Nutrient Recovery Tech Helps Treatment Plant

The process helps clean the effluent by removing these nutrients and ultimately transforms them into an efficient, reusable feedstock

In recent years, a number of groundbreaking developments in the field of wastewater treatment have paved the way for utilities to better manage and improve operations. Biological technologies, advanced reuse and recycling techniques and progressive green-based practices have led to various economic, environmental and societal benefits that can help reduce costs, conserve energy, sustain the environment, and improve customer service.

One resourceful process currently trending in the wastewater industry and bringing these benefits to light is nutrient recovery. Nutrient recovery is the practice of recovering nutrients such as nitrogen and phosphorus from used water streams that would otherwise be discarded and converting them into an environmental friendly fertilizer used for ecological and agricultural purposes. This process helps clean the effluent by removing these nutrients and ultimately transforms them into an efficient, reusable feedstock.

Wastewater typically contains a large amount of nutrients -- particularly phosphorus -- that can pose a harmful threat to infrastructure and the environment, causing problems such as eutrophication in waterbodies and a buildup of struvite in mechanical systems. By utilizing nutrient recovery, wastewater plants can mitigate these challenges while improving water quality and meeting stringent phosphorus discharge limits.

The recovery process also offers municipalities an opportunity to generate revenue while providing agricultural businesses with refined, usable phosphorus -- an increasingly scarce natural resource. Moreover, it enables wastewater entities to serve as more than just treatment facilities but ultimately as resource recovery agents, transforming the perception of traditional wastewater treatment.

Such is the case with the Metropolitan Water Reclamation District (MWRD) of Greater Chicago's Stickney Water Reclamation Plant. Located in the city of Cicero, Ill., the 85-year-old facility -- the largest secondary wastewater treatment plant in the world -- will soon begin reclaiming large amounts of nitrogen and phosphorus using an innovative nutrient recovery system from Vancouver-based Ostara Nutrient Recovery Technologies Inc. The new system will ultimately help the facility safeguard vital water resources and improve overall operations.

"We're out there really trying to test and see what can transform this market in terms of lowering our energy usage, recovering resources and providing a return on investment (ROI) for our constituents," said David St. Pierre, MWRD executive director. "We started talking about how we can actively address nutrients, in particular phosphorus, in our waterways," he said. "We looked at the Stickney plant to see if it was a candidate for the Ostara process, and we decided that it was. So being a water quality agency that supports improving the environment, we just felt that was the right thing to do."

The Stickney plant currently treats up to 1.4 billion gallons of water per day (MGD) and serves 2.4 million people in the Chicago areas and the surrounding suburbs. Scheduled for completion in the fall of 2015, the Ostara project will equip the facility with the capacity to produce between 10,000 and 15,000 tons of enhanced efficiency fertilizer annually, making it the largest project of its kind in the world. Ostara will provide all equipment for the program as well as offer operations and maintenance assistance to MWRD once completed. In addition, the company will partner with Overland Park, Kansas-based Black & Veatch, who will provide design, procurement and construction services.

MWRD opted to implement Ostara's technology at the Stickney plant given that it is currently incorporating biological phosphorus removal. "Stickney is the easiest plant to get there. We have carbon at the plant that allows us to have phosphorus uptake," said St. Pierre.

Through its proprietary Pearl® process, Ostara diverts nutrient-rich wastewater streams into a fluidized bed reactor and combines it with compounds such as magnesium chloride and, on occasion, sodium hydroxide, where small struvite "seeds" are formed. This reactor controls the chemistry formation of the seeds and ultimately recovers them in the form of highly pure crystalline pellets, which can grow in diameters of 1.0 to 3.5 mm. This finished material is a high-grade, slow-release end-product that Ostara harvests, dries, packages, and markets as a commercial fertilizer called Crystal Green®.

"What Ostara is doing is providing a third exit for phosphorus from the system," said Steve Wirtel, Ostara senior vice president of technology solution sales. "We've taken this vicious cycle of removal in the biology (release in the digester and recycle back to the plant) and we've converted that into a virtuous cycle where you have … recovery in our system because what we're making is struvite but in an engineered form."

Source: Water World

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