Development of Biochar-Amended Landfill Cover for Landfill Gas Mitigation.

摘要

Under anaerobic biodegradation, landfilled municipal solid waste generates landfill gas, which mainly consists of CH4 and CO2. Mitigation of landfill gas is essential for both pollution prevention and global warming control. In general, landfill cover soils can partially remove CH4 with the oxidation activities of methanotrophic bacteria. However, optimal cover soil composition is still needed to enhance the methanotrophic activities for substantial reduction in CH4 emissions. Chemical and physical characteristics and geotechnical properties of soil, biochar, and biochar-amended soil were determined. Both column and batch experiments were conducted using soil alone and soil amended with biochar to quantify the effects of biochar amendment on degradation of CH4 by methanotrophic bacteria. The effect of methane adsorption to biochar and biochar-amended soil was also studied, which provided favorable conditions for methanotrophic oxidation to improve degradation of methane within the cover. The amendment of biochar to landfill cover soil improved the physical and chemical characteristics. The results demonstrated that amendment of biochar to cover soil can greatly improve the CH4 oxidation capability of landfill cover soil system. Biochar facilitates the oxidation process by enlarging the oxidation layer of landfill covers and provides more microbial culture density which will result in higher oxidation efficiency. Overall, this study demonstrated that the biochar-amended soil cover may be best suited for small and/or old, abandoned landfills where a gas collection system is not required and the gas-to-energy systems are not applicable.