SAINT JOUAN DES GUERETS Wastewater Treatment Plant, Saint-Jouan-des-Guérets, Brittany

The SAINT JOUAN DES GUERETS wastewater treatment plant is located in Saint-Jouan-des-Guérets, a commune in the Ille-et-Vilaine department of Brittany, France. It serves a population of approximately 4,000 residents and operates with advanced treatment technology, ensuring high-quality effluent before discharge. As an advanced treatment facility, it goes beyond secondary treatment to remove nutrients and other pollutants, meeting stringent French and European standards. The plant has a designed capacity of 7,500 m³/day and currently treats an average daily flow of 713.59 m³/day, indicating significant spare capacity. Under the EU Urban Waste Water Treatment Directive (91/271/EEC), plants serving agglomerations of this size are required to provide secondary treatment, but this facility exceeds that requirement with advanced treatment. The plant discharges treated wastewater into the local watershed, which ultimately drains into the English Channel via the Rance River estuary. Its proximity to the coast (within 10 km) means the advanced treatment is critical for protecting marine water quality and coastal ecosystems in the Saint-Malo area.

The plant discharges into the Rance River basin, which flows into the English Channel near Saint-Malo. The Rance estuary supports diverse aquatic life and is an important migratory corridor for fish species. The advanced treatment helps protect the coastal waters of the English Channel from nutrient pollution and eutrophication, preserving the ecological balance of this sensitive marine environment.