Characterization of Dissolved Organic Matter in Landfill Leachate during Two–Stage Membrane Bioreactor Treatment

Abstract

Landfill leachate is a complex wastewater containing high concentration of dissolved organic matter (DOM). In this study, DOM in raw leachate and treated water from pilot–scale two–stage membrane bioreactor (MBR) installed at solid waste disposal site were investigated by using fractionation method, fluorescence excitation–emission matrix spectroscopy (FEEM) and fourier transform infrared (FTIR). The fractionation results showed hydrophilic (Hyl) compound was the most abundant fraction in DOM of raw leachate, whereas the dominant fraction of DOM in mixed liquor inside MBR and its effluent was fulvic acid (FA). The fluorescent peaks of protein-like, humic and fulvic–like substances were detected in influent DOM, while the fluorescence peaks of MBR and effluent DOM were humic and fulvic-like substances. From the FTIR results, absorption bands that could be related to humic acid (HA) and FA were found in both MBR and effluent DOM. The characterization of DOM indicated that the most of Hyl and protein–like substances could be significantly removed by microbial process in MBR. Furthermore, a part of humic substance (HA and FA) could be eliminated by microbial and filtration processes.