Unterweissenbach Wastewater Treatment Plant, Unterweißenbach, Oberösterreich

Unterweissenbach wastewater treatment plant is located in Unterweißenbach, a municipality in the Bezirk Freistadt district of Oberösterreich, Austria. The plant serves a population of approximately 2,069 people, placing it in the small agglomeration category under EU regulations. The plant employs advanced treatment processes, which go beyond the secondary treatment standard required by the EU Urban Waste Water Treatment Directive (91/271/EEC) for agglomerations of this size. With a designed capacity of 4,200 m³/day and an actual discharge volume of 629.82 m³/day, the facility operates well within its capacity, indicating robust infrastructure for current loads. Treated effluent from the plant is discharged into local watercourses that ultimately drain into the Danube River basin, contributing to the Black Sea watershed. The advanced treatment level helps protect downstream aquatic ecosystems, including sensitive areas in the Danube Delta, by reducing nutrient loads and organic pollutants.

The plant discharges into small streams in the Mühlviertel region, which flow into the Danube River via the Naarn or Aist rivers. The Danube is a major European waterway that drains into the Black Sea, supporting diverse aquatic life and migratory fish species. The advanced treatment at Unterweissenbach helps minimize nutrient enrichment in downstream waters, which is critical for maintaining ecological balance in the Danube basin.