Hydraulic and disinfection efficiency of an ozonation contactor for a municipal water treatment plant using computational fluid dynamics

Abstract

ABSTRACTDetermination of hydrodynamic characteristics and disinfection efficiency are important factors in the operational study of the ozone contactors. In the present work, a full‐scale ozonation contactor for a municipal water treatment plant was simulated by computational fluid dynamics (CFD) approach. The Eulerian multiphase, k–ϵ turbulence, and kinetic‐based reaction models were implemented in a finite volume framework to predict the hydraulic parameters, ozone concentration distribution, total organic carbon (TOC) reduction, and concentration‐contact time (CT) values in the contactor. The reaction kinetics for ozone decay was determined by experimental data collected via the contactor. The quality of mesh near the walls and the results independence on the mesh density were probed to determine the optimal grid density. For the first time, the accuracy of the model was evaluated in contrast with experimental data of TOC reductions during ozonation process. The pulse tracer study and flow field indicated recirculation, dead zones, and therefore non‐optimized baffle configuration in the contactor. The predicted CT values indicated that in the cold and hot months, the ozone dosage must increase by a factor of 3–5 relative to the current dosage values to achieve disinfection log‐inactivation credit for pathogens. Using the CFD simulation results, the correlation between ozone dosage and CT values for the hot and cold months in the ozonation contactor was predicted.