Duty Cycling Influences Current Generation in Multi-Anode Environmental Microbial Fuel Cells

Journal Article · Tue May 01 00:00:00 EDT 2012 · Environmental Science and Technology

DOI:https://doi.org/10.1021/es204622m· OSTI ID:1211137

Gardel, EJ; Nielsen, ME; Grisdela, PT; Girguis, PR

Improving microbial fuel cell (MFC) performance continues to be the subject of research, yet the role of operating conditions, specifically duty cycling, on MFC performance has been modestly addressed. We present a series of studies in which we use a 15-anode environmental MFC to explore how duty cycling (variations in the time an anode is connected) influences cumulative charge, current, and microbial composition. The data reveal particular switching intervals that result in the greatest time-normalized current. When disconnection times are sufficiently short, there is a striking decrease in current due to an increase in the overall electrode reaction resistance. This was observed over a number of whole cell potentials. Based on these results, we posit that replenishment of depleted electron donors within the biofilm and surrounding diffusion layer is necessary for maximum charge transfer, and that proton flux may be not limiting in the highly buffered aqueous phases that are common among environmental MFCs. Surprisingly, microbial diversity analyses found no discernible difference in gross community composition among duty cycling treatments, suggesting that duty cycling itself has little or no effect. Such duty cycling experiments are valuable in determining which factors govern performance of bioelectrochemical systems and might also be used to optimize field-deployed systems.

• Sponsoring Organization: USDOE Advanced Research Projects Agency - Energy (ARPA-E)
• DOE Contract Number: DE-AR0000079
• OSTI ID: 1211137
• Journal Information: Environmental Science and Technology, Vol. 46, Issue 9; ISSN 0013-936X
• Country of Publication: United States
• Language: English