Analysis Of Gas Production Performance And Nutrient Changes Of Biogas Slurry From Co-digestion Of Pretreated Corn Straw And Cow Dun

With the CPC Central Committee and the State Council vigorously promoting the construction of rural biogas,anaerobic fermentation technology has become an important part of the fuel engineering,providing strong support for rural environmental improvement and sustainable development.However,in the anaerobic digestion project,there are problems such as low methane yield of straw fermentation alone and easy acidification stop.Therefore,in this paper,cow dung and corn straw are used as anaerobic fermentation raw materials to solve the problem of low gas production rate of straw and easy acidification:Frozen corn stalks were pretreated.The hemicellulose,cellulose and lignin of frozen corn stalks under different temperatures and different time conditions were measured by the normal form washing method,and the concentrations of total nitrogen,ammonia nitrogen and total phosphorus in the water soluble substances produced during the freezing process were measured.The results showed that freezing pretreatment could not reduce the lignin content of corn straw,but freezing could increase the cellulose and hemicellulose content of corn straw.The test group with the best effect of improving the cellulose content was treated at-20 ℃ for 48 hours,with an increase rate of 10.13% and 41.08% compared with the control.The best effect of improving the hemicellulose content was-35 ℃ for 24 hours,with an increase rate of 51.22% and a hemicellulose content of 30.14%.Frozen pretreatment is effective for increasing the concentration of total nitrogen,ammonia nitrogen and COD in the dissolved matter,but has no effect on increasing the concentration of total phosphorus.The best treatment condition of freezing pretreatment effect is 56.4h at-5 ℃.At this time,the fitting value of COD concentration value is 6669.0mg/L,with a 95% prediction interval(6556.96781.0).The fitting value of total nitrogen concentration is 296.86mg/L,with a 95% prediction interval(275.9317.8).The fitting value of ammonia nitrogen concentration is 110.0mg/L,with a 95% prediction interval(104.3115.6).The pretreated corn straw and cow dung were used as fermentation raw materials.The methane yield of cow dung: corn stalk VS mass ratio of 7:3,8:2 and 9:1 was 59.90,51.60 and47.14 m L/g VS,respectively.There is little difference in methane yield between different ratios.The order of methane yield is 7:3>8:2>9:1.There is no acidification phenomenon during the test.The pretreatment of corn straw and cow dung fermentation test showed that the pretreatment did not improve the gas production performance of corn straw.The methane yield of corn stalk was decreased by freezing treatment and alkali treatment.The methane yield of co-digestion of corn straw and cow dung with alkali pretreatment or freezing pretreatment was lower than that of the untreated dung stalk ratio test group,and the methane yield was lower than that of the single cow dung fermentation group.