Amanze Charles, Anaman Richmond, Ssekimpi Dennis, Ontita Nyambane Clive, Zeng Weimin
School of Minerals Processing and Bioengineering, Central South University, Changsha, 410083, China.
School of Metallurgy and Environment, Central South University, Changsha, 410083, China.
Bioprocess Biosyst Eng. 2025 Sep;48(9):1599-1617. doi: 10.1007/s00449-025-03199-1. Epub 2025 Jul 28.
Electroplating wastewater, characterized by high concentrations of bivalent copper (Cu⁺) and nickel (Ni⁺), poses significant environmental and health risks. This study explores the potential of novel Enterococcus species AMZ3, AMZ8, and AMZ5 as biocatalysts in bioelectrochemical systems (BES) for the dual purpose of electricity generation and heavy metal recovery. The strains were isolated from microbial fuel cell (MFC) biofilms and evaluated in single-chamber MFCs and dual-compartment systems. A mixed culture of the strains outperformed individual species, achieving a peak power and current densities of 439.78 mW/m and 5.31 A/m, respectively. In addition, the system achieved a remarkable chemical oxygen demand removal efficiency of 94.6 ± 11.23% and a Coulombic efficiency of 33.7 ± 7.11%. Enhanced electrocatalytic activity in mixed-culture systems was attributed to synergistic microbial interactions, superior biofilm formation, and elevated extracellular polymeric substance protein content. Cyclic voltammetry and electrochemical impedance spectroscopy revealed reduced internal resistance and robust electron transfer pathways in the reactor containing the biofilms of the mixed Enterococcus species. Furthermore, BES with the mixed Enterococcus biofilms achieved copper and nickel removal efficiencies of 99.99 ± 0.01 and 99.96 ± 0.02%, respectively. The reduction and recovery of these metals occurred at the cathode, where copper was predominantly recovered as Cu through bioelectrochemical reduction, while nickel was recovered as metallic Ni through bioelectrochemical reduction, with surface-bound Ni⁺ also detected, likely formed post-deposition due to oxidative surface processes, as revealed by SEM-EDX, XRD, and XPS analyses. These findings establish the feasibility of mixed Enterococcus cultures in sustainable wastewater treatment, paving the way for scalable BES applications.
电镀废水的特点是含有高浓度的二价铜（Cu⁺）和镍（Ni⁺），对环境和健康构成重大风险。本研究探索了新型肠球菌AMZ3、AMZ8和AMZ5作为生物电化学系统（BES）中生物催化剂的潜力，以实现发电和重金属回收的双重目的。这些菌株从微生物燃料电池（MFC）生物膜中分离出来，并在单室MFC和双室系统中进行评估。菌株的混合培养表现优于单个物种，分别实现了439.78 mW/m的峰值功率密度和5.31 A/m的电流密度。此外，该系统实现了94.6±11.23%的显著化学需氧量去除效率和33.7±7.11%的库仑效率。混合培养系统中增强的电催化活性归因于协同的微生物相互作用、优异的生物膜形成和细胞外聚合物蛋白质含量的提高。循环伏安法和电化学阻抗谱显示，含有混合肠球菌生物膜的反应器内部电阻降低，电子转移途径稳健。此外，具有混合肠球菌生物膜的BES分别实现了99.99±0.01%和99.96±0.02%的铜和镍去除效率。这些金属的还原和回收发生在阴极，其中铜主要通过生物电化学还原以Cu的形式回收，而镍通过生物电化学还原以金属Ni的形式回收，扫描电子显微镜-能谱仪（SEM-EDX）、X射线衍射（XRD）和X射线光电子能谱（XPS）分析表明，表面结合的Ni⁺也被检测到，可能是由于氧化表面过程在沉积后形成的。这些发现确立了混合肠球菌培养物在可持续废水处理中的可行性，为可扩展的BES应用铺平了道路。
