Changes in Dissolved Organic Matter by Fluorescence Excitation-Emission Matrix Analysis during Palm Oil Mill Effluent Treatment Using Dielectric Barrier Discharge

This study explored the treatability of dissolved organic matter (DOM) in palm oil mill effluent (POME) by dielectric barrier discharge (DBD) treatment under aerated and non-aerated conditions at different electric voltages of 15, 20, and 25 kV. The DOM composition was monitored by fluorescence excitation-emission matrix (EEM) analysis, and tryptophan-like Peak 2 and humic-like Peak 5 were dominant in POME. Chemical oxygen demand (COD), biochemical oxygen demand (BOD), and total solids (TS) were significantly removed by DBD treatment under aerated and non-aerated conditions by 93–98%, 96–98%, and 78–83%, respectively. The relative changes Peak 3/Peak 2 revealed the DOM treatability by DBD treatment, where more protein-like substances were reduced than humic-like substances, owing to the different composition interaction against the oxidation reaction performed by reactive species (O3, •OH, H2O2) generated from the DBD reactor. In contrast, humic-like substances increased after DBD treatment under aerated and non-aerated conditions. Fluorescence indices demonstrated that DBD treatment caused significant changes in the fluorescence index (FI), while no significant changes were observed in the humification index (HIX) and biological index (BIX). This study provides useful information on the changes in DOM from POME after DBD treatment, evaluated by fluorescence EEM analysis.