Method and system for treating drinking water

Abstract

The present invention provides a new and improved method for treating drinking water in a drinking water treatment plant that provides for substantial or complete removal of chlorine dioxide and an associated by-product from water when chlorine dioxide is used as an initial disinfectant and/or chemical oxidizing agent. More particularly, the present invention provides a means for decreasing undesirable residual amounts of chlorine dioxide and chlorite ion using ferrous chloride. The novel process includes the addition of chlorine dioxide for disinfection/oxidation of the process water, a first sedimentation basin for processing the water and/or providing adequate chlorine dioxide contact time, the addition of ferrous chloride for treating the water and removing residual amounts of chlorine dioxide and chlorite ion, a source of chlorine (or alternative oxidizing agent) to precipitate residual ferrous iron, a second sedimentation basin, or similar settling mechanism, for processing the water after it has been mixed and reacted with the ferrous chloride and the oxidizing agent, and a filter for processing the water following the second sedimentation basin.

Dependencies are inferred from the claim text.