Departamento de Ingeniería Civil y Centro de Recursos Hídricos para La Agricultura y Minería (CRHIAM), Universidad de Concepción, Barrio Universitario, Concepción, Chile.
Departamento de Acuicultura, Universidad Católica del Norte, Larrondo, 1281, Coquimbo, Chile; Escuela de Prevención de Riesgos y Medio Ambiente, Universidad Católica del Norte, Larrondo, 1281, Coquimbo, Chile.
J Environ Manage. 2021 Apr 15;284:112086. doi: 10.1016/j.jenvman.2021.112086. Epub 2021 Feb 9.
In this study, we evaluate the long term operation of a bench-scale reactor which simulates a permeable reactive barrier with sulfidic diffusive exchange (SDES PRB) to treat acid mine drainage (AMD), considering that treatment costs are very sensitive to the useful life for passive reactors. Its functioning was evaluated for a much longer period of 591 days compared to previous SDES PRB studies, with two influents simulating moderately and highly acid groundwater contaminated by AMD. First, we fed water amended with 200 mg/L Zn and 3300 mg/L SO at pH 4.9; and after, water with 450 mg/L Fe, 100 mg/L Zn, 10 mg/L Ni, 5 mg/L Cu and 3600 mg/L SO at pH 2.5. Biologically produced sulfide and alkalinity were enough to remove both metals and acidity (~99%) from the moderately acidic water, while with the highly acidic water, they resulted in significant removal of the metals reaching up to 87% and 79% of total Fe and Zn, respectively. Furthermore, no inhibitory effect was apparent, as the sulfate reduction rates in the two experiments did not vary significantly (averages close to 0.2 mol/m-d), despite the much higher acidity and metal load in the second case. Hence, the SDES PRB protected the microbial consortium from metal toxicity and acidity in the long-term, and thus is suitable for remediation of AMD contaminated groundwater with high concentrations of metals, extending the operational range of conventional biological PRBs. Furthermore, an economic evaluation shows that SDES costs can be competitive with the costs of conventional chemical precipitation if the enhanced reactivity that SDES technology offers is realized.
在这项研究中，我们评估了一个模拟可渗透反应屏障中硫化物扩散交换（SDES PRB）处理酸性矿山排水（AMD）的中试规模反应器的长期运行情况，因为处理成本对被动式反应器的有效寿命非常敏感。与之前的 SDES PRB 研究相比，该反应器的运行时间要长得多，达到了 591 天，使用了两种模拟中度和高度酸性受 AMD 污染的地下水的进水。首先，我们用 200 mg/L Zn 和 3300 mg/L SO 调节进水至 pH 值 4.9；然后，我们用 450 mg/L Fe、100 mg/L Zn、10 mg/L Ni、5 mg/L Cu 和 3600 mg/L SO 调节进水至 pH 值 2.5。生物产生的硫化物和碱度足以去除中度酸性水中的两种金属和酸度（~99%），而对于高度酸性的水，它们分别导致金属的去除率显著提高，达到 87%和 79%。此外，硫酸盐还原速率在两个实验中并没有显著差异（平均值接近 0.2 mol/m-d），这表明尽管第二种情况下酸度和金属负荷更高，但并没有明显的抑制作用。因此，SDES PRB 在长期内保护了微生物群落免受金属毒性和酸度的影响，从而适用于修复高浓度金属污染的 AMD 地下水，扩展了传统生物 PRB 的操作范围。此外，经济评估表明，如果实现了 SDES 技术提供的增强反应性，那么 SDES 的成本可以与传统化学沉淀的成本竞争。
