Treatment for medicine residues is established by using ozone
At Egå Wastewater Treatment Plant, Aarhus Vand is in the process of installing an ozone treatment system. Ozone breaks down medicine residue and other environmentally harmful substances. The new facility helps protect the aquatic environment around Aarhus even better.
Wastewater from Danish Super Hospitals contains traces of medicine, and the wastewater from Aarhus University Hospital is no exception. Most medicine residues are broken down during biological treatment processes, but a small amount remains.
Extra treatment benefits local water environment
To protect the Bay of Aarhus and the Egå stream even better, Aarhus Vand introduce treatment for medicine residues. As one of the first utilities in Denmark, Aarhus Vand is installing ozone as an additional step in the wastewater treatment at Egå. Ozone technology is well-tested abroad, e.g in Switzerland and in Denmark the technology is relatively new.
We are installing an ozone system because it has a lower CO2 footprint than other technologies removing medicine residues. Ozone is effective against a wide range of harmful substances. This also prepares us for future treatment requirements.
87% of residue comes from households
Following the Danish Environment Agency, Aarhus Vand, Aarhus Municipality, and Aarhus University Hospital analyzed wastewater at both the hospital and Egå. The analysis showed that 87% of medicine residues derive from private households, with the rest from the hospital.
“Since such a large share comes from households, it makes the most sense—and gives the greatest environmental benefit—to treat wastewater at Egå,” Maj Møller Sørensen explains. Aarhus Municipality granted an amendment to the discharge permit in June 2023, requiring treatment for four types of pharmaceutical residues that are not sufficiently removed by the current process.
Ozone technology breaks down micropollutants
The new ozone system breaks down organic micropollutants into harmless substances, which are then removed by filtration after the treatment.
We receive liquid oxygen, which is converted into ozone in a generator. When the water comes into contact with ozone, harmful substances are broken down. The treated water then passes through the existing sand filter.
VAM A/S and Krüger A/S selected as suppliers
The entrepreneur company VAM A/S and the consulting engineering firm Krüger A/S - part of Veolia supplies the ozone system. The two companies have collaborated with Aarhus Vand on the project design.
Currently VAM A/S is constructing a new machine building and a contact tank where the water reacts with ozone.
This is an important project for us, where we contribute with the execution of structures and civil works. We are proud to be at the front of a project introducing new treatment solutions for the utility sector. The project is progressing as planned in close collaboration with well-known and highly competent partners.
The ozone system will serve as a fourth treatment stage, connected after the existing secondary clarifiers. It has been designed to integrate seamlessly with the current plant.
We are very pleased to build one of Denmark’s first ozone facilities for removing medicine residues. This technology represents an important step forward in protecting our water environment and meeting future requirements for wastewater treatment. We are excited about this challenging task, where we contribute primarily with process engineering expertise as project integrator.
The new facility provides valuable learning for the future
Aarhus Vand looks forward to the project, which will deliver essential knowledge and experience to meet the requirements of the EU Urban Wastewater Directive. These insights will also be crucial when integrating a fourth treatment stage at the upcoming Aarhus ReWater plant.
Project Facts:
- Supplier of ozone system: Consortium of VAM A/S and Krüger A/S
- Construction start: August 2025
- Expected completion: 2026
- Technology benefits: Ozone treatment has a lower CO₂ footprint than alternative technologies and effectively removes a wide range of micropollutants