Abstract: Biofilm on anode can influence anode's performance in microbial fuel cells(MFCs). Biofilm growth is influenced by anode surface area. The effect of anode structure on the maximum power output of MFC was investigated by changing lengths or numbers of carbon fibers as anode. For the length effect of carbon fiber anode, the highest maximum power density 10.50 W·m^-2 is appeared at 1 cm-length. The maximum power density decreases sharply as the carbon fiber length further increase. When the anodes are constructed with different numbers of 2 cm-length of carbon fibers, the maximum power is proportional to amount of carbon fiber(s) (1-4 carbon fiber(s)). The maximum power for the anode with 4 pieces of 2 cm-length carbon fiber is 2.92 W·m^-2, which is 2.78 times that generated with a single carbon fiber with the length of 8 cm. The biofilm on the carbon fibers surface could be observed by optical microscopy. The biofilm is much thicker at the place near current leading-out terminal than that at other parts of carbon fiber due to the resistance of the carbon fiber. These results indicate that increase of carbon fiber length can enlarge anode surface area, but can not significantly improve performance of anode.

Key words: microbial fuel cells, carbon fiber, anode structure, biomass

摘要： 微生物燃料电池（MFCs）阳极性能受生物膜的影响，而生物膜则直接与阳极表面积有关。以不同长度和数量的碳纤维丝作为阳极，研究了阳极构造和表面积对MFC输出功率的影响。当阳极为单根长度为1 cm碳纤维丝时，MFC产生的最大功率密度最高，为10.50 W·m^-2，随着碳纤维丝长度逐渐增加（2～14 cm），MFC产生的最大功率显著下降。以多根的长度为2 cm碳纤维丝构成阳极时，MFC的功率与根数（1～4 根）呈正比，当采用4根2 cm纤维丝时，MFC的最大功率密度为2.92 W·m^-2，该数值为单根8 cm碳纤维丝的2.78倍。观察碳纤维丝长度方向上的生物膜的分布表明：受碳纤维欧姆电阻的影响，在碳纤维丝电流引出端附近的生物量明显大于碳纤维其他地方，这说明：增加纤维丝长度虽可提高阳极的表面积，但并不能提高阳极的产电性能。

关键词: 微生物燃料电池, 碳纤维材料, 阳极结构, 生物量