菌群预处理对高粱秸秆乙醇-甲烷联合转化效率的影响

生物燃料的生产和利用可减少人类对化石能源的依赖。秸秆富含木质纤维素，是生产生物燃料的重要原料之一，但其结构致密、复杂，生物降解难度大，需要预处理以提高能源转化效率。本研究利用复合菌系MC1预处理高粱秸秆，分析了不同处理时间秸秆的降解特性，比较了秸秆单产甲烷发酵与乙醇-甲烷联产发酵的生物转化效率。结果表明：复合菌系MC1能有效降解高粱秸秆，预处理5 d秸秆的质量损失率达到39.64%，其水解液中可溶性化学需氧量（sCOD）及挥发性有机酸（VFAs）浓度达到最高，分别为8.10 g·L^-1和2.92 g·L^-1。预处理后秸秆单产甲烷发酵时，5 d-预处理体系的甲烷产量（以挥发性固体计）最大，达到180.68mL·g^-1，比未处理秸秆提高了60.56%。预处理后秸秆乙醇-甲烷联产发酵时，5 d-预处理体系乙醇（以挥发性固体计）和甲烷产量最高，分别为79.18 g·kg^-1和239.50 mL·g^-1，比未处理秸秆分别提高了173.78%和138.74%，且总产能达到11 947.04 kJ·kg^-1，是未处理秸秆总产能的2.45倍。高粱秸秆预处理后进行乙醇-甲烷联产比其单产甲烷总产能高出8.21%~65.06%，表明微生物菌群MC1预处理与乙醇-甲烷联合转化是提高高粱秸秆能源转化效率的有效手段。

Effects of microbial pretreatment on ethanol-methane co-conversion efficiency of sorghum straw

The production and utilization of biofuels can reduce human dependence on fossil energy. Straw is rich in lignocellulose and is an important raw material for biofuel production. However, its structure is compact and complex, and thus it is difficult to biodegrade. Therefore, pretreatment is needed to improve the energy conversion efficiency. In this study, the degradation characteristics of sorghum straw under different treatment times were analyzed by pretreating sorghum straw with MC1, and the bioenergy conversion efficiency was compared between methane fermentation only and combined fermentation of ethanol and methane. The results showed that MC1 could effectively degrade sorghum straw, and the weight loss rate of straw pretreated for 5 d reached 39.64%. The concentrations of soluble chemical oxygen demand and volatile fatty acids in the hydrolysate reached maximum levels of 8.10 g·L^-1 and 2.92 g·L^-1, respectively. When the pretreated straw produced methane only, the methane yield of the 5 d pretreatment system was the highest, reaching 180.68 mL·g^-1 VS, which was 60.56% higher than that of untreated straw. When ethanol-methane co-production and fermentation of pretreated straw was conducted, the ethanol and methane yields of the 5 d straw pretreatment system were the highest at 79.18 g·kg^-1 VS and 239.50 mL·g^-1 VS, respectively, which were 173.78% and 138.74% higher than those of untreated straw, respectively. The total energy yield was 11 947.04 kJ·kg^-1 VS, which was 2.45 times higher than that of untreated straw. The total energy yield of ethanol-methane co-fermentation of sorghum straw was approximately 8.21%~65.06% higher than that of methane fermentation only, which further indicates that MC1 pretreatment and ethanol-methane co-fermentation are effective means to improve the energy conversion efficiency of sorghum straw.