汽爆秸秆高温固态发酵沼气的研究

Study on biogas production by thermophilic solid-state fermentation from steam exploded corn stalk

沼气液态深层发酵及秸秆的物理、化学和生物预处理方式存在效率低、污染重等问题。为了解决这些问题,对蒸汽爆破预处理方式以及固态发酵在玉米秸秆沼气化中的应用进行了研究。秸秆经过蒸汽爆破预处理后,在50℃的高温条件下进行固态发酵沼气,甲烷产量达到138.2 mL/g TS。通过单因素实验优化,确定最佳发酵条件为:固液比1∶7,初始pH值7.5,接种量35%,NH4HCO3添加量0.04 g/g干汽爆秸秆,纤维素酶用量30 IU/g干汽爆秸秆,发酵温度50℃。在上述实验条件下,汽爆秸秆的甲烷产量提高至153.0 mL/g TS,是未汽爆秸秆的2.9倍。发酵后秸秆纤维素和半纤维素的降解率分别为59.86%和67.22%。因此,蒸汽爆破预处理有助于提高秸秆的产气量和降解率。高温固态发酵不仅可以缩短发酵延迟期,提高产气效率,而且发酵结束后不会产生大量废液,对环境友好。

Biogas production by submerged culture and the physical, chemical, biological pretreatment of stalk have encountered with some key problems, such as low efficiency and serious pollution. Based on it, steam explosion pretreatment method and solid-state fermentation have been researched in biogas production from corn stalk. After steam explosion pretreatment, methane yield from corn stalk reached 138.2 mL/g TS, at thermophilie condition of 50 ℃ , by solid-state fermentation. With the single factor experimental optimization, the optimal conditions obtained were as follows ： 1 ： 7 of solid-liquid ratio, 7.5 of initial pH, 35% of inoculum size,0.04 g of NH4HCO3 addition per gram dry steam exploded corn stalk, 30 IU of cellulase addition per gram dry steam ex- ploded corn stalk and 50℃ of fermentation temperature. Under the above controlled experimental conditions, the methane yield of steam exploded corn stalk was high up to 153.0 mL/g TS, which was 2.9 times of that with no steam explosion pretreatmcnt. The degradation rate of cellulose and hemieellulose after fermentation was 59.86% and 67.22% , respectively. Therefore, steam explosion pretreatment help improve the biogas production of corn stalk effectively with high degradation rate. Thermophilic solid-state fermentation could shorten the lag phase, enhance the biogas production efficiency. Meantime, the fermentation process produces less wastewater, which is friendly to the environment.