ARA St Aegyd am Neuwalde 1739 LF - Advanced Wastewater Treatment in Amt Mitterbach, Austria

ARA St Aegyd am Neuwalde 1739 LF is a wastewater treatment facility located in Amt Mitterbach, a locality within the municipality of St. Aegyd am Neuwalde in the Bezirk Lilienfeld district of Niederösterreich, Austria. The plant serves a population of 2,134 and has a designed capacity of 3,500 m³/day, with an average discharge volume of 411.96 m³/day. 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 small agglomerations (under 10,000 population equivalent) in sensitive areas, advanced treatment is often mandated to reduce nutrient loads. The plant's operation is integrated into Austria's national water management framework, which enforces strict effluent standards for nitrogen and phosphorus removal. The treated effluent is discharged into a local watercourse that ultimately drains into the Danube River basin, contributing to the Black Sea watershed. The surrounding region is characterized by forested hills and alpine streams, making the protection of water quality essential for aquatic ecosystems and downstream communities.

The plant discharges into a small stream that flows into the Salza River, a tributary of the Enns River, which joins the Danube River. The Danube carries the water through Austria and several other countries before reaching the Black Sea. The local watershed supports sensitive aquatic habitats, including populations of brown trout and other cold-water species. Advanced treatment helps minimize nutrient enrichment and protects the ecological integrity of these alpine streams.