A novel oxidation-reduction combined treatment of dye wastewater: dual-target removal of conventional pollutants and AOX.

In order to improve the removal efficiency of COD and chromaticity, ozone catalytic oxidation is widely used in the treatment of dye wastewater. In this study, however, adsorbable organic halides (AOX) by-products were found to be generated during the oxidation process, leading to a significant increase in wastewater toxicity. The toxic equivalent contribution of AOX pollutants reached 45 % after ozone catalytic oxidation process, indicating an urgent need for further removal of AOX in the effluent. Therefore, an ozone catalytic oxidation-electrocatalytic reduction combined treatment was developed in this study. Experimental evidence proved that ozone catalytic oxidation stage can destroy the benzene ring structure and reduce the C-X bond orders of AOX pollutants, which is beneficial for subsequent electrocatalytic reduction dehalogenation. After optimizing the operating conditions through response surface methodology, the oxidation-reduction combined process showed good treatment effects on COD, total nitrogen and AOX pollutants in dye wastewater, and its effluent ultimately met the discharge requirements. As evidenced by luminescent bacteria, Chlorella vulgaris and zebrafish toxicity tests, the oxidation-reduction combined treatment significantly reduced the toxicity of dye wastewater. This study provides valuable insights into the performance and application potential of oxidation-reduction combined treatment, paving the way for efficient remediation of dye wastewater.