Ozone Treatment of Small Water Systems

Large-scale Municipal Potable Water Treatment Plants have been utilizing ozone for many purposes since 1906. Ozone's applications based on its being the strongest oxidant and chemical disinfectant available commercially are well proven, as evidenced by the more than 3,000 plants throughout the world, which rely on it. Yet, to apply ozone safely and cost effectively requires a rather complex engineered subsystem, e.g., the ozone generator, feed gas treatment, power supply, gas/liquid contacting, and contactor off-gas destruction. In considering the use of ozone to treat drinking water in small systems, the first problem to be overcome is how to miniaturize the ozonation system components so that small water systems can (a) install ozonation, (b) operate and control ozone systems, and (c) do so affordably. In this paper available information is summarized on ozone's applications in water systems treating less than 1 MGD (e.g., plants that serve less than 10,000 persons). Results of an ongoing survey of U.S. small-scale ozone system suppliers are presented. An updated listing of operational U.S. ozone water treatment plants shows more than 260 total installations, with more than half of these (149) in plants serving less than 10,000 persons. An additional listing of 363 identified single family U.S. residences (but more than 2,000 additional installations are known to be in service) use a novel treatment system designed for treating water in a storage tank. A special filter unit is submerged in the tank through which ozone (from the externally mounted ozone generator) is fed. Precipitated iron, manganese and other insolubles are constantly removed by the filter, which is removed and washed out periodically.