BOOK OF ABSTRACTS 73 IHSS&IWA26 / BRNO / CZECHIA / 23–28 August 2026 Tuesday, 25 August 2026 / Hall B+C Research Frontiers SL30 Liquid Ferrate as Chloride Free Alternative to Conventional Ferric Coagulant: NOM Removal and Its Post-Coagulation Consequences Lap-Cuong Hua1, Almohanad Abusultan2, Maria Kennedy1 1 IHE-Delft Institute for Water Education, Water Supply, Sanitation and Environmental Engineering Department, Westvest 7, Delft 2611 AX, the Netherlands; lc.hua@um-ihe.org 2 NV PWN Water Supply Company North-Holland, 1990 AC, Velserbroek 2113, the Netherlands Stringent chloride regulation in the Netherlands (≤150 mg/L in finished drinking water) creates a direct compliance conflict with conventional FeCl3 coagulation, as chloride residue from coagulant dosing is inherent to the process. For example, 20 mg Fe/L adds approximately 28 mg/L chloride, consuming nearly 20% of the regulatory headroom at a time when source water salinization is intensifying. Beyond chloride, NOM removal remains the central treatment objective for longresidence-time reservoir sources, where refractory low-MW organics dominate and resist conventional coagulation. Liquid ferrate (Fe(VI), FerSol®) offers a chloride-free alternative with the dual advantages of oxidation and coagulation, providing a potentially superior route for NOM transformation and removal. This study presents a systematic investigation of Fe(VI) applied to treat long-residencetime reservoir water, examining how single and combined dosing strategies affect NOM removal across multiple characterization dimensions and benchmarking their consequences for post-coagulation processes. Coagulation performance: single and combined dosing Under single dosing at 20 mg Fe/L (pH 8, low velocity gradient), Fe(VI) matched Fe(III) in turbidity removal (96%) and residual iron (<0.1 mg/L) while fully eliminating chloride input. However, Fe(VI) yielded lower DOC removal (32% vs. 41–43%) and UVT (93% vs. 95–96%), attributable to its dominance of colloidal over monomeric Fe species as revealed by the Ferron time-dependence method. This likely caused the shifting of the coagulation mechanism from charge neutralization toward adsorption, which is less effective for the low-MW NOM characteristic of this source. At equivalent total iron (20 mg Fe/L), combined dosing strategies using Fe(III) and Fe(VI) generally underperformed single Fe(III) in DOC and UVT removal, though turbidity performance remained comparable. Among combined approaches, sequential Fe(III)-first → Fe(VI) achieved the highest NOM removal, with approximately 80% and 75% removal of biopolymer and humic fractions respectively by LC-OCD at pH 8. This result demonstrates that pre-formed
RkJQdWJsaXNoZXIy NDA4Mjc=