Study On The Stabilization Process And Microbial Diversity Of Anaerobic And Semi-aerobic Bioreactor Landfill Waste

Sanitary landfill is the main treatment method of municipal solid waste in my country.The bioreactor landfill has obvious advantages in operating cost,stabilization rate,improvement of landfill leachate water quality,and landfill gas recycling.The bioreactor landfill mainly relies on the role of microorganisms in the landfill system,but different landfill methods,landfill time and environmental conditions will affect the number and composition of the microbial community inside the reactor.Therefore,in this paper,an anaerobic bioreactor landfill(ANBL)and a semi-aerobic bioreactor landfill(SABL)were built on a laboratory scale.First,by analyzing the changes in the physical characteristics of landfill waste,the water quality characteristics of the leachate,and the law of landfill gas emissions,to investigate the anaerobic and semi-aerobic bioreactor landfills stabilization law differences;secondly,through long-term monitoring of the microbial diversity of the reactor,reveal the number of microorganisms and the change and evolution of community composition in the stabilization process of anaerobic and semi-aerobic bioreactor landfills,explore the relationship between changes in microbial diversity and the law of garbage stabilization;finally,through long-term monitoring of the denitrification function microorganisms in the reactor,to study the number of denitrification function microorganisms,community composition changes and dominant bacteria in the stabilization process of anaerobic and semi-aerobic bioreactor landfills,and to explore the relationship between changes in nitrogen pollutants in the leachate and denitrification microorganisms.the result shows:(1)By the end of 240 days of landfill,the removal rates of COD in the leachate produced by ANBL and SABL were 54.09% and 67.46%,respectively,the removal rates of TOC were 34.29% and 56.40%,the removal rates of TN were 40.72% and 63.85%,and ammonia nitrogen was removed.The rates are 32.45% and 55.30% respectively.SABL have better degree of garbage degradation,concentration of organic matter in the leachate and nitrogenous pollutants.It shows that the degradation rate of SABL garbage is better than that of ANBL,and SABL can greatly shorten the time of garbage stabilization and realize the rapid stabilization of garbage degradation.(2)In the early stage of landfill,the internal microbial community structure of ANBL and SABL is similar.The dominant bacteria phyla are Proteobacteria,Bacteroides,Firmicutes and Actinobacteria,of which Actinobacteria accounted for the largest proportion;as the garbage stabilizes During the process,the composition of the microbial community in ANBL and SABL has changed significantly.The dominant flora of ANBL has changed from Actinobacteria to Gammaproteobacteria,while the dominant flora in SABL is still Actinobacteria,indicating that the SABL landfill has higher operational stability and waste biodegradation better.The changes of ANBL and SABL microbial communities are mainly affected by the environmental temperature and the p H value of the leachate.Among them,Gammaproteobacteria has the strongest adaptability to environmental impacts.It can still grow and reproduce well under low temperature,low oxygen and high concentrations of pollutants.Play the most important role in the landfill process.The changes of ANBL and SABL microbial communities are significantly related to the changes in the organic concentration of the leachate.In the early stage of landfill,ANBL has a higher abundance of microorganisms with aromatic metabolism,and the internal ecological environment of ANBL is more conducive to the removal of humus in the leachate;The abundance of microorganisms with carbon pollutant conversion function in SABL is higher,and SABL is more conducive to the removal of carbon pollutants from landfills.(3)The nitrogen removal ability of SABL is obviously better than that of ANBL.As the landfill progressed,the number of denitrification microorganisms in SABL and ANBL showed a gradual downward trend.The dominant species of denitrification microorganisms are Nitrosomonas,Nitrosopumilus and Azoarcus.In the process of landfill waste degradation,the main transformation pathways of nitrogen pollutants in the bioreactor are full nitrification and denitrification,short nitrification and denitrification and Anammox,Among them,SABL internal microenvironment is more conducive to nitrification and denitrification process,ANBL internal ecological environment is more conducive to Anammox process,SABL nitrogen removal function microbial abundance is higher,SABL is more conducive to the removal of nitrogen pollutants in landfills.