IJSRST173160 | Received: 08 Feb-2017 | Accepted : 14 Feb-2017 | January-February-2017 [(3)1: 285-293 ] © 2017 IJSRST | Volume 3 | Issue 1 | Print ISSN: 2395-6011 | Online ISSN: 2395-602X Themed Section: Science and Technology 285 Evaluation of Electrochemical and Fenton Processes in the Treatment of Mature Landfill Leachates Alan Oliveira 1 , Alexandre Cerqueira 1 , Paulo Souza* 2 , Michelle Rigo 1 , Julieta Paiva 1 , Monica Marques 1 1 Environmental Technology Laboratory, State University of Rio de Janeiro, Rio de Janeiro, Rio de Janeiro, Brazil * 2 Osorio Foundation, Ministry of Defense of Brazil, Rio de Janeiro, Rio de Janeiro, Brazil ABSTRACT In this study, the effects of various operating conditions (reaction time, current intensity, pH and H 2 O 2 concentration) in treatment of old municipal landfill leachates by using electrochemical processes (electroflocculation, electro-Fenton and combined electroflocculation+electro-Fenton) was compared to Fenton's reagent oxidation process. The results of this work showed that, E-Fenton technology may be used efficiently for treatment of old municipal landfill leachates by using appropriate operating conditions. The best removal efficiency was obtained when the following operating conditions were used: reaction time of 30 minutes, current intensity of 2A, H 2 O 2 concentration of 0.5% and pH=3. In these conditions, the removal efficiencies achieved for chemical oxygen demand, colour and turbidity were, respectively: 70±2%, 92±2% and 92±2%. The results obtained by the present study revealed that the E-Fenton electrochemical process was efficient in the removal of high concentrations of chemical oxygen demand, colour and turbidity and could be an environmentally promising alternative for the treatment of mature landfills leachates. Furthermore, this process showed lower energy cost and consumption of electrodes Keywords: Landfill Leachate, Electro-Fenton, Electroflocculation, Alternating Current and Fenton I. INTRODUCTION Sanitary landfilling, although environmentally inadequate, is the most common alternative to treat old landfill leachate, mainly in countries like China, Brazil, India and others. Leachate is a liquid that has been seeped through the solid waste disposed in a landfill and contains extracted, dissolved or suspended materials [1]. Therefore, developing treatment technologies for landfill leachate requires further research to obtaining an efficient and economically viable process, aiming to reduce its potential to harm water resources, soil and biota. In old landfills, the leachate is characterized by a high chemical oxygen demand (COD) due to presence of non-biodegradable and high toxic organic compounds [2 -6], which requires the use of technologies, that can even be combined to increase their efficiency, to minimize the amount of pollutants to an acceptable level before its discharge into water flow [7, 8]. Among these technologies, stands outElectroflocculation (EF), Fenton, Electro-Fenton (E-Fenton) and Electrofloccculation- Electro-Fenton (EF+E-Fenton) combined processes. Electroflocculation (EF) is a process wherein flocculating metal ions are electrolytically added to the effluent by an anode and gas micro bubbles are released by acathode. The flocculating metal ions adhere to water pollutants increasing their size, and the gas micro bubbles capture the flocculated pollutants that float to the surface, from where they can be easily removed. By an appropriate choice of electrode materials, this process can remove a wide variety of pollutants without needing chemicals or filters [9 – 14]. When using direct current (DC) technology, the anode oxidation causes formation of an impermeable oxide layer over the cathode which increases the electrode resistivity. Along the time, the efficiency of EF process declines. This problem can be minimized by addition of sacrificial electrodes in parallel configuration to the electrolytic cell [15, 16]. Furthermore, to reduce the cathode passivation and