Optimization of Fenton and electro-Fenton oxidation of biologically treated coking wastewater using response surface methodology

► Treatment of biologically stabilized coking wastewater by Fenton and electro-Fenton. ► Optimization of operating parameter using response surface methodology. ► Fenton and electro-Fenton reaction resulted in 75.1% and 55.8% of TOC removal, respectively, under optimum conditions. In this study, Fenton and electro-Fenton were employed to treat biologically stabilized coking wastewater, i.e. the effluent of a biological coking wastewater treatment. The Box–Behnken experimental design (BBD) and response surface methodology (RSM) were used to design and optimize the performance of both processes. The regression quadratic model describing the TOC removal efficiency of Fenton and electro-Fenton process was developed and validated by the analysis of variances (ANOVA), respectively. The significance levels of linear and interaction effects of the reaction parameters on processes efficiencies were obtained. The optimum parameters were determined as pH 4, 1.2 h reaction time, 40 mM of Fe 2+ and H 2O 2 for Fenton reaction; and pH 4, 1.8 h reaction time, 0.6 mM of Fe 2+ and 3.7 mA/cm 2 of current density for electro-Fenton. The corresponding TOC removal efficiencies were about 75% and 55% for Fenton and electro-Fenton, respectively. Both Fenton and electro-Fenton are effective in advanced treatment for coking wastewater, and the response surface methodology is suitable for the design and optimization of the processes.