Creating a valuable fertilizer at Marselisborg plant in Aarhus

Phosphorus is non-renewable resource essential that is being used in agriculture and food production. Depletion of phosphorus is foreseen within this century and therefore there is a growing need to seek alternatives and different ways of extraction.
Our mission

Phosphorus recovery from wastewater 

Today, phosphorus is mostly obtained from mined phosphate rock, highly limited in resources in Morocco, China and USA. Due to its geographical limitations, recovery and reuse of phosphorus is gaining the attention globally. 20% of current world demand of phosphorus could be covered by recovery from wastewater.

Without reuse of phosphorus, depletion is foreseen in 100 years from now and the European Commission has classified phosphorus among the 20 “critical materials”.
Our solution

Technology that contributes to the circular economy and resource recycling

We developed a solution that extracts phosphorus via struvite from wastewater and turns it into a fertilizer.


The heart of Phosphogreen™ process consists injecting magnesium chloride to obtain precipitation-crystallization of struvite. Struvite is then extracted at the bottom of the reactor, washed, drained and dried before packaging.

Our results

Mass balance with up to 50% phosphorus recovery 

Our technology recovers phosphorus from a side stream in wastewater treatment plant and operates on two streams of phosphorus reject water. This configuration allows to recover 40-50% of the phosphorus from incoming water.

Phosphogreen™ solution was fist implemented in a full-scale at Marselisborg wastewater treatment plant located in Aarhus.

The main reason was to solve an existing problem with struvite scaling in old and new pipes and present sand in digesters. Implementation of phosphorus recovery would eliminate those issues meanwhile increasing a green image of the client’s wastewater plant and its contribution to circular economy.

Total struvite production ranges between 650-800kg per day that can be sold on the market as agricultural fertilizers containing:

  • 12,5% phosphorus
  • 5,5% nitrogen
  • 10% magnesium

with granules sizes between 1 to 3 mm.

SUEZ Phosphogreen™ solution at Marselisborg WWTP

Credit: SUEZ Water Denmark

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