Heiligenkreuz am Waasen Wastewater Treatment Plant - Steiermark, Austria

The Heiligenkreuz am Waasen wastewater treatment plant is located in the municipality of Heiligenkreuz am Waasen in the district of Leibnitz, Steiermark, Austria. The plant serves a population of approximately 7,059 and is classified as a small to medium agglomeration under Austrian and EU regulations. The plant provides advanced treatment, which goes beyond the secondary treatment required by the EU Urban Waste Water Treatment Directive (91/271/EEC) for agglomerations of this size. With a designed capacity of 7,000 m³/day and an actual discharge volume of 923.11 m³/day, the plant operates well within its capacity, indicating efficient management. The treated effluent is discharged into local watercourses that eventually drain into the Mur River, a major tributary of the Drava River, which flows into the Danube and ultimately the Black Sea. The plant plays a key role in protecting the water quality of the Mur River basin and the downstream aquatic ecosystems.

The plant discharges into small streams that feed into the Mur River, which flows through Steiermark and into Slovenia and Croatia before joining the Drava. The Mur River supports diverse aquatic life and is an important ecological corridor in the region. The advanced treatment helps reduce nutrient loads, protecting downstream water bodies from eutrophication and maintaining biodiversity in the Mur-Drava-Danube river system.