嗜热菌群介导下微生物电解池对煤生物甲烷化的促进机制

Mechanism of microbial electrolysis cell in enhancing coal bioconversion to methane by thermophilic bacteria

  • 摘要: 研究深部高温环境下煤厌氧发酵产甲烷是扩大煤层气生物工程应用范畴的重要环节,而如何提升高温煤厌氧发酵效果和二氧化碳减排的潜力是该环节的关键。微生物电解池被证实在强化有机物厌氧降解方面潜力巨大。55 ℃为嗜热型产甲烷菌的最适温度,在此温度下微生物电解池对煤厌氧发酵产甲烷的影响尚不明确。为此以中国平顶山地区的贫瘦煤为底物,在55 ℃下构建常规厌氧发酵系统(AD)和微生物电解池厌氧发酵系统(MEC-AD),通过对生物气产量、关键液相产物变化、无机离子变化、溶解性有机质以及微生物群落结构等的测试和分析,系统探讨了微生物电解池在高温环境中对煤厌氧发酵的强化机制。结果表明:MEC-AD系统延长了煤厌氧发酵的周期,同时显著提高了生物甲烷的产量,相较于AD系统提高了45.3%。MEC与AD的耦合显著提高了水解、产酸菌群中TepidanaerobacterAcetomicrobiumClostridium_sensu_stricto_1的相对丰度,增强了其活性,从而提高了对煤的降解能力,为后续的厌氧发酵积蓄了更充足的营养物质。从代谢功能方面来看,MEC-AD通过促进糖酵解过程、丙酸和丁酸的氧化来提高煤厌氧发酵系统的水解和产酸能力。另外,MEC-AD系统氢营养型产甲烷的效率的提高是通过提高催化乙酸氧化的速率来实现的。这一认识为煤层气生物工程在深部应用效果的提升及潜力的发挥提供了理论依据,推动了深部煤层气产业化进程。

     

    Abstract: Investigating the anaerobic methane production of coal in deep coal seams under high-temperature conditions is a crucial aspect of broadening the application scope of Coalbed Gas Bioengineering. The critical factor in enhancing the efficiency of high-temperature coal anaerobic digestion and the potential for carbon dioxide emission reduction is found within this process. Microbial electrolysis cell has demonstrated significant potential in optimizing the anaerobic degradation of organic matter. 55 °C is the optimal temperature for thermophilic methanogens. However, the influence of microbial electrolysis cell on coal anaerobic digestion for methane production at this temperature remains unclear. To achieve this objective, the present study utilizes meager lean coal sourced from the Pingdingshan region of China as substrates. A conventional anaerobic digestion system (AD) and a microbial electrolysis cell-anaerobic digestion system (MEC-AD) are both implemented at a temperature of 55 ℃. The enhancement mechanism of microbial electrolysis cell for coal anaerobic digestion was systematically investigated through the testing and analysis of biogas yield, variations in key liquid phase products, changes in inorganic ions, dissolved organic matter, and microbial community structure under high-temperature conditions. The results indicated that the MEC-AD system extended the duration of coal anaerobic digestion while significantly improving biogas production, achieving an increase of 45.3% compared to the AD system. The relative abundance and activity of hydrolytic and acidogenic bacterial communities were enhanced by the integration of MEC with AD, particularly Tepidanaerobacter, Acetomicrobium, and Clostridium_sensu_stricto_1. Consequently, the coal degradation capacity was enhanced and the accumulation of nutrients for subsequent anaerobic digestion was facilitated. From the metabolic function perspective, the hydrolytic and acidogenic capacities of coal anaerobic digestion system were enhanced by MEC-AD through facilitating the glycolysis process and the oxidation of propionate and butyrate. Furthermore, the enhancement of hydrogenotrophic methane production efficiency in the MEC-AD system was achieved through an increased rate of acetic acid oxidation catalysis. This understanding provides a theoretical framework for enhancing the effectiveness and potential of Coalbed Gas Bioengineering in deep coal seams, thereby advancing the industrialization process of deep coalbed methane.

     

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