Angai Joanne U, Ptacek Carol J, Pakostova Eva, Bain Jeff G, Verbuyst Brent R, Blowes David W
Department of Earth and Environmental Sciences, Faculty of Science, University of Waterloo, Waterloo, Ontario, Canada.
Department of Earth and Environmental Sciences, Faculty of Science, University of Waterloo, Waterloo, Ontario, Canada.
J Hazard Mater. 2022 Feb 15;424(Pt A):127295. doi: 10.1016/j.jhazmat.2021.127295. Epub 2021 Sep 20.
Acid mine drainage and the associated contaminants, including As and metals, are ongoing environmental issues. Passive remediation technologies have the potential to remove As from mine waste effluents. A series of laboratory column experiments was conducted to evaluate the effectiveness of varying mixtures of organic carbon (OC), zero-valent iron (ZVI), and limestone for the treatment of As, metals, SO, and acidity in groundwater from an abandoned gold mine. The onset of bacterially-mediated SO reduction was indicated by a decrease in Eh, a decline in aqueous SO concentrations coupled with enrichment of δS, and the presence of sulfate-reducing bacteria and HS. Removal of As was observed within the first 3 cm of reactive material, to values below 10 µg L, representing > 99.9% removal. An increase in pH from 3.5 to circumneutral values and removal of metals including Al, Cu, and Zn was also observed. Synchrotron results suggest As was removed through precipitation of As-crystalline phases such as realgar and orpiment, or through adsorption as As(V) on ferrihydrite. The results indicate the potential for a mixture of OC and ZVI to remove As from acidic, mine-impacted water.
酸性矿山排水及相关污染物，包括砷和金属，是持续存在的环境问题。被动修复技术有潜力从矿山废水排放物中去除砷。进行了一系列实验室柱实验，以评估有机碳（OC）、零价铁（ZVI）和石灰石的不同混合物对处理废弃金矿地下水中的砷、金属、硫酸根和酸度的有效性。细菌介导的硫酸根还原的开始表现为氧化还原电位（Eh）降低、水溶态硫酸根浓度下降以及δS富集，同时存在硫酸盐还原菌和硫化氢。在反应性材料的前3厘米内观察到砷的去除，去除后的值低于10微克/升，去除率大于99.9%。还观察到pH从3.5升高到接近中性的值，以及包括铝、铜和锌在内的金属的去除。同步加速器结果表明，砷是通过雄黄和雌黄等砷结晶相的沉淀，或通过以五价砷（As(V)）形式吸附在水铁矿上而被去除的。结果表明，有机碳和零价铁的混合物有潜力从受矿山影响的酸性水中去除砷。
