Mittleres Steyrtal Wastewater Treatment Plant, Steinbach an der Steyr, Austria

Mittleres Steyrtal is an advanced wastewater treatment plant located in Steinbach an der Steyr, in the state of Oberösterreich, Austria. The facility serves a population of approximately 3,375 people and has a designed capacity of 5,000 m³/day, with an average discharge volume of 457.56 m³/day. As an advanced treatment plant, Mittleres Steyrtal provides nutrient removal beyond secondary treatment, aligning with the requirements of the EU Urban Waste Water Treatment Directive (91/271/EEC) for sensitive areas. The plant's scale places it in the small agglomeration category, for which secondary treatment is typically mandated, but the advanced level indicates additional environmental protection measures. The plant discharges treated wastewater into the local watershed, which ultimately drains into the Steyr River and then the Enns River, a tributary of the Danube. The Danube flows into the Black Sea, making this plant part of a large international basin. The advanced treatment helps protect downstream aquatic ecosystems and supports water quality in the Danube River system.

The plant discharges into the Steyr River, a tributary of the Enns River, which flows into the Danube River and eventually reaches the Black Sea. The watershed supports diverse aquatic life and is important for migratory fish species. Advanced treatment at this plant helps reduce nutrient loads, protecting downstream water quality in this ecologically sensitive river system.