Comparison of a novel electro-Fenton method with Fenton's reagent in treating a highly contaminated wastewater.

This study applied a novel electrochemical process called the Fered-Fenton method to treat a highly concentrated wastewater. By combining electrochemical reduction and chemical oxidation, the process can remove organic compounds and heavy metals in a batch reactor. A PVC-stabilizer processing wastewater was treated in this investigation owing to its high heavy metal concentration (Pb = 7,500 mg/l) and high organic concentration (COD = 11,000 mg/l). The major organic component was acetate. Direct anodic oxidation showed no effect on COD removal. Fenton's method only removed 36% of COD using 4,000 mg-Fe2+/l and 28,000 mg-H2O2/l dosage. In the Fered-Fenton process, about 89% of COD was removed with 2,000 mg-Fe3+/l and 28,000 mg-H2O2/l. Furthermore, the COD removal attained an efficiency of about 98% for 56,000 mg-H2O2/l used. Results presented herein demonstrate that the Fered-Fenton method is superior to direct anodic oxidation and Fenton's method in this case. Furthermore, the changes of the intermediate compounds including acetate, oxadate, and formate during the reaction were analyzed, which provided us with the information to propose degradation reactions of the wastewater in this system.