Study On Forced Aerated Composting Of Digested Sewage Sludge And Maize Straw

In this research, the forced aeration composting technique was used for composting of digested sludge and maize straw, and analyzed the changing rules of physical, chemical and biological indicators, at the conditions of differrnt initial C/N ration, ventilation and low ambient temperature, and analyzed the succession changes of the microbial population structure.In the studying of the index of physical chemistry and biological properties during forced aeration composting of digested sludge and maize straw under different initial C/N ratios, there were three piles and the initial C/N ratios were 25, 20and 14 respectively. The results showed that the temperature of all piles increased successfully, and kept for 12d, 16d and 5d above 55℃respectively, which had been up to the national standard. During the composting process, total organic carbon, C/N ratio and moisture content obviously declined, but he content of NO₃^--N, cation exchange capacity increased. pH, NH₄⁺-N, electrical conductivity originally increased and then declined. The seed germination index was 97%, 96% and 69% on day 40, respectively. Fourier transform infrared spectroscopy showed a reduction in aliphatic components, and a relative increase in aromatic components. In the research, PCR-DGGE and gene sequencing technology were used to analyse the diversity of microbial population and the succession changes of the microbial population structure during the composting processes under different initial C/N ratios. With the changes of the composting temperature, the structure of microbial population changed at the same time, and the dominant population also had big difference. But Clostridium sp.9B4,Clostridium sp.6-44 and Bacillales bacterium P371 existed during the three different composting processes. Microbial diversity was better in the NO.1 composting pile (C/N ratio was 25) and the NO.2 composting pile (C/N ratio was 20) than the NO.3 composting pile (C/N ratio was 14).In the studying of the index of physical chemistry and biological properties during forced aeration composting of digested sludge and maize straw under different ventilation, which haved three ventilation of 50L/min, 100L/min and 150L/min, and the initial C/N ratios were all 20. The result showed that the temperature of the three piles could increase successfully, and kept for 12d, 14d and 10d above 55℃respectively. During the composting process, total organic carbon, C/N ratio and moisture content obviously declined, but he content of NO₃^--N, cation exchange capacity increased. pH, NH4₊^-N, electrical conductivity originally increased and then declined. The seed germination index was 91%, 96% and 82% on day 35, respectively. Fourier transform infrared spectroscopy showed a reduction in aliphatic components, and a relative increase in aromatic components. In the research, PCR-DGGE and gene sequencing technology were used to analyse the diversity of microbial population and the succession changes of the microbial population structure during the composting processes under different ventilation. With the changes of the composting temperature, the structure of microbial population changed at the same time, and the dominant population also had big difference. But Anaerobaculum mobile,Bacillus sp.SG1,Ureibacillus thermosphaericus and Sedimentibacter sp.B4 existed during the three different composting processes. Microbial diversity was better in the NO.1 composting pile (the ventilation was 50L/min) and the NO.2 composting pile (the ventilation was 100L/min) than the NO.3 composting pile (the ventilation was 150L/min).The study on index of physical chemistry and biological properties during forced aeration composting of digested sludge and maize straw under low ambient temperature was based on the first parts about forced aeration composting of digested sludge and maize straw C/N ratio and ventilation optimzed, and the initial C/N ratio was 20, ventilation was 100L/min. The temperature of the pile could increase successfully, and the middle temperature above 55℃kept for 9d. During the composting process, total organic carbon, C/N ratio and moisture content obviously declined, but he content of NO3--N, cation exchange capacity, heavy metals, humus, humic acid, fulvic acid and HI increased. pH, NH₄⁺-N, electrical conductivity, cellulose, urease and protease activity originally increased and then declined. The seed germination index was 84% on day 35. In the research, PCR-DGGE and gene sequencing technology were used to analyse the diversity of microbial population and the succession changes of the microbial population structure under low ambient temperature. With the changes of the composting temperature, the structure of microbial population changed at the same time, and the dominant population also had big difference. Proteiniphilum acetatigenes, Clostridium ultunense, and other 5 microbial strains existed during the whole composting process, and Clostridium aurantibutyricum was eliminated with the temperature increasing. Kineococcus xinjiangensis, Laceyella putida and other 3 microbial strains appear as new microbial strains during the composting process.