The Experimental Research On Anaerobic Fermentation Characteristics Of Mixed Livestock Manure

With the development of large-scale stockbreeding industry, the environment of the breeding area has been polluted seriously by large number of animal waste. Anaerobic fermentation technology can treat manure, which could not only achieve biomass energy——methane but also apply the residuals as fertilizer. Thus the environmental pollution can be solved and utilization of manure as energy can be met. To improve the methane production efficiency and solve the problem of low efficiency for single kind of manure in fermentation, it's necessary to investigate the combinations by the mixed manures during anaerobic fermentation process.In this experiment, chicken manure pig, manure and cattle manure are used for the material. The temperature is controlled at 35℃, and the concentration is TS=8%.Two aspects have been investigated in the experiment. The first is the comparison between chicken manure pig, manure and cattle manure based on sequence batch experiment. The cycle of the experiment is 21 days and the purpose is establishing groundwork for the consecutive mixed experiment. The second is the consecutive mixed anaerobic fermentation experiment which is completed by mixing chicken manure and pig manure separately with cattle manure, and the cycle of the experiment is 96 days. Because the gas productivity of cattle manure in the cattle manure anaerobic fermentation is lower, the higher and ultimate gas productivity is investigated by mixing chicken manure and pig manure separately with cattle manure according to the difference of C/N of chicken manure, pig manure and cattle manure. The following results are achieved from the experiment.Firstly, In the process of anaerobic fermentation, the difference of fermentation material has no significant influence on pH. By mixing chicken manure with cattle manure, pH is influenced significantly by the change of percentage content of chicken manure in the total solid of mixture solution. By mixing pig manure with cattle manure, pH is influenced indistinctively by the change of percentage content of chicken manure in the total solid of mixture solution.Secondly, it indicates that different fermentation materials have little influence on the total quantity of volatilization acid and the content of the component in the volatilization acid.By mixing chicken manure with cattle manure, VFA and the main component of VFA is influenced significant by the change of percentage content of chicken manure in the total solid of mixture solution. By mixing pig manure with cattle manure, VFA and the main component of VFA is influenced indistinctively by the change of percentage content of chicken manure in the total solid of mixture solution.Thirdly, When the reaction conducts at 21st day, the maximum of COD(Chemical Oxygen Demand) removal rate from the three group of material are 46.9%,50.8% and 39.8% and the daily mean COD removal rate is insufficiency 2.5%.In the process of consecutive mixed anaerobic fermentation experiment, the daily mean COD removal rate is 5%~7%.By comparing consecutive experiment with sequencing batch experiment, we found that the COD removal rate of the former one is relatively superior.Fourth, In the process of 21 days experiment, the average volume gas productivities of chicken manure, pig manure and cattle manure are 1.26 L/(L·d),1.01 L/(L·d) and 0.93 L/(L·d) during the anaerobic fermentation process, the maximal volume gas productivities are 1.78 L/(L·d),1.46 L/(L·d)and 1.35 L/(L·d),the maximum of percentage of methane are 83.5%,76.5% and 72.5%. Chicken manure mixed with cattle manure , the volume gas productivity in the first group of experiment reaches 2.23 L/(L·d)when the ratio of chicken manure in total solid is 50%,and the methane gas productivity reaches 1.89 L/(L·d),the methane percentage content reaches 85.3% when the ratio is 30%. Pig manure mixed with cattle manure, the volume gas productivity reaches 1.99 L/(L·d) when the ratio of cattle manure in total solid is 70%,and the methane gas productivity reaches 1.55 L/(L·d),the methane percentage content reaches 83.4% when ratio is 40%.It is proved from the above multi-factorial analysis that volume gas productivity of single manure can be improved by hybrid manure anaerobic fermentation, and the efficiency of continuous anaerobic fermentation is better than the sequencing batch anaerobic fermentation.