Wastewater yields fertilizer source
Updated: Thursday, February 21, 2013 11:10 AM
Equipment maker ramps up efforts to reclaim phosphorus
By JOHN O'CONNELL
POCATELLO, Idaho -- To meet strict federal clean water standards, the city of Pocatello could find itself in the fertilizer business, producing a high-quality phosphate product that has proven especially effective on potatoes.
Last September, the Environmental Protection Agency imposed a new permit on Pocatello, allowing its sewage treatment plant to discharge no more than 25.1 pounds of phosphorus per day into the impaired Portneuf River. The city, which averaged 40 pounds of daily phosphorus discharge in 2012, has five years to comply.
Pocatello officials are mulling proposals from two companies involved in a relatively new industry, manufacturing cones that crystallize phosphorus in wastewater into a mineral called struvite. Magnesium and other chemicals are added in the cones to aid in the process as effluent flows through.
Seattle-based Multiform Harvest, which completed a struvite facility in Boise last fall and one in Yakima, Wash., last summer, allows municipalities free use of its patented designs in exchange for ownership of any struvite they make.
Ostara Nutrient Recovery Technologies, based in Vancouver, British Columbia, would charge the city to build the structure, with the promise of buying back struvite as a means of recouping the investment.
Pocatello Water Pollution Control Superintendent Jon Herrick said cones would supplement the biological process the city uses to consume phosphorus in wastewater. Additional filters and chemicals might also be necessary, he said.
Multiform President Keith Bowers said dairies have also expressed interest, and he's building a system for a large dairy on the East Coast.
Bowers, who started selling fertilizer last November, explained struvite is less water soluble than conventional phosphate fertilizer, which plants absorb with about 20 percent efficiency. Struvite doesn't bind with the soil or leach away in water, so plants use the slow-release product with about 80 percent efficiency, he said.
Ostara receives roughly 1,500 tons per year of struvite, marketed as Crystal Green, from its treatment facilities, including two in Portland suburbs, and expects to double that quantity when new plants come online.
Steve Wirtel, an Ostara senior vice president, said the company has had discussions with major fertilizer manufacturers about selling its product as an additive for their blends. Mosaic Co. has a demonstration project at a Florida facility, using Ostara cones to capture phosphate wasted in fertilizer production.
"Phosphorus is a limited resource that all of us need to live," Wirtel said. "We've got to do something to close the loop on phosphorus. If we continue to send it off into the oceans ... we're going to run out."
Dan Froehlich, the company's vice president of agronomy, said the company has done several trials, including one with Oregon State University, to test struvite on crops. They found it highly effective on potatoes and alfalfa.
The two Washington processed potato farmers who fertilized with struvite in trials last season have increased orders of the product for this season, Froehlich said. He said struvite has improved potato yields in trials by 4 to 22 percent but is most effective when used in tandem with conventional phosphate fertilizer to aid in root development.