Landfill Leachate Treatment Using Coupled, Sequential Coagulation-flocculation and Advanced Oxidation Processes

Abstract

This study evaluated the efficiency of Fenton (Fe/H2O2) and photo-assisted Fenton (Fe2+/H2O2/UV) reactions combined with coagulation-flocculation (C-F) processes to remove the chemical oxygen demand (COD) in a landfill leachate from Mexico at a laboratory scale. The C-F experiments were carried out in jar test equipment using different FeSO4 concentrations (0.0, 0.6, 1.0, 3, and 6 mM) at pH = 3.0. The effluent from the C-F processes were then treated using the Fenton reaction. The experiments were carried out in a 500 mL glass reactor fillet with 250 mL of landfill leachate. Different molar ratio concentrations (Fe/H2O2) were tested (e.g., 1.6, 3.3, 30, 40 and 75), and the reaction was followed until COD analysis showed no significant further variation in concentration or until 90 min of reaction time were completed. The photo-assisted Fenton reaction was carried out using a UV lamp (365 nm, 5 mW) with the same Fe/H2O2 molar ratio values described above. The results suggested that the photo-assisted Fenton process is the most efficient oxidation method for removing organic matter and color in the leachate. The photo-assisted Fenton process removed 68% of the COD and 90% of the color at pH = 3 over 30 minutes of reaction time using a H2O2/Fe molar ratio equal to 75 only using a third of the reaction time of the previous process.