| As a large agricultural country,China has a large amount of agricultural waste and many varieties.Anaerobic dry fermentation has the advantages of water conservation,convenient management,high gas production rate and low processing cost.It can not only reduce the environmental pressure of agricultural waste,but also be an effective way to realize the utilization of agricultural waste resources.Mixed anaerobic fermentation can be Better balance nutrients,synergy between organic matter in the fermentation process,enhance biogas production and stabilize the process,thus effectively solving environmental pollution and energy shortage problems.With the deepening of the concept of environmental protection and sustainable development,the research of mixed anaerobic dry fermentation is the current hot spot and key development trend.In this paper,sheep manure,cassava residue,bagasse and rice straw were used as raw materials to carry out single factor experiments at medium temperature(37 ?).The solids ratio,carbon to nitrogen ratio and fecal material ratio were studied for anaerobic dry fermentation.influences.Based on the results of single factor experiment,the three-factor interaction effect of solid content,carbon-nitrogen ratio and mixing ratio on the anaerobic dryness under the three combinations of sheep manure and cassava residue,bagasse and rice straw was studied.The effect of fermentation gas production,and the tuse of response surface analysis,to obtain the optimal process combination.Experiment 1.Study on the effect of different solid content on anaerobic dry fermentation of four agricultural wastesThe solid content of-sheep manure has a significant effect on the biogas pro duction by anaerobic fermentation.Under the three conditions of solid content,the cumulative gas production of TS in 20%of the test group is the largest.There was no significant difference in daily gas production between the three solids ratios of cassava residue.With the increase of substrate concentration,the gas production efficiency decreased,and the solid content of the test group was 15%.The difference of daily gas production between the three solids ratios of rice straw was extremely significant.The anaerobic fermentation efficiency was the highest under the condition of 20%solid content,and the cumulative gas produc tion per unit TS was the largest.There was no significant difference in daily gas production between the three solid content rates of bagasse.The anaerobic fermentation efficiency was the highest under the condition of solid content of 15%,and the cumulative gas production per unit TS was the largestExperiment 2.Effect of carbon to nitrogen ratio on anaerobic dry fermentation of cassava residue,bagasse and rice strawThere was no significant difference in daily gas production between the three carbon-nitrogen ratios of rice straw.Compared with the unregulated test group,the cumulative gas production of the carbon-nitrogen ratio of 25 and 30 increased by 7.03%and 14.6%,respectivelyThe difference of daily carbon production between the three carbon-nitrogen ratios of cassava residue is extremely significant.The biogas production is best under the condition of carbon-nitrogen ratio of 30.The carbon-nitrogen ratio has a great influence on the anaerobic fermentation of cassava residue.Conducive to the anaerobic digestion of cassava residueThe difference in daily cumulative gas production between the three carbon-nitrogen ratios of bagasse was extremely significant.The cumulative gas production per unit of the test group with a carbon-nitrogen ratio of 25 was 160.82NmL/g,compared with 30 carbon and nitrogen.The cumulative gas production of the nitrogen-adjusted test group decreased by 5.96%and 28.01%,respectively.From the perspective of gas production rate,the carbon-nitrogen ratio is the best in the 25 test group.From the perspective of gas production stability,the gas production trend of the test group with carbon-nitrogen ratio of O 25 and 30 is relatively stable,slowly decreasing,and less fluctuating.In the selected interval of this experiment,25 is the optimum carbon to nitrogen ratio for sugarcane bagasse anaerobic fermentationExperiment 3.Experimental study on anaerobic dry fermentation of sheep manure with cassava residue,bagasse and rice strawThe mixed fermentation test of sheep manure and rice straw,under the thre e ratios,the cumulative gas production was the largest at 3:1.The difference bet ween the ratios of 1:1 and 1:0 and 0:1 was not significant.The difference betwee n the mixing ratios of 2:1 and 1:0 and 0:1 was not significant.The mixing ratios were 3:I and l1:0,0:1.The difference between the groups was significantThe mixed fermentation test of sheep manure and cassava residue showed the largest cumulative gas production at a ratio of 3:1.The difference between the cumulative gas production groups was extremely significant.The difference between the mixing ratios of 1:0 and 1:1,2:1,and 3:1 was not significant.The IImixing ratios were 0:1 and 1:1,2:1,and 3:1.The difference is extremely signific antMixed fermentation test of sheep manure and bagasse,the cumulative gas production was the largest when the ratio was 3:1.The difference of daily gas production between the mixing ratio of 1:1 and 1:0 and 0:1 was not significant The difference of daily gas production between the mixing ratios of 2:1 and 1:0 and 0:1 was not significant,and the mixing ratio was 3:1 and 1:There was a significant difference in daily gas production between 0 and 0:1 groups Experiment 4.Optimization of biogas production by anaerobic fermentation of two raw materials by response surface methodology(1)Optimization test results of response surface of sheep manure and rice strawThe effects of various factors on the cumulative gas production of mixed fermentation of sheep manure and rice straw were reduced according to the solid content ratio,mixing ratio and carbon to nitrogen ratio.The optimum analysis was obtained.When the solid content was 17.33%,the carbon to nitrogen ratio was 22.84.When the mixing ratio of the manure straw was 2.33,the cumulative gas production was the maximum value of 7937.07NmL.(2)Optimization results of response surface of sheep manure and cassava residueThe influence degree of various factors on the cumulative gas production of mixed fermentation of sheep manure and cassava residue decreased in turn according to solid content ratio,mixing ratio and carbon to nitrogen ratio.Using optimization analysis,when the solid content rate is 19.72%,the carbon-nitrogen ratio is 25.02,and the mixed ratio of sheep manure straw is 2.09,the cumulative gas production is the maximum value of 10059.3NmL.(3)Optimization results of response surface of sheep manure and bagasseThe influence degree of various factors on the cumulative gas production of mixed fermentation of sheep manure and bagasse was weakened according to the solid content,carbon to nitrogen ratio and mixing ratio.According to the optimization analysis,when the coding levels of the three factors are 0.85,-0.50,-0.03,the corresponding solid content is 19.25%,the carbon to nitrogen ratio is 22.51,and the mixed ratio of sheep manure and straw is 1.97.The cumulative gas production is the maximum 5452.61NmL. |
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