College of Safety and Emergency Management and Engineering, Taiyuan University of Technology, Taiyuan, 030024, China.
Key Laboratory of In-Situ Property-Improving Mining of Ministry of Education, Taiyuan University of Technology, Taiyuan, 030024, China.
Environ Sci Pollut Res Int. 2023 Jul;30(34):82834-82850. doi: 10.1007/s11356-023-27945-8. Epub 2023 Jun 19.
Biomethane generation by coal degradation not only can increase coalbed methane (CBM) reserves, namely, microbially enhanced coalbed methane (MECBM), but also has a significant effect on the pore structure of coal which is the key factor in CBM extraction. The transformation and migration of organics in coal are essential to pore development under the action of microorganisms. Here, the biodegradation of bituminous coal and lignite to produce methane and the cultivation with inhibition of methanogenic activity by 2-bromoethanesulfonate (BES) were performed to analyze the effect of biodegradation on coal pore development by determining the changes of the pore structure and the organics in culture solution and coal. The results showed that the maximum methane productions from bituminous coal and lignite were 117.69 μmol/g and 166.55 μmol/g, respectively. Biodegradation mainly affected the development of micropore whose specific surface area (SSA) and pore volume (PV) decreased while the fractal dimension increased. After biodegradation, various organics were generated which were partly released into culture solution while a large number of them remained in residual coal. The content of newly generated heterocyclic organics and oxygen-containing aromatics in bituminous coal was 11.21% and 20.21%. And the content of heterocyclic organics in bituminous coal was negatively correlated with SSA and PV but positively correlated with the fractal dimension which suggested that the retention of organics contributed greatly to the decrease of pore development. But the retention effect on pore structure was relatively poor in lignite. Besides, microorganisms were observed around fissures in both coal samples after biodegradation which would not be conducive to the porosity of coal on the micron scale. These results revealed that the effect of biodegradation on pore development of coal was governed by the combined action of organics degradation to produce methane and organics retention in coal whose contributions were antagonistic and determined by coal rank and pore aperture. The better development of MECBM needs to enhance organics biodegradation and reduce organics retention in coal.
煤降解产生生物甲烷不仅可以增加煤层气（CBM）储量，即微生物增强煤层气（MECBM），而且对煤层的孔隙结构有显著影响，而孔隙结构是 CBM 开采的关键因素。在微生物的作用下，煤中有机物的转化和迁移对孔隙的发育至关重要。在这里，通过 2-溴乙磺酸盐（BES）抑制产甲烷活性的方式，对烟煤和褐煤进行生物降解以产生甲烷，并进行培养，以通过测定孔隙结构和培养液和煤中有机物的变化来分析生物降解对煤孔隙发育的影响。结果表明，烟煤和褐煤的最大甲烷产量分别为 117.69 μmol/g 和 166.55 μmol/g。生物降解主要影响微孔的发育，其比表面积（SSA）和孔体积（PV）减小，分形维数增加。生物降解后，生成了各种有机物，部分释放到培养液中，而大量有机物残留在残余煤中。烟煤中新生成的杂环有机物和含氧芳烃的含量分别为 11.21%和 20.21%。并且烟煤中杂环有机物的含量与 SSA 和 PV 呈负相关，与分形维数呈正相关，这表明有机物的保留对孔隙发育的减少有很大贡献。但是褐煤对孔隙结构的保留效果相对较差。此外，生物降解后在两个煤样的裂隙周围观察到微生物，这不利于煤的微米级孔隙度。这些结果表明，生物降解对煤孔隙发育的影响是由产甲烷和煤中有机物保留这两种作用的共同作用决定的，这两种作用的贡献是拮抗的，取决于煤阶和孔径。更好地发展 MECBM 需要增强有机物的生物降解和减少煤中有机物的保留。
