Q-210. The Use of Immobilized Methanotrophic Bacteria for Biodegradation of Landfill Methane Emissions

B. Adams1, F. Besnard1, L. Talmadge1, J. Bogner2, J. Oliver1, H. Hilger1;
1Univ. of North Carolina, Charlotte, NC, 2Landfills +, Inc., Wheaton, IL.

Methanotrophic bacteria oxidize methane to carbon dioxide and water, and they are abundant in landfills where they biodegrade methane passing through soil or compost covers. Although highly engineered bio-based systems exist to trap and collect methane generated after landfill closure, no such system exists for open, active landfill cells. Data suggest that significant amounts of methane can be produced soon after waste placement, and large amounts of methane may enter the atmosphere before final capping and gas collection system installation. This paper will report on investigations to assess the methane oxidation capabilities of immobilized methanotrophic bacteria in a “biotarp” that could be used to control emissions from open landfill cells. A population of methanotrophic bacteria enriched from landfill cover soil was immobilized by adsorption onto various combinations of commercial materials with varying physical properties. Batch studies were conducted under a 10% methane-in-air headspace, and gas chromatography was used to measure the relative performance of the bacteria on different material supports. The results showed that methanotrophs adsorbed to synthetic geotextile with high density and water absorbency yielded the best methane uptake rates. Methane oxidation rates by the adsorbed cells were assessed at varying temperatures, under 12-hour starvation cycles, and after agitation in water to simulate hard rainfall. A continuous flow bioreactor designed to simulate field gas flux rates was used to examine biotarp prototypes based on the results from batch experiments. Methanotroph-embedded biotarp samples tested in continuous flow landfill gas simulation chambers (methane flux was 22.5 g/m2/day) retained good methane oxidation activity when tested in batch after three weeks of incubation. Field trials of the methane oxidation capacity of immobilized methanotrophs are underway using flux chambers atop recently placed waste at a local landfill. Data will be presented on the methane biodegradation activity of the immobilized cells under batch, continuous flow, and field conditions.