Effect of cathode types on long-term performance and anode bacterial communities in microbial fuel cells.

Effects of cathode types on the long-term stability of microbial fuel cell (MFC) and the anodic microbial communities were studied using K(3)Fe(CN)(6) catholyte (R1), air cathode (R2) and biocathode (R3) over a testing time of 400 d. Upon 400 d of testing, the maximum power densities (P(max)) of R1 and R2 decreased by 44% and 37%, and the Coulombic efficiencies (CEs) decreased 8.4% (R1) and 2.0% (R2), respectively, using the performances on 10d as the comparison basis. Conversely, the P(max) and CE of R3 increased by 68.2% and 116.8%, respectively. The non-ohmic resistances (R(no)) in all tests were the principal contributors of cell internal resistances. Phylogenetic analyses revealed that the microbial communities on anodic surface varied with cathode types and operational history.