Reclaimed Water Program
-- formerly the Water Reuse Program

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Overview of Standard and Advanced Wastewater Treatment Processes

Most of King County's wastewater flows to one of two regional treatment plants where the wastewater flows through a series of treatment processes that remove waste from the water and protect public health and the environment.
 

Typically, wastewater treatment begins with primary treatment where solids are separated from liquids. This happens in sedimentation tanks.

The next phase is called secondary treatment. It is also called biological treatment because oxygen is added to activate the living microorganisms (such as bacteria) that eat the dissolved organic material still in the wastewater. We use an 'activated sludge' treatment process where the organisms are maintained at a very high level to accelerate the consumption process.

After secondary treatment, King County disinfects the treated wastewater and returms it to the environment.

Some of the water treated at the regional treatment plants is reclaimed. Reclaimed water must be treated beyond secondary treatment to meet Washington State Departments of Health and Ecology Class A standards.

This advanced treatment involves an additional filtration step to remove any remaining solids and an extended disinfection process.

To learn more

• Reclaimed Water Home
• Treatment Alternatives for Reclaimed Water
• Advanced treatment technology at
  • Brightwater Treatment Plant
  • Carnation Treatment Plant
• For more information about King County's Reclaimed Water Program, contact Jo Sullivan at 206-296-8361 or by e-mail.

For questions about the Wastewater Treatment Division Web site, please send an e-mail message. For general information about the division, contact us at:

Department of Natural Resources and Parks
Wastewater Treatment Division
201 S. Jackson St., Suite 505
Seattle, WA 98104-3855
Phone: 206-684-1280
Fax: 206-684-1741
Telecommunication device for the deaf (TTY): 711

Updated: April 2, 2008

Also of interest

Biosolids Recycling
Endocrine disrupting chemicals in the environment