Effect of Temperature on the Catalytic Ability of Electrochemically Active Biofilm as Anode Catalyst in Microbial Fuel Cells

In this study we report the effect of temperature on the catalytic ability of an electrochemically active biofilm based on mixed-culture to oxidize acetate and found the optimum temperature showing maximal catalytic activity and power output. Electrochemical characterization of biofilm and power output and internal resistance of microbial fuel cell (MFC) have been investigated at different temperatures. When temperature increased from 30 to 45 degrees C the catalytic ability of biofilms to oxidize acetate increased following the Arrhenius law with apparent activation energy of 44.85 kJ/mol. At temperatures higher than 48 degrees C, however, the bioelectrocatalytic current decreased. At 53 degrees C the bacterial metabolism was in inactivation. The optimum working temperature of the biofilm was 45 degrees C, producing current of 1339 mu A cm(-2). This current was almost three times higher than 527 mu A cm(-2) at 30 degrees C. The MFC performance at different temperatures showed consistent temperature dependence to that of a semi-batch cell, which implies that anode catalytic ability in MFC is the main limit factor for increasing power output. A maximum power output of 1065 mW m(-2) was also observed at 45 degrees C and it was 1.5 times higher than 764 mW m(-2) at 30 degrees C. The increased MFC performance from 30 degrees C to 45 degrees C is lower in comparison with about three times higher increase in semi-batch cells. This could be due to other factors such as proton migration rate in membrane of MFC, which can be seen from that the internal resistance value of 121.5 Omega in the MFC at 45 degrees C was only slightly lower than 177.6 Omega at 30 degrees C. Also, some other factors such as cell configuration which would limit the power output and can be further optimized. This work contributes to the study of influence from temperature on anodic electrochemically active biofilm activity and their subsequent influence on MFC performance and reports the optimal temperature for biofilm activity based on mixed-culture.