Development of a microbial process for methane generation from bituminous coal at thermophilic conditions

• Formation water of Banaskantha coal-mines was used as a source of microbes.
• Methanogenic consortium CBM 4 was enriched from Banaskantha coal mine at 60 °C.
• Consortium CBM 4 showed methane generation from bituminous coal at 60 °C.
• Various environmental factors for biogenic CBM production were optimized.

There has been a growing interest in coal bed methane (CBM) both for energy production and reduction of greenhouse gases. CBM has been used as an alternative fossil resource and methane generation from coal reservoirs and is contributing in meeting clean energy demand. India has CBM generating potential but lacks in technology for in situ biogenic methane generation from its coal reservoirs. Therefore, to explore the possibility of enhancing biogenic methane production in coal seams particularly those present at greater depth, in this study, a thermophilic methanogenic consortium was enriched from samples collected from Banaskantha coal mines (depth of about 1200 m) of western India that had bottom-hole temperature of around 62 °C. Microbes were enriched with 1% (w/v) bituminous coal obtained from the same coal mines. Subsequently, effect of coal loading, temperature, pH and salinity were optimized for enhanced CBM generation for the selected consortium CBM 4. Maximum methane production of 22.9 mM/g of coal was observed by the thermophilic methanogenic consortium CBM 4 at temperature 60 °C, pH 7.5 and salinity 0.1% NaCl. This study suggested that the selected consortium isolated from Banaskantha coal mines is capable of utilizing high rank bituminous coal as a carbon–energy source at thermophilic condition. Thus, indicating a possibility of stimulating or augmenting this consortium in coal seams of similar temperature and to develop a microbial process for enhanced CBM generation.

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