Synergic mechanisms of electricity generation and bisphenol a degradation in a novel photocatalytic-microbial fuel cell equipped with a TiO2-C-BiVO4 photo-anode and a biofilm-anode

Abstract

To provide a promising strategy for coping with the issues of energy shortage and wastewater treatment, a novel single-chamber photocatalytic-microbial fuel cell (PC-MFC) equipped with a photo-anode and a biofilm-anode was firstly established to degrade bisphenol A (BPA). The results showed that due to the ex-situ dual-anode configuration, the output voltage increased rapidly and maintained for three cycles with the maximum voltage of 0.55 V. In addition to the electrochemically-active bacteria (EAB) including Geobacter and Pseudomonas, TiO2-C-BiVO4 with Z-scheme was induced into PC-MFC as photoanode, which not only contributed the photoelectrons to electricity generation, but also functioned as redox mediator to regulate extracellular electron transfer (EET) processes. Within 12 h, the degradation and mineralization efficiency of BPA achieved 96.98% and 82.80%, respectively. Under the simulated solar irradiation, extra reactive oxygen species (ROS) induced by TiO2-C-BiVO4 and extracellular polymeric substances (EPS) in the biofilm contributed primarily to BPA degradation, assisted by the biodegradation of the functional bacteria and algae. The degradation routes of BPA were revealed based on the degradation intermediates detected by UPLC-MS and DFT calculation. Moreover, the toxicity of BPA was almost eliminated according to ECOSAR procedure, since the toxic intermediates can be fixed onto EPS as the microbial protective layer, and further degraded by ROS into the products with relatively high bioavailability, which enhanced the electricity generation. Thus, this study provided a novel way for advanced treatment of organic chemicals and power recovery from the wastewater to boost carbon neutralization.