Constructing aerotolerant bioanode with flat and compact biofilm for high power generation of microbial fuel cells

Abstract

Reducing electrode spacing is consideredthemost effective way to maximize the power density of microbial fuel cell (MFC) due totheeffective reduction of internal resistance. However, reducing electrode spacing presents the challenge of diffusing oxygen from the cathode to the anode, therebyreducinganode performance.Constructing aerotolerant anode may be one of the effective ways to minimize the effect of oxygen on anode performance.Here, wereportthat usingsmall external resistance ormaintaining high nitrogen sparging rate during bioanode enrichment could significantly enhance the aerotolerant characteristic ofthebioanode. The voltage loss affected by oxygenwassignificantly reduced and, as a result, the power density of the compact electrode assembly MFCincreasedby 85% reaching4300 mW/m2.Theaerotolerant bioanodehada flat and compact biofilm structure andalarger laminar boundary layer (over 300 μm)to reduceoxygen diffusion,whiletheaerointolerant bioanodehada rough and porous biofilm structure andasmaller laminar boundary layer (less than 80 μm). The microbial community of all the bioanodeswasdominated by Geobacter (over 55%). Therefore, this study providesasample way to constructanaerotolerant bioanode for high power generationinMFCs.