A single chambered air cathode anaerobic fluidized bed microbial fuel cell (AFB-MFC) was simultaneously used to dispose of the real boiler cleaning wastewater (BCW) containing a high concentration of citric acid and to generate renewable energy. At the temperature of 40 degrees C and flow rate of 5.22 mL/s, the removal efficiency and power density were improved in AFB-MFC with the abiotic cathode of the Pt/C modified carbon cloth. With the real boiler cleaning wastewater fed as substrate, the maximal removal efficiency of chemical oxygen demand (COD) in AFB-MFC was up to 90 %, which was higher than the corresponding value of 84 % obtained in the anaerobic biological fluidized bed reactor (ABFBR). The maximum voltage and the maximum power density were 424.6 mV and 18.68 mW/m(2), respectively, when the external resistance was 5000 omega. Furthermore, the Haldane inhibition model was well fitted with experiment data (R-2 = 0.97-0.98) in AFB-MFC/ABFBR. The inhibition of citric acid degradation in ABFBR was stronger than that of AFB-MFC. The bioelectrochemical system of AFB-MFC not only improved the charge transfer and but also accelerated the reaction rate of citric acid. The reduction of the ferric ion and oxidation of ferrous ion in AFB-MFC played important roles in the degradation reaction of critic acid.