Evaluation of integrated UFCW-MFC reactor for azo dye wastewater treatment and simultaneous bioelectricity generation

Abstract

An up-flow constructed wetland (UFCW) incorporating a novel membrane-less air-cathode single-chamber microbial fuel cell (MFC) was designed to treat dye wastewater and simultaneously generate bioelectricity. The performance of UFCW-MFC was evaluated via Methyl Orange (MO) and chemical oxygen demand (COD) removal rates and the output voltage. For comparison, the performance of a single UFCW was also assessed. A repeatable and stable voltage output of about 0.44±0.2 V was obtained in UFCW-MFC. The MO and COD removal rates in UFCW-MFC were 93.5 and 57.2%, respectively, significantly higher than those in single UFCW (75.4 and 42.6%, respectively), suggesting the obvious enhancement of electrodes on MO and COD removal. The anode zone of UFCW-MFC made the most contribution to MO and COD removal compared with other layers. The oxidation-reduction potential (ORP) and dissolved oxygen (DO) profiles showed that the anaerobic environment was well developed in the lower part of UFCW-MFC (0–24 cm) and the upper part (41–42 cm) had a good aerobic environment, thus greatly contributing to the MO anaerobic reduction and aerobic degradation of breakdown products. These results obtained here suggest that the UFCW-MFC may provide an effective alternative for the treatment of dye wastewater and simultaneous bioelectricity generation.