Treatment of dairy wastewater and performance comparison of three different electrodes in microbial fuel cell system

Dual-chambered microbial fuel cells were tested in batch mode with three different electrodes: graphite rod, graphite felt, and carbon cloth as anodes and cathodes. Dairy wastewater, after sedimentation (initial chemical oxygen demand of 1,357 mg/L), was the feed for microbial fuel cell. The inoculum for the experiments conducted was a mixed culture of anaerobic microorganisms sourced from dairy wastewater. This study aimed to evaluate the performance of three electrodes in microbial fuel cell on the basis of their power generation and their wastewater treatment efficiency (chemical oxygen demand, total organic carbon content, turbidity), respectively. Carbon cloth produced the maximum open circuit voltage and power density (0.847 V and 1.36 W/m(2)) followed by graphite felt (0.812 V and 1.22 W/m(2)) and graphite rod (0.658 V and 0.78 W/m(2)). From the polarization studies, it was found that external resistance of 100 Omega produced the maximum power density for all the three electrodes. Electron transfer ability of the electrodes in dairy wastewater was measured by cyclic voltammetry. Biofilm growth on the surface of the anode was visualized by scanning electron microscopy. Chemical oxygen demand removal efficiency was found to be more in microbial fuel cell with carbon cloths and was estimated to be 91.3%. There was a significant reduction of total organic carbon content and turbidity in wastewater by the deployment of the three electrodes. Even though the power generated through these microbial fuel cells is low, efficiency in water treatment was found to be high. Thus, microbial fuel cells can be used in dairy industries to treat wastewater and simultaneously generate power effectively.