Deciphering three-dimensional bioanode configuration for augmenting power generation and nitrogen removal in air-cathode microbial fuel cells.

In this study, the engineering-oriented three-dimensional (3D) bioanode concept was applied, demonstrating that spiral-stairs-like/rolled carbon felt (SCF/RCF) configurations achieved good performances in air-cathode microbial fuel cells (ACMFCs). With the 3D anodes, ACMFCs generated significantly higher power densities of 1535 mW/m (SCF) and 1800 mW/m (RCF), compared with that of a traditional flat carbon felt anode (FCF, 315 mW/m). The coulombic efficiency of 15.39% at SCF anode and 14.34% at RCF anode also is higher than the 7.93% at FCF anode. The 3D anode ACMFCs exhibited favorable removal of chemical oxygen demand (96% of SCF and RCF) and total nitrogen (97% of SCF, 99% of RCF). Further results show that three-dimensional anode structures could enrich more electrode surface biomass and diversify the biofilm microbial communities for promoting bioelectroactivity, denitrification, and nitrification. These results demonstrate that three-dimensional anodes with active biofilm is a promising strategy for creating scalable MFCs-based wastewater treatment system.