Lassing Wastewater Treatment Plant, Döllach, Steiermark, Austria

The Lassing wastewater treatment plant is located in Döllach, a locality in the municipality of Lassing, Bezirk Liezen, Steiermark, Austria. The plant serves a population of 3,744 and operates with advanced treatment processes, ensuring high-quality effluent. Its designed capacity is 2,400 m³/day, with an average discharge volume of 483.47 m³/day. As an advanced treatment facility, Lassing goes beyond secondary treatment to remove nutrients and other pollutants, meeting stringent Austrian and EU standards. Austria implements the EU Urban Waste Water Treatment Directive (91/271/EEC), which requires advanced treatment for sensitive areas. The plant's scale corresponds to a small agglomeration under the directive. The treated effluent is discharged into the local watershed, which drains into the Enns River, a tributary of the Danube. The Danube ultimately flows into the Black Sea. The plant plays a crucial role in protecting the Enns and Danube ecosystems from nutrient pollution and organic loads.

The Lassing plant discharges into the Enns River basin, which flows northward to join the Danube near Enns. The Danube then travels through Central and Eastern Europe to the Black Sea. The Enns supports diverse aquatic life, including fish species such as grayling and brown trout. Advanced treatment at Lassing helps reduce nutrient inputs, mitigating eutrophication risks in downstream water bodies.