Reduction of cod in Nam Son landfill leachate by electro-fenton as secondary treatment after alectrocoagulation pretreatment

Abstract

The unstable composition and properties of pollutants, together with very high concentration of pollutants such as ammonia nitrogen, COD and especially persistent compounds such as polyaromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), heavy metals, so leachate is the object that is very difficult to deal with. In fact, after a pretreatment as electrocoagulation, over 73 % of COD has been treated from Nam Son landfill leachate, however the output value of COD still exceeds the QCVN 40:2011/BTNMT, column B. So, using electro-fenton technique as secondary treatment, just after an electrocoagulation pre-treatment was studied. This electro-fenton system using Pt gauze and carbon felt as an anode and a cathode respectively in order to electrochemically produce in situ hydrogen peroxide and regenerate Fe²⁺ catalyst, currently applied on the effectiveness in reducing COD in Nam Son landfill leachate was examined. At the optimal condition: pH 3, applied current of 1A, Fe²⁺ concentration of 0.1 mM, Na₂SO₄ concentration of 0.05 M, 77.2 % COD decrease could be reached within 60 min and the output value of COD is 130.9 mg.L-1 , according to QCVN 40:2011/BTNMT, column B. The research results indicated that the combination of an electrocoagulation with an electro-fenton process can effectively reduce the level of COD in Nam Son landfill leachate.