Life cycle assessment of novel biogeochemical cover versus conventional soil cover

Abstract

The aim of this study is to evaluate the functional performance and environmental impacts of recently proposed biogeochemical cover (BGCC) system at a municipal solid waste landfill and compare with the conventional soil cover (SC) system. The functional performance of the cover systems was assessed through infiltration, methane emissions and slope stability analyses. In addition, life cycle assessment (LCA) was performed to evaluate the environmental impacts of the cover systems. The study also assessed the effect of various factors such as biochar manufacturing process, mode of transportation (fossil fuel powered vehicles versus electric powered vehicles), and transportation distance for raw materials supply on the environmental impacts. The results showed that the BGCC can significantly reduce the greenhouse gas emissions and global warming in comparison to the SC due to the use of biochar amended soil and basic oxygen furnace (BOF) slag. BGCC had 69 times more reduction in global warming impacts than SC which was attributed to the high methane oxidation potential of the biochar amended soil and carbon dioxide sequestration capacity of BOF slag. Moreover, BGCC had lesser environmental impacts than SC, mainly in the categories of eutrophication, carcinogens, non-carcinogens, respiratory effects, and ecotoxicity. Reducing transportation distance for biochar supply led to further reduction of the environmental impacts associated with the BGCC. For example, reducing the biochar procurement distance from 300 km to 100 km reduced the impacts from smog, acidification, eutrophication, and fossil fuel depletion by 14%, 13%, 5% and 14%, respectively. In addition, switching the vehicle from diesel powered to electric powered for transportation of raw materials led to significant reduction in fossil fuel depletion, smog, acidification and ecotoxicity in both BGCC and SC. For example, the fossil fuel depletion reduced by 97% and 39% in BGCC and SC, respectively by switching the fuel source. In addition, BGCC had overall positive impact on the human health and ecosystem whereas SC showed potential damage to human health. Overall, BGCC system proves to be an environmentally sustainable alternative to landfill cover system with significant potential for mitigation of greenhouse gases and odor from MSW landfills.