USA: +1 262 764 3651   |   Europe: +49 40 6699 680-0   |   Media Release

The Problem

struvit crystals

Struvite Mineral Buildup Causes Reduced Wastewater Treatment Plant Capacity

In wastewater treatment plants with biological phosphate elimination, high phosphate concentrations occur in the digester’s anaerobic environment.

As a result, struvite (or MAP: magnesium ammonium phosphate) builds up inside the pipes, pumps and process equipment, causing problems including:

  • Reduced plant capacity due to decreased flow through
    the digester’s pipes
  • Reduced dewatering efficiency due to increased water
    bounding effects in the sludge by high phosphate levels
  • Increased phosphate loads in the return liquor, which
    leads to a less efficient phosphate-elimination process
    and causes crystallization problems in pipes and pumps

Read on to see how AirPrex® solves the struvite problem.

Our Solution

How AirPrex Optimizes the Sludge Treatment Process Like No Other System

Until now, the main methods of struvite removal have been:

  • Costly, recurring chemical treatments
  • Phosphorus removal after dewatering


Unlike these other systems, AirPrex is a complete sludge optimization and phosphorus recovery system that’s installed between anaerobic digestion and dewatering. The boundary conditions for struvite precipitation are set by air stripping in the AirPrex reactor and the addition of a magnesium chemical product. This combination of biological phosphate elimination and the AirPrex system achieves unrivaled effectiveness in terms of wastewater dewatering efficiency and cost savings.

Read more about the process in WE&T magazine.

Or, explore the results you can achieve.

View the AirPrex Photo Gallery


AirPrex Removes Struvite while Significantly Improving Efficiency

The AirPrex process has been designed to produce maximum return on investment and make a significant impact on your treatment plant’s cost of operations. The elimination of struvite through this unique process leads to a 90 to 95 percent phosphate reduction in the returned liquor (up to 15 percent related to the incoming P-load).

case study

About cnp

cnp Technology Water and Biosolids Corporation
designs and supplies systems for nutrient recovery and
sludge optimization. Led by a team of wastewater industry
veterans and supported globally by engineers with decades
of experience in biosolids treatment, cnp continues to
pioneer innovative wastewater system solutions.


Our Executive Team

Rudi Bogner - CEO
Gerhard Forstner - President
Bernd Kalauch - Chief Technical Officer

Contact Us


cnp-Technology Water and Biosolids Corp.

9535 58th Place | Kenosha, WI 53144

+1 262 764 3651, Fax: +1 262 764 8705


cnp-Technology Water and Biosolids GmbH

Merkurring 46 | 22143 Hamburg

+49 40 6699 680-0, Fax: +49 40 6699 680-29

An Optimal Struvite Solution – and Easy to Implement

Your partners at cnp can easily incorporate this value-producing technology into your operation in any plant setting, including retrofitting it to your existing infrastructure. Contact us today to get started.