Semriach Wastewater Treatment Plant, Peggau, Steiermark, Austria

The Semriach wastewater treatment plant is located in Peggau, a municipality in the Bezirk Graz-Umgebung district of Steiermark, Austria. The plant serves a population of 1,160 and operates with advanced treatment processes, ensuring high-quality effluent before discharge. With a designed capacity of 3,000 m³/day and an actual discharge volume of 320 m³/day, the plant operates well below its capacity, indicating room for future growth. As an Austrian facility, it complies with the EU Urban Waste Water Treatment Directive (91/271/EEC), which mandates secondary treatment for agglomerations of this size, but the plant exceeds requirements with advanced treatment. The treated effluent is discharged into the local water system, which ultimately drains into the Mur River and then the Drava River, contributing to the Danube basin. The plant plays a key role in protecting the region's water quality and supporting the ecological health of downstream aquatic habitats.

The plant discharges into a tributary of the Mur River, which flows through Steiermark before joining the Drava River and eventually the Danube. The Mur River supports diverse aquatic life and is an important corridor for fish migration. The advanced treatment at Semriach helps reduce nutrient loads, protecting downstream ecosystems from eutrophication.