This study constructed multiple-anode SMFCs with different anode spacing and investigated their long-term performance. Results show that multiple anodes extended electricity generation from SMFCs due to increased anode surface area, but the distance between the anodes showed limited effects on power output. Power generation was seriously inhibited when temperature was below 20 degrees C, but system recovered once temperature rose based to ambient condition. The degradation of readily oxidizable organic matter (ROOM) and decomposition of refractory organics occurred simultaneously. Worms' growth in the sediment destabilized power output, caused the increase of COD and decrease of pH and DO in water layer, and affected the microbial communities in sediments. ANME-2D related to anaerobic oxidation of methane was enriched around anodes and might benefit electron transfer in SMFCs. (C) 2017 Elsevier Ltd. All rights reserved.