Abstract Submission: A recent disinfection study was conducted to optimize disinfection efficiency by analyzing hydraulic retention times (HRT) and selecting optimal sampling locations using computational fluid dynamics (CFD) modeling. CFD simulations were performed on two liquids treatment trains (North and South) to evaluate disinfection chemical mixing performance and predict the actual HRT compared to the theoretical HRT. On-line disinfectant residual analyzers (demand and decay) were to be added to optimize disinfection performance to the process control system, however the exact analyzer sampling location needed to accommodate both diurnal minimum and maximum flows. Sampling locations were determined where the peracetic acid (PAA) concentration reached approximately 0.5 mg/L, minimizing the impacts of biofouling and PAA decay. This concentration threshold was critical for ensuring accurate measurements at the analyzers before decay rendered PAA undetectable. In the North plant, bench-scale testing in the contact tank complemented the CFD analysis, with PAA concentrations measured at multiple locations to validate optimal sampling points. The CFD findings allowed precise placement of the sampling locations for the decay analyzers, improving disinfection monitoring and operational efficiency. This study demonstrates the efficacy of CFD modeling as a tool for optimizing disinfection performance in complex disinfection systems.
