实验室条件下褐煤生物气生成的化学影响因素

Chemical factors influencing lignite biogenic gas production in laboratory condition

在实验室条件下,分别添加0.2 mol/L乙酸钠、0.2 mol/L甲酸和5 mg/L酵母浸出液作为外源碳源,研究煤层本源菌作用下褐煤生物气生成潜力和生成过程中的化学影响因素。结果表明,软褐煤和硬褐煤中有机物质都能作为独立碳源生成生物气,软褐煤生成速率(0.18 m L/(g·d))大于硬褐煤(0.13 m L/(g·d)),其组分均主要由CH4和CO2组成。有机碳源的加入对褐煤生物气生成速率和气体组分影响各异。0.2 mol/L乙酸钠可以提前甲烷的初始生成时间,同时提高生成速率,显著增加CH4含量,但总体不会影响煤样本身产生的甲烷量;0.2 mol/L甲酸不仅可以激活产甲烷菌活性,而且可以有效增加褐煤生物气产量和CH4含量,且成熟度低的软褐煤增加的效果更明显;5 mg/L酵母浸出液对产甲烷菌有抑制作用。氯仿沥青A含量高可能是导致软褐煤生物气产率高的主要原因;DOC对褐煤生物气生成影响不大。研究认为煤基质中底物可利用性和外源有机碳源类型是影响地下煤层中甲烷生成的重要因素。

Lignite samples were investigated for their ability to support microbial methane production with parent bacteria in laboratory incubations,with 0. 2 mol / L sodium acetate,0. 2 mol / L formic acid and 5 mg / L yeast extract as exogenous organic carbon sources respectively. Results show that the organic matter in both soft and hard lignite samples could be used as independent carbon sources to produce biogas. Production rate of soft lignite（ 0. 18 m L /（ g·d）） is higher than that of hard lignite（ 0. 13 m L /（ g·d））. The simulated biogases are composited by CH4 and CO2. The influence characteristics of exogenous carbon sources on the biogas production rates and gas compositions are different.Sodium acetate（ 0. 2 mol / L） could lead to an earlier generating time of lignite and a increasing production rate,but could not change the production of lignite biogas. Formic acid（ 0. 2 mol / L） could not only activate methanogen activities,but also increase the lignite biogas production and CH4 concentration,which effect is more significant for soft lignite. Yeast extract（ 5 mg / L） inhibites the activities of methanogen in the incubation. The high concentration of chloroform bitumen might be the dominate reason for the high production rate of soft lignite. DOC could not affect the biogasproduction significantly. The results indicate that the substrate availability within the coal and different types of exogenous organic carbon sources are two factors that may influence the lignite biogas production.