Abstract: Methane production through anaerobic digestion (AD) using agricultural straw is an important way to resolve the energy shortage in rural China. However, the AD technology is limited by low conversion efficiency due to recalcitrant nature of lignocellulosic structure in the straw. In the present study, the effect of sodium hydroxide (NaOH) pretreatment at three temperatures on the biogasification performance of corn straw through AD was evaluated by using a laboratory-scale, continuous anaerobic biogas digester. NaOH pretreatment was effective in biodegradation of the lignocellulosic structure of corn straw. The cellulose content of pretreated straw was decreased by 24.4% to 33.2%, the hemicellulose content decreased by 14.2% to 52.4%, and the lignin content decreased by 9.3% to 29.3%, compared with those of untreated straw. The highest methane yield, 188.7 ml CH₄·(g VS)^-1, was achieved when the corn straw was pretreated with 8% NaOH at 55℃, which was 84.2% higher than that of untreated straw. Therefore, pretreatment of 8% NaOH at 55℃ is recommended to improve biodegradability and enhance anaerobic digestibility of straw.

Key words: methane yield, anaerobic digestion, NaOH, pretreatment, corn straw

摘要： 利用农作物秸秆进行厌氧发酵生产沼气是解决我国农村能源紧张的重要途径，然而秸秆中难以降解的木质纤维结构导致在发酵过程中甲烷转化率较低。利用自行设计的可控性恒温发酵装置，以玉米秸秆为发酵原料，分析了在不同温度条件下氢氧化钠（NaOH）预处理对秸秆木质纤维结构以及厌氧发酵产气效率的影响。结果表明，NaOH预处理能够显著降低玉米秸秆的木质纤维素含量，与未预处理的秸秆相比，经NaOH处理后的秸秆纤维素含量降低了24.4%～33.2%，半纤维素含量降低了14.2%～52.4%，木质素含量降低了9.3%～29.3%。在6%、8%和10%浓度中，经8%NaOH处理的秸秆在55℃下的甲烷产量最高，达到188.7 ml CH₄·（g VS）^-1，较未处理的增加了84.2%，因此可作为提高秸秆厌氧发酵产气效率的预处理方法。

关键词: 甲烷产量, 厌氧发酵, NaOH, 预处理, 玉米秸秆