George A. Platt Elliott P. Barnhart Randy Hiebart Robert Hyatt Matthew W. Fields Robin Gerlach Katherine J. Davis 2019 <p><span>ubsurface coal environments, where biogenic coal-to-methane conversion occurs, are difficult to access, resulting in inherent challenges and expenses for&nbsp;</span><i>in situ</i><span>experiments. Previous batch reactor studies provided insights into specific processes, pathways, kinetics, and engineering strategies, but field-relevance is restricted due to limited substrate availability or byproduct accumulation that may influence reactions or metabolisms. In this study, continuous-flow column reactors were used to overcome some batch limitations, improve the understanding of&nbsp;</span><i>in situ</i><span>conditions, and increase field-relevance for subsurface engineering technology development. The bench-scale reactor system was constructed to investigate the addition of algal amendment for enhancing microbial coal-to-methane conversion previously developed in batch systems. Four reactor columns were packed with coal and inoculated with a microbial consortium from the same Flowers-Goodale coal bed. Two reactors were amended with&nbsp;</span>¹³<span>C-labeled algal amendment on day 0, and two were unamended. On day 61, one previously amended and one previously unamended reactor were re-amended. Produced gases were captured in a gas trap, and CH</span>₄<span>&nbsp;and CO</span>₂<span>&nbsp;were quantified. The reactor amended twice produced 1712.6 µmol CH</span>₄<span>&nbsp;(4.6% as&nbsp;</span>¹³<span>CH</span>₄<span>). The reactor amended only on day 0 produced 1485.5 µmol CH</span>₄<span>&nbsp;(2.6% as&nbsp;</span>¹³<span>CH</span>₄<span>). The reactor amended only on day 61 produced 278.9 µmol CH</span>₄<span>&nbsp;(3.9% as&nbsp;</span>¹³<span>CH</span>₄<span>). The reactor with no amendment produced no measurable gases for the duration of the 172-day experiment. Amendment increased the rate of coal-to-methane conversion and total gas production; most of the produced gases were due to coal conversion with only small contributions (&lt;7%) from amendment conversion.</span></p> application/pdf 10.1016/j.fuel.2019.115905 en Elsevier Biogenic coal-to-methane conversion can be enhanced with small additions of algal amendment in field-relevant upflow column reactors article