Performance of Biocover in Mitigating Fugitive Methane Emissions from Municipal Solid Waste Landfills in Cold Climates

Manipulation of landfill covers to maximize oxidation capacity provides a promising complementary strategy for the control of methane emissions from landfills. Engineered biocovers (i.e., a mixture of soil and organic matter) can be used for gas emission control in landfills. One of the key factors affecting methane oxidation and methane removal by engineered biocovers in general is the temperature in the biocover material, which is in turn influenced by the ambient temperature. This study compares the efficacy of methane removal in a biocover consisting of a mature compost and soil mixture at different temperatures using three column tests. Methane removal efficiencies and temporal variation of methane mass flux were determined based on measured methane content at different locations within the biocover material profiles. In all cases, methane content at the top was considerably lower than that of the inflow. However, the efficiency of the column at 22°C was significantly higher than that of the one placed at 11°C. Based on scanning electron microscopy images taken from the upper section of the columns, evident formation of stacks of materials and reduction of pore spaces in all cases were observed and were interpreted qualitatively as a consequence of biological activity leading to formation of bacterial colonies, biofilm, or carbonate precipitate over biocover material particles.