Brewster Emma Thompson, Pozo Guillermo, Batstone Damien J, Freguia Stefano, Ledezma Pablo
Advanced Water Management Centre, The University of Queensland St Lucia QLD 4072 Australia
RSC Adv. 2018 May 22;8(33):18682-18689. doi: 10.1039/c8ra03153c. eCollection 2018 May 17.
Microbial electrochemical processes have potential to remediate acid mine drainage (AMD) wastewaters which are highly acidic and rich in sulfate and heavy metals, without the need for extensive chemical dosing. In this manuscript, a novel hybrid microbial/electrochemical remediation process which uses a 3-reactor system - a precipitation vessel, an electrochemical reactor and a microbial electrochemical reactor with a sulfate-reducing biocathode - was modelled. To evaluate the long-term operability of this system, a dynamic model for the fluxes of 140 different ionic species was developed and calibrated using laboratory-scale experimental data. The model identified that when the reactors are operating in the desired state, the coulombic efficiency of sulfate removal from AMD is high (91%). Modelling also identified that a periodic electrolyte purge is required to prevent the build-up of Cl ions in the microbial electrochemical reactor. The model furthermore studied the fate of sulfate and carbon in the system. For sulfate, it was found that only 29% can be converted into elemental sulfur, with the rest complexating with metals in the precipitation vessel. Finally, the model shows that the flux of inorganic carbon under the current operational strategy is insufficient to maintain the autotrophic sulfate-reducing biomass. The modelling approach demonstrates that a change in system operational strategies plus close monitoring of overlooked ionic species (such as Cl and HCO ) are key towards the scaling-up of this technology.
微生物电化学过程有潜力修复酸性矿山排水（AMD）废水，这类废水酸性很强，富含硫酸盐和重金属，且无需大量投加化学药剂。在本论文中，对一种新型的微生物/电化学混合修复工艺进行了建模，该工艺采用三反应器系统——一个沉淀容器、一个电化学反应器和一个带有硫酸盐还原生物阴极的微生物电化学反应器。为评估该系统的长期可操作性，利用实验室规模的实验数据开发并校准了一个包含140种不同离子通量的动态模型。该模型确定，当反应器按预期状态运行时，从AMD中去除硫酸盐的库仑效率很高（91%）。建模还确定需要定期进行电解液吹扫，以防止微生物电化学反应器中Cl离子的积累。该模型还研究了系统中硫酸盐和碳的去向。对于硫酸盐，发现只有29%能转化为元素硫，其余部分在沉淀容器中与金属络合。最后，该模型表明，在当前运行策略下，无机碳通量不足以维持自养硫酸盐还原生物质。建模方法表明，改变系统运行策略以及密切监测被忽视的离子种类（如Cl和HCO）是扩大该技术规模的关键。
