Ozone is a valuable alternate to chlorine for the disinfection of wastewater and water. It generates no chlorinated organics and leaves no residuals harmful to human health or toxic to marine life.The ozone reacts through free radical or polar mechanisms under water treatment conditions depending on pH and other factors. The mechanism of bacterial disinfection is not completely understood.The ozone-hydrogen peroxide system is a powerful oxidizing medium and has been shown to remove refractory dissolved organics from deionized water and from industrial wastewater much more effectively than ozone alone. It is believed to generate hydroxyl radicals and operate through a free radical mechanism. The reaction of ozone alone proceeds through a free radical mechanism under alkaline conditions and free radical and polar mechanisms under neutral conditions.The disinfection effect of a chemical usually parallels its oxidation potential. The hydroxyl radical, the active agent of the ozone-hydrogen peroxide system, is a substantially stronger oxidant than ozone or chlorine.This project would be the first feasibility evaluation of the ozone-hydrogen peroxide system as a disinfectant. Furthermore, the results should indicate whether the free radical or polar reaction of ozone is more important for disinfection.