An application-oriented stackable horizontal MFC (SHMFC) was designed and proved to be capable for sewage treatment and simultaneously energy recovery. The system consisted of multiple stackable 250 L modules, which is the largest single MFC module by far. Domestic wastewater was fed into SHMFC in horizontal advection. During the stable operation period, a maximum current 0.435 +/- 0.010 A in each module was observed under the external resistance of 1 X and the maximum power density was 116 mW. The effluent COD was 70 +/- 17 mg L-1 with a removal rate of 79 +/- 7% and the effluent TN was 13 +/- 3 mg L-1 with a removal rate of 71 +/- 8%. From the comparison between SHMFC module (250 L) and 4-cm cubic MFC (28 mL), the internal resistance distribution changes and the contact resistance becomes assignable and even limiting factor in the enlargement. (C) 2014 Elsevier Ltd. All rights reserved.