AWWA JAW6782

Source water near Paris, France has deteriorated in recent years, necessitating a reevaluation of traditional chemical treatment of drinking water. This article outlines the evaluative process used by the Compagnie Generale des Eaux and discusses present treatment methods. Currently, natural biologic purification in conjunction with activated carbon reduces the amount of chemical reagents needed and also improves the taste of the water. Ozone is used before filtration, before activated carbon filtration, and after carbon filtration. This article also discusses the application of chlorine at the final point in the treatment train for purposes of reducing the formation of undesirable byproducts such as trihalomethanes. The cost of these improved techniques is highlighted, indicating only a 6 percent increase over traditional chemical reagent costs. Organics removal has increased 15 percent, while bacterial growth within the distribution system has declined. Future developments in the new treatment train will be affected by a variety of factors, including the following: maximum aluminum content of water used for hemodialysis home treatments; nitrate concentrations in groundwaters; construction of high-quality water softening facilities; and costs of sludge conditioning and various technical solutions such as coagulant substitution. Includes 70 references, tables, figures.