GRIGNOLS 2 Wastewater Treatment Plant, Sillas, Nouvelle-Aquitaine, France

GRIGNOLS 2 is a municipal wastewater treatment plant located in Sillas, within the Gironde department of Nouvelle-Aquitaine, France. It serves a population of approximately 2,345 people, classifying it as a small agglomeration under French and EU regulations. The plant is situated in a rural area near the town of Grignols. The plant provides secondary treatment, which is the standard required by the EU Urban Waste Water Treatment Directive (91/271/EEC) for agglomerations of this size. Its designed capacity is 2,000 m³/day, and the reported discharge volume is 418.34 m³/day, indicating operational headroom. Secondary treatment typically involves biological processes to reduce organic matter and suspended solids. Treated effluent is discharged into local watercourses that drain into the Garonne River basin, eventually reaching the Atlantic Ocean via the Gironde estuary. The plant plays a key role in protecting the region's water quality, supporting aquatic ecosystems and downstream uses such as agriculture and recreation.

The plant discharges into the Garonne River basin, which flows through southwestern France to the Gironde estuary and the Atlantic Ocean. This watershed supports diverse aquatic life, including migratory fish species such as Atlantic salmon and European eel. The region's agricultural activities rely on clean water from these rivers, making effective wastewater treatment essential for maintaining ecological balance and water quality.