Effects of reaction conditions on the oxidation efficiency in the Fenton process

The purpose of this study is to efficiently operate Fenton’s oxidation process with quantitative analysis of the amount of the organic substances removed by oxidation and coagulation in treatment of the non-biodegradable landfill leachate by Fenton’s reagents. The sample used was the biologically treated leachate in the Kimpo metropolitan landfill site in Korea and its COD, BOD5, NH3–N and Cl− concentrations were about 1500, 30, 1300 and 4500 mg/l, respectively. The COD removal by oxidation of the organic substances with hydrogen peroxide was most efficient in the pH range of 2.5–4. However, it drastically decreased according to the pH value above 5. The COD removal efficiency by coagulation increased with the increase of the ferrous sulfate dosage, but the overall efficiency over a minimum dosage of 500 mg/l was scarcely changed. The efficiency of hydrogen peroxide actually used in the oxidation of the organic substances was only about 45%. The optimum range of the coagulation pH to maximize the COD removal efficiency by coagulation was 3–6, but that was slightly lower than the pH range of 6–9 generally known in the literature.