The demonstration project is being carried out at the Ulrum wastewater treatment plant.

Why here?

Both of the water authorities involved (Noorderzijlvest and Wetterskip Fryslân) have wastewater treatment plants that are potentially attractive for implementing CADoS. After consultation the project team defined a number of preconditions for the research location:

  • the treatment plant had to be a bio-P installation (i.e. a treatment plant with an anaerobic selector) where phosphate is removed almost entirely biologically and stored in the sludge. This is where it is possible to determine the saving on metal salts achievable by dewatering before the sludge becomes anaerobic;
  • it had to be a small treatment plant preferably capable of using a single fine sieve to process the entire influent flow and where the level of investment is low;
  • the treatment performance risks had to be limited, even if the technology is operated at the limits of its potential.

The Ulrum wastewater treatment plant is a small bio-P installation. In summer the sludge content in the aeration tank is 1.0 – 1.5 g/l and there is hardly any growth. The challenge is to maintain with the fine sieve a sludge content of 0.5 – 1.0 g/l in summer.

Ulrum is situated almost on the border between Friesland and Groningen provinces and is centrally located for all project partners.

Do you want to visit the location?
U can visit the CADoS-installation only with an employee of Noorderzijlvest. Please make an appointment with Klaas Vleems, 00316 206 16 354 or

Onderzoekslocatie - rwzi Ulrum

RWZI Ulrum (Lydia Balkema)