Bioanodes in bioelectrochemical systems produce an electrical current by removing organics in wastewater. Capacitive bioanode granules, functioning as charge storage and bioanode surface, were circulated between charging and discharging in a newly developed moving bed reactor. Single bioanodes granules showed the potential for high current densities. In the moving bed reactor contact time for discharging was increased, which allowed a current of 43 mA/cm3: three to twenty times higher than previous reactors, and at a larger scale. Fixed bed bioanodes produced half of this current. The discharge cell design was further studied as a bioanode and under abiotic conditions. The results show fully charged granules produce a high discharge current, and the electrical resistance is more important than the ionic resistance for the capacitive current. Further analysis showed ions released during discharging increased the local electrolyte conductivity, which is promising for treatment of low conductivity wastewater.