Verma Gaurav, Reddy Krishna R, Green Stefan J
University of Illinois Chicago, Department of Civil, Materials, and Environmental Engineering, 842 West Taylor Street, Chicago, IL 60607, USA.
Core Laboratory Services, Rush University Medical Center, 1750 West Harrison, Chicago, IL 60612, USA.
Sci Total Environ. 2025 Apr 25;974:179192. doi: 10.1016/j.scitotenv.2025.179192. Epub 2025 Mar 26.
Fugitive emissions of methane (CH) and carbon dioxide (CO) from municipal solid waste (MSW) landfills pose significant environmental risks if not captured. To address this, researchers at the University of Illinois Chicago developed a biogeochemical cover (BGCC) comprising a biochar-amended soil (BAS) layer and a basic oxygen furnace (BOF) slag layer to simultaneously mitigate CH and CO. Previous laboratory experiments with BGCC comprising pinewood-derived biochar (PW)-amended soil and BOF slag (BGCC-PWBOF) demonstrated substantial potential for CH and CO mitigation. However, reliance on PW biochar and BOF slag may face challenges due to limited availability near landfill site location, which motivated the investigation of BGCC, which consists of different biochar and alkaline materials. Therefore, this study compared two BGCC configurations-one with rice husk biochar and cement kiln dust (BGCC-RHCKD) and another with pinewood biochar and BOF slag (BGCC-PWBOF)-against a conventional soil cover (SC) system in a laboratory column experiment. All three covers were exposed to synthetic landfill gas across four phases with varying CH influx rates. Surface emissions and gas concentrations were continuously monitored. After the experiment, the covers were dismantled, and samples from multiple depths were collected for physico-chemical characterization, microbial community analysis, and batch tests to determine CH oxidation rates and residual carbonation capacity. Results showed that under moderate CH influx rates (20.77-22.80 g CH/m-day) in Phase 1, BGCC-RHCKD and SC achieved peak CH removal efficiencies of 67.3 % and 74.2 %, respectively. The CKD layer in BGCC-RHCKD maintained 100 % CO removal across all phases without breakthrough, whereas BOF slag in BGCC-PWBOF experienced breakthrough after 16-22 days due to desiccation. The highest CH oxidation rates reached 2042.8 μg CH/g-day (BGCC-RHCKD), 455.3 μg CH/g-day (BGCC-PWBOF), and 372.1 μg CH/g-day (SC) and were strongly correlated with the relative abundance of methylotrophic bacteria, especially Methylobacter luteus, in 16S rRNA gene amplicon profiles. Overall, the BGCC-RHCKD system offers an effective solution for mitigating both CH₄ and CO₂ emissions, while the SC system is effective for CH₄ emissions.
城市固体废弃物（MSW）填埋场中甲烷（CH₄）和二氧化碳（CO₂）的逃逸排放如果不加以捕获，会带来重大的环境风险。为解决这一问题，伊利诺伊大学芝加哥分校的研究人员开发了一种生物地球化学覆盖层（BGCC），它由生物炭改良土壤（BAS）层和碱性氧气转炉（BOF）炉渣层组成，以同时减少CH₄和CO₂排放。先前对包含松木衍生生物炭（PW）改良土壤和BOF炉渣的BGCC（BGCC - PWBOF）进行的实验室实验表明，其在减少CH₄和CO₂排放方面具有巨大潜力。然而，由于填埋场附近这些材料的可用性有限，依赖PW生物炭和BOF炉渣可能面临挑战，这促使人们对由不同生物炭和碱性材料组成的BGCC进行研究。因此，本研究在实验室柱实验中，将两种BGCC配置——一种是稻壳生物炭和水泥窑灰（BGCC - RHCKD），另一种是松木生物炭和BOF炉渣（BGCC - PWBOF）——与传统土壤覆盖层（SC）系统进行了比较。所有三种覆盖层在四个阶段都暴露于合成垃圾填埋气中，CH₄流入速率各不相同。持续监测表面排放和气体浓度。实验结束后，拆除覆盖层，从多个深度采集样本进行物理化学表征、微生物群落分析以及批次测试，以确定CH₄氧化速率和残余碳酸化能力。结果表明，在第1阶段中等CH₄流入速率（20.77 - 22.80 g CH₄/m²·天）下，BGCC - RHCKD和SC的CH₄去除效率峰值分别达到67.3%和74.2%。BGCC - RHCKD中的CKD层在所有阶段都保持100%的CO₂去除率且无穿透现象，而BGCC - PWBOF中的BOF炉渣在16 - 22天后因干燥出现了穿透。最高CH₄氧化速率分别达到2042.8 μg CH₄/g·天（BGCC - RHCKD）、455.3 μg CH₄/g·天（BGCC - PWBOF）和372.1 μg CH₄/g·天（SC），并且与16S rRNA基因扩增子图谱中甲基营养细菌的相对丰度密切相关，尤其是黄色甲基杆菌。总体而言，BGCC - RHCKD系统为减少CH₄和CO₂排放提供了一种有效解决方案，而SC系统对CH₄排放有效。
