Stainach Wastewater Treatment Plant, Stainach-Pürgg, Steiermark, Austria

The Stainach wastewater treatment plant is located in the town of Stainach-Pürgg, in the district of Liezen, Steiermark, Austria. It serves a population of approximately 2,208 residents, making it a small-scale municipal facility. The plant is situated along the B320 road in the Enns River valley, a region characterized by alpine terrain and rural settlements. The plant employs advanced treatment processes, which go beyond the secondary treatment standards required by the EU Urban Waste Water Treatment Directive (91/271/EEC). For small agglomerations under 10,000 population equivalent, the directive mandates appropriate treatment, and Austria often implements stricter nutrient removal standards due to sensitive receiving waters. The plant's designed capacity is 4,250 cubic meters per day, with an actual discharge volume of 431.40 cubic meters per day, indicating significant reserve capacity. The treated effluent is discharged into local watercourses that ultimately drain into the Enns River, a major tributary of the Danube River. The Danube flows into the Black Sea, making this plant part of a large international river basin. The advanced treatment helps protect downstream aquatic ecosystems, including fish spawning grounds and biodiversity in the Danube Delta.

The plant discharges into the Enns River watershed, which flows northward to join the Danube near Enns. The Danube then travels through several countries before reaching the Black Sea. The Enns River supports diverse aquatic life, including salmonid populations, and its water quality is critical for downstream ecosystems. The advanced treatment at Stainach helps reduce nutrient loads that could otherwise contribute to eutrophication in the Danube and Black Sea.