Treatment of landfill leachate by electrocoagulation method

Having complex structure and characteristics dependent on the age of landfill, leachate is one of those wastewaters difficult to treat. Along with developing technology, the search for higher-efficiency- and lower-cost-treatment techniques for leachate treatment is of priority. Today, electrocoagulation method with a number of advantages is encountered among advanced treatment techniques. In this study, the treatibility of leachate in a shorter period of tme with lower costs was investigated. Leachate samples were obtained from Odayeri Sanitary Landfill Site (Istanbul) during the study. Conventional coagulation and electrocoagulation were first compared in the aspects of COD removal rate, sludge production and sulfate concentration change. During the study, pH, temperature and spesific ionic conductivity were continuously observed. Ammonium nitrogen and COD removal efficiencies were tried to be increased by the use of aluminum and iron electrodes. Only after then was invstigated the effects of current density and mixing operation on optimal removal efficiencies. Besides, optimum reaction time was investigated for one-hour-current application. The energy need of electrocoagulation and different current densities were determined. The results showed that, for 1, 5, 15 and 30 minutes, ammonium nitrogen removal efficiencies were 8,8%, 9,6%, 11,2% and 14,6%, respectively. When ammonia stripping and pH adjustion are applied to increase ammonia removal, the efficiency reached 24,4%. COD removal efficiencies for the same reaction times were 45,5%, 49,2%, 53,6% and 59,1%, respectively. After 30 min of operation, pH of leachate increased from 8,2 to 9,6 and temperature increased from 23,7?C to 29,7?C. The results of the study revealed that electrocoagulation method can be used as a preliminary treatment method for leachate treament. Keywords: Leachate, electrochemical treatment, electrocoagulation, COD, ammonium nitrogen, mixing, aeration, optimisation.