Enhancing microbial fuel cell performance through algal oxygenation: A novel approach for sustainable energy generation

Abstract

Microbial fuel cells (MFCs) present promising technology for sustainable wastewater treatment and energy generation. In this study, we operated an algae-MFC system to investigate its performance in terms of electricity generation and wastewater treatment capacity. The MFC reactor, with the support of a separate algae vessel providing oxygen-rich water to the cathode chamber, was continuously operated with varying organic loading rates to the anode with the synthetic wastewater. Results showed that the algae-MFC achieved a stable electricity generation, reaching a maximum power density of 840 mW m-3 at the highest chemical oxygen demand (COD) loading rate (0.30 kg m-3 h-1). Furthermore, the system could remove 75% of COD at a short HRT of 4 h. Coulombic efficiency was unexpectedly low, from 0.35% to 0.70%, indicating the need of energy recovery improvement from wastewater. A challenge of internal resistance increase over time was identified and discussed. Future prospects were discussed including the algae integrating directly into the cathode chamber to enhance the nitrogen removal and to explore the co-cultivation possibility of microalgae and autotrophic bacteria for a simultaneous removal of organic substances and nutrients. Overall, this study demonstrated the application potential of algae-MFC systems for sustainable wastewater treatment and energy production.