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Drinking water ozonation is continually facing new challenges because of more and morestringent regulations on disinfection and disinfection byproducts. The commonly used CTapproach often underestimates disinfection efficiency, therefore it is not suitable to be used foroptimization of system design and operation. In this study, a two phase CFD model has beendeveloped to address all the major components of ozonation processes: contactor hydraulics,ozone mass transfer, ozone decay, microbial inactivation, and disinfection byproduct formationkinetics. The CFD model was applied to simulate ozone contactor performance at the MannheimWater Treatment Plant in Ontario, Canada. The results show that the CFD method predictssignificantly higher CT values than the traditional CTsub10/sub method (up to 250%) using ozoneresiduals at 6 monitoring points within the contactor. The 13 year old Mannheim ozone systemhas recently been modified to include new liquid oxygen-fed ozone generators in order toenhance operational flexibility and remove some diffusers from the system. The modellingresults suggest that these changes have led to an increase in effective residence time. The CFDmodel was also applied to optimize ozone contactor performance at the DesBaillets WaterTreatment Plant in Montreal, Canada. Numerical results are in good agreement with full-scaletracer experimental data. The CFD predicted flow fields show that recirculation zones and shortcircuiting exist in the DesBaillets contactors. The current simulation results suggest that theinstallation of additional, appropriately located, baffles would increase the residence time andimprove disinfection efficiency. It is anticipated that the work will demonstrate that the CFDapproach is an efficient tool for improving the ozone disinfection performance of existing watertreatment plants and designing new ozonation systems. Includes 15 references, figures.

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Edition: Vol. - No. Published: 11/01/2005 Number of Pages: 10 File Size: 1 file , 930 KB