GOALI: Innovative Biochar-Slag-Soil Cover System for Zero Emissions at Landfills

University Of Illinois At Chicago, Chicago IL

Investigators

Abstract

Anaerobic decomposition of municipal solid waste in landfills predominantly produces methane (CH4) and carbon dioxide (CO2). Fugitive CH4 and CO2 emissions from landfill surfaces that are not targeted by landfill gas (LFG) collection systems escape into the atmosphere and cause detrimental impacts on public health and the environment. Alternate cover systems such as biocovers have emerged as a low-cost alternative to mitigate these fugitive emissions. Biochar, a highly porous material derived from gasification of biomass such as waste wood, has shown to be an effective biocover material that enhances microbial oxidation of CH4 to CO2 thereby mitigating the CH4 emissions to atmosphere. However, the problem of LFG emissions still remains unsolved due to the impending emissions of CO2 into the atmosphere. Steel slag, a byproduct from steel making industries, because of its high alkalinity has shown to mineralize CO2 to stable carbonates. The potential use of steel slag to mitigate LFG emissions has not been explored. This Grant Opportunities for Academic Liaison with Industry (GOALI) project conceptualizes and aims to achieve zero emissions from landfills by using steel slag in combination with biochar as a landfill cover material to mitigate the CH4 and CO2 emissions at landfills. Moreover, such application provides a commercial outlet for discarded steel slag fines, which have no established beneficial use currently. In order to achieve this overarching goal, the project aims to delineate the fundamental biogeochemistry that governs the simultaneous oxidation of CH4 to CO2 and subsequent carbonation of CO2 in steel slag while optimizing the key influencing parameters that control the CO2 uptake by steel slag. This interdisciplinary research involving geoenvironmental engineering, microbiology, geochemistry and sustainable engineering provides a unique opportunity for students to participate, learn and explore research in various domains of science and engineering. This study uniquely attempts to harness biogeochemical reactions associated with biochar and steel slag to achieve zero emissions from landfills. An integrated research program, consisting of controlled laboratory batch and column experiments and field demonstration, will be conducted to specifically investigate: (1) physical, geochemical and geotechnical properties of steel slag and it's amendment with biochar and soil; (2) the fundamental mechanisms including adsorption/carbonation that govern CO2 sequestration by steel slag in combination with biochar and soil; (3) the effect of various factors including moisture, temperature, particle size, and CO2 loading that control the carbonation by steel slag individually and in combination with biochar and soil; (4) ageing/weathering effects on steel slag fines and its impact on microbial activity and oxidation in biochar and soil; (5) the transport and diffusion properties of a simulated biochar-slag-soil cover system and it's performance under the influence of transient and dynamic changes in gas flow and environmental conditions; and (6) the performance of the new cover system with variable gas production under field conditions and it's practical applicability with a full-scale field demonstration.