Seattle Public Utilities Mami Hara, General Manager/CEO

Ozone Generation and Injection Facility

  • Ozone generator disinfects water and improves taste.

The heart of the Cedar Water Treatment Facility is a coupled ozone/ultraviolet (UV) process. This two-step process both disinfects and improves taste and odor in a highly efficient and cost-effective manner.

Water is pumped from Lake Youngs and piped to the ozone injection facility. Here liquid oxygen is transformed into a gas and a portion of the oxygen is converted to ozone. The ozone is transferred to the water by diffusing the gas into the flow within concrete injection chambers. The water must stay in contact with the ozone for about 10 to 15 minutes to complete the oxidation and disinfection processes that improve the taste and odor of the water and disinfect bacteria, viruses, and Giardia.

Typically, this process involves construction of large, covered concrete structures; however, our facility uses two existing 78-inch-diameter pipelines as the ozone contact chambers. Ozonation occurs as the water travels from the ozone injection facility to the UV disinfection facility. Using the existing pipelines resulted in substantial reduction in costs and impacts on the site.