Chemical and electrochemical combined processes to treat sanitary landfill leachates

Abstract

The application of combined chemical coagulation and electrochemical oxidation processes to treat a leachate from an intermunicipal sanitary landfill was evaluated. Chemical coagulation (CC) experiments were performed with lime (Ca(OH)2), and the influence of the lime concentration, stirring speed and assay duration were studied. In the electrochemical oxidation (EO) assays, a boron-doped diamond anode was used, and two applied current intensities were tested. It was also evaluated the influence of the lime concentration used in the CC pre-treatment on the EO performance. In the CC assays, the highest COD removals were obtained for lime concentrations of 20 and 25 g L-1, at 100 rpm stirring speed, during 2 h. In the CC+EO combined treatment the highest removals were obtained at the applied current intensity of 0.6 A, being the influence of the lime concentration used in the pre-treatment almost insignificant. The highest current efficiency was obtained for the combined treatment with EO assays performed at 0.4 A.