Keywords: 
• anaerobic fluidized bed microbial fuel cell /
• catholyte /
• electricity generation /
• wastewater treatment /
• substrate

Abstract: In order to improve the performance of anaerobic fluidized bed microbial fuel cell (AFB-MFC) and look for cheap， easy to get and no pollution catholyte for two chambers’ MFC， the effects of catholyte and substrate concentration on electricity generation and wastewater treatment were studied. The AFB-MFC system was operated under the conditions of aeration rate of 16～24 L/h， 35±2℃， distance between the bottom of cathode and the inner bottom of cathode chamber of 17.3 cm， external resistance of 250 Ω， hydraulic retention time (HRT) of 14.0～14.9 h and influent pH of 7.81~8.37. The results showed that the best electricity generation was resulted from using tap water as catholyte among buffer solution， anode effluent and tap water. The removal efficiency of substrate was not affected by catholyte. The pH and conductivity of catholyte increased with operation time when tap water was used as catholyte. And COD removal efficiency was 80.11%～89.29%. Voltage and power density increased with time at the beginning， then they stabilized at 440～452 mV and 48.40～51.08 mW/m2. The COD removal efficiency was not affected by substrate concentration， but voltage and power density decreased with the increase of substrate concentration. When the COD concentration of substrate increased from 3 307.09 mg/L to 9 520 mg/L， the COD removal efficiency was 85.77%～94.44% and the voltage and power density decreased from 449 mV and 50.40 mW/m2 to 406 mV and 41.21 mW/m2. Secondary pollution and effects of catholyte to anodic microorganisms can be avoided and high power output was achieved when tap water was used as catholyte.