Multiparametric control for enhanced biofilm selection in microbial fuel cells

BACKGROUND: Microbial fuel cells (MFCs) directly convert the chemical energy present in wastewater into electricity. Enriching exoelectrogenic bacteria in the anode biofilm is a current and challenging research target. A multiparametric control strategy, focused on organic loading rate (OLR) and external resistance (R-ext) parameters, is here proposed to enhance microbial selection in MFCs. RESULTS: The study examines the performance of a swine manure fed MFC working at optimal electrical condition. Maximum power point tracking (MPPT) control was adopted to continuously optimize applied R-ext. Subsequent OLR decreases were performed to gradually improve anodic biofilm exoelectrogenic activity. The study demonstrates that high OLRs (11.2 kg COD m(-3) d(-1)) limit MFC electrochemical losses, and increase absolute values of organic removal rate (4.6 kg COD m(-3) d(-1)) and current production (14.9 mA). On the other hand, low OLR adoption (0.7 kg COD m(-3) d(-1)) results in higher organic matter removal (52%) and coulombic efficiency (higher than 70%) of the MFC. CONCLUSION: A multiparametric control for MFCs is proposed. Combining MPPT control and low OLR results in rapid improvement of exoelectrogenic activity in MFCs biofilm. The developed strategy may be useful for future MFCs applications, in order to achieve efficient start-up and sustainable operation. (C) 2015 Society of Chemical Industry