| The purpose of this paper is to study the effect of biological pretreatment on the biogas production potential of anaerobic fermentation using raw materials which content high lignocellulose.There are three pretreatment methods used in this study,which are pretreated with biogas slurry,pretreated with mixed microbe composed of Phanerochaete chrysosporium and Trametes hirsuta and pretreated with combined method.What the paper studied were the effects of pretreatment on the change of lignocellulose content and gas production.The main goal is to increase biogas production and methane content reduction time,ultimately improve the efficiency produce biogas with corn stalks.The conclusions are as follow.(1)Carrying out the method of response surface analysis to optimize the process for producing biogas by pretreatment of corn stalk with biogas slurry.Taking the actual situation into account,the processing is the biogas slurry addition was 19.08%TS,temperature was(30 ± 1)? and time was 5 d.The degradation rate of lignocellulose was 11.95%,the biogas production value was increased by more than 30.76% and the peak methane content increased by 24.95%compared with the group donot pretreatment,and the T80(time to 80% biogas production)was shortened by 27.27%.(2)Optimizing the ratio of the composite fungus strains by single factor,it was found that the proportion of the added strains was significantly higher than that of the other groups in the group of Trametes hirsuta : Phanerochaete chrysosporium= 3:1.Through the response surface Box-Behnken design,the optimal pretreatment process at this ratio was 6% of bacterial liquid,the temperature was 28.5 ?,and the pretreatment time was 11 days.The degradation rate of lignocellulose reached 16.73%,which increased the gas production by 51.73% and the peak methane content increased by 22.48% compared with the control group without pretreatment.T80(time taken to 80% biogas production)was shortened by 31.81%.(3)In the jointed pretreatment,three different pretreatment methods were used.They were first using the biogas slurry and then using the composite microbial agent,first using the composite microbial agent and then using the biogas slurry,and adding the composite microbial agent to the biogas slurry.It was found that when the composite microbial agent was added to the biogas slurry at a ratio of 6% by volume,the degradation rate of lignocellulose was thehighest,reaching 15.38%,and the biogas production could be increased by 40.41%.The peak methane content can be increased by 31.37% compared with the untreated group.When pretreatment time was 6 days,T80 reduced 9 days.(4)Comparing the changes of the flora before and after the pretreatment of the biogas slurry,it was found that the relative abundance of the strict anaerobic species in the archaea decreased significantly,and the frequency of Methanothrix decreased by 30.51%.The relative abundance of fungi changed significantly,and the relative abundance of species degradable lignocellulose increased significantly.The relative abundance of Cladosporium in the mixed group was21.35%.The relative abundance of Alternaria is 10.91%.The relative abundance of species in the bacteria against protein degradation varies greatly.In summary,the corn stalk is pretreated with the biogas slurry and the composite microbial agent,and the lignocellulose can be effectively degraded,and the gas production and the methane content in the produced biogas can be increased.There is also a reduction in the lag time during anaerobic fermentation.The combination of the biogas slurry and the composite microbial agent in the combined pretreatment group was the best.The microbial abundance of Cladosporium and Alternaria degradable proteins in the biogas slurry during pretreatment is improved. |
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