Among many anthropogenic sources of greenhouse gases (GHG), landfill emissions, consisting of methane (CH_4) and carbon dioxide (CO_2), are one of the major contributors of anthropogenic GHG. In recent years, various innovative landfill biocovers have been investigated and developed to mitigate the emissions of methane (CH4) from municipal solid waste (MSW) landfills. However, the problem of CO_2 emissions [which constitute about 40% of landfill gas (LFG)] from MSW landfills still remains unresolved. An innovative cover system which consists of basic oxygen furnace (BOF) slag with biochar amended soil is being developed to mitigate CH_4 and CO_2 emissions from landfills. The biochar amended soil is effective in mitigating CH_4 emissions by microbial methane oxidation, while BOF slag could be effective in sequestering CO_2 emissions by carbonation mechanisms. However, the properties of BOF slag vary based on several factors such as mineralogical composition of slag, particle size, moisture content, and temperature. In this study, CO_2 sequestration potential of BOF slag was evaluated under synthetic LFG condition. The performance of the BOF slag in sequestering CO_2 under different moisture condition was also examined. The results showed that BOF slag can sequester substantial amount of CO_2 under LFG condition. The study also enlightened the importance of moisture for initiating carbonation reaction; however, the moisture alone was not the controlling parameter for CO_2 sequestration. The mineralogy of the BOF slag plays an important role in determining CO_2 sequestration capacity of the slag.
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