Synergistic degradation of o-chlorophenol in aerobic microbial fuel cells with a coupled photocatalytic-bioelectrochemical anode

An aerobic single-chamber microbial fuel cell (MFC) system coupled with a photocatalytic-bioelectrochemical anode is constructed for the synergistic degradation of o-chlorophenol (2-CP). Dissolved oxygen (DO) is utilized by photocatalytic and biological processes to enhance the removal of 2-CP. The degradation efficiency for 2-CP is significantly improved (DO decreases from 6.17 to 0.02 mg/L in 8 h), showing that the mean 2-CP removal efficiency (300 mg/L) is 67.1%, higher than those obtained with the anaerobic photocatalytic MFC (31.4%), aerobic MFC (20.5%), and anaerobic MFC (17.7%). Interesting, DO enhances the abundance of Geobacter sp. from 2.31 to 22.5% while enriching the biomass. In addition, the abundance of chlorophenol-degrading bacteria Azospirillum sp. and electrogenic bacteria Comamonadaceae fam. increase from 0.3 to 17.0% and 0.48 to 32.1% with illumination, respectively. Illumination and DO facilitate the cathodic oxidation-reduction reaction and upgrade electricity production from 134 to 255 mW/m 2 . The electrogenic bacteria rely on the electron transfer pathway of nicotinamide adenine dinucleotide dehydrogenase , succinate dehydrogenase, and terminal oxidase. Unlike the traditional anaerobic mode, the intimate coupling of photocatalysis and bio-electrocatalysis under aerobic conditions provides a more effective strategy for treating wastewater containing refractory pollutants and broadens the scope of MFC technology applications.