Erik R Coats

The ability of microbial communities to exchange electrons with inert electrodes has fueled decades of scientific curiosity and laboratory investigations. Numerous studies have focused on developing applications of bioelectrochemical systems for energy generation, chemical synthesis, and sensor design. In particular, microbial fuel cells (MFCs) have been proposed as a promising technology for energy recovery from organic sources, including domestic and industrial wastewater. Many studies demonstrated the utility of microbial fuel cells in the treatment of wastewater in various reactor sizes from milliliter to cubic meter scale. In order to develop MFCs to be a viable technology for commercial applications, researchers aimed to optimize MFC operation, including optimizing MFC design, electrode materials and geometry, microbial community enrichment, startup and power harvesting strategies. Most studies have reported startup strategies that includes connecting MFCs to a load, including resistors, capacitors, and power management systems. In this study, we demonstrate an active MFC startup strategy by controlling the potential of both the anode and cathode during the initial microbial community enrichment. The anode and cathode potentials are controlled using a custom dual potentiostat relative to a common Ag/AgCl reference electrode, with a common auxiliary electrode as a current sink/source. Active MFC startup strategy is demonstrated in a large scale reactor (1200 liter) treating domestic wastewater. Sixteen MFCs (16 anodes and 16 cathodes) are enriched, each using an independent dual potentiostat. Each anode and cathode is a 30 cm x 30 cm carbon fabric electrode, and the counter electrode is a 30 cm x 30 cm x 1 cm graphite felt electrode. Dual potentiostats are connected to a computer using a data acquisition system to record anodic and cathodic current during enrichment. After reaching steady state current, each MFC is connected to a power management system that stores the harvested energy in a supercapacitor. The supercapacitors are discharged intermittently to power small air pumps used to aerate the cathodes.