Research For Municipal Sludge Aerobic Composting Process And Microbial Community Composition

To avoid the resource waste and environmental pollution which was caused by China's current urban sludge and agricultural wastes weren't rationally used.An integrated reactor which is based on SIEMENS S7-300 PLC automatic control system was designed.To study the influence of control methods and process parameters to the test results and define mature standards.The aerobic composting test was made which using urban sludge and mushroom residue as raw materials,the high-throughput sequencing technology was used to study the succession of the microbial community,and the microbial community composition during the composting process.The correlation between the changes in the microbial community and environmental factors were revealed.Test results showed that:(1)The self-designed composting device consists of a main fermentation device and a PLC control system.The control system can realize different compost ventilation control methods through reprogramming without increasing the hardware cost.(2)Based on the time control method,the effect of ventilation rates and frequency for the composting process were studied by reprogramming.Analyzing the physicochemical and biological indicators of composting process,All the compost products were met the requirements of maturity.Analyzing results showed that the speed of the ventilation are 0.1,0.4,0.6,0.3,0.6m~3/h,the frequency is single/unit hour,and the intermittent time is 15 minutes,which got higher weight loss and less nitrogen loss during composting.(3)Based on the optimized parameters,this paper studies the effects of additional microbial agent for microbial population changes and compost products.Analyzing the physical and chemical properties of the products and process parameters.It shows that:additional microbial agent can accelerate the temperature increase,extend the high temperature zone,reduce nitrogen loss,and accelerate the maturation of composition.Which didn't change the types of dominant bacteria but changed the relative abundance of the dominant genera.(4)Based on the optimized parameters,in this paper,the high-throughput sequencing technology was used to study the microbial community.The results showed that the microbial community succession is obvious during composting.for the bacterial community,the phylum sclerenchyma was the dominant bacteria in the high-temperature stage,while the phylum Proteus and Bacteroides were dominant except the high-temperature stage;for the fungal community,the ascomycetes existed in the whole process,The abundance reached the highest after the high temperature stage,unclassified-k-fungi and Trichoderma were the dominant microflora in the high temperature stage.The redundancy analysis showed that the influence of physical,chemical and biological indexes for bacterial/fungal community were:om>oxygen content>TN>pH>water content>GI>T>ammonia>EC;om>oxygen content>water content>GI>TN>pH>EC>T>ammonia.