When extracting phosphor, struvite turns into money instead of clogged pipes!

Stjernholm has been selected as manufacturer and marketing organisation for a new, epochal facility that turns a problem into a resource – and a future source of income for the purification plant.

The plant has been developed in cooperation with the organisations Aarhus Vand and Herning Vand, as well as the companies Norconsult and Grundfos, for the purpose of extracting struvite (also known as struvite stones) from waste water to prevent clogged pipes, heat exchangers, centrifuges etc.

In addition, it has turned out that the struvite, which is extracted during the process, has a chemical composition and structure that makes it well-suited for use as a phosphor fertiliser, and as we import our entire phosphor consumption (currently 11,000 tons per year), we welcome the possibility of selling the recycled phosphor – called PhosphorCare – as an attractive fertiliser product.

The plant works by sending a slip stream of waste water with a high phosphor and nitrogen concentration through a reactor and adding magnesium salt. Through correct regulation, a phosphor- and nitrogen-containing granulate is precipitated which is an excellent fertiliser with both physical and chemical features similar to mineral fertilisers.

The calculated payback time is less than 7 years – achieved only through operational savings. The income from the sale of PhosphorCare is additional.

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When you cooperate with us, you know that we are focusing on delivering a solution to you that adds value to your facility.


  • Minimisation of costs related to cleaning and exchange of pipes and exchangers
  • Lower man-hour costs
  • Every savings – prevent performance reductions in pipes and pumps
  • Payback time 4-7 years – depending on the price of pure phosphor
  • 10% sludge reduction


  • Environmental improvements – recycling of phosphor which is a scarce resource
  • Lower CO2 emissions – any plant 0.05 tons CO2/year


  • The staff is not required to struggle with struvite removal in pipes and other installations.
  • Work-friendly

Thomas Fleischer Christiansen

92 15 22 15

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Stjernholm A/S

Stjernholm A/S
Langelandsvej 4A
8940 Randers SV
CVR: 28 88 49 66
+45 70 20 25 05


Stjernholm US Inc

Post Oak Blvd.
Suite 1910
Houston, TX 77056 US
+1 346 388 2791