| China is one of the countries with the most abundant of straw resources in the world,which could provide sufficient raw materials for the research and development of straw biogas.However,cellulose,hemicellulose and lignin,the main components of straw,form a compact spatial structure,its biogas fermentation utilization rate was low.In this study,corn straw was used as the main raw material to explore the yellow silage quality and biogas production,single-phase and two-phase anaerobic fermentation and process optimization of yellow silage corn straw mixed with cow manure,in order to obtain the high-efficiency anaerobic biogas production scheme of yellow silage corn straw and provide theoretical basis for the large-scale production of biogas.1.During the process of corn straw yellow silage,the addition(Add by mass ratio)of microbial agents and cassava distiller's grains could improve the yellow silage quality of corn straw.After added with 0.5‰microbial agent,1‰microbial agent and 10%cassava distiller's grains respectively,the lactic acid content of corn straw silage was0.46%,0.47%and 0.28%,the acetic acid content was 0.31%,0.39%and 0.41%.After corn straw was added with 10%cassava distiller's grains,Compared with the control group,the peak gas production was 1~2 days ahead of time,and the TS methane conversion rate was 279.39 m3/t.2.Yellow silage corn straw and dry yellow corn straw were mixed with cow manure respectively for high-temperature single-phase semi-continuous anaerobic fermentation,and the gas production effect were the best when the ratio was 2:1.The effect of yellow corn straw mixed with cow manure was better than that dry yellow corn straw mixed with cow manure.The methane concentration was 57.63%,the methane production rate of TS was 270.57 m~3/t,and the volume methane production rate was0.77 L/L·d.Compared with the mixed anaerobic fermentation of dry yellow corn straw and cattle manure,it increased by 8.08%,19.28%and 18.46%,respectively,and compared with the pure yellow silage corn straw,it increased by 7.38%,3.15%and2.67%,respectively.3.The optimum conditions for single-phase anaerobic fermentation of yellow silage corn straw mixed with cattle manure were HRT20 d?OLR3.5 kg/m~3·d.Average methane concentration was 54.95%,TS methane production was 259.13 m~3/t,and volumetric methane production was 0.91 L/L·d.4.The results showed that the mixed fermentation acidification phase of yellow silage corn straw mixed with cattle manure(pH value range is 6.32~7.42,VFAs content range is 4258 mg/L~7209 mg/L)was better than that of dry corn straw mixed with cattle manure(pH value range is 6.79~7.47,VFAs content range was 2322~4838 mg/L).They had the same type of acid production,which were mainly acetic acid.5.In the anaerobic fermentation of yellow silage corn straw mixed with cattle manure for medium temperature acidification-high temperature methanogenic of two-phase semi-continuous,when the ratio of yellow silage corn straw and cattle manure was 5:1,the gas production was the best,the methane concentration was 61.95%,the methane production rate of TS was 274.84 m~3/t,and the volumetric methane production rate was 0.79 L/L·d,which was 5.86%,10.93%and 11.27%higher than that of dry corn straw mixed with cattle manure.6.The optimum conditions for the two-phase anaerobic fermentation of yellow silage corn straw mixed with cattle manure were HRT15 d,OLR4.5 kg/m~3·d,average methane concentration was 62.71%,TS methane production was 287.20 m~3/t and volumetric methane production was 1.29 L/L·d,Compared with the single-phase semi-continuous anaerobic fermentation under the optimal process conditions,the improvement was 14.12%,10.83%and 41.76%,respectively. |
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