Performance of liter-scale microbial fuel cells with electrode arrays: Effect of array pattern

Scale-up of microbial fuel cells requires the application of compact structure with well-arranged multi-electrode. For better understanding of electrode design, two liter-scale microbial fuel cells with staggered array (MFC-S) and inline array (MFC-I) were constructed using graphite rod electrodes. The effects of electrode array pattern on MFC startup, power generation, anodic current distribution, COD removal and coulombic efficiency were evaluated. The results showed that MFC-S had a faster startup with higher voltage output compared with MFC-I. Moreover, the maximum power density (23.8 W/m3) of MFC-S was approximately one quarter higher than that of MFC-I (19.1 W/m3) due to the structure-induced better mass transfer of staggered array. No noticeable difference in anodic current maldistribution between the two MFCs was observed at a similar cell current. For a batch feeding mode, compared with MFC-I, MFC-S had a slightly higher COD removal efficiency (84.3%) but much higher coulombic efficiency (82.3%) with a nonuniform segment CE distribution.