Relationship of methane and electricity production in two-chamber microbial fuel cell using sewage sludge as substrate

• Methane production could enhance the electricity production from sewage sludge.
• Methane production could improve the performance of MFC used sludge as substrate.
• Simultaneous methane and electricity production could maintain a suitable pH.
• Simultaneous methane and electricity production could enhance reduction of sludge.
• Sludge reduction could alleviate competition between methane and electricity production.

The relationship of methane and electricity production from sewage sludge in a two-chamber microbial fuel cell (MFC) was studied. The results showed that methane production in the anode chamber could enhance the electricity production from sewage sludge, and the output voltage of the MFC with methane production (0.505–0.600 V) was higher than that of the MFC without it (0.506–0.576 V) in the stable electricity-producing stage. The polarization curves analysis of the two MFCs suggested that methane production could improve the performance characteristics of the MFC. Simultaneous methane and electricity production from sludge in the two-chamber MFC could maintain the mixed sludge in a suitable pH range in the anode chamber for electricity production. Meanwhile, simultaneous methane and electricity production could enhance the hydrolysis of sludge, which increased the reduction of sludge concentration (about 8.31% VSS) and offered more substrates to alleviate the competition between methane and electricity production. Additionally, the addition of 2-Bromoethanesulfonate (BES) could substantially affect the dominant archaea but had little effect on the dominant bacteria in the anode chamber.