Centre for Water and Environmental Sanitation, University Mayor de San Simon, Cochabamba, Bolivia.
Department of Chemical Engineering, K.U. Leuven, Heverlee, Belgium.
Environ Technol. 2021 Mar;42(8):1283-1291. doi: 10.1080/09593330.2019.1665109. Epub 2019 Sep 13.
The environmental contamination due to mining activities in the Andean region of Bolivia is a serious concern, as it leads to highly acidic (pH 2.4) acid mine drainage (AMD), severely polluted by sulfate (>12,000 mg L). Passive bioreactors entailing biological sulfate reduction and removal of metals through sulfide precipitation have been recognized as a promising biotechnology. The reactivity of mixtures containing locally available substrates: sheep manure, compost and straw, was assessed through batch experiments conducted with a synthetic solution simulating the composition of AMD from San José mine (Oruro). The removal of sulfate and metals was successful in all reactors, at the end of the experiment (56 days) sulfate concentrations dropped to 1378-2081 mg L, corresponding to a removal efficiency between 84% and 89%, while average removal for Fe, Zn, Pb, and Cd were 99.8%, 98.5%, 94.7%, 98.6%, respectively. The sulfate and metal removal showed three phases. In the first phase, the removal was independent of the organic composition and attributable to pH-controlled mechanisms i.e. adsorption, precipitation of oxy(hydroxides) and co-precipitation. During the second phase, sulfate and metals concentrations remained rather constant; while in the third phase, the removal was affected by the organic matter composition. Sulfate removal rate attained the highest values (227-243 mg L d) in the third phase, and it was attributable to biological reduction with not sulfate limitation. The depletion of nutrients rather than the sulfate availability may have limited the sulfate removal at the end of the experiment.
玻利维亚安第斯地区采矿活动造成的环境污染是一个严重的问题，因为它会导致高度酸性（pH 值 2.4）的酸性矿山排水（AMD），严重受到硫酸盐（>12,000mg/L）的污染。已经认识到包含生物硫酸盐还原和通过硫化物沉淀去除金属的被动生物反应器是一种很有前途的生物技术。通过使用模拟 San José 矿（奥鲁罗）AMD 组成的合成溶液进行的批量实验评估了含有本地可用基质的混合物的反应性：羊粪、堆肥和稻草。在所有反应器中，硫酸盐和金属的去除都很成功，在实验结束时（56 天），硫酸盐浓度降至 1378-2081mg/L，相应的去除效率在 84%至 89%之间，而 Fe、Zn、Pb 和 Cd 的平均去除率分别为 99.8%、98.5%、94.7%和 98.6%。硫酸盐和金属的去除显示出三个阶段。在第一阶段，去除与有机成分无关，归因于 pH 控制机制，即吸附、氧（氢）氧化物沉淀和共沉淀。在第二阶段，硫酸盐和金属浓度保持相对稳定；而在第三阶段，去除受到有机物组成的影响。硫酸盐去除率在第三阶段达到最高值（227-243mg/L/d），这归因于不受硫酸盐限制的生物还原。在实验结束时，可能是由于营养物质的消耗而不是硫酸盐的可用性限制了硫酸盐的去除。
