Landfill leachate treatment with electrocoagulation: optimization by using Taguchi method

Abstract

In this study, the electrocoagulation (EC) method was used to treat landfill leachate (LL). pH, reaction time (electrolysis time) and current density were selected as independent parameters for an experimental design employing Taguchi orthogonal arrays. These independent parameters were varied at five different levels (pH: 3, 5, 7, 9 and 11; reaction time: 5, 10, 15, 20 and 25 min; current density: 10, 20, 30, 40 and 50 mA/cm(2)) to determine their effects on the removal efficiencies of selected dependent parameters. COD, soluble COD (sCOD) and color were selected as the dependent parameters and analyzed at the beginning and end of each batch experiment. Aluminum and iron electrodes were used for separate batch studies. The maximum removal efficiencies of COD, sCOD and color with Al electrode pairs were found to be 62% (for 3-5-2 levels), 51% (for 4-4-2 levels) and 88% (for 1-5-5 levels), respectively. Moreover, the removal efficiencies of COD, sCOD and color with Fe electrodes pairs were found to be 39% (for 4-3-1 levels), 39% (for 1-1-1 levels) and 81% (for 1-5-5 levels), respectively. The operational costs of LL treatment with Al electrodes pairs were calculated to be between 3.64 and 4.53 USD$/m(3) LL. According to the Taguchi method, the contributions of pH, current density and reaction time to COD removal efficiency were found to be 79.35%, 6.45% and 4.46%, respectively.