Optimization of the Catalytic Ozonation Process via MgO in Presence of Persulfate for Removal of Dye from Real Textile Wastewater Applying Fractional Factorial 3-Level Design

Background and purpose: Using catalysts to enhance the efficiency of the ozonation process (known as catalytic ozonation process) has received much attention in recent years. This study aimed at examining the overall feasibility of using catalysts ozone as catalyst in ozonation process for decolorization and mineralization of a real textile wastewater in presence of persulfate. Materials and methods: This experimental study was conducted on a laboratory scale reactor using a semi-batch mode. The effect of persulfate, ozone flow rate, reaction time and catalytic dose in dye and COD was investigated in an optimal state of textile wastewater. To obtain optimization test, the experiment was performed by fractional factorial method at three-level factorial (3k−p) with a high resolution (VI). Results: In this study, 15 min contact time (P = 0.006) and 0.5g/L dose of catalyst (P=0.029) had the best effect on color removal. Moreover, the interaction of these parameters were found to be significant (P= 0.025). The optimum condition for color removal was achieved at 15 min reaction time, ozone flow rate of 2 L/min, 1.5 mM persulfate and catalyst dosage of 0.5 g/L. Optimum efficiency removal for color and COD in textile wastewater were 96% and 75%, respectively. Conclusion: Application of nano-magnesium oxide with ozone in presence of persulfate showed synergistic effect and buffering property in decolorization and mineralization of textile wastewater. It also increases the efficacy of color removal and improves mineralization so, there would be no need for pH adjustment.