IHSS&IWA26 / BRNO / CZECHIA / 23–28 August 2026 BOOK OF ABSTRACTS 152 Soil Organic Matter, Caustobiolites, and Biochar Thursday, 27 August 2026 / Hall B SL76 Analysis of Natural Organic Matter Removal and Structure Changes Using PEMBased Electrochemical Oxidation Yeji Seo1, Jongkwan Park2* 1 Department of Environmental Engineering, Changwon National University, Republic of Korea, 20257597@gs.cwnu.ac.kr 2 Department of Environment & Energy Engineering, Changwon National University, Republic of Korea, jkpark2019@changwon.ac.kr Natural organic matter (NOM), including humic and fulvic acid present in drinking water sources and effluents from water treatment plants, contributes to various environmental issues such as the formation of disinfection by-products (DBPs), heavy metal complexation, and membrane fouling. Recently, electrochemical oxidation processes have attracted attention as advanced treatment technologies capable of addressing these challenges. This study aims to evaluate the removal efficiency of NOM and investigate structural changes before and after treatment using proton exchange membrane (PEM)-based electrochemical oxidation. Experiments were conducted using refractory NOM components, including humic acid (HA, 5 mg-C/L as TOC basis), protein-like organic matter, bovine serum albumin (BSA, 5 mg-C/L) and effluent organic matter (EfOM, 5 mg-C/L). A PEM electrochemical system was operated under a constant current density of 40mA/cm2, and sodium chloride (NaCl, 5 g/L) was added as an electrolyte to generate hypochlorous acid (HOCl) for indirect oxidation. Removal efficiency was assessed using dissolved organic carbon (DOC), while UV254 absorbance and specific UV absorbance (SUVA) were analyzed to characterize organic matter properties. Furthermore, fluorescence excitation-emission matrix (EEM), fluorescence index (FI), biological index (BIX), humification index (HIX), and HPLC-SEC (high-performance liquid chromatography–size exclusion chromatography) were employed to examine structural changes. Under indirect oxidation conditions, DOC removal efficiencies were 34.6% for humic acid, 51.1% for BSA, and 49.8% for EfOM. Continuous oxidation over 8 hours resulted in a gradual decrease in HIX (1.35 → 0.868) and a shift toward lower molecular weight fractions in HPLC-SEC analysis, confirming sustained degradation of refractory NOM. This study demonstrates that PEMbased electrochemical oxidation is an effective technology for removing refractory natural organic matter and altering its structural characteristics. The results highlight its potential as an advanced water treatment process capable of achieving high treatment
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