Wastewater treatment plant, Oberursel

In order to minimise the discharge of phosphates into the neighbouring Urselbach River, the City of Oberursel is building a flocculation and filtration plant comprising an engine building and a filtration building between January 2022 and March 2024. The filtration plant will be fed from a new intermediary pumping station, and the flocculant will be added at the existing precipitant plant. The Düsseldorf branch of PORR Ingenieurbau is carrying out the structural work at the wastewater treatment facility. As the filtration plant is located in the flooding area of the Urselbach, the construction work has to be performed in a watertight pit. 

The Urselbach rises below the Großer Feldberg Mountain in the Hochtaunus region and flows into the Nidda River near Heddenheim. The idyllic river is a popular hiking destination because of its historic mills and water wheels, and yet its biological balance, like that of all bodies of water, must be constantly monitored. According to official readings, almost 3,000 kilograms of dissolved phosphorus were released into the Urselbach in 2016 alone.

High levels of phosphorus in water bodies lead to increased growth of algae and aquatic plants and reduce the oxygen content in the water. For this reason, improving the quality of the water has been on the political agenda for many years. 

Flocculation and filtration plant removes phosphorus and solids from the wastewater 

For several years now, the Oberursel wastewater treatment plant has been implementing a phased plan for phosphorus elimination in order to be able to meet the increasingly stringent environmental regulations in the future as well. The ultimate goal is to reduce the levels to a daily average of no more than 0.2 milligrams per litre. 2020 saw the opening of a state-of-the-art precipitant station, where most of the phosphorus compounds are precipitated from the wastewater, and a flocculation and filtration plant will be built on the site by the end of 2023. It is designed to further reduce the phosphate and solids content of the wastewater before it is discharged into the Urselbach.