不同时间NaOH预处理对玉米秸秆中温厌氧发酵的影响

摘要

Effects of different pretreatment time of NaOH on anaerobic fermentation of corn straw with 0 ‰, 4 ‰ and 12 ‰ NaOH respectively pretreated for 3 d, 7 d, 14 d, 21 d and 28 d were studied using the "system of anaerobic fermentation technology"designed by us at mesophilic temperatures (35 ℃), and aims to provide a theoretical basis for high efficient application of corn straw in biogas production. The results showed that NaOH pretreatment could improve biogas yields and the rate of biogas production under anaerobic fermentation of corn straw at mesophilic temperatures, and the treatment of 4‰ NaOH was the most effective and better than that of 0‰ and 12‰, the optimum pretreatment time of 4‰ NaOH was 7 d and stopped biogas production at 111 days using 16.0 g corn straw as anaerobic fermentation materials, the total biogas yields was 7411.00 mL, the cumulative biogas yields reached more than 90% of the total biogas yields as standard of fermentation complete, and it need 78 d to complete the fermentation, the cumulative biogas yields was 6672.60 mL, the average daily biogas yields was 85.55 mL·d-1, and the cumulative biogas yields of dry matter was 417.04 mL·g-1. The prediction model of optimal combination also showed that the treatment of 4‰ NaOH was the most effective, and the optimum pretreatment time was 9.48 d after 84.00 d completed fermentation, the rate of biogas production was 60.29 mL, the maximum cumulative biogas yields of dry matter was 316.52 mL·g-1, the result were in agreement with measured results. In conclusion, It was feasible by properly extend pretreatment corn straw time to reduce the dosage of alkali under mesophilic anaerobic fermentation, and the effect of 4‰ NaOH pretreatment corn straw for 9.48 d was the best.%通过自行设计的厌氧发酵装置,采用0‰、4‰和12‰的NaOH溶液对玉米秸秆预处理3、7、14、21 d和28 d,研究不同时间NaOH预处理对玉米秸秆中温(35℃)厌氧发酵的影响,旨为玉米秸秆在沼气生产中的高效应用提供理论依据.结果表明,采用NaOH预处理可以提高玉米秸秆中温厌氧发酵时的产气量和产气速率,其中4‰NaOH预处理的效果好于0‰和12‰,而且以预处理7 d的效果最好.以16.0 g玉米秸秆为发酵原料时,111 d产气停止,总产气量为7411.00 mL,若以累积产气量达到总产气量的90%以上作为发酵完成标准,则78 d发酵完成,可累积产气6672.60 mL,日均产气85.55 mL,干物质累积产气量为417.04 mL·g-1.最优组合预测模型同样显示,4‰NaOH预处理效果最好,最佳预处理时间为9.48 d,84.00 d发酵完全,产气速率为60.29 mL·d-1,最大干物质累积产气量为316.52 mL·g-1,这与实测值具有良好的一致性.综合判断,在玉米秸秆中温厌氧发酵时,通过适当延长预处理时间来减少碱液用量是可行的,其中以4‰NaOH预处理9.48 d效果最好.