Isserstedt Wastewater Treatment Plant, Jena, Thüringen, Germany

Isserstedt wastewater treatment plant was located in the Isserstedt district of Jena, in the state of Thüringen, Germany. It served a population of approximately 1,942 people, classifying it as a small agglomeration under the EU Urban Waste Water Treatment Directive (91/271/EEC). The plant is now closed. The facility provided advanced treatment, which goes beyond the secondary treatment standard required by the EU directive for freshwater discharges. With a designed capacity of 2,500 m³/day and an average discharge volume of 491.47 m³/day, the plant operated well below its capacity. As a German plant, it was subject to the national Wasserhaushaltsgesetz (Water Resources Act) and the Abwasserverordnung (Wastewater Ordinance), which set stringent effluent limits. The treated effluent was discharged into local watercourses that ultimately drain into the Saale River, a tributary of the Elbe, which flows into the North Sea. The plant's advanced treatment helped protect the sensitive aquatic ecosystems of the Saale and Elbe basins, supporting biodiversity and water quality downstream.

The plant discharged into the Saale River basin, part of the Elbe watershed that drains into the North Sea. The Saale and its tributaries support diverse aquatic life, including fish species such as the European eel and various migratory fish. Advanced treatment at Isserstedt helped reduce nutrient loads, protecting downstream water quality in the Elbe estuary and the North Sea.