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Abstract: Based on energetic analysis, a novel approach for copper electrodeposition via cathodic reduction in microbial fuel cells (MFCs) was proposed for the removal of copper and recovery of copper solids as metal copper and/or Cu2O in a cathode with simultaneous electricity generation with organic matter. This was examined by using dual-chamber MFCs (chamber volume, 1L) with different concentrations of CuSO4 solution (50.3±5.8, 183.3±0.4, 482.4±9.6, 1007.9±52.0 and 6412.5±26.7mg Cu2+/L) as catholyte at pH 4.7, and different resistors (0, 15, 390 and 1000Ω) as external load. With glucose as a substrate and anaerobic sludge as an inoculum, the maximum power density generated was 339mW/m3 at an initial 6412.5±26.7mg Cu2+/L concentration. High Cu2+ removal efficiency (>99%) and final Cu2+ concentration below the USA EPA maximum contaminant level (MCL) for drinking water (1.3mg/L) was observed at an initial 196.2±0.4mg Cu2+/L concentration with an external resistor of 15Ω, or without an external resistor. X-ray diffraction analysis confirmed that Cu2+ was reduced to cuprous oxide (Cu2O) and metal copper (Cu) on the cathodes. Non-reduced brochantite precipitates were observed as major copper precipitates in the MFC with a high initial Cu2+ concentration (0.1M) but not in the others. The sustainability of high Cu2+ removal (>96%) by MFC was further examined by fed-batch mode for eight cycles. [Copyright &y& Elsevier]

Abstract: A membrane-free baffled microbial fuel cell (MFC) was developed to treat synthetic Cu(II) sulfate containing wastewater in cathode chamber and synthetic glucose-containing wastewater fed to anode chamber. Maximum power density of 314mW/m3 with columbic efficiency of 5.3% was obtained using initial Cu2+ concentration of 6400mg/L. Higher current density favored the cathodic reduction of Cu2+, and removal of Cu2+ by 70% was observed within 144h using initial concentration of 500mg/L. Powder X-ray diffraction (XRD) analysis indicated that the Cu2+ was reduced to Cu2O or Cu2O plus Cu which deposited on the cathode, and the deficient cathodic reducibility resulted in the formation of Cu4(OH)6SO4 at high initial Cu2+ concentration (500–6400mg/L). This study suggested a novel low-cost approach to remove and recover Cu(II) from Cu2+-containing wastewater using MFC-type reactor. [Copyright &y& Elsevier]

Abstract: This work studied an alkalophilic Gram-positive bacterium, Corynebacterium sp. strain MFC03, for its ability to produce electricity in the absence of an exogenous mediator under alkaline pH in microbial fuel cells (MFCs). The experimental results demonstrated that the strain MFC03 was capable of utilizing organic acids, sugars and alcohols as electron donors to generate electricity under above desired conditions. At an optimal pH of 9.0, the glucose-fed MFC achieved a maximum power density of 7.3mW/m2 and a Coulombic efficiency (CE) of 5.9%. In the presence of 0.1mM anthroquinone-2,6-disulfonate (AQDS), the maximum power density was enhanced to 41.8mW/m2 and CE was increased to 18.4%. The cyclic voltammetry measurements revealed that the electron transfer mechanism in the strain MFC03-based MFC was mainly via the excreted redox compounds in the medium solution. [Copyright &y& Elsevier]

Abstract: Microbial fuel cells (MFCs) represent a new method for simultaneous wastewater treatment and biological electricity generation. In this study, an air-cathode MFC with membrane electrode assembly was operated over four batch cycles (a total period of 140 d) and results indicated that starch processing wastewater containing 4852mg/l of chemical oxygen demand could be used as substrate to produce electricity with this MFC. Maximum voltage output and power density of 490.8mV and 239.4mW/m2 (a current density of 893.3mA/m2) were approached in the third cycle, which also had the minimum internal resistance of about 120Ω and maximum coulombic efficiency of 8.0%. Removal efficiencies of chemical oxygen demand and ammonia-nitrogen increased as a function of time, and maximum amounted to 98.0% and 90.6%, respectively. Scanning electron microscope image revealed that short rod shaped bacillus were the dominant bacteria on the biofilm of the anode, whose electrochemical activity was proved by cyclic voltammetry. These results demonstrate that starch processing wastewater can be used for power generation in MFCs and also can be treated with high removal efficiencies of chemical oxygen demand and ammonia-nitrogen. [Copyright &y& Elsevier]