BOOK OF ABSTRACTS 273 IHSS&IWA26 / BRNO / CZECHIA / 23–28 August 2026 Hall A Poster Session / Technologies and Applications P5.10 Influence of NOM on Visible-Light Photocatalytic Treatment of Pharmaceutical Contaminants in Water Treatment Processes Jong Kwon Choe1, Cheehun Han2, Yongju Choi3 1 Seoul National University, Department of Civil, Urban and Environmental Engineering, 1 Gwanak-ro, Gwanak-gu, Seoul, Republic of Korea 08826, jkchoe@snu.ac.kr 2 Seoul National University, Department of Civil, Urban and Environmental Engineering 3 Seoul National University, Department of Civil, Urban and Environmental Engineering This study evaluates the influence of natural organic matter (NOM) on the performance of a tungsten trioxide (WO3)-based visible-light photocatalyst for the removal of pharmaceuticals and personal care products (PPCPs) in water treatment processes. A total of 14 PPCPs frequently detected in surface waters across South Korea were investigated. Under visible-light irradiation, WO3 achieved up to 99% removal of PPCPs in deionized water within 1 h, except for iopromide. However, photocatalytic degradation was significantly suppressed in real water matrices, including influent, post-filtration effluent, and postactivated carbon (post-AC) effluent, where the median half-life (t1/2) of PPCPs increased by 42-, 35-, and 15-fold, respectively. Mechanistic analysis revealed that bicarbonate (HCO3⁻) moderately inhibited PPCP degradation, increasing median t1/2 by 1.7-fold, whereas other inorganic constituents had negligible effects at environmentally relevant concentrations. In contrast, NOM emerged as the dominant inhibitory factor, critically governing photocatalytic efficiency. Both NOM composition—specifically the relative abundance of humic-like versus protein-like components—and dissolved organic carbon concentrations played key roles in determining degradation kinetics. Based on these findings, a quantitative performance benchmark is proposed for practical application: visible-light photocatalytic systems must achieve steady-state hydroxyl radical (HO•) concentrations on the order of 1.2 × 10⁻¹² M (approximately 180 times higher than those generated by WO3 under current conditions) or alternatively employ oxidation pathways less susceptible to scavenging by NOM and bicarbonate while maintaining high selectivity toward target PPCPs. These results highlight the critical need to account for NOM characteristics when designing and implementing photocatalytic water treatment systems. Acknowledgement This work was supported by the National Research Foundation of Korea (NRFRS-2025-25416704).
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