Coal production and preparation generates massive quantities of coal waste, resulting in an environmental problem as well as financial liability associated with its storage and maintenance. This study was aimed at exploring a strategy to convert coal waste to methane via bio-conversion, thus converting a liability to a resource, with the added benefit of improved economics. To start with, samples of formation water were collected from a coalbed methane operation in southern Illinois. Microorganisms present in these samples were detected through use of next generation DNA sequencing. With this knowledge of the microbial population in the formation water, different amendments were tested for enhancing the methane yield. Addition of one nutrient solution resulted in methane productivity of 120 ft~3/ton in 30 days. Based on a second round of DNA sequencing results, the adapted microbial consortium was found to be dramatically different from the original community initially identified in the formation water. In particular, regarding methane producing archaea (methanogens), the overall population was down from an original 25 different species to nine. The major methanogens changed from the order of Methanobacteriales to Methanomicrobiales. To understand the pathway from coal to methane, metaproteomic proteins associated with the adapted microbial consortium were identified through state-of-the-art mass spectrometric analysis. Significant amounts of proteins produced by bacterial species were found to be involved in substrate binding and transport, cell movement, and oxidative stress. Key enzymes associated with archaea for CO_2 reduction, oxidation of formate, and utilization of acetate and methanol were also detected. Finally, the original and "amended" coal samples were tested for sorption and diffusion behavior. Results clearly demonstrated that there was a significant increase in surface area of coal as a result of bio-conversion; however, this would not translate to increased storage capacity at anticipated pressures. Second, there was significant improvement in diffusion characteristics as a result of continued bio-conversion, suggesting that the movement of gas within the coal matrix would be enhanced.
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