Original: English OZONE

Although ozone has been known for over 100 years, and although it has been used in water treatment for over 100 years, it has not found widespread use as a disinfectant in the water industry. Statistics are not quite reliable, but probably less than 1 percent of the water treatment plants worldwide use it. The major reason for its low use are the costs. Compared to chlorine it is much more costly. Since the water industry has always been trying to provide safe drinking water at the lowest cost it is understandable that it never has been in wide use. But all of this is changing, and actually very rapidly. The regulations for disinfection byproducts in Europe and the US, and guidelines by international organizations such as the World Health Organization, force the utilities to lower the trihalomethanes in drinking water which makes the continued use of chlorine in many cases impossible. This fact combined with the insistence of consumers to receive taste and odorless drinking water points to the use of ozone since it does not only disinfect but also reduces color and odor by oxidizing the organic substances found in water. The paper will describe the ozonation process in detail, and by way of example describe the retrofitting of the treatment process in the City of Ann Arbor, Michigan which installed an ozone facility two years ago. While the water always met water quality standards, the taste and odor were not always good and acceptable. After the 2installation of the ozone process, it was rated the best tasting water in Michigan. 1