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.

Landfill leachate treatment by sequential membrane bioreactor and electro-oxidation processes

“…As shown in Table 3, the mentioned removal efficiency was satisfactory for the current intensity of above 2 A, treatment time of 120 min, cathode and anode type of Ti and Nb/BDD, respectively. As Fernandes et al (2015) stated constant COD rate with current density higher than 40 mA/cm 2 , current intensity of 3 A (current density of 46 mA/cm 2 ) was selected as the upper range of our test. For understanding the effect of each factor on EOP, FD model was run for eight sets of experiment and the following mathematical models of COD and TOC removal efficiencies was gained by design expert software (Eqs.…”

Landfill Leachate Treatment by Combining Coagulation and Advanced Electrochemical Oxidation Techniques

“…[32] Electrochemical methods (a typical AOP), in particular, have been extensively investigated for the treatment of organic and inorganic pollutants that are found in several types of effluents. [46][47][48][49][50][51][52][53][54][55][56][57][58][59] This indicates that the type of electrode material does not, per se, ensure greater efficiency in these processes. Depending on the electrode material, this species may be weakly adsorbed on the surface of the electrode, favoring mainly the mineralization of organic substances.…”

“…[31,32] In the case of electrochemical treatments of RLL, BDD electrodes have shown remarkably good performance superior to that of other electrode materials, as described in detail by Mandal et al [31] In addition, although process performance is strongly dependent on the initial condition of RLL (young or old), parameters such as COD removal rates and energy consumption have proved to differ significantly, even when the same electrode material is used (BDD). [46][47][48][49][50][51][52][53][54][55][56][57][58][59] This indicates that the type of electrode material does not, per se, ensure greater efficiency in these processes. In this context, specific knowledge about the management of parameters such as applied current density, inter-electrode gap, hydrodynamic regime, ratio of electrode surface area to effluent volume, reactor geometry, etc., is essential to ensure greater process efficiency.…”