Research project 2021–2025

Schäfersee-Verfahren® was scientifically investigated and further developed between 2021 and 2025 within a collaborative research project funded by the German Federal Ministry of Education and Research (BMBF). The aim of the project was to systematically analyse the ecological and microbial effects of the method in different types of impacted water bodies and to further develop the technical system so that controlled and long-term stable operation becomes possible.

Building on practical experience gained prior to the project, the method was investigated and further developed under real operational conditions. Particular attention was given to how the targeted control of nitrate and oxygen inputs affects redox processes, microbial communities and internal nutrient fluxes in aquatic systems. Many of the investigated water bodies had previously shown typical impact symptoms such as oxygen-depleted deep water zones, formation of putrefaction gases, odour events and recurring release of nutrients from the sediment.

Three very different project lakes were investigated in detail: Schäfersee in Berlin, Fennsee in Berlin and Jröne Meerke in Neuss. Together they represent a spectrum ranging from a stratified urban lake to a highly impacted stormwater-dominated water body and an artificial groundwater lake with a small anoxic deep zone.

Key results

The project demonstrated that Schäfersee-Verfahren® can stabilise heavily impacted water body sections in a targeted manner. In the investigated systems improvements were observed particularly in oxygen conditions, redox potential and in the suppression of strongly reducing processes. As a result, the formation of putrefaction gases, hydrogen sulphide odours and critical stress situations could be significantly reduced.

In Schäfersee, particularly clear changes were observed in the deep water: stable positive redox conditions, a significant reduction in phosphorus concentrations and a sustained improvement of the ecological situation in the treated area. Processes that had previously led regularly to oxygen depletion and odour problems could be stabilised over the long term.

In Jröne Meerke the seasonally reduced deep-water environment could be stabilised. At Fennsee the project showed that the method can also be operated successfully and in a controlled manner in a highly impacted and comparatively shallow stormwater-influenced water body.

The results also demonstrate that the effectiveness of the method depends strongly on site-specific operational control. Dosing and operation must be adapted to the individual conditions of each water body and are based on continuous observation of limnological and chemical processes.

Topics investigated in the project

The scientific programme included chemical, microbiological and technical investigations. Parameters studied included oxygen, redox potential, nitrate, ammonium, phosphorus and organic loads in both water and sediment. In addition, changes in microbial communities were analysed in order to better understand the long-term stability of the treatment approach.

One important result of the project was that the method is not restricted to a single lake type. Schäfersee-Verfahren® proved effective both in a stratified urban lake and in smaller or shallower problem water bodies. This transformed what initially was a site-specific solution into a broadly applicable approach for the ecological stabilisation of heavily impacted aquatic systems.

Further information

Further information on the research project, the final scientific reports, intellectual property rights and public media coverage can be found via the links below. In addition to the scientific documentation, the technical basis of the process is protected by patent; the name Schäfersee-Verfahren® is also a registered trademark of Büro Wassmann.