Abstract：The double-chamber microbial fuel cell systems (MFCs) were constructed with excess sludge as anodic substrate and potassium dichromate as catholyte. The effects of the initial concentrations of both excess sludge and Cr (VI) on MFC systems were investigated. According to the results, the MFC systems with sludge concentrations of 8~12 g/L presented almost the same degradation rates of Cr (VI), and a high removal efficiency of 99% was achieved. When the initial concentration of excess sludge was 10 g/L, the MFC system arrived at the best performance with an inner resistance of 108 Ω and maximum power density of 3621 mW/m3. A higher initial concentration of Cr (VI) could keep a longer period of stable high output voltage, but had no obvious effect on the sludge degradation in the anode chamber. Furthermore, the reduction products adhered on the surface of carbon cloth in the cathode chamber were demonstrated to be Cr (III), which led to decrease of total chromium in cathode solution. The MFC system with fuel recovery from excess sludge could be a promising technology, which is able to simultaneously address energy issues and environmental concerns associated with excess sludge and electroplating wastewater.