Pierce County Testing New Bacteria Treatment At Chambers Creek Properties

(Editor's note: An earlier version of this article incorrectly stated the cost of the pilot project. Changes have been reflected in the article)

Bacteria eat up nitrogen to preserve the quality of a body of water teeming with life. 

It’s not something out of a science-fiction novel.

It’s sewage treatment technology unlike almost any other in the U.S. that Pierce County is testing at its Wastewater Water Treatment Plant at Chambers Creek Properties.

If the $150,000 pilot project is successful, Pierce County would be among the first in this country to use the process on its system.

The process is known as de-ammonification, or DEMON for short.

It uses a naturally-occurring bacteria (anammox) to efficiently remove nitrogen from wastewater before the treated effluent is discharged to the environment – in our case, to Puget Sound.

A full-blown DEMON processing plant would require an $11 million investment, but officials say it would pay for itself – almost immediately – by reducing the number and size the amount and size of new biological process tanks.

“The ammonia that typically would go out to the receiving streams is just converted into another state,” according to WWTP Superintendent Larry Ekstrom. “It’s better that it goes out as nitrogen gas than go out into the receiving streams and impact the growth of the algae.”

The process, if implemented, could eliminate Pierce County’s need to purchase an estimated 900 gallons of methanol per day, which the traditional nitrogen removal process calls for. Pierce County says methanol costs $2 to $4 per gallon, which can add up to $1.3 million per year in plant operating costs.

The study is part of the county’s plans to replace aging equipment and expand capacity at the University Place plant, which will require an estimated $305 million worth of work. With more development, Pierce County acknowledges the need to prepare for the future. (Check out Patch's coverage of the expansion later today)

“Our job is to remove contaminants from the wastewater we receive from over 250,000 customers, and return clean, treated water to Puget Sound,” said Ryan Dooley, project manager for the Pierce County Sewer Utility. “We’re excited to test this.”

Funding for the expansion comes from sewer ratepayer fees and connection charges.

State and federal agencies are studying the extent that pollutants such as nitrogen may harm the health of Puget Sound. As new discharge standards are being considered, Pierce County is laying the foundation to be able to meet them.

Patents for the DEMON process, equipment and specialized bacteria seed sludge are held by Drs. Bernard Wett of Austria and Geert Nyhuis of Switzerland. Dr. Wett is personally supervising the DEMON treatment plant startup.

The efficiency of DEMON comes from the anammox bacteria’s ability to shortcut the conversion of nitrite and ammonium (a compound similar to ammonia) to nitrogen gas, a process called anaerobic ammonium oxidation. According to Dr. Wett, it’s possible to remove 90 percent of ammonia and up to 86 percent of all nitrogen from incoming wastewater depending on conditions.

Scientists first discovered the microbial anammox process in nature as part of the nitrogen cycle about 20 years ago. It is now known to be present worldwide in oceans, soil, and lakes. Its specific use as a wastewater treatment process has led to multiple application patents in several European countries.

For details, go to www.piercecountywa.org/sewerexpansion.