Comparison of performance of an earthen plate and nafion as membrane separators in dual chamber microbial fuel cells

The performance of microbial fuel cells (MFC) employing an earthen plate as a membrane separator is compared to that using Nafion 117 in an identical up-flow dual-chambered cylindrical cell configuration. The MFC configuration is of a cylindrical outer cathode chamber separated by the membrane from a concentric rectangular inner anode chamber. The fuel cells, operated under continuous mode at hydraulic retention time of 12 hr, achieved average chemical oxygen demand removal efficiency of 60% and 48%, for the Nafion and earthen plate separators, respectively. The microbial fuel cells based on the earthen plate separator generated slightly lower average (28%) and maximum (48%) power densities than Nafion separator which is likely due to the higher membrane resistance. The earthen plate separator is 99% cheaper than the Nafion membrane, showing promise as an alternate separator for application to MFC technology. © 2018, Gheorghe Asachi Technical University of Iasi, Romania. All rights reserved

Application of silver-tin dioxide composite cathode catalyst for enhancing performance of microbial desalination cell

Microbial desalination cell (MDC) is a novel bioelectrochemical system, capable of removing salts and organic matter from wastewater simultaneously. For improving the performance, a carbon supported silver-tin dioxide (Ag-SnO2) composite was synthesized and used as cathode catalyst in a five-chambered MDC (MDC-1). The results were compared with MDC-2 having no catalyst on the cathode. Saline water with a NaCl concentration of 20 g/L was used to evaluate the desalination efficiency of both the MDCs. The electrochemical studies such as cyclic voltammetry and linear sweep voltammetry of the cathode of MDC-1 revealed the superior reduction kinetics. Increased desalination efficiency was observed in MDC-1 (72.6 ± 3.0%) due to presence of Ag-SnO2 catalyst as compared to MDC-2 (57.9 ± 8.6%). Maximum power density of 1.47 W/m3, demonstrated by MDC-1, was noted to be 1.67 times higher than that of MDC-2 (0.88 W/m3). In addition, the coulombic efficiency of MDC-1 was observed to be 14.4 ± 0.2%, which was significantly higher than that observed in MDC-2 (9.5 ± 0.3%). Performance results confirmed the excellent catalytic activity of Ag-SnO2 composite catalyst to be used on the cathode of MDCs, to take forward this cutting-edge technology for field scale application. Keywords: Cathode catalyst, Desalination, Microbial desalination cell, Microbial fuel cell, Oxygen reduction reactio