Role of Landfill Cover Materials in Mitigating GHG Emissions in Biogeochemical Landfill Cover System

Municipal solid waste (MSW) landfills are known to be one of the major sources of greenhouse gas (GHG) emissions into the atmosphere. In order to alleviate these emissions, an innovative biogeochemical cover system is proposed to mitigate both methane (CH4) and carbon dioxide (CO2) emissions, which are the predominant gases in landfill gas (LFG) emissions. This paper investigates four materials: soil, non-activated biochar, methanotrophic activated biochar, and basic oxygen furnace (BOF) slag for their CH4 and CO2 uptake capacity. First, the physical and chemical properties of the four materials were tested. Thereafter, several series of batch tests were conducted to determine CH4 and CO2 uptake by each material. The results demonstrate that the soil has the potential to oxidize CH4 into CO2 due to presence of CH4 oxidizing (methanotrophic) bacteria, while the BOF steel slag has potential to sequester CO2. The methanotrophic activated biochar showed enhanced biological activity due to high methanotrophic population, mitigating CH4 efficiently. However, the non-activated biochar had little to no effect on the uptake of either CH4 or CO2. Finally, the combination of these cover materials at different proportions in different configurations is being investigated to optimize the biogeochemical cover system to mitigate both CH4 and CO2 emissions.