Methane Oxidation Biosystem In Landfill Fugitive Emissions Using Conventional Cover Soil And Compost As Alternative Substrate – A Field Study

Abstract

Landfill is an important anthropogenic source of greenhouse gases (GHG). Aiming at methane mitigation through the use of a cover layer in the form of fugitive emissions, this study investigated the methane passive bioxidation in a Brazilian landfill in biofilters under two conditions: control column (packing material using a 60 cm landfill cover soil with ≅0.8% organic matter) and enriched column (packing material using 45 cm landfill cover soil and 15 cm mixture of cover soil plus compost with ≅6% organic matter). The biogas was collected from a vertical drain pipe of a four-year-old cell and injected into the base of the columns with a high inlet loading (1000 g CH4 .m - ².d - ¹ at standard temperature and pressure conditions) in the upward flow mode. Ten campaigns were carried out for six months in order to determine the efficiency of the methane oxidation in each column. Parameters related to the biogas oxidation were also determined, such as soil temperature and moisture content and nutrients content in both filter beds. The oxidation global efficiencies were higher in the enriched column throughout all campaigns, with »71 and »95% for the control and enriched columns, respectively. Our study demonstrated that the use of substrates with high organic matter content and low cost (such as the compost) in landfill cover layers might present high efficacy in the reduction of methane fugitive emissions. Landfill is an important anthropogenic source of greenhouse gases (GHG). Aiming at methane mitigation through the use of a cover layer in the form of fugitive emissions, this study investigated the methane passive bio-oxidation in a Brazilian landfill in biofilters under two conditions: control column (packing material using only landfill cover soil with ≅0.8% organic matter) and enriched column (packing material using 45 cm landfill cover soil and 15 cm mixture of cover soil plus compost with ≅6% organic matter). Biogas was collected from a vertical drain pipe of a four-year-old cell and injected into the base of the columns with a high inlet loading (1000 gCH4.m-².d-¹) in upward flow mode. Ten campaigns were carried out for six months in order to determine the efficiency of the methane oxidation in each column. Soil temperature, moisture and nutrients content in both filter beds were also determined. The oxidation global efficiencies were higher in the enriched column throughout all campaigns, with »71 and »95% for the control and enriched columns, respectively, demonstrating that this technology can be applied even in landfills where there is no energy recovery from biogas (as in most landfills in developing countries). Our study demonstrated that the use of substrates with high organic matter content and low cost in landfill cover layers might present high efficacy in the reduction of methane fugitive emissions. Even operating in field-scale conditions, the results of this study were comparable to those obtained with biofilters on lab-scale (under controlled operational conditions).