The voltage and the power production of four pure cultures and a mixed culture in five identical continuous-flow microbial fuel cells (MFCs) were evaluated and compared in the present study. Each microbial fuel cell was operated at four different flow rates with the external load resistance of 1000Ω The result shows that good linear relationship between COD degradation rate and flow rate was obtained on the MFCs inoculated with Pseudomonas putida, Corynebacterium glutamicum and Comamonas testosteroni, not on the one inoculated with Arthrobacter polychromogenes. However, the relationship between COD degradation rate and flow rate on the MFC inoculated with mixed culture could be expressed as a binary quadratic equation. A lower influent pH favored the organic removal efficiency and degradation rate in the anode chamber of MFCs. The result also shows that the voltage outputs increased with the flow rate (shorter retention time) of anode chambers. However, good linear relationships between voltage and flow rate were only seen on the MFCs inoculated with Comamonas testosteroni and mixed culture. Among the five MFCs, the one inoculated with mixed culture displayed the highest voltage output at the same COD loading than others.
