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

垃圾填埋场中城市固体废物的厌氧分解主要产生甲烷(CH4)和二氧化碳(CO2)。来自垃圾填埋场表面的逃逸CH4和二氧化碳排放不是垃圾填埋气(LFG)收集系统的目标，它们逃逸到大气中，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，已经成为减少这些逃逸排放的低成本替代方案。生物炭是一种由废弃木材等生物质气化而成的高度多孔的材料，已被证明是一种有效的生物覆盖材料，可以促进微生物将甲烷氧化为二氧化碳，从而减少向大气排放甲烷。然而，由于二氧化碳即将排放到大气中，垃圾填埋气的排放问题仍然没有得到解决。钢渣是炼钢工业的副产品，由于其高碱度，已显示出能将二氧化碳矿化成稳定的碳酸盐。钢渣用于减少垃圾焚烧气体排放的潜在用途尚未得到探索。GOALI学术联系机会(GOALI)项目概念化并旨在通过使用钢渣和生物炭作为垃圾填埋场覆盖材料来减少垃圾填埋场的CH4和二氧化碳排放，从而实现垃圾填埋场的零排放。此外，这种应用为目前还没有确定的有益用途的废弃钢渣微粉提供了一个商业出路。为了实现这一总体目标，该项目旨在描述控制钢渣中CH4同时氧化为二氧化碳和随后的二氧化碳碳化的基本生物地球化学，同时优化控制钢渣吸收二氧化碳的关键影响参数。这项涉及地质环境工程、微生物学、地球化学和可持续工程的跨学科研究为学生提供了一个参与、学习和探索各个科学和工程领域的研究的独特机会。这项研究独特地尝试利用与生物炭和钢渣相关的生物地球化学反应来实现垃圾填埋场的零排放。综合研究计划将通过实验室控制的批实验、柱实验和现场演示，具体研究：(1)钢渣的物理、地球化学和岩土性质及其与生物炭和土壤的改性；(2)钢渣与生物炭和土壤结合固定二氧化碳的基本机理；(3)水分、温度、粒度和CO2负荷量等各种因素对钢渣单独和与生物炭和土壤联合碳化的影响；(4)钢渣微粉的老化/风化效应及其对生物炭和土壤中微生物活性和氧化的影响；(5)模拟生物炭-矿渣-土壤覆盖系统的迁移和扩散特性及其在气流和环境条件瞬变和动态变化影响下的性能；(6)新型可变产气量覆盖系统在野外条件下的性能及其实际适用性。

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.