Optimization of stabilized leachate treatment using ozone/persulfate in the advanced oxidation process

Highlights: ► Ozone and persulfate reagent (O3/S2O82-) was used to treat stabilized leachate. ► Central composite design (CCD) with response surface methodology (RSM) was applied. ► Operating variables including ozone and persulfate dosage, pH variance, and reaction time. ► Optimum removal of COD, color, and NH3–N was 72%, 96%, and 76%, respectively. ► A good value of ozone consumption (OC) obtained with 0.60 (kg O3/kg COD). - Abstract: The objective of this study was to investigate the performance of employing persulfate reagent in the advanced oxidation of ozone to treat stabilized landfill leachate in an ozone reactor. A central composite design (CCD) with response surface methodology (RSM) was applied to evaluate the relationships between operating variables, such as ozone and persulfate dosages, pH, and reaction time, to identify the optimum operating conditions. Quadratic models for the following four responses proved to be significant with very low probabilities (<0.0001): COD, color, NH3–N, and ozone consumption (OC). The obtained optimum conditions included a reaction time of 210 min, 30 g/m3 ozone, 1 g/1 g COD0/S2O82- ratio, and pH 10. The experimental results were corresponded well with predicted models (COD, color, and NH3–N removal rates of 72%, 96%, and 76%, respectively, and 0.60 (kg O3/kg COD OC). The results obtained in the stabilized leachate treatment were compared with those from other treatment processes, such as ozone only and persulfate S2O82- only, to evaluate its effectiveness. The combined method (i.e., O3/S2O82-) achieved higher removal efficiencies for COD, color, and NH3–N compared with other studied applications. Furthermore, the new method is more efficient than ozone/Fenton in advanced oxidation process in the treatment of the same studied leachate