State Key Laboratory of Geomechanics and Geotechnical Engineering, Institute of Rock and Soil Mechanics, Chinese Academy of Sciences, Wuhan, 430071, China; IRSM-CAS/HK PolyU Joint Laboratory on Solid Waste Science, Hung Hom, Kowloon, Hong Kong, China.
Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China.
Chemosphere. 2021 May;271:129868. doi: 10.1016/j.chemosphere.2021.129868. Epub 2021 Feb 6.
Arsenic (As) is a naturally occurring trace element that may pose a threat to human health and the ecosystem, while effective remediation and sustainable reuse of As-containing soil is a challenge. This study investigated the geoenvironmental characteristics of a geogenic As-rich soil, and green binders (ground granulated blast slag (GGBS) and cement blends) were employed for the stabilization/solidification (S/S) of the soil under field-relevant conditions. Results indicate that the use of 10% binder could effectively immobilize As and chemical stabilization/physical encapsulation jointly determined the leaching characteristics of the S/S soils. The geogenic As could be effectively immobilized at the pH range of 5.5-6.5. The increasing use of GGBS enhanced the strength of the 28-d cured S/S soils because of long-term pozzolanic reaction, but also slightly improved the As leachability. Besides, the moisture content of the contaminated soils should be suitably adjusted to allow for desirable compaction of S/S soils, which resulted in high compressive strength and low of As leachability. Results show that soil moisture content of 20% was the most appropriate, which resulted in the highest strength and relatively lower As leaching. In summary, this study presents a sustainable S/S binder for recycling As-contaminated soil by using a combination of cement and GGBS.
砷（As）是一种天然存在的微量元素，可能对人类健康和生态系统构成威胁，而含砷土壤的有效修复和可持续再利用是一个挑战。本研究调查了一种地质成因的富砷土壤的地球环境特征，并在现场相关条件下使用绿色胶凝材料（矿渣粉和水泥混合物）对土壤进行稳定/固化（S/S）。结果表明，使用 10%的胶凝材料可以有效地固定砷，化学稳定/物理封装共同决定了 S/S 土壤的浸出特性。在 pH 值为 5.5-6.5 的范围内，可以有效地固定地质成因的砷。随着矿渣粉用量的增加，由于长期的火山灰反应，28 天养护的 S/S 土壤的强度得到增强，但也略微提高了砷的浸出率。此外，应适当调整污染土壤的含水量，以便对 S/S 土壤进行理想的压实，从而获得较高的抗压强度和较低的砷浸出率。结果表明，土壤含水量为 20%时最为适宜，此时强度最高，砷浸出率相对较低。总之，本研究通过使用水泥和矿渣粉的组合，为回收含砷土壤提供了一种可持续的 S/S 胶凝材料。
