Treatment of Old Leachate by Electro-Coagulation: A Case Study for Leachate of Kahrizak Landfill in Tehran

Leachate of urban solid waste landfills is one of the most important of environmental concerns. Today, electro-coagulation is considered as a method for leachate treatment. In this process coagulants are produced during metallic electrode dissolution. In this article, treatability of old leachate of Kahrizak landfill of Tehran by electro-coagulation method was studied. The study was done in laboratory scale by using steel electrodes grades ST-12, ST-37, and CK-45 and measuring COD, SS and ORP parameters. COD removal was obtained 42.66, 34.37 and 35.2 percent for ST-12, ST-37 and CK-45 electrodes while the operation time and current were 100 min and 7.2 A for initial COD concentration of 160,000 mg/l. COD removal increased 6.78, 4.38 and 12.12 percent when the operation time increased to 140 min, respectively. As well, COD removal was increased 38.98, 22.64 and 25.38 percent and SS removal was enhanced 16.4, 19.79 and 18.71 percent for ST-12, ST-37 and CK-45 electrodes, while the current density increased from 33.33 to 66.166 A/m2. The results also showed ST-12 electrode had the best efficiency for leachate treatment with COD and SS removal of 64.67% and 98.79% respectively while the current density was 66.166 A/m2 equals charge’s loading of 46.155 F/m3.