Phosphorus Recovery by Methods Beyond Struvite Precipitation

Unintentional phosphate precipitation at water resource recovery facilities (WRRFs) causes operation and maintenance challenges. With global phosphorus (P) scarcity looming and receiving water eutrophication caused by excess discharges of P, intentional P recovery at WRRFs has been gaining traction. To date, struvite recovery as slow release fertilizer has been the focus of P recovery. However, struvite recovery is not always the most cost-effective approach, especially when phosphate fertilizers cost considerably less than the cost to recover struvite as fertilizer. The aim of this state-ofan-art review paper is to discuss P recovery as calcium phosphate, which could be a fertilizer feedstock and incurs less chemical costs to produce. Calcium phosphate also offers broader applications for other industrial uses beyond fertilizers since the composition is close to mined phosphate rock. A strategic approach for a regional reclaimed phosphate reserve is proposed to secure the most economical future supply of P.