Dec 6, 2019

What is your technology?

The CalPrex™ system exclusively licensed to CNP by Nutrient Recovery and Upcycling (NRU), is a phosphorus removal and recovery technology with applications in municipal, industrial, and agricultural wastewater treatment. The CalPrex system recovers phosphorus in the form of a calcium phosphate mineral called brushite, a valuable fertilizer product.


What are the benefits of implementing your technology?

The CalPrex process is uniquely suited for recovering a high rate of soluble phosphorus by adding calcium hydroxide – a relatively inexpensive input. The system can work at facilities with anaerobic digesters, aerobic digesters, and post anaerobic denitrification without the need of ammonium in solution. For anaerobic digesters, CalPrex incorporates a thickened sludge fermentation tank to increase the amount of soluble and reactive species of phosphorus, thereby increasing the phosphorus recovery potential. The system diverts over 50% of total phosphorus from the methane digester and, ultimately, from resulting biosolids. For aerobic and post anaerobic denitrification applications, the CalPrex system uses the biosolids dewatering filtrate or centrate and can also recover over 50% of the total phosphorus. 

Through the CNP and NRU partnership, CNP will manufacture and implement the technology at facilities and NRU will handle the recovered fertilizer material under its Steady State™ brand. NRU will offer facilities implementing CalPrex a source of revenue through the sales of the recovered phosphorus. 


Has the technology been tested, demonstrated, or implemented anywhere to date?

The CalPrex system has operated and been optimized during five 10-gallon-per-minute pilot runs at two locations – Woodridge, Illinois and Madison, Wisconsin.


What are some of the next steps needed to advance the technology?

A peer review of the WRF project findings is being conducted, and the results will be disseminated to the industry through the LIFT Link platform. These results will help water resource recovery facilities evaluate and benchmark alternatives for phosphorus removal, with the ultimate goal of helping utilities to use phosphorus recovery technologies such as CalPrex™ to 1) mitigate operations and maintenance issues related to struvite scaling and poor sludge dewaterability and 2) meet increasingly stringent regulations on phosphorus discharge.

Additionally, the launch of NRU’s Steady State fertilizer brand serves as an outlet for recovered phosphorus sales. Fertilizer products and garden kits can be pre-ordered on Kickstarter before December 28, 2019. A successful Kickstarter project will mean that NRU can provide fertilizers featuring recovered phosphorus to home consumers and, in turn, offer facilities interested in CalPrex an even higher value proposition. 


How has LIFT helped, or how can LIFT help?

In the fall of 2018, WRF and LIFT helped organize a collaborative research project with 11 organizations involving Milwaukee Metro, Denver Metro, Boston Metro, Madison Metro, the Colorado School of Mines, the University of Wisconsin – Madison, Rock River Labs, Hazen & Sawyer, Black and Veatch, Nutrient Recovery and Upcycling, and Centrisys-CNP. The goal of the project was to demonstrate and perform an independent validation of the CalPrex technology with a 10-gpm pilot system operating at Madison’s Nine Springs facility in Madison, WI. Preliminary results from this project indicate 65% solubilization rate in the fermented sludge. From there, 44% of the total phosphorus was captured with 89% soluble phosphorus reduction in the CalPrex reactor. 

For more information about the Steady State brand, visit the Kickstarter campaign page, check out the website, or follow @newsteadystate on Twitter, Instagram, Facebook, and YouTube. 

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