H2O2 Oxidation of Pre-Coagulated Semi Aerobic Leachate

Heavily polluted wastewater from sanitary landfill presents the leachate characteristics that need special treatment and disposal. Concentration of chemical oxygen demand (COD), ammonia nitrogen (NH₃-N), heavy metal and other pollutant content are often larger than standard requirement after applying biological/physico-chemical treatment.Thus, the combination of coagulationflocculation and chemical oxidation treatment has been investigated. Using the jar-test procedure and stirrer, the physico-chemical conditions were optimized. It concerns the most effective coagulant between ferric chloride (FeCl₃) and poly-aluminum chloride (PACl), the optimal pH and the H₂O₂ as the most effective chemical oxidant. The optimum pH and dosage of PACl and FeCl₃ were obtained as 7 and 2.0 g/L, 5 and 1.0 g/L respectively. Iron salts were proved to be more efficient than aluminum ones, resulting in COD reduction (up to 59%) whereas the corresponding values using alum was lower (50%). The optimum pH and dosage of PACl and ferric chloride for optimum oxidation process was; 300 mg/L at pH7 and 300 mg/L at pH 6 respectively. Oxidation process gave significant effect to the removal of suspended solids and turbidity (up to 94%) using supernatant contain with ion Fe³⁺ at pH 7.

Keywords
Coagulation and flocculation, Alum, Ferric chloride, Oxidation, Hydrogen peroxide