Multi response optimization of waste activated sludge oxidation and azo dye reduction in microbial fuel cell

Microbial fuel cell technology draws attention with its ability to directly recover electrical energy from various organic materials. In this study, the operating conditions affecting the oxidation-reduction and electricity generation efficiency of MFC were optimized using the Taguchi Experimental Design model. Optimization was carried out for maximum power density, coulombic efficiency, azo dye removal, and COD removal. With the determined optimum conditions (cathode pH of 3.0, cathode oxygen status of anaerobic, anode substrate of pre-treated, external resistance of 100 Ω, cathode electrode type of plain carbon, cathode electrode surface of 22 cm², cathode conductivity of 20 µs/cm), 177.03 mW/m² power density, 7.50% coulombic efficiency, 91.26% azo dye removal efficiency and 21.61% COD removal efficiency were obtained. By Pareto analysis, it was determined that the power density, coulombic efficiency and COD removal efficiency were most affected by the substrate type at the anode, and the azo dye removal was most affected by the catholyte pH. The maximum power density and internal resistance of the MFC operated under optimum conditions were determined as 145.11 mW/m² and 243.30 Ω, respectively by the polarization curve. Cyclic voltammetry was also performed for the electrochemical characterization of MFC operated under optimum conditions. An anodic peak at -183.2 mV and a cathodic peak at -181.2 mV was visible in the CV curve.