Textile wastewater treatment with Ozone/Fenton process: Effect of pH

Abstract

In this study, ozone/Fenton process was applied to biologically treated textile wastewater (Dissolved organic carbon, (DOC): 150 mg/L, color 500 Pt-Co) to investigate residual color and DOC removal. Ozone dose and Fe+2/H2O2 molar ratio was kept constant at 1.28mg/min and 1:1, respectively. Initially, ozone and Fenton process (Fe+2/H2O2) was optimized separately under varying pH (4-9). Afterwards, effect of the varying pH values (4-6-8) on combined ozone/Fenton process was studied to optimize the color removal performance. System performance was evaluated by color, organic carbon and mixed liquor suspended solids (MLSS) parameters. Increasing pH increased color removal efficiency, which was evaluated based on influent and effluent parameters, for ozone process. However, relatively lower pH values (pH 4) were efficient for Fenton process. When combined ozone/Fenton process was applied, maximum color and DOC removal was obtained at pH 4, corresponding to 73%, 4% removal efficiencies, respectively. In this study, combination of ozone and Fenton processes provided higher color removal efficiency and lower sludge formation compared to separate ozone and Fenton process.