SENAS Wastewater Treatment Plant, Sénas, Provence-Alpes-Côte d'Azur

The SENAS wastewater treatment plant is located in Sénas, a commune in the Bouches-du-Rhône department of the Provence-Alpes-Côte d'Azur region in southern France. It serves a population of approximately 4,986 residents, classifying it as a small agglomeration under French and EU regulations. The plant provides secondary treatment, which is the standard required by the EU Urban Waste Water Treatment Directive (91/271/EEC) for freshwater discharges from agglomerations of this size. Its designed capacity is 5,000 m³/day, and current discharge volume is 889.49 m³/day, indicating ample reserve capacity. The treated effluent is discharged into the local watershed, which ultimately drains into the Mediterranean Sea via the Durance River and the Rhône River. The plant plays a key role in protecting downstream water quality, including the Camargue delta, a ecologically sensitive area that supports diverse aquatic life and migratory birds.

The plant's discharge enters the local drainage network, which flows into the Durance River, a major tributary of the Rhône River. The Rhône then flows into the Mediterranean Sea near the Camargue delta. This region is ecologically significant, supporting diverse aquatic habitats and serving as an important corridor for migratory birds. The secondary treatment provided by the plant helps reduce nutrient and organic loads, mitigating eutrophication risks in downstream waters.