| In recent years,because of antibiotics has strengthen bio-resistance to them,induced the formation of resistance bacteria and Antibiotic resistance Genes(ARGs),causing environmental ARGs pollution and harming the human health.In this experiment,municipal sludge was selected as the research object.By setting three different external ambient temperatures(30℃,50℃ and 55℃),adding super thermophilic bacteria agent,super thermophilic bacteria agent and mixed compost of biochar in different proportions,the changes of physicochemical properties,microbial diversity and ARGs abundance of the reactor were studied.The relationship between the physicochemical properties of the reactor,microbial diversity and the abundance of ARGs was analyzed to reveal the reduction mechanism of ARGs in the sludge by different composting methods.Mainly draw the following research conclusions:(1)Appropriate increase of external ambient temperature can increase the temperature of the compost and accelerate the compost ripening process.The compost ripening speed and degree under external ambient temperature of 50℃ and 55℃ are significantly higher than30℃.The degree and rate of composting with superthermophilic bacteria were both higher than those of ordinary compost.The compost temperature reached the highest value on the second day,the GI value of the compost on the 24 th day reached 57.89%,and the GI value of the compost on the 50 th day reached 73.5%.Biochar can increase the heap temperature in the high temperature period.The ultra-high temperature compost group(HT),the biochar proportion 2% compost group(HT2)and the biochar proportion 5% compost group(HT5)all began to reach the maturity on the 24 th day,and the GI value reached the highest on the 50 th day.The amount of biochar added is proportional to the GI value and maturity of the compost.(2)The relative abundance of bacterial community can be reduced by increasing the ambient temperature,adding superthermophilic bacteria,superthermophilic bacteria and a certain proportion of biochar.In the early stage of composting,the bacterial community composition of the three composting methods was the same,and the majority of them were Proteobacteria,Bacteroidetes,Firmicutes,Actinobacteria and Chlorococci.At the end of composting,the microbial community composition of different composting methods was different.The dominant bacteria phyla of composting at 50℃ and 55℃ were Actinobacteria,while the dominant bacteria phyla of composting at 30℃ were Proteobacteria,Bacteroidetes,Chlorocurbacteria and Actinobacteria.Proteobacteria and Actinobacteria were the dominant phyla of ultra-high temperature compost,the dominant species of common composting bacteria are Bacteroides,Proteobacteria,Chloroflexus and Actinomycetes,and the dominant species of HT,HT2 and HT5 composting are Proteobacteria and Actinomycetes.Firmicutes were the dominant bacteria in Qingdao Engineering Composting(GCCT)at high temperature,and Bacteroidetes was the dominant bacteria at the end of composting.(3)At the end of composting,the absolute content of ARGs and MGEs of different composting treatment methods decreased.The total removal rates of ARGs and Inti1 in 50℃and 55℃ composting were 66%～83% and over 92%,respectively.The total removal rate of ARGs and Inti1 reached 86.3% and 95.7%,which were much higher than that of ordinary compost at ultra-high temperature.The total removal rate of ARGs and Inti1 by HT5 was95.9% and 99.5%,which were much higher than that of HT,HT2 and GCCT.Different composting conditions mainly affect the activity and abundance of microorganisms by increasing the temperature of the composting reactor,which in turn affects the abundance of ARGs and MGEs in the composting reactor.Therefore,the combination of appropriately increasing the external temperature,adding super thermophilic bacteria,super thermophilic bacteria and certain proportion of biochar can quickly reduce the ARGs and MGES in the sludge,which provides a theoretical basis for the engineering composting,and has a certain feasibility. |
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