Performance of Ozone/Fenton in the Advanced Oxidation Process of Semi-Aerobic Landfill Leachate

Leachate pollution is one of the main problems in landfilling, and researchers have yet to find an effective solution to this problem. The technology that can be used may differ based on the type of leachate produced. In Malaysia, the most problematic pollutants in semi-aerobic (stabilized) leachate are chemical oxygen demand (COD), ammoniacal nitrogen, and color. In the present study, the performance of ozone/Fenton in advanced oxidation process in removing these pollutants was investigated. The optimal dosages of Fenton reagent (0.05 mol L-1 (1,700 mg/L) H2O2 and 0.05 mol L-1 (2,800 mg/L) Fe2+) were determined through preliminary experiments and added to the leachate sample into the ozone reactor. The input ozone concentration in a 2 L leachate sample was 80 g/m3NTP ± 0.5% under 1 bar pressure. The initial COD varied between 250 and 2360 mg/L, color varied between 470 Pt. Co. to 4530 Pt. Co., and NH3-N varied between 150 mg/L to 1170 mg/L. Accordingly, the maximum removal efficiency was 87% for COD, 100% for color, and 22% for NH3-N at lowest leachate concentration. The lowest amount of consumed ozone (1.28 KgO3/ Kg COD) corresponds to the initial concentration of COD (2000 mg/L) with 60% removal of COD during 1 h ozonation. Moreover, the biodegradability (BOD5/COD) ratio improved from 0.09 in raw leachate to 0.27 at 500 mg/L initial COD. The current study revealed that the use of ozone/Fenton (O3/H2O2/Fe2+) in advanced oxidation process is more efficient in removing COD and color in low concentrations of semi-aerobic stabilized leachate and in improving biodegradability.