Optimization of electro-Fenton oxidation of biologically pretreated coal gasification wastewater by response surface methodology

The response surface methodology coupled with central composite design was applied to optimize the operational parameters of electro-Fenton (EF) as advanced treatment of biologically pretreated coal gasification wastewater. The integration of TOC, COD, and total phenols removal was selected as the response for model establishment and optimization. A quadratic model with high significance was developed to predict the treatment performance and optimize process parameters. The optimal parameters were determined as pH 3.83, 1.44 mmol L⁻¹ of Fe²⁺ concentration, and 16.28 mA cm⁻² of current density, with the predicted optimal integration removal efficiency of 73.29%. TOC decay in the EF under optimal condition followed pseudo-first-order kinetic reaction with the apparent rate constant of 0.0103 min⁻¹. The mass transfer constant was determined to be 4.29 × 10⁻⁵ m s⁻¹ at the optimal current density. The results demonstrated that EF could serve as a technically feasible and cost-effective method with potential applications for the advanced treatment of biologically stabilized coal gasification wastewater.