Oxidative degradation of organic pollutants in high chloride wastewater

With the rapid economic development in China, the total amount of high chloride wastewater produced by the chemical industry has been steadily increasing. The high-chlorine wastewater typically contains a significant amount of recalcitrant organic pollutants and high concentrations of chloride ions, which must be appropriate treated to meet national standards before being discharged. This study aims to evaluate the efficiency of Fenton oxidation, Ozone oxidation, and the combined Fenton/Ozone oxidation process in removing organic pollutants from high-chlorine wastewater, using Chemical Oxygen Demand (COD) as the primary evaluation indicator. The results indicate that the combined Fenton/Ozone process achieves a COD removal efficiency of 75.87% and a total organic carbon (TOC) removal efficiency of 94.89%. Compared to the individual application of Fenton oxidation and Ozone oxidation, the combined process improved COD removal efficiency by 13.37% and 6.40%, respectively. Additionally, pre-treatment with bismuth sulfate to remove chloride ions from high-chlorine wastewater can effectively enhance the COD removal efficiency of the combined Fenton/Ozone process to 81.64%. Free radical scavenging experiments suggest that the pre-removal of chloride ions can increase the utilization rate of •OH radicals, thereby enhancing the oxidation efficiency of the Fenton/Ozone process. This study provides new insights and theoretical guidance for the removal of organic pollutants from high-chlorine wastewater.