Statistical Comparison of Response Surface Methodology–Based Central Composite Design and Hybrid Central Composite Design for Paper Mill Wastewater Treatment by Electrocoagulation

Abstract

Response surface methodology is a widely used mathematical tool for optimization and recently fast growing toward wastewater treatment process optimization. Paper mill wastewater treatment by electrocoagulation using RSM has been found widespread with use of central composite design. The present research work deals with the comparison of central composite design and hybrid central composite design for treatment of paper mill wastewater by electrocoagulation. The advantages and drawbacks of both designs were described, and detailed statistical evaluation of applied models was performed. The set of experimental runs was determined by using RSM-based central composite design and hybrid central composite design to evaluate the individual and interactive impacts of process parameters on treatment effectiveness. The impact of essential process factors pH (Asghar et al. 2014; Ashrafi et al. 2015; Azadi et al. 2015; Bellebia et al. 2011; Box and Behnken 1960; Box and Wilson 1951; Chen et al. 2000; Chollom et al. 2019), conductivity (3.15–10 mS/cm), electrode distance (1–2.5 cm), and current density (5–20 mA/cm2) on three response parameters of chemical oxygen demand, color, and total dissolved solid was evaluated. Regression coefficient and p value for all response variables are > 0.90 and < 0.05 respectively. For both designs, central composite design and hybrid central composite design indicate that both models are statistically significant and are in well agreement with predicted and experimental data. Comparison of the distribution of responses in the design region between central composite design and a hybrid central composite design in single curve is represented by fraction of design space. Derringer desirability for all response optimizations over optimum operating conditions is determined at hundred design point for global solution.