Study On Substance Transformation And Microbial Population Structure In Chicken Manure/Sawdust Forced Ventilation Compost

The forced aeration composting technique and time-temperature control system were used for the composting of chicken manure. In the research of high temperature compost experiment, its major materials are chicken manure and sawdust, and it studies impaction of initial C/N ratio and ventilation on compost maturity and stability. In the experiment, physical, chemical and biologic index have been studied to use into estimate compost maturity and stability. The following results have been obtained:In studying of the impaction of initial C/N ratio to compost maturity and stability, there are three piles and their initial C/N ratio are 12, 18, and 28 respectively. The results showed that the temperature of pile No.3, with an initial C/N ratio 28, increased fast, and the days its temperature above 50℃and 55℃were 10d and 6d respectively, the E.Coli in pile 3 is reduced greatly and reached 10² at last, which had been up to the national standard. The Generation Index(GI) in pile 3 was 93.3%, which indicate the compost is completely mature. Contemporary, pile 1 and pile 2 which has a low initial C/N ratio, their E.Coli were reached 10⁴ at last, which could not accord with the national standard. Finally, the GI of pile 1 and pile 2 were 58.9% and 74.1% respectively, which indicate the compost is not completely mature.In studying of the impaction of ventilation on compost maturity and stability, three piles were set, which has a ventilation of 2m³/h, 3m³/h and 4m³/h respectively. In results, the temperature of pile 2 with a ventilation of 3m³/h, increased fast, and the days its temperature above 50℃and 55℃were 11d and 8d respectively, the E.Coli in pile 2 is reduced greatly and reached 10² at last, which had been up to the national standard. The GI in pile 2 was 91.8%, which indicate the compost is completely mature. while pile 3 with a ventilation of 4m³/h, its temperature above 50℃is only 1d and its E.Coli was 10⁴ at last, which could not accord with the national standard. The GI of pile 3 was 74% in the end, which indicate the compost was not mature completely.NH₄⁺-N,NO₃^--N,GI and the humic Index can applied to maturity evaluation of compost productions well. The compost which is mature, the process of NH₄⁺-N transform into NO₃—N is obvious. GI of the compost should higher than 80%; Stable and high molecular weight humic acid accounts for larger proportion in compost productions, and unstable fulvic acid accounts for less proportion.The activation of microbial enzyme and the change of oxygen consumption rate can reflect the stability of compost better. In a more stable compost, the activation of microbial enzyme and the oxygen consumption rate keep lower, which indicate the property of compost material is stable.In studying of the impaction of initial C/N ratio on compost maturity and stability, PCR-DGGE was used to analyse the structure of the microbial communities. The result showed that the successional of microbial communities of the compost is strong during the composting process. In different stage of the composting process, the dominate microbial communities differs. In the initial stages and the high temperature stage, the quantity of microbe is less. And when the temperature declined, the quantity of microbe became more and more, this result accord with the results by conventional culture. Through the analyse of comparability of the samples, we can find pile 3 with a more exquisite composting process, the comparability between its first sample and final sample is 41%,which is obviously lower than pile 1 and pile 2.pile 1 and pile 2 has a comparability 63% and 52% respectively. This indicate the successional of microbial communities in pile 3 is stronger.