Kinetics of electrooxidation of landfill leachate in a three-dimensional carbon bed electrochemical reactor

The electrooxidation of high strength leachate from an industrial solid waste landfill site was carried out in a three-dimensional carbon bed electrode reactor (TDR). This paper discusses the kinetics and mechanism of electrooxidation on the basis of time course variation of COD, TOC and TKN (total Kjeldahl nitrogen) from the raw leachate. The batch experiments were run at different applied currents (1–3 A) for a period of 6 h. A two-stage pseudo-first order reaction kinetics model was developed based on the initial rapid removal of pollutants (Phase I) followed by slow oxidation kinetics (Phase II). About 60–64% COD was removed within 1 h with a rate constant 5.83 × 10−3 min−1 in Phase I, which was near 5–7 times greater than that of Phase II (0.81–1.03 × 10−3 min−1). The mineralization efficiency was found to be significant in the range 0.83–0.84. The apparent faradic efficiency and specific energy consumption for COD removal were also estimated. The mechanism of electrooxidation was discussed with the help of adsorption, kinetic and SEM results.