Sieverstedt Wastewater Treatment Plant, Stenderup, Schleswig-Holstein, Germany

The Sieverstedt wastewater treatment plant is located in the Stenderup district of Sieverstedt, within the Schleswig-Flensburg district of Schleswig-Holstein, Germany. It served a small population of 1,098 people before its operational status was listed as closed. The plant was designed with a capacity of 2,150 m³/day and discharged an average volume of 277.88 m³/day. Although the plant is now closed, it operated with advanced treatment technology, which exceeds the secondary treatment standard required by the EU Urban Waste Water Treatment Directive (91/271/EEC) for agglomerations under 2,000 population equivalent. German wastewater facilities are regulated under the Water Resources Act (WHG) and the Waste Water Ordinance (AbwV), which set strict effluent limits for nutrients and other pollutants. The area drains into the Treene River system, which flows into the Eider River and ultimately the North Sea. The region is characterized by agricultural land and small watercourses, making nutrient removal important for protecting downstream aquatic ecosystems.

The Sieverstedt plant is situated in the catchment of the Treene River, a tributary of the Eider River, which discharges into the North Sea near Tönning. The Treene and Eider rivers support diverse aquatic life and are important for migratory fish species. The surrounding landscape is predominantly agricultural, so treated effluent quality is critical to prevent nutrient enrichment in these sensitive water bodies.