Bio-cathodic treatment of toluene and nutrients in an integrated bubble column-microbial fuel cell: Electricity...

An integrated bubble column reactor-microbial fuel cell (BCR-MFC) was developed for simultaneous aerobic toluene vapor biodegradation, nitrification, heterotrophic denitrification, and electricity generation. The BCR-MFC was tested under various inlet loading rates (ILRs) of toluene to the bio-cathode chamber. The maximum elimination capacity (EC_max) reached 248 g m^-3 h^-1 at an ILR of 456 g m^-3 h^-1. Optimal performance occurred at an ILR of 306 g m^-3 h^-1, yielding an EC of 208 g m^-3 h^-1 and a voltage output of 522 mV based on the integrated efficiency parameter (ε). The highest power density (4.8 W m^-3) was obtained at the lowest ILR (70 ± 6 g m^-3 h^-1). At an ILR of 316 ± 30 g m^-3 h^-1, NH₄⁺-N decreased from 1.3 g L^-1 to 0.134 g L^-1, and NOₓ^--N from 1.3 g L^-1 to 0.239 g L^-1. Microbial community analysis revealed increased abundance of toluene-degrading bacteria, heterotrophic denitrifiers, and nitrifiers, including Pseudomonas, Paracoccus, Zoogloea, and Bacillus. These results highlight the BCR-MFC ability to couple efficient toluene degradation with nitrogen compound removal while producing bioelectricity, facilitated by the coexistence of essential microbial species in the bio-cathode chamber.