Vonnas Wastewater Treatment Plant - Advanced Treatment in Auvergne-Rhône-Alpes

The Vonnas wastewater treatment plant is located in the commune of Vonnas, within the Ain department of the Auvergne-Rhône-Alpes region in eastern France. It serves a population of approximately 4,600 residents, placing it in the small-to-medium agglomeration category under French regulations. The plant employs advanced treatment processes, which go beyond the secondary treatment required by the EU Urban Waste Water Treatment Directive (91/271/EEC) for agglomerations of this size. It has a designed capacity of 4,500 m³/day and currently discharges an average of 820.63 m³/day of treated effluent. The treated wastewater is discharged into the local watershed, which ultimately drains into the Saône River and then the Rhône River, a major European waterway flowing into the Mediterranean Sea. The plant's advanced treatment helps protect downstream aquatic ecosystems and supports the region's water quality objectives.

The plant discharges into the local watercourse, part of the Saône River basin, which flows into the Rhône River and eventually the Mediterranean Sea. The Rhône is a ecologically significant river supporting diverse aquatic life and migratory fish species. Advanced treatment at this plant helps reduce nutrient loading and protects downstream water quality in this sensitive river system.