WRF Launches Project to Demonstrate Phosphorus Recovery Using CalPrex System

Jul 1, 2019

DENVER, CO 11/30/18 – The Water Research Foundation (WRF) has launched a project, Demonstrating the CalPrex™ System for High Efficiency Phosphorus Recovery (5004), between the Milwaukee Metropolitan Sewerage District (Milwaukee, Wisconsin), Madison Metropolitan Sewerage District (Madison, Wisconsin), Metro Wastewater Reclamation District (Denver, Colorado), Massachusetts Water Resources Authority (Boston, Massachusetts), and Centrisys/CNP (Kenosha, Wisconsin), to demonstrate a high-rate, pre-digestion phosphorus removal and recovery technology. The technology, developed at the University of Wisconsin-Madison and licensed from Nutrient Recovery and Upcycling (NRU) by Centrisys/CNP under the name CalPrex™, ran as a ~10 gallon per minute pilot system from October through the end of November 2018 at the Madison Metropolitan Sewerage District. The demonstration has provided high-quality data that will allow utilities to evaluate high-rate phosphorus recovery and its effects on phosphorus load management.

The CalPrex™ phosphorus removal and recovery system incorporates a thickened sludge fermentation tank to increase the amount of soluble and reactive species of phosphorus, thereby increasing the recovery potential of that phosphorus. The system diverts over 50% of soluble phosphorus from the methane digester and, ultimately, from resulting biosolids. The CalPrex™ system recovers phosphorus in the form of brushite, a calcium phosphate mineral with high potential as a slow-release phosphorus fertilizer. The project will support and leverage efforts that NRU is undertaking in conjunction with a USDA SBIR grant and a supporting grant from the Center for Technology Commercialization in Wisconsin to establish brushite in the fertilizer market.

Results of the project will help water resource recovery facilities (WRRFs) evaluate and benchmark state-of-the-art alternatives for removing phosphorus from sludge going to digesters. The goal is for utilities to use phosphorus recovery technologies such as CalPrex™ to mitigate operations and maintenance issues related to struvite scaling in pipes and poor sludge dewaterability. Simultaneously, WRRFs implementing such technologies will better meet increasingly stringent regulations on phosphorus while recovering a valuable fertilizer. An expert review of the project findings will be conducted, and the results will be disseminated to industry professionals through the WRF LIFT Link platform in May 2019.  

About WRF

The Water Research Foundation is a 501c3 organization officially formed in January 2018 after the merger of the Water Environment & Reuse Foundation and Water Research Foundation. The merged Foundation is the leading water research organization, funding research, pilot projects, and technology demonstrations that maximize the value of all water, including wastewater, stormwater, drinking water, and recycled water. Learn more at www.werf.org or www.waterrf.org.