The wastewater treatment plant of the future is located in Egå

Using cutting edge new technologies

With the ambitious goal of achieving a net energy production of 150%  on power generation alone at Egå WWTP, we, as turnkey contractor for Aarhus water, have introduced new and innovative technologies for the plant. The project is supported by EUDP with just over 8 million. kr.

In order to achieve the high energy gain, it has been necessary to bring more technologies into play,  and one of the most important parameters in the expansion has been to ensure synergies between new technologies, processes and components.

The main ideas of the project are:

  • Dynamic outlet of carbon on Salnes® filters for maximising the carbon input to the new digester. Large and expensive primary tanks that often cause odor problems are not necessary when using Salnes®filters. Salnes®filters can be established at wastewater treatment plants close to urban areas.
  • Pulp treatment with Anammox bacteria (DEMON®) which minimises internal nitrogen loading, and feeds process tanks with Anammox bacteria.
  • "Cold Anammox" process in process tanks (EssDe®). Annamox bacteria in the process tanks purifies the wastewater with a reduced consumption of carbon and oxygen, which allows even more primary sludge than with a traditional plant.
  • High-efficiency gas generator, for power and heat production based on the biogas produced.
  • Additional power generation on an ORC, Organic Rankine Cycle. The excess heat energy is used for evaporation of a propellant that drives a turbine with a generator. This way is able to produce about 10% more kWh, and thereby sales to the electrical power network is increased. Instead of venting the heat to the atmosphere, electricity is produced!
  • Finally, a thorough review of all the plant's installations for energy optimisation.


The renovation of Egå wastewater treatment plant is carried out by EnviDan A/S together with Per Aarsleff A/S, and the plant was completed in 2016.

The project is conducted in cooperation with Grontmij and Eliqio as technology supplier of EssDe®. DEMON® and Salsnes® as suppliers of belt filters.

Jens  Albrechtsen