APEGBC Innovation Magazine: 2016 | 2017 Project Highlights
Process Reclaims Minerals from Chicago-area Sewage
The Metropolitan Water Reclamation District of Greater Chicago (MWRD) faced higher regulatory limits affecting effluent discharge permits. Its wastewater system was also experiencing struvite mineral build-up at their Stickney plant, the world’s largest wastewater treatment facility.
Ostara’s Pearl process provided a solution. The Pearl’s fluidized bed reactor recovers phosphorus and nitrogen from nutrient-rich wastewater liquor, reclaiming more than 85 percent of phosphorus and up to 15 percent of nitrogen from wastewater streams before they accumulate as struvite in pipes and equipment.
In the reactor, magnesium is added to wastewater under a controlled pH, causing the nutrients to crystallize. The reactor design enables the granules to grow to the size and purity used in standard fertilizer blends, and to be harvested directly from the reactor. They can then be dried and bagged for distribution and sale from the Stickney plant.
The process has increased Stickney’s operational efficiency by preventing struvite build-up, reducing loads on other plant processes, and supporting MWRD’s clean-water mandate.
APEGBC members: Ahren Britton, P.Eng., Derek Lycke, P.Eng., Lani (Mahilan) Somasunderam, P.Eng., David Alexander, P.Eng., Sam Leung, P.Eng.