More stringent nutrient regulations for both land application and the sale of biosolids are driving water resource recovery facilities (WRRFs) to evaluate technologies that remove and recover phosphorus in a cost-effective and sustainable manner. This project sought to independently validate the CalPrex phosphorus removal and recovery system. The research results will help WRRFs evaluate and benchmark alternatives for removing phosphorus from sludge going to digesters, address operations and maintenance issues related to struvite scaling in pipes and poor sludge dewaterability, better meet increasingly stringent regulations on phosphorus, and recover valuable fertilizer. Research partners: Metro Wastewater Reclamation District of Denver and Milwaukee Metropolitan Sewerage District. Published in 2021.