BOOK OF ABSTRACTS 23 IHSS&IWA26 / BRNO / CZECHIA / 23–28 August 2026 Monday, 24 August 2026 / Hall B+C Analysis and Characterization SL5 Characterization of Dissolved Organic Matter and its Relationship with Carbonaceous and Nitrogenous Disinfection By-Products Formation in Drinking Water Treatment Anne Kamau1, Peter Jarvis2, Bruce Jefferson3, John Haley4 1 Cranfield University, Cranfield Water Science Institute (CWSI), Cranfield, Bedfordshire, United Kingdom, MK 43 0 AL, A.Kamau@cranfield.ac.uk 2 Cranfield University, Cranfield Water Science Institute (CWSI), Cranfield, Bedfordshire, United Kingdom, MK 43 0 AL 3 Cranfield University, Cranfield Water Science Institute (CWSI), Cranfield, Bedfordshire, United Kingdom, MK 43 0 AL 4 UK Water Industry Research (UKWIR) Ltd, London, United Kingdom, SW1 0BH Dissolved organic matter (DOM) is a key indicator of drinking water source quality and a principal precursor of disinfection by-products (DBPs), yet bulk parameters often provide limited insight into DOM reactivity, particularly for emerging nitrogenous DBPs (NDBPs). This study presents an integrated assessment of DOM occurrence, characteristics and DBP formation potential (DBPFP) in raw and treated waters across multiple UK drinking water sources (lowland and upland surface water, groundwater) and associated water treatment works. Source water dissolved organic carbon (DOC) concentrations ranged from 0.30 – 9.35 mgL-1 C, with treated water DOC typically reduced by 2.9% - 80%, while dissolved organic nitrogen (DON) ranged from 16.4% – 22.0%, depending on the treatment processes employed. Excitation-emission (EEM) fluorescence spectroscopy coupled with fluorescence regional integration (FRI) was used to characterize DOM in water. The results showed variable distribution of humic-like (terrestrial and microbial) and proteinlike fractions among the different source water types. Treatment processes resulted in preferential removal of humic-like fluorescence, with reductions of 40% – 70% observed through conventional treatment processes, while protein-like components were more recalcitrant and, in some cases, relatively enriched following treatment. DBP formation potential experiments indicated trihalomethane formation potentials in the range of 11.86 – 86.34 µg.mgC⁻¹, haloacetic acid formation potentials of 38.58–260 µg. mgC⁻¹ as HAA9, haloacetonitriles formation potentials of 0.87–31.99 µg. mgC⁻¹ and haloacetamides formation potentials of 0.78–5.74 µg.mgC⁻¹ with higher DBPFP consistently associated with raw waters containing humic‑rich DOM. Strong correlations were observed between humic‑like fluorescence
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