Tanna Wastewater Treatment Plant, Zollgrün, Thüringen, Germany

The Tanna wastewater treatment plant is located in the Frankendorf district of Zollgrün, a locality within the town of Tanna in the Saale-Orla-Kreis district of Thüringen, Germany. The plant served a population of approximately 1,605 people and was designed with a capacity of 2,500 m³ per day, with a recorded discharge volume of 406.19 m³ per day. The facility is now closed. As an advanced treatment plant, Tanna provided a high level of wastewater purification, likely including nutrient removal, which is typical for plants in sensitive catchment areas under the EU Urban Waste Water Treatment Directive (91/271/EEC). For agglomerations of this size (under 2,000 population equivalent), the directive requires appropriate treatment, and advanced treatment goes beyond the secondary standard, often implemented to protect receiving water bodies. The plant's discharge likely entered a local watercourse within the Saale river basin, which ultimately drains into the Elbe River and then the North Sea. The Thüringen region is characterized by forested hills and agricultural land, and the plant's advanced treatment helped minimize nutrient loading to downstream ecosystems, supporting water quality in the Saale and Elbe systems.

The Tanna plant discharged into a local tributary of the Saale River, which flows northward through Thüringen and Saxony-Anhalt before joining the Elbe River. The Elbe then empties into the North Sea near Cuxhaven. The Saale basin supports diverse aquatic life, including fish species such as barbel and grayling, and the advanced treatment at Tanna helped reduce eutrophication risks in downstream waters. The region's mixed agricultural and forested landscape means that nutrient control from wastewater is important for maintaining ecological balance.