Designing High Concentration Ozone Contactors for Drinking Water Treatment Plants

The design of high concentration ozone contacting systems requires special attention to ensure that mass transfer, mixing and disinfection objectives are met when low volumetric gas flow rates are used. This becomes especially critical when the ozone contactor is designed for primary disinfection and must meet CT (ozone concentration multiplied by contact time] disinfection values. This paper presents design guidelines for high concentration ozone contactors. These guidelines then are applied to the design of a new 55-mgd two-stage ozonation potable water plant for Henrico County, Virginia. Finally, a new type of in–line ozone injection contactor is presented as an alternative to fine-bubble diffusion contactors to provide primary disinfection.