Innovative Biogeochemical Cover to Mitigate Landfill Gas Emissions: Investigation of Controlling Parameters Based on Batch and Column Experiments

Abstract

Municipal solid waste (MSW) landfills generate different gases mainly methane (CH4) and carbon dioxide (CO2) during the process of waste decomposition. Modern landfills are provided with gas collection systems, however, significant amount of landfill gas (LFG) escapes into the atmosphere, making landfills one of the largest anthropogenic sources of CH4 and CO2 emissions. Several researchers have investigated various alternative landfill cover systems, such as biocovers, in order to mitigate CH4 transport across landfill covers by enhancing microbial CH4 oxidation. In recent years, biochar as an organic amendment has shown promise in enhanced microbial oxidation due to its inert/stable chemical nature, high surface area, high internal porosity, and high moisture holding capacity. However, in all these efforts, little regard is given to the CO2 that still escapes into the atmosphere in undesirable amounts. The current study introduces the concept of biogeochemical cover, which uses steel slag in conjunction with biochar-amended soil to mitigate fugitive emissions from a landfill. The current study compares the CO2 sequestration potential of steel slag, mainly basic oxygen furnace (BOF) slag under various environmental conditions that may prevail in the landfill cover. BOF slag shows significant CO2 sequestration potential under variable conditions including moisture, temperature, gas flow conditions, and BOF slag type and particle size. The results suggest that the use of BOF slag could be a cost effective and green solution to the problems of fugitive LFG emissions.