在美国,城市固体废物(MSW)垃圾填埋场是甲烷(CH4)排放的重要来源。导致全球变暖。当前的垃圾填埋气(LFG)管理方法,比如垃圾填埋场系统和LFG收集系统,不要完全阻止LFG释放。生物覆盖物具有通过微生物氧化减少CH4排放的潜力。然而,LFG还含有二氧化碳(CO2)和痕量硫化氢(H2S),具体取决于废物成分,温度,水分含量,废物的年龄。开发了一种创新的生物地球化学覆盖物(BGCC)来解决这些问题。该覆盖物包括覆盖有碱性氧气炉(BOF)钢渣层的基于生物炭的生物覆盖层。基于生物炭的生物覆盖层氧化CH4排放,而BOF炉渣层通过碳酸化和硫化反应机理减少CO2和H2S。BGCC系统的现场性能仍未检查。因此,开发了模拟近场条件的大型储罐设置,以评估BGCC系统同时减轻LFG中CH4,CO2和H2S的能力。合成LFG在五个不同阶段通过BGCC,每个设计用于模拟不同的气体成分和典型的垃圾填埋场的通量率。在每个阶段监测沿深度的气体剖面,并测量了气体去除效率。测试后,提取生物覆盖物和BOF炉渣样品进行理化性质分析。还对从生物覆盖层和BOF炉渣层提取的样品进行了批量测试,以确定潜在的CH4氧化速率和残留的CO2封存能力。结果表明,BGCC系统的CH4去除效率随CH4通量的增加而降低,在中等流入量(23.9-25.5gCH4/m2-天)下达到最高去除率(74.7-79.7%),并在最高流入量(57.5gCH4/m2-天)下降低至最低去除率(27.4%)。在BGCC系统的生物覆盖层中的阶段3期间发生了完全的H2S去除。CH4氧化率在上部附近最高(277.9µgCH4/g-天),在生物覆盖层的较深区域最低。在坦克实验中,由于BOF炉渣层干燥,156天后发生CO2穿透,水分调节后,平均剩余碳酸能力为46gCO2/kg炉渣。总的来说,BGCC系统有效地减轻了LFG排放,包括CH4、CO2和H2S,在中等通量率下,显示作为LFG管理的全面解决方案的承诺。
Municipal solid waste (MSW) landfills are a significant source of methane (CH4) emissions in the United States, contributing to global warming. Current landfill gas (LFG) management methods, like the landfill cover system and LFG collection system, do not entirely prevent LFG release. Biocovers have the potential to reduce CH4 emissions through microbial oxidation. However, LFG also contains carbon dioxide (CO2) and trace hydrogen sulfide (H2S) depending on waste composition, temperature, moisture content, and age of waste. An innovative biogeochemical cover (BGCC) was developed to tackle these concerns. This cover comprises a biochar-based biocover layer overlaid with a basic oxygen furnace (BOF) steel slag layer. The biochar-based biocover layer oxidizes CH4 emissions, while the BOF slag layer reduces CO2 and H2S through carbonation and sulfidation reaction mechanisms. The BGCC system\'s field performance remains unexamined. Therefore, a large-scale tank setup simulating near-field conditions was developed to evaluate the BGCC system\'s ability to mitigate CH4, CO2, and H2S from LFG simultaneously. Synthetic LFG was passed through the BGCC in five distinct phases, each designed to simulate the varying gas compositions and flux rates typical of MSW landfill. Gas profiles along the depth were monitored during each phase, and gas removal efficiency was measured. After testing, biocover and BOF slag samples were extracted to analyze physico-chemical properties. Batch tests were also conducted on samples extracted from the biocover and BOF slag layers to determine potential CH4 oxidation rates and residual CO2 sequestration capacity. The results showed that the BGCC system\'s CH4 removal efficiency decreased with higher CH4 flux rates, achieving its highest removal (74.7-79.7%) at moderate influx rates (23.9-25.5 g CH4/m2-day) and reducing to its lowest removal (27.4%) at the highest influx rate (57.5 g CH4/m2-day). Complete H2S removal occurred during Phase 3 in the biocover layer of BGCC system. CH4 oxidation rates were highest near the upper (277.9 µg CH4/g-day) and lowest in the deeper region of the biocover layer. In the tank experiment, CO2 breakthrough occurred after 156 days due to drying of the BOF slag layer, with an average residual carbonation capacity of 46 gCO2/kg slag after moisture adjustment. Overall, the BGCC system effectively mitigated LFG emissions, including CH4, CO2, and H2S, at moderate flux rates, showing promise as a comprehensive solution for LFG management.