A new system will remove the Yakima plant's extra struvite, which can then be used as fertilizer. What comes out looks like white, BB-sized pellets.
credit:
Courtney Flatt
The Yakima facility will go online next week. As construction wraps up at the Yakima facility, workers install pumps underneath the floor.
credit:
Courtney Flatt
Clean Water Services recovers nutrients from its wastewater treatment process in Tigard, Oregon and converts the nutrients to fertilizer. Photo: Bonnie Stewart May 2012.
credit:
Bonnie Stewart
If you live in Central Washington, the Portland suburbs or Idaho’s capital, then odds are what comes out of your sewage treatment plant will help grow crops — thanks to the Northwest’s concentration of cutting-edge recycling technology.
There are only a half-dozen of these new systems in the United States. They treat sewage by separating nutrients from discharge and recycling them into fertilizer for farmers and horticulturalists. Four of these facilities are in the Pacific Northwest.
One such plant is opening in Yakima. Another just started operating in the Portland suburb of Hillsboro, about 20 miles from the Northwest’s first such facility in Tigard. The Northwest’s fourth is being built in Boise, Idaho.
Normal wastewater treatment generates excess phosphorous and ammonia. These nutrients can harm aquatic life and cause fish kills and algal blooms.
In wastewater systems, the extra nutrients crystalize and form struvite. (Struvite is more commonly found in kidney stones.) And it creates problems as water moves through treatment plants. The struvite collects on valves and clog pipes and pumps. That means more money spent on maintenance.
“It’s caused such a problem for years,” says Scott Schafer, Yakima’s wastewater division manager. “Maintenance complaining about it because you have to take the pumps out of service. The pipes, you have to descale them. It’s essentially like hard water build-up.”
A new system that will come online next week will remove this extra struvite, which can then be used as fertilizer. What comes out looks like white, BB-sized pellets.
Yakima wastewater managers expect multiple benefits: removing phosphorous from the wastewater, creating fertilizer, and streamlining the treatment process. The new system cost about $1 million, and the city is working out a plan to sell the fertilizer to Multiform Harvest, the company that created the technology.
Multiform’s Keith Bowers represents the brains behind Yakima’s new system. He says the fertilizer will be produced off-site.
“We have some processes where we can form it to different shapes and sizes, and we can also blend other nutrients into it and basically custom-create products for particular growers,” Bowers says.
Struvite is a slow-release fertilizer, meaning it doesn’t leach out and it creates less agricultural runoff. It’s a relatively new material in the world of fertilizers.
Washington State University researchers recently studied struvite’s performance in greenhouses, which rely on frequent fertilizer applications. In an experiment comparing struvite and fertilizers containing phosphorous, struvite fared the same – if not better – than the normal fertilizer.
Bowers also hopes to eventually use this technology to remove phosphorous from dairy and hog farm digester waste. He says experiments will begin at the largest East Coast dairy this summer.
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As construction wraps up at the Yakima facility, workers install pumps underneath the floor. Two 20-foot tall cones are almost ready to filter water next week.
“There seem to be a lot of sites, not only in municipal sewage plants, but also industrial that are just watching the first few plants,” Bowers says. “So, if it goes well, there could be a very rapid increase in the number of plants.”
“No pressure,” wasterwater manager Scott Schafer laughs.
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