fermentation process of chicken manure,eventually lead to a decline in gas production performance of anaerobic fermentation or even a system collapse.And the extensive use of antibiotics induces the production of antibiotic resistance genes?ARGs?,which pollute the environment and endanger human health.Therefore,the influence of antibiotics on the anaerobic fermentation characteristics of chicken manure has receive more and more attention.In this study,chicken manure was used as anaerobic fermentation raw material,and the comparison test was carried out by the batch test and sequencing batch test,respectively.Grasped the inhibition threshold of OTC for anaerobic fermentation of chicken manure,through analysis of gas production and physical and chemical characteristics of fermentation liquid,elucidated the effects of OTC on the transformation of chicken manure anaerobic fermentation,and combined with OTC to change the abundance of ARGs in chicken manure anaerobic digestion,further revealed the mechanism of the effect of OTC on the microbiology of chicken manure anaerobic fermentation.The research results provided a theoretical basis for the engineering application of chicken manure anaerobic fermentation.The main conclusions obtained were as follows:?1?In the batch experiment,when the concentration of OTC was 5-10 mg·L^-1,caused a certain promoting effect on anaerobic fermentation of chicken manure;when the OTC was25-300 mg·L^-1,caused a certain inhibitory effect on the cumulative methanogenesis,and as the concentration of OTC increased,the inhibition rate increased,the corresponding OTC removal rate decreased.The inhibition threshold was 24.32 mg·L^-1.The order of utilization of the methanogens for each VFAs was:acetic acid>propionic acid>isobutyric acid.?2?In the sequencing batch test,when the concentration of OTC was 2.5-25mg·L^-1,it caused a certain promoting effect on anaerobic fermentation of chicken manure;when OTC was 50-150 mg·L^-1,it caused a certain inhibitory effect on the cumulative methanogenesis,and as the concentration of OTC increased,the inhibition rate increased,the corresponding OTC removal rate decreased.The inhibition threshold was 30.83mg·L^-1,it increased by 26.77%compared to batch testing.?3?The addition of OTC significantly increased the absolute abundance of tetM,tetQ,tetW,intI1 and intI2 during anaerobic fermentation,it indicated that OTC addition improved the abundance of ARGs and MGEs,but reduced the abundance of tetC.Spearman and Network analysis showed that int I1 and int I2 were important components of ARGs horizontal transfer,and the changes of ARGs were mainly affected by pH and OTC concentration,the fermentation products need further treatmented to reduce the risks ARGs pose to the environment.?4?Different concentrations of biochar(5-50g·L^-1)can promoted the anaerobic fermentation of chicken manure.The degradation rate of TCOD,SCOD and OTC in the anaerobic fermentation system increased with the increase concentration of biochar.When the concentration of biochar was low,sludge adsorption was dominant,while biodegradation and biochar adsorption were dominant at higher concentrations.