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Advanced treatment technology at Brightwater

Video: installation of membrane bioreactor filters (MBRs) at the Brightwater Treatment Plant (April 2011)

The Brightwater Treatment Plant is being designed to meet or exceed stringent water quality standards for effluent discharge or reclaimed water production. The treatment plant will use an advanced treatment technology called a membrane bioreactor (MBR) system instead of the large round settling tanks used in conventional plants. The membranes are immersed in wastewater. The MBR system draws wastewater through hollow fibers with microscopic pores small enough to filter out particulate matter and even individual bacteria.

The MBR system needs less space, simplifies odor control, and produces better water quality than traditional wastewater treatment.

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

The treatment plant will have large membrane units called cassettes like the one shown above.


This close-up of an individual strand shows how gentle suction pulls clean water through microscopic pores.

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. 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. 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 was recently acquired by GE Water & Process Technologies, and the membranes are now called GE’s ZeeWeed Membrane Bioreactor technology.)

"We selected Zenon’s membrane bioreactor system for our new plants because of its performance in providing consistently higher water quality," said King County Executive Ron Sims. "We are confident that Zenon’s technology will help us to preserve our 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 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."

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