Treatment of Landfill Leachate by Using Fenton and Photo-Fenton Processes

The paper deals with the study on the use of the Fenton and photo-Fenton process for the treatment of landfill leachates from a stabilized landfill site. The effluents were characterized by pH of 8.1, color: 1320 mg Pt/L, COD of 1670 mg/L, of BOD₅ 155 mg/L, conductivity of 10.3 mS/cm, absorbance of UV₂₅₄ 0.332 and turbidity of 11 NTU. It has been shown that by using Fe(II) and hydrogen peroxide in the Fenton reaction, the organic compounds expressed as COD can be efficiently removed from the effluents. The process was carried out at various doses of H₂O₂ and Fe(II), using different reaction times in the Fenton process and different times of exposure in the photo-Fenton process. The best conditions for the Fenton process were obtained with a Fe/COD ratio of 1.4 and a H₂O₂/Fe molar ratio of 3.2. Under these conditions, the removal efficiency of COD was 85.8%. It was also shown that additional UV irradiation of leachate in the so-called photo-Fenton process and the use of appropriate hydrogen peroxide dosing conditions, can increase the effectiveness of COD removal. The maximum effect of COD removal in the photo-Fenton process was 70.7% at a dose of H₂O₂ 3.3 g/L and a dose of Fe(II) of 0.6g Fe/L. An additional advantage of the photo-Fenton process is the ability to shorten the reaction time and reduce the dose of iron, which can thus reduce the amount of deposits generated.