IDENTIFYING THE SOURCE, PATHWAYS, AND RATES OF ENHANCED MICROBIAL COALBED METHANE PRODUCTION
Previous studies have demonstrated enhanced biogenic CBM production in the laboratory by stimulation with nutrient addition. To improve the understanding of the mechanisms of CBM stimulation, different biostimulants (microalgae, cyanobacteria and yeast) were added to coal from the Powder River Basin (Montana) and non-coal containing treatments at two concentrations (0.1 g/L and 0.5 g/l). In 111 days, the unstimulated, coal-only condition produced 676 µg CH4/g coal at a maximum rate of 16.3 µg CH4/g coal/day. All biostimulated treatments demonstrated CBM enhancement relative to the unstimulated treatments in excess of the expected methane production from the stimulant itself. The lower biostimulant concentration resulted in a 2.5X increase in total methane production and 3X the maximum rate. The higher biostimulant concentration resulted in a 3.5X increase in total methane and 4X the maximum rate. All non-coal conditions produced less methane overall and had lower maximum production rates when compared to coal conditions. However, methane production in non-coal conditions were greater for yeast extracts compared to the algal or cyanobacterial biostimulants. This presentation will provide details of our efforts to delineate the exact pathways of CBM enhancement by combining isotopic labelling and microbial community analysis approaches with traditional productivity enhancement experiments.