Ozonation processes continue to be an attractive treatment option for water utilities. Utilities are required to meet the disinfection requirements (accrue the CT credits) mandated by the Surface Water Treatment Rule while meeting the regulatory limits on halogenated disinfection byproducts in accordance with the Safe Drinking Water Act. Utilities can use ozone as a primary disinfectant, thereby reducing the amount of chlorine required for secondary disinfection, and correspondingly lowering the formation of disinfection byproducts. To date, there are no well-established models for predicting the concentration of ozone in the liquid phase in ozone gas-liquid contactors in order to meet the CT requirements for primary disinfection by ozone. This work is part of a research project studying mass transfer, reaction, and dispersion in ozone contactors.