Treatment of cardboard factory wastewater using ozone-assisted electrocoagulation process: optimization through response surface methodology.

Cardboard factory wastewater is usually known by high chemical oxygen demand (COD), color, phenols, lignin, and its derivatives, and usual treatment techniques are not able to treat such wastewaters. This study aimed to investigate the efficiency of ozone-assisted electrocoagulation process (EC/O) for the treatment of real cardboard wastewater. The parameters influencing COD removal in the EC/O process were optimized using response surface methodology. Regard to the statistical model, the optimum conditions were obtained at current density 9.6 mA/cm, time 20 min, and pH 12. At optimal condition, EC/O process removed 74.7% and 97.5% of COD and color, which was higher compared to ozonation and EC processes separately. The COD removal followed pseudo-first-order kinetic with the coefficient correlation of 0.97 and the reaction rate constant of 0.073 1/min. To sum up, the combined electrocoagulation process with ozonation could be used satisfactorily for removing pollutants from real cardboard wastewater.