ARA Zwentendorf 225 TU Wastewater Treatment Plant, Erpersdorf, Niederösterreich

ARA Zwentendorf 225 TU is a wastewater treatment plant located in Erpersdorf, a locality within the municipality of Zwentendorf an der Donau in Niederösterreich, Austria. The plant serves a population of approximately 9,500 people, placing it in the category of a small to medium agglomeration under EU classification. As a plant in Austria, it operates under the EU Urban Waste Water Treatment Directive (91/271/EEC), which requires secondary treatment for agglomerations of this size. The directive also mandates more advanced treatment if the receiving waters are designated as sensitive areas. Compliance with the directive ensures appropriate treatment standards. The plant's treated effluent is discharged into the local watershed, which ultimately drains into the Danube River via the Donau basin. The Danube is a major European waterway that flows into the Black Sea, supporting diverse aquatic ecosystems and providing water for agriculture, industry, and recreation. The plant plays a key role in protecting the water quality of this important river system.

The plant discharges into the Danube River basin, which flows through Austria and several other countries before reaching the Black Sea. The Danube supports a rich diversity of fish, birds, and other wildlife, and is an important migratory corridor for many species. The plant's treatment helps maintain water quality in this ecologically significant river system.