From wastewater to valuable fertiliser

Aaby Wastewater Treatment Plant in Aarhus uses a simple technique to extract phosphorus via struvite from the wastewater and turn it into a valuable fertiliser.

This product is available under the name of PhosphorCareTM. It is the first full-scale demonstration plant to test the viability of renewable phosphate production in Denmark. In the long term the plant will be able to extract 40 - 60 percent of the amount of phosphorus in the wastewater.

It is the result of a collaboration between a number of private and public partners, and with it comes the added bonus that the challenges of clogged-up pipes in the sewage works have been considerably minimised. This, in turn, reduces the expenses of maintaining the sewage works.

Recovering phosphorus has great potential. If similar systems were established at the 50 largest plants in Denmark, the country would be more or less self-sufficient in phosphorus. Phosphate is a finite resource with few global suppliers.

With the world facing twin crises of excessive energy use and diminishing resources, the project is consistent with Aarhus Vand’s corporate focus on sustainability. It is in the planning to introduce this process to two additional plants.

The partnership behind the project also includes two other Danish water utilities (Herning Vand and Horsens Vand), Grundfos, Norconsult and the Danish Agricultural Advisory Service.