Influences of different substrates on simulated lignite biogas production

Using lignite samples, selected from Zhaotong basin, Yunnan province, China, as the parent source, simulating experiments of lignite biogas were conducted with 0.1% methanol, 5 mg/L yeast extract and 0.2 mol/L sodium acetate solutions as the exogenous substance respectively. Variation characteristics of gas production, gas composition, VFA content and activity of coenzyme F420 in the simulated process were analyzed to discuss the influence of different substrates on lignite biogas generation. The results show that 0.1% methanol and 5 mg/L yeast extract solutions increase VFA contents in the biogas generation system (p < 0.05) and inhibit coenzyme F420 and methanogen activities significantly, so they decrease both gas amounts (p < 0.05) and CH4 contents (p < 0.05). 0.2 mol/L sodium acetate solution activates coenzyme F420 and methanogen activities and improves the efficiency of enzymatic reaction, so the gas quantity (p < 0.05) and the CH4 content (p < 0.01) increase significantly. Therefore, sodium acetate can be one kind of good exogenous substance for the generation of lignite biogenic gas.