Bioengineering and Environmental Sciences Lab, Department of Energy and Environmental Engineering (DEEE), CSIR-Indian Institute of Chemical Technology (CSIR-IICT), Hyderabad 500007, India; Academy of Scientific and Innovative Research (AcSIR), CSIR-Indian Institute of Chemical Technology (CSIR-IICT) campus, Hyderabad 500007, India.
Water and Steam Chemistry Division, Chemistry Group, Bhabha Atomic Research Centre, Kalpakkam 603102, Tamil Nadu, India; Homi Bhabha National Institute, Anushakti Nagar, Mumbai 400094, India.
J Hazard Mater. 2020 Nov 15;399:122843. doi: 10.1016/j.jhazmat.2020.122843. Epub 2020 May 18.
Metal(loid)s are used in various industrial activities and widely spread across the environmental settings in various forms and concentrations. Extended releases of metal(loid)s above the regulatory levels cause environmental and health hazards disturbing the ecological balance. Innovative processes for treating the metal(loid)-contaminated sites and recovery of metal(loid)s from disposed waste streams employing biotechnological routes provide a sustainable way forward. Conventional metal recovery technologies demand high energy and/or resource inputs, which are either uneconomic or unsustainable. Microbial electrochemical systems are promising for removal and recovery of metal(loid)s from metal(loid)-laden wastewaters. In this communication, a bioelectrochemical system (BES) was designed and operated with selenium (Se) oxyanion at varied concentrations as terminal electron acceptor (TEA) for reduction of selenite (Se) to elemental selenium (Se) in the abiotic cathode chamber. The influence of varied concentrations of Se towards Se recovery at the cathode was also evaluated for its regulatory role on the electrometabolism of anode-respiring bacteria. This study observed 26.4% Se recovery (cathode; selenite removal efficiency: 73.6%) along with organic substrate degradation of 74% (anode). With increase in the initial selenite concentration, there was a proportional increase in the dehydrogenase activity. Bioelectrochemical characterization depicted increased anodic electrogenic performance with the influence of varied Se concentrations as TEA and resulted in a maximum power density of 0.034 W/m. The selenite reduction (cathode) was evaluated through spectroscopic, compositional and structural analysis. X-ray diffraction and Raman spectroscopy showed the amorphous nature, while Energy Dispersive X-ray spectroscopy confirmed precipitates of the deposited Se recovered from the cathode chamber. Scanning electron microscopic images clearly depicted the Se depositions (spherical shaped; sized approximately 200 nm in diameter) on the electrode and cathode chamber. This study showed the potential of BES in converting soluble Se to insoluble Se at the abiotic cathode for metal recovery.
金属（类）在各种工业活动中得到广泛应用，并以各种形式和浓度广泛分布于环境中。金属（类）超过规定水平的持续释放会对环境和健康造成危害，扰乱生态平衡。采用生物技术途径处理受金属（类）污染的场地和从处理过的废物流中回收金属（类）的创新工艺提供了一种可持续的前进方向。传统的金属回收技术需要高能量和/或资源投入，这要么不经济，要么不可持续。微生物电化学系统有望从含金属（类）的废水中去除和回收金属（类）。在本通讯中，设计并运行了一个生物电化学系统（BES），以硒（Se）作为终端电子受体（TEA），在不同浓度下处理硒酸盐（Se），将其还原为非生物阴极室中的元素硒（Se）。还评估了不同浓度的 Se 对阴极处 Se 回收的影响，以研究其对阳极呼吸细菌电代谢的调节作用。该研究观察到 26.4%的 Se 回收（阴极；硒酸盐去除效率：73.6%），同时有机底物降解 74%（阳极）。随着初始硒酸盐浓度的增加，脱氢酶活性呈比例增加。生物电化学特性描述了随着 TEA 浓度的变化，阳极的电生成性能得到了提高，并产生了 0.034 W/m 的最大功率密度。通过光谱、组成和结构分析评估了硒酸盐的还原（阴极）。X 射线衍射和拉曼光谱显示出非晶态性质，而能量色散 X 射线光谱证实了从阴极室回收的沉积硒的沉淀物。扫描电子显微镜图像清楚地显示了电极和阴极室上硒的沉积（球形；直径约 200nm）。这项研究表明，BES 具有在非生物阴极将可溶性硒转化为不溶性硒以回收金属的潜力。
