Mark H Griese

US Patent:

53146298, May 24, 1994

Filed:

Nov 6, 1992

Appl. No.:

7/972795

Inventors:

Mark H. Griese - Evansville IN
Ronald S. Bialosky - Newburgh IN

Assignee:

Evansville Water & Sewer Utility - Evansville IN

International Classification:

C02F 176

US Classification:

210754

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.