Anodic Oxidation of Effluents from Stages of MBR-UF Municipal Landfill Leachate Treatment Plant

Abstract

This study used boron-doped diamond electrode on niobium substrate (Nb/boron-doped diamond [BDD]) for the anodic oxidation of landfill leachate in a batch reactor. Raw leachate and biologically pretreated effluent samples were collected from each step of the existing unit operation of a municipal landfill leachate treatment plant (Kocaeli-Turkey). The influence of parameters, such as treatment time, initial pH (3.50-10.0), and applied current density (j = 76-1,060 A/m(2)), on the removal of total organic carbon (TOC), chemical oxygen demand (COD), and ammonium nitrogen (NH4+-N) was assessed. The highest pollutant removal efficiencies were obtained at leachate inherent pH (6.50-8.75), moreover, pollutant removal rates increased with the increase in current density. The NH4+-N removal mainly occurred by indirect oxidation and well fitted second-order kinetics, whereas COD removal followed pseudo first-order kinetics. The optimum current density ensuring simultaneous removal of COD and NH4+-N was 756 and 455 A/m(2)for raw leachate and for pretreated effluents, respectively. Under these optimums, nearly complete NH4+-N removal was attained, while >= 97% removal of TOC and COD was recorded. Herein, we present anodic oxidation as a suitable alternative for treatment of both stabilized raw leachate and effluents from stages of the membrane bioreactor/ultrafiltration treatment plant for the abatement of COD, TOC, and NH4+-N.