Irdning Wastewater Treatment Plant, Irdning-Donnersbachtal, Styria, Austria

The Irdning wastewater treatment plant is located in Irdning-Donnersbachtal, a municipality in the Liezen district of Styria, Austria. The plant serves a population of 3,838 and is designed to handle a capacity of 4,000 m³ per day, with an average discharge volume of 818.77 m³ per day. The plant employs advanced treatment processes, which go beyond the secondary treatment required by the EU Urban Waste Water Treatment Directive (91/271/EEC) for agglomerations of this size. This level of treatment typically includes nutrient removal to protect sensitive water bodies. The treated effluent is discharged into local waterways that ultimately drain into the Enns River, a tributary of the Danube. The Danube flows into the Black Sea, making this plant part of a vast international river basin. Advanced treatment helps protect downstream ecosystems and water quality.

The plant discharges into the Enns River basin, which flows into the Danube and eventually the Black Sea. This watershed supports diverse aquatic life and is important for migratory fish species. Advanced treatment reduces nutrient loads, helping to prevent eutrophication in downstream waters.