Chemical Engineering Department, Research Institute for Chemical and Environmental Technologies (ITQUIMA), University of Castilla La Mancha UCLM, 13071 Ciudad Real, Spain.
Chemical Engineering Department, Research Institute for Chemical and Environmental Technologies (ITQUIMA), University of Castilla La Mancha UCLM, 13071 Ciudad Real, Spain.
Environ Res. 2023 Dec 1;238(Pt 2):117183. doi: 10.1016/j.envres.2023.117183. Epub 2023 Sep 27.
This work utilizes a combined biological-electrochemical technique for the in-situ removal of metals from polluted mine tailings. As the main novelty point it is proposed to use electrokinetics (EK) for the in-situ activation of a bioleaching mechanism into the tailings, in order to promote biological dissolution of metal sulphides (Step 1), and for the subsequent removal of leached metals by EK transport out of the tailings (Step 2). Mine tailings were collected from an abandoned Pb/Zn mine located in central-southern Spain. EK-bioleaching experiments were performed under batch mode using a lab scale EK cell. A mixed microbial culture of autochthonous acidophilic bacteria grown from the tailings was used. Direct current with polarity reversal vs alternate current was evaluated in Step 1. In turn, different biological strategies were used: biostimulation, bioaugmentation and the abiotic reference test (EK alone). It was observed that bioleaching activation was very low during Step 1, because it was difficult to maintain acidic pH in the whole soil, but then it worked correctly during Step 2. It was confirmed that microorganisms successfully contributed to the in-situ solubilization of the metal sulphides as final metal removal rates were improved compared to the conventional abiotic EK (best increases of around 40% for Cu, 162% for Pb, 18% for Zn, 13% for Mn, 40% for Ni and 15% for Cr). Alternate current seemed to be the best option. The tailings concentrations of Fe, Al, Cu, Mn, Ni and Pb after treatment comply with regulations, but Pb, Cd and Zn concentrations exceed the maximum values. From the data obtained in this work it has been observed that EK-bioleaching could be feasible, but some upgrades and future work must be done in order to optimize experimental conditions, especially the control of soil pH in acidic values.
本工作利用组合生物电化学技术原位去除污染矿山尾矿中的金属。主要新颖之处在于提议将电动（EK）用于尾矿中生物浸出机制的原位激活，以促进金属硫化物的生物溶解（步骤 1），并随后通过 EK 运输将浸出的金属从尾矿中去除（步骤 2）。尾矿取自西班牙中南部一个废弃的 Pb/Zn 矿。EK 生物浸出实验采用实验室规模的 EK 电池进行分批模式进行。使用从尾矿中生长的混合土著嗜酸细菌的混合微生物培养物。在步骤 1 中评估了直流对交流电的极性反转。反过来，使用了不同的生物策略：生物刺激、生物增强和非生物参考测试（仅 EK）。观察到在步骤 1 中生物浸出的激活非常低，因为很难在整个土壤中维持酸性 pH，但随后在步骤 2 中正常工作。证实微生物成功地有助于金属硫化物的原位溶解，因为与常规非生物 EK 相比，最终金属去除率得到提高（Cu 的最佳增加约为 40%，Pb 为 162%，Zn 为 18%，Mn 为 13%，Ni 为 40%和 Cr 为 15%）。交流电似乎是最佳选择。处理后尾矿中 Fe、Al、Cu、Mn、Ni 和 Pb 的浓度符合规定，但 Pb、Cd 和 Zn 的浓度超过了最大值。从本工作获得的数据观察到，EK 生物浸出可能是可行的，但必须进行一些升级和未来的工作，以优化实验条件，特别是控制酸性土壤 pH 值。
