Investigating the Efficiency of Combination of Ozone Based Advanced Oxidation Process and Nanobubbles in Removing the Chemical Oxygen Demand (COD) from Zar Grain Refinery Industrial Wastewater

Abstract

This study was designed to evaluate the efficiency of a combined Advanced Oxidation Process (AOP) and Ozone Nanobubbles (NB) for treating industrial wastewater from the Zar Grain Refinery. To this end, the optimal concentrations of three oxidizing agents including ozone (O3), hydrogen peroxide (H2O2), and iron chloride (FeCl3) were initially determined using Response Surface Methodology (RSM) and Central Composite Design (CCD). In each experiment, wastewater samples from the Zar Grain Refinery were treated under consistent conditions with varying concentrations of the oxidizing compounds. Then, through multi-objective optimization, an optimal value of O3, H2O2, and FeCl3 was calculated to achieve maximum wastewater treatment efficiency. The results indicated that O3 had the most significant impact on reducing wastewater COD rates, showing approximately a 75% increase in COD removal efficiency. Regression models revealed that the interactive and non-linear effects of the oxidizing agents on COD reduction were significant. Based on these findings, it can be concluded that the combined AOPs would demonstrate high efficiency in removing COD from Zar Grain Refinery industrial wastewater. Finally, in addition to investigating the efficiency of the AOP process in treating wastewater from other industries, it is recommended that further studies be conducted to optimize other operational parameters influencing the wastewater treatment process, such as reaction time and temperature.