COD and color removal from real textile dyeing effluent using intensification of ozonation and Fenton (O3/Fe2+/H2O2) processes: optimization using RSM

Abstract Textile dyeing effluent (TDE) contains number of organics and undesired recalcitrant dyes hence its treatment is required. The intensification of ozonation and Fenton (O3/Fe2+/H2O2) processes for the removing of recalcitrant dyes from real TDE was explored. The process parameters viz. ozone concentration, initial pH, Fe2+, and H2O2 concentrations are optimized using the central composite design (CCD) of the response surface method (RSM). Because the RSM well acceptable tool for process optimization by using the relationships between multiple input variables and a desired output. The high coefficient of determination (R2 = 0.9599 for Color and R2 = 0.9761 for chemical oxygen demand (COD) indicated an excellent correlation between the experimental and RSM-predicted values of COD and color removal efficiency. The optimum RSM-predicted color and COD removal efficiencies of 89.17%, and 82.52%, respectively, were obtained at an ozone concentration of 70 mgL−1, Fe2+ concentration of 1748 mgL−1, H2O2 concentration of 8.65 mlL−1, and pH 3. The O3/Fe2+/H2O2 process was found to have greater treatment efficiency and cost-effectiveness than ozonation alone. At the optimum condition first order reaction is fitted well as compared to second and Behnajady–Modirshahla–Ghanbary (BMG) model. Undesired degraded products are settle down with sludge. Graphical Abstract