Integrated resiliency and sustainability assessment of biogeochemical cover system to mitigate landfill gas emissions

Municipal solid waste (MSW) landfills are the third-largest anthropogenic source of methane (CH₄) emissions in the United States, emitting 103.7 million metric tons of CO₂-equivalent in 2019. Despite engineered gas collection and soil cover systems, fugitive landfill gas (LFG) emissions, principally CH₄ and CO₂, remain substantial. An innovative biogeochemical cover (BGCC) system integrates a CH₄-oxidation layer (MOL) of biochar-amended soil with a CO₂-sequestration layer (CSL) incorporating alkaline industrial byproducts, namely basic oxygen furnace (BOF) slag or cement kiln dust (CKD). Laboratory column experiments evaluated two configurations: BGCC-PWBOF (pinewood-biochar -MOL with BOF-slag -CSL) and BGCC-RHCKD (rice-husk-biochar -MOL with CKD-CSL), both demonstrating mitigation of CH₄ and CO₂ emissions. Recognizing the urgency of climate mitigation, increasing climate-induced stresses, and the need for sustainable engineering, this study comparatively evaluates BGCC versus conventional soil cover (SC) systems using the tiered quantitative assessment of life-cycle sustainability and resiliency (TQUALICSR) framework. A comprehensive resilience assessment examined technical performance under representative climate shocks and quantified triple-bottom-line (TBL) implications in the event of failure; in parallel, a sustainability assessment spanned environmental, social, and economic dimensions. Results indicate that BGCC-RHCKD outperforms BGCC-PWBOF and SC in both resilience and sustainability. In addition, both BGCCs enable the beneficial use of materials such as biochar feedstocks, BOF slag, and CKD, otherwise destined for disposal, advancing waste-to-resource circularity. The findings indicate superior environmental sustainability, economic viability, and social acceptability for BGCC-RHCKD, providing a compelling case for its adoption as an alternative to conventional SC for enhanced mitigation and resource circularity across diverse operating conditions.