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

城市固体废物在填埋场的厌氧分解主要产生甲烷（CH 4）和二氧化碳（CO2）。 垃圾填埋场表面的CH 4和CO2散逸性排放物不是垃圾填埋场气体收集系统的目标，它们会散逸到大气中，对公众健康和环境造成有害影响。 替代覆盖系统，如生物覆盖物，已成为减少这些散逸性排放的低成本替代方案。 生物炭是一种高度多孔的材料，来源于生物质如废木材的气化，已被证明是一种有效的生物覆盖材料，其增强了CH 4向CO2的微生物氧化，从而减少了CH 4向大气的排放。 然而，由于即将向大气中排放CO2，LFG排放的问题仍然没有解决。 钢渣是炼钢工业的副产品，由于其高碱度，已显示出将CO2矿化为稳定的碳酸盐。 尚未探索使用钢渣减少填埋气体排放的可能性。 这个学术界与工业界联络的赠款机会（GOALI）项目概念化并旨在通过使用钢渣与生物炭结合作为垃圾填埋场覆盖材料来减少垃圾填埋场的CH 4和CO2排放，从而实现垃圾填埋场的零排放。 此外，这样的应用为废弃的钢渣细粉提供了商业出口，其目前还没有确定的有益用途。 为了实现这一总体目标，该项目的目的是描绘基本的生物地球化学，同时控制钢渣中CH 4氧化为CO2和随后的CO2碳酸化，同时优化控制钢渣吸收CO2的关键影响参数。这项跨学科的研究涉及地球环境工程，微生物学，地球化学和可持续工程，为学生提供了一个独特的机会，参与，学习和探索科学和工程的各个领域的研究。这项研究独特地试图利用生物炭和钢渣相关的生物地球化学反应，以实现垃圾填埋场的零排放。 本研究将通过实验室批量、柱控实验和现场示范相结合的方法，对钢渣及其生物炭和土壤的物理、地球化学和岩土工程性质进行研究，探讨钢渣与生物炭和土壤复合固碳的基本机理，包括吸附/碳酸化作用;（3）水分、温度、粒度和CO2负荷等各种因素对钢渣单独以及与生物炭和土壤组合的碳酸化作用的影响;（4）钢渣粉的老化/风化作用及其对生物炭和土壤中微生物活性和氧化作用的影响;（5）模拟生物炭-炉渣-土壤覆盖系统的输运扩散特性及其在气流和环境条件的瞬态和动态变化影响下的表现;（6）在现场条件下，新型变产气量覆盖系统的性能及其实用性，并进行了全尺寸现场示范。

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.