Optimization of parameters for methane oxidation in landfill cover compost materials

Abstract

This research evaluated the efficacy of two compost materials, yard and leaf waste compost (YLWC) and biosolids compost (BSC) at oxidizing methane (CH4) in a series of laboratory experiments. Initial batch incubation of the YLWC under a 20% CH4-in-air headspace yielded higher CH4 oxidation rates than were observed in the same YLWC tested one year prior (higher raBOD), due to less competition for oxygen with heterotrophic bacteria. Very little CH4 oxidation was observed in the BSC, with moisture content (MC), heavy metals, and methanotrophic inoculum determined to not be limiting variables. Long-term batch tests (>100 days) indicated the highest CH4 oxidation rates in 1:1 and 1:4 (YLWC:BSC) mixing ratios (360-380 µmol g(d.w.)-1 d-1). Column tests found that a 1:4 mixing ratio at a MC of 40% ww (with addition of a methanotroph-enriched compost extract) has the potential to remove a significant portion of the CH4 flowing through a landfill biocover.