PROJECT: Wastewater

Green Bay Struvite Recovery Facility

Green Bay, Wisconsin


Green Bay Metropolitan Sewerage District

Construction Value:

$3 Million


T-O Engineers performed detailed design and construction services for a struvite harvesting facility at the Green Bay Metropolitan Sewerage District. The struvite system was part of a broader biosolids management upgrade at Green Bay Metro called R2E2, and filled a critical role in the nutrient management strategy for the plant. The system is designed to treat approximately 565,000 gallons per day of side stream flow and remove 88% of orthophosphate in the form of struvite.

Struvite (magnesium ammonium phosphate hexahydrate) has long been an undesirable tenant inside pipes, pumps, and digesters at wastewater plants which perform anaerobic digestion in the solids handling stream. Struvite harvesting systems are a cutting edge technology designed to recover nitrogen and phosphorus outside of the anaerobic digester, thus relieving the maintenance issues related to struvite buildup in the system. In addition, struvite is a natural fertilizer, and is therefore a source of revenue for the plant.

Only a handful of struvite recovery facilities are installed at wastewater plants in the United States. T-O Engineers  has designed three full-scale struvite harvesting systems, including one which dries the struvite to achieve Class A solids. Our fundamental knowledge of struvite chemistry and recovery sets us apart in the wastewater industry, and demonstrates our willingness to adopt new technologies we know will benefit our clients.