Trace substances are increasingly presenting municipal sewage treatment plants with major challenges. The legal requirements are increasing, not least due to the amended municipal wastewater directive (KARL), which stipulates the expansion of certain municipal sewage treatment plants with an additional fourth purification stage.
In order to be able to meet these challenges, the new trace substances center should look for solutions – as individual as possible and adapted to the requirements of the different systems in the state of Schleswig-Holstein. The employees of the Laboratory for Urban Water Management and Waste Technology at TH Lübeck have been working on measures to protect water bodies for two decades.
VAK in Reinfeld expanded to include a pilot plant for the 4th cleaning stage
The university’s experimental and training sewage treatment plant (VAK), located in Reinfeld on the site of the municipal sewage treatment plant, has now been expanded by the end of 2025. There are currently a handful of blue and red containers around the actual test hall – these are pilot systems for the so-called fourth cleaning stage.
The fourth stage of purification is a relatively new addition to wastewater treatment plants. The basis is an EU directive that stipulates that classic sewage treatment plants, with their usually three-stage process, cannot adequately remove many micropollutants. The list of potentially harmful substances is long. One example is the active ingredient diclofenac, which is present in painkillers. It mainly gets into lakes and rivers via wastewater – for example by washing off pain ointments. Even in small doses it can have a toxic effect on fish and other aquatic life.
And this is exactly where the research and development project of the TH Lübeck in cooperation with the state of Schleswig-Holstein comes into play. The tests on the fourth purification stage are intended to ensure that, in the case of diclofenac, for example, 80 percent of the trace substances can be retained – currently it is 20 to 30 percent, according to the local head of the VAK, Prof. Dr.-Ing. Kai Wellbrock, explains.
Environment Minister Tobias Goldschmidt was a guest at the start of the project
Environment Minister Tobias Goldschmidt is also on site at the start of the commissioning of the pilot plants and explains: The new trace substance center will support municipalities in this project and bring science and practitioners together. I am convinced that the trace substances center will become a project with charisma that will achieve a lot of good things for the people in our country: for innovative water management, for applied research and for healthy water in Schleswig-Holstein.
The pilot plant for the fourth cleaning stage consists of several modular and transportable process stages. The VAK team’s options include ozonation and filtration using activated carbon. The procedures can be used individually, but also in combination. Since they are directly connected to the wastewater treatment plant system, testing and research can be carried out under real conditions. The advantage: The containers with the different process stages can also be used in other systems and thus influence the decision-making process as to how the respective systems could be converted with regard to the fourth cleaning stage.
Trace Substance Center: Interface between science and practice
At the Reinfeld location there has been a symbiotic collaboration between the TH Lübeck and the municipal sewage treatment plant for more than 20 years. Reinfeld’s mayor Roald Wramp also emphasizes this once again: We are proud to be the host of such an experimental and training wastewater treatment plant
and added: This also plays a central role in the training of skilled workers.
Muriel Helbig, President of TH Lübeck, emphasizes: This is an important step on the path to sustainable water management and an important project for us as a technical university at the interface between science and practice.
The trace substances center will combine exactly what the technical university stands for: practical, applied teaching and research with solutions for the community.