Effects of Biochar-Amendment to Landfill Cover Soil on Microbial Methane Oxidation: Initial Results

Abstract

Biochar amendments to landfill covers have been proposed as an economic solution to reduce methane emissions from landfills without gas recovery systems, or in conjunction with gas recovery for near-complete methane removal in new landfills. In this study, column experiments are used to simulate the effects of biochar amendments to landfill cover soils for methane mitigation. Acrylic columns were packed with coarse gravel and filled with either soil or 20% biochar/80% soil. Measurements of CH4, CO2, and temperature along the depth of the column allowed the determination of gas profiles and oxidation efficiencies over the course of the experiment. DNA-based assays and isotopic measurements (δ13 CH4 and δ13 CO2 [£]) were used to infer the extent of microbial oxidation and to evaluate the distribution of methanotrophs within each column. qPCR targeting the pmoA (particulate methane monoxygenase) gene indicate a higher number of methanotrophs exist in the biochar-amended column, supporting the observed higher rates of methane oxidation. Batch incubation experiments were conducted to determine Michaelis-Menten kinetic parameters for methane oxidation. Initial results indicate that biochar is effective in increasing methanotrophic activity and promoting methane oxidation.