不同温度条件粪秆结构配比及尿素、纤维素酶对沼气产量的影响

    Effects of ratios of manure and straw, urea and cellulose on biogas yields at different temperatures

    • 摘要: 提高农村户用沼气的产气量和秸秆等农业废弃物利用效率,是当前循环农业领域面临的主要问题。通过利用自行设计的可控性厌氧发酵装置,在室内模拟农村户用沼气发酵过程,研究在不同温度条件下作物秸秆和禽畜粪便配比以及添加尿素和纤维酶对沼气产量的影响。结果表明,20~35℃范围内,粪秆配比的产气量随温度升高而升高。35℃条件下,2.5 kg料液发酵50 d,鸡粪和秸秆配比(干物质量比)以2︰1的产气量高于其它粪秆比例,其中鸡粪与玉米秆2︰1(干物质量比)总产气量最高,达51120 mL。在发酵中期(发酵后28 d),向2.5 kg发酵料液中添加2.5 g尿素和2.0 g纤维素酶,均显著提高沼气产量,平均增加99.8%和40.8%,且鸡粪与麦秆2︰1配比产气量增幅最大,分别为261.2%,117.3%。研究20℃粪秆厌氧发酵环境pH值动态变化,表明其呈动态变化,发酵初期pH值平均为6.8,发酵中期平均为6.4,随后缓慢回升至6.6。因此,适宜的温度,合理的秸秆配比、添加一定量酶和尿素是提高产气量的有效措施。

       

      Abstract: How to increase biogas yield and improve the utilization efficiency of crop residues and other agricultural wastes is a major problem in modern circular agricultural field. A simulation experiment using self-designed constant-temperature anaerobic fermentation equipment was conducted in indoor conditions. Effects of different ratios of chicken manure to crop residues under different temperature on the gas production were studied. The effect of adding urea and cellulose to biogas digester was also investigated. The crop residues included rice straw, wheat straw and corn straw. Results showed that the biogas production of each treatment rose with the increase of temperature in the range of 20~35℃. The highest yield was observed when the ratio of chicken manure to straw (dry matter quantity) was 2︰1 at 35℃, among which the ratio of chicken manure to corn straw at 2:1 had the maximal yield, up to 51120 mL in 50 days and the fermentation material was 2.5 kg. Both adding urea (2.5 g) and cellulose (2 g) into 2.5 kg fermentation material could significantly increase yields in the middle of fermentation, after fermentation for 28 days, the average increment was 99.8% and 40.8%, respectively. Compared with other groups, the group with the ratio of chicken manure to wheat straw at 2:1 had the highest increasing range, that is, 261.2% and 117.3%, respectively. Dynamic changes of the pH value were found at 20℃, with average pH value 6.8 at earlier fermentation stage, 6.4 at middle stage, then it slowly rose to 6.6. Therefore, suitable temperature, reasonable ratio of manure to straw as well as adding proper amount of urea and cellulose can effectively improve the biogas yield.

       

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