Probsteierhagen Wastewater Treatment Plant | Schleswig-Holstein, Germany

The Probsteierhagen wastewater treatment plant is located in the municipality of Probsteierhagen, within the district of Plön in Schleswig-Holstein, Germany. It serves a population of approximately 2,324 residents, placing it in the small agglomeration category under the EU Urban Waste Water Treatment Directive (91/271/EEC). The plant is situated near the Baltic Sea coast, within 10 km of the shoreline. The facility employs advanced treatment processes, which go beyond the secondary treatment standard required by the EU Directive for agglomerations of this size. The plant has a designed capacity of 3,500 m³/day and currently discharges 348.68 m³/day of treated wastewater. As a German plant, it operates under the national implementation of the EU Directive, which mandates strict effluent quality standards to protect sensitive coastal waters. The treated effluent is discharged into local watercourses that drain into the Baltic Sea, a semi-enclosed sea with limited water exchange and high ecological sensitivity. The Baltic Sea is subject to eutrophication pressures from nutrient inputs, making advanced nutrient removal at coastal plants critical for marine ecosystem health. The plant's advanced treatment helps reduce nitrogen and phosphorus loads, supporting the goals of the Helsinki Commission (HELCOM) for Baltic Sea protection.

The plant discharges into small streams that flow into the Baltic Sea near the Kiel Fjord area. The Baltic Sea is a brackish water body with unique ecological characteristics, including low biodiversity but high sensitivity to nutrient pollution. Eutrophication from nitrogen and phosphorus inputs is a major concern, leading to algal blooms and oxygen depletion. The plant's advanced treatment helps mitigate these impacts by removing nutrients before discharge, supporting the health of coastal habitats and fisheries.