Optimising the proportion of pure and mixed culture in inoculum to enhance the performance of microbial fuel cells

Single-chambered microbial fuel cells (MFCs) were inoculated with different proportions of Shewanella putrefaciens and mixed-anaerobic sludge, viz. 100:0% (MFC-1), 0:100% (MFC-2), 10:90% (MFC-3), 30:70% (MFC-4) and 50:50% (MFC-5). Performance of these MFCs was evaluated using different electrochemical analyses. Due to specific substrate-selectivity, MFC-1 showed lower power (1.22 W.m−3) than MFC-2 (2.15 W.m−3). Power performance increased from 2.21 (MFC-3) to 2.56 W.m−3 (MFC-4) with increased fraction of Shewanella from 10 to 30% in the inoculum, and power density further enhanced to 3.1 W.m−3 in MFC-5 inoculated with equal-fraction of Shewanella and mixed sludge. Bioelectrochemical analyses showed higher electron transfer rate and lower charge-transfer resistance in MFC-5 due to synergy between both the inoculums and promoted the electron transfer at anode. Thus, inoculation of MFC with equal-fraction of mixed-anaerobic sludge and Shewanella showed effective bio-augmentation to improve the anodic bioactivity and power generation from MFC.