Abstract: A microbial fuel cell was constructed by using new methylene blue as the electron mediator and E.coli as the biocatalyst. The open circuit voltage of the MFC is 0.760 V and the short circuit current is 1.108 mA. The maximum power output is 116 mW/m² with the corresponding current density 390 mA/m². The performances of MFCs which use neutral red or new methylene blue as the electron mediator were also compared. The results show that the MFC which uses new methylene blue as the electron mediator has a lower open circuit voltage and higher steady short circuit current than those MFC which use neutral red as electron mediator. When the discharge current density is larger than 114 mA/cm², the former has a higher power density and better stability than the latter.

Key words: Microbial fuel cell, New methylene blue, E.coli, Neutral red