Carnation Wastewater Treatment Facility

More about the treatment plant design

Overview of standard and advanced wastewater treatment processes

New wastewater treatment filters will help provide drought-proof source
of reclaimed water

Carnation will have five large membrane units called cassettes like the one shown above.

A close-up of the individual strands in action.

The membrane bioreactor (MBR) system will be used instead of large round settling tanks used in conventional plants. The MBR system needs less space, simplifies odor control and produces better water quality than traditional wastewater treatment.

King County has selected a vendor for an innovative process that treats wastewater to such a high level it can be used safely as a drought-proof water source for irrigation, wetland enhancement and other beneficial uses. King County evaluated the opportunities to use reclaimed water in Carnation. The wetland enhancement emerged as the best use of the water because there are no viable year-round water users at this time. Potential reclaimed water users will be reevaluated in the future. Membrane technology will be installed to filter wastewater at both the Carnation and Brightwater wastewater treatment plants.

King County is buying the membranes from the Zenon Environmental Corp. (external link) of Ontario, Canada. Wastewater treatment plants in California, Colorado, Michigan, Georgia, Florida, Ontario and other locations around the world use Zenon membranes. Zenon membranes are also used around the world to produce drinking water.

Zenon’s membrane bioreactor system was selected because of its performance in providing consistently higher water quality. Because the treated wastewater will be discharged into the Snoqualmie River or treated to reclaimed water standards and used to enhance a wetland at Chinook Bend Natural Area, protecting salmon, fish and people as well as the community of Carnation was imperative. Zenon’s technology will help preserve the surrounding environment.

The MBR system can produce Class A reclaimed water, which meets strict standards of the state departments of Ecology and Health for use in non-drinking purposes.Those purposes include landscape and agricultural irrigation, heating and cooling, and industrial processing as well as safe discharges into freshwater. The Carnation plant will initially be able to treat up to 400,000 gallons a day.

“The wastewater will be seven to 10 times cleaner than typical secondary treated wastewater,” Christie True, manager of the wastewater capital improvement program said. “Secondary treatment already meets tough environmental requirements for discharges into Puget Sound. By reducing the discharge of pollutants even more with the MBR process, we’ll further improve water quality and protect the Snoqualmie River and surrounding environment.”