The Effect of Suspended Sludge on Electricity Generation in Microbial Fuel Cells

Analyzing effect of suspended sludge on power production is important to better understand how to improve microbial fuel cells (MFCs). In this paper, a comparison of two parallel single-chambered MFCs with or without suspended sludge operated in fed-batch mode was investigated to study the effect of suspended sludge on electricity generation. For the power generation from the glucose wastewater, both MFCs generated the steady voltage of 0.45~0.50 V. However compared to the MFC without suspended sludge, Coulombic efficiency of the MFC with suspended sludge was slight lower (2.3%-2.5%) than that without suspended sludge (2.9-3.1%) and the duration of stationary phase in each cycle with suspended sludge was 13.7~29.8% shorter than that of without suspended sludge. These results show that no obvious positive effect of suspended sludge on power generation was observed for MFC using glucose wastewater. When feces sewage was used, unlike the steady voltage (0.43-0.47 V) and Coulombic efficiency (3.5-3.9%) from MFC with suspended sludge, the working voltage (0.45-0.65 V) and Coulombic efficiency (1.5~4.3%) from the system without suspended sludge was fluctuant, therefore suspended sludge is necessary to obtain steady power output from more recalcitrant complex compounds.