Adsorption/Ozonation integration for intensified ethyl acetate plant wastewater treatment: Process optimization and sensitivity analysis assessment

Abstract

For the first time, the ethyl acetate production plant wastewater was treated using a batch adsorption/ozonation integrated process. The wastewater contained alcoholic pollutants (majorly, ethanol) and the discharge of this wastewater could result in serious risks to the environment. The operational variables including reaction time (10 to 60 min), temperature (20 to 60 °C), ozone flowrate (4 to 12 L/min) and granular activated carbon (GAC) dose (5 to 15 g) were optimized by applying response surface methodology, where the removal of chemical oxygen demand (COD) was aimed to be maximized as the target variable. The optimal conditions were obtained at the reaction time of 60 min, temperature of 60 °C, GAC dose of 10 g and ozone flowrate of 8 L/min, which resulted in COD removal of 98.5 %. Characterization analyses revealed that ozonation could support in-situ regeneration of the GAC and provide a synergistic effect on the COD removal enhancement. The separation kinetics of the integrated process was also assessed and found to be superior than those of the standalone operations. Sobol sensitivity analysis results uncovered that the reaction temperature by 85 % and the binary interaction of the reaction time and temperature by near 7 % impact shares were the most effective parameters on the COD removal. Isothermal studies showed that the adsorption of ethanol on GAC is physical, multilayer and heterogeneous. Consequently, the integrated adsorption/ozonation process has been approved as a potential method for the treatment of ethyl acetate plant wastewater.