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 uti-lized 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/m2. 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.