Cissac-Médoc Wastewater Treatment Plant | Secondary Treatment, Nouvelle-Aquitaine

The Cissac-Médoc wastewater treatment plant is located in the commune of Cissac-Médoc, within the Gironde department of Nouvelle-Aquitaine, France. It serves a population of approximately 1,223 residents, classifying it as a small agglomeration under French and EU regulations. The plant is situated near the Atlantic coast, less than 10 km from the shoreline. The facility provides secondary treatment, which is the minimum standard required by the EU Urban Waste Water Treatment Directive (91/271/EEC) for freshwater discharges from agglomerations of this size. Secondary treatment typically involves biological processes to reduce organic matter and suspended solids. The plant has a designed capacity of 3,600 m³/day and a reported discharge volume of 218.18 m³/day. The treated effluent is discharged into the local watershed, which ultimately drains into the Gironde estuary and then the Atlantic Ocean. The plant plays a key role in protecting the sensitive coastal and estuarine environment from nutrient pollution and pathogens. Its operation is subject to French national regulations implementing the EU directive, ensuring compliance with water quality standards for the protection of downstream ecosystems.

The plant discharges into the local watershed that feeds the Gironde estuary, one of the largest estuaries in Europe, which then flows into the Bay of Biscay (Atlantic Ocean). This estuary supports diverse aquatic life, including migratory fish species, and is ecologically sensitive due to its role as a nursery for marine organisms. The proximity to the coast (within 10 km) means that any nutrient or pathogen discharge could directly impact coastal water quality and marine habitats.