| Antibiotic residue belongs to hazardous waste,which not only contains a lot of nitrogen-containing organic matter,but also contains a lot of residual antibiotics.If it is not handled properly,it will bring a great threat to the ecological environment and people’s health,especially the residual antibiotics will induce the microbial production of antibiotic resistance genes（ARGs）in the environment.In order to realize the harmless treatment and resource utilization of antibiotic residue,and explore effective removal methods of ARGs in the environment,this study adopted anaerobic digestion technology to treat oxytetracycline residue.On the basis of optimizing the process,using biochar as exogenous fortifying agent,the enhancement effect of biochar on anaerobic digestion of oxytetracycline residue was explored,and the removal of residual oxytetracycline residue and the mechanism and mechanism of ARGs change were analyzed.The main conclusions are as follows:1)According to the study on the effect of anaerobic digestion under five different solid contents（4%,8%,12%,16%and 20%）,When the solid content is greater than 8%,the concentrations of ammonia nitrogen and volatile fatty acid（VFAs）in the system are more than 2000 mg·L-1 and 4000 mg·L-1,respectively,which have obvious inhibition effect on the system,and the removal efficiency of organic matter in the gas production efficiency is reduced to below 80%.Therefore,when TS is 4%,the reaction effect of oxytetracycline residue anaerobic digestion system is the best.2)Based on the optimal solid content,the strengthening effects of different types of biochar on anaerobic digestion were explored.The results showed that the addition of biochar and nano-Fe modified biochar could reduce the concentration of ammonia nitrogen,relieve ammonia stress,promote the transformation and consumption of VFAs,and improve the stability of the system.The gas production efficiency of the system can be increased by 20.74%and 15.49%to more than 115.20 m L·g-1,respectively.The removal efficiency of organic matter in the control group was increased from 91.08%to94.32%and 96.57%,respectively.In addition,biochar also had a certain strengthening effect on the removal of residual oxytetracycin.Compared with the control group,the removal efficiency was increased by 2.37%and 4.82%,respectively,and the final system residual oxytetracycin content could be reduced to less than 10 mg·L-1.3)The changes of ARGs in the reaction system were analyzed to explore the enhancement effect of biochar on ARGs removal.The results showed that the addition of biochar and nano zero-valent iron modified biochar could promote the decrease of aad A,ant（2"）-I,qac Edelta1 and sul1 abundance.Moreover,the strengthening effect of nano-Fe zero-valent biochar was greater than that of biochar,and the removal efficiency of aad A,ant（2"）-I and qac Edelta1 was increased by 33.54%,9.06%and 24.21%,respectively.In this study,the technological conditions of anaerobic digestion of oxytetracycline residue were optimized,and the changes of residual oxytetracycline and ARGs in the anaerobic digestion system of oxytetracycline residue were analyzed,and their mechanism was further analyzed.The research results provide a new idea for the removal of ARGs,and provide theoretical reference and technical support for the harmless treatment and resource utilization of antibiotic bacterial residue. |
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