The variation of power generation with organic substrates in single-chamber microbial fuel cells (SCMFCs)

The wastewaters consist of diverse types of organic substrates that can be used as the carbon sources for power generation. To explore the utilization of some of these organics, the electricity generation from three substrates (acetate, ethanol, and glucose) was examined over a concentration range of 0.5–35 mM in single-chamber microbial fuel cells (SCMFCs). The power density generated from glucose was the highest at 401 mW/m2 followed by acetate and ethanol at 368 mW/m2 and 302 mW/m2, respectively. The voltage increased with substrate concentration of 0.5–20 mM, but significantly decreased at high substrate concentrations of 20–35 mM. Kinetic analysis indicated that the inhibition in the ethanol-fed MFCs was the highest at the concentration of 35 mM, while inhibition in glucose-fed MFCs was the lowest at the concentration of 20 mM. These were in accordance with the extents of voltage decrease at high substrate concentration. Moreover, the effect of the distance between anode and cathode on voltage generation was also investigated. The reduction of the electrode distance by 33% in the glucose-fed MFCs reduced the internal resistance by 73% and led to 20% increase in voltage generation.