Integration of pre-colonized and mediator immobilized mixed culture for the improvement of electricity production of microbial fuel cells

Abstract

In this study, we have immobilized bacterial cells with mediators as bioaugmentation to increase the numbers of bacterial cells in anodic biofilm for better microbial fuel cell (MFC) performance. Four individual bacterial strains (strain E1, strain SCS5, strain B2 and Shewanella putrefaciens) and their mixed culture were first evaluated for electricity production in MFCs. The mixed culture MFC produced higher power density (3.021 Wm−3) than pure strains. The pre-colonized (PC) biofilms together with mediator immobilized mixed culture (MIMC) beads as bioanodes further enhanced the performance of MFCs. Integrated PC/MIMC MFCs containing anthraquinine-2,6-disulfonate (AQDS) and Fe3O4 immobilized mixed culture beads produced 1.50 and 1.47 times power density with respect to mixed culture biofilm, respectively. AQDS immobilization showed better performance compared to Fe3O4 in energy output. The integrated use of PC biofilms and MIMC exhibited lower charge transfer resistance than corresponding individual anode biofilms in MFCs according to electrochemical impedance spectroscopy analysis. The MFC having PC/MIMC as anode showed the ability to store electrons generated by bacteria, but the biocapacitance of anode was altered after integrating MIMC bead particles. Thus, the collective use of PC biofilm and MIMC beads will be one of the potential choices for improving MFC performance.