Michigan Water Environment Association’s recent Sustainable Energy Seminar included a panel discussion on “Nitrogen & Phosphorous Harvesting and Reuse” moderated by Donohue’s Mike Harvey. The panel consisted of Josh Gable of Centrisys Corporation and Allen Williams of Donohue. Allen’s presentation covered:
- What is struvite and why recover it?
- Technologies available for struvite recovery
- AirPrex and NuReSys piloting case studies
- Evaluation and design of an Ostara struvite harvesting system for St. Cloud, MN
Struvite (Magnesium-Ammonium-Phosphate) can be captured from flow streams within WWTPs and subsequently utilized as a slow release fertilizer. Struvite harvesting may improve biosolids dewatering, reduce plant effluent phosphorus, reduce equipment maintenance, and provide a revenue source for the WWTP. Harvesting struvite from sidestreams can be accomplished through technologies provided by Ostara, Multiform Harvest, and NuReSys.
A full-scale sidestream struvite harvesting system is being constructed at the St. Cloud WWTF to maximum production of a high value struvite product, reduce biosolids phosphorus content, and reduce sidestream nutrient loadings. Alternatively, AirPrex and NuReSys offer technologies to form and remove struvite in biosolids prior to dewatering. These harvesting technologies have been piloted at numerous WWTPs and have resulted in dewatered cake improvement of 2-5% TS, decreased polymer requirement, decreased sidestream nutrient loadings, and decreased biosolids phosphorus content.