Komaei Alireza, Moazami Arman, Ghadir Pooria, Soroush Abbas, Javadi Akbar A
Department of Civil and Environmental Engineering, Amirkabir University of Technology, Tehran, Iran.
Department of Civil and Environmental Engineering, University of Strathclyde, Glasgow G1 1XJ, United Kingdom; Department of Engineering, University of Exeter, Exeter EX4 4QF, United Kingdom.
Sci Total Environ. 2025 Jun 15;981:179612. doi: 10.1016/j.scitotenv.2025.179612. Epub 2025 May 8.
Soil pollution by heavy metals has emerged as a critical environmental issue, posing significant threats to human health, food security, and environmental sustainability. Particularly in industrial and mining areas, the high levels of pollutants such as lead, chromium, and cadmium degrade soil quality and create potential risks for ecosystems. This study explores the stabilization and solidification of lead, chromium, and cadmium-contaminated clayey sand using Ca(OH) and NaCO-activated waste materials, specifically slag and natural zeolite, aimed at improving mechanical strength, reducing leachability, and enhancing environmental sustainability. Unconfined compressive strength tests revealed that soil samples treated with 20 wt% Ca(OH) and NaCO-activated slag exhibited a UCS of 4449 kPa after 28 days, a 75-fold increase over untreated soil, far exceeding the U.S. EPA's minimum requirement for landfill stabilization. X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM) analyses confirmed the formation of calcium-aluminosilicate hydrate (C(A)SH) gels and secondary products like ettringite, which contributed to the substantial strength gain. Toxicity characteristic leaching procedure (TCLP) leachability tests, showed that Ca(OH) and NaCO-activated slag achieved up to 95 %, 92 %, and 98 % reductions in lead, chromium, and cadmium leachability, respectively, all below EPA regulatory thresholds. Permeability tests demonstrated a significant decrease in hydraulic conductivity, with up to a 97 % reduction, indicating the treated soil's improved resistance to contaminant migration. Life cycle assessment (LCA) showed that the proposed Ca(OH) and NaCO-activated slag and zeolite-based system reduced CO emissions by 75 % compared to conventional Portland cement stabilization, while maintaining equivalent performance in UCS and metal immobilization.
重金属土壤污染已成为一个关键的环境问题，对人类健康、粮食安全和环境可持续性构成重大威胁。特别是在工业和矿区，铅、铬和镉等高污染物水平会降低土壤质量，并给生态系统带来潜在风险。本研究探索了使用Ca(OH)和NaCO活化的废料（即矿渣和天然沸石）对铅、铬和镉污染的黏质砂土进行稳定化和固化处理，旨在提高机械强度、降低浸出性并增强环境可持续性。无侧限抗压强度试验表明，用20 wt% Ca(OH)和NaCO活化矿渣处理的土壤样品在28天后的无侧限抗压强度为4449 kPa，比未处理的土壤提高了75倍，远远超过美国环保署对填埋场稳定化的最低要求。X射线衍射（XRD）和场发射扫描电子显微镜（FE-SEM）分析证实形成了钙铝硅酸盐水合物（C(A)SH）凝胶和钙矾石等次生产物，这有助于强度大幅提高。毒性特征浸出程序（TCLP）浸出性试验表明Ca(OH)和NaCO活化矿渣分别使铅、铬和镉的浸出性降低了95%、92%和98%，均低于美国环保署的监管阈值。渗透性试验表明水力传导率显著降低，降幅高达97%，表明处理后的土壤对污染物迁移的抗性增强。生命周期评估（LCA）表明，与传统的波特兰水泥稳定化相比，所提出的Ca(OH)和NaCO活化矿渣及沸石基体系可将二氧化碳排放量减少75%，同时在无侧限抗压强度和金属固定方面保持同等性能。
