LANGONNET Pont Mahe Wastewater Treatment Plant, Langonnet, Bretagne

LANGONNET Pont Mahe is a municipal wastewater treatment plant located in Langonnet, a commune in the Morbihan department of Bretagne, France. The plant serves a population of approximately 2,867 people and has a designed capacity of 3,000 m³/day, with an average discharge volume of 511.47 m³/day. 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. Advanced treatment typically includes nutrient removal (nitrogen and phosphorus) to protect sensitive receiving waters. As a French facility, it operates under national regulations transposing the EU directive, with permits issued by the local water agency (Agence de l'Eau). The treated effluent is discharged into a local watercourse that ultimately drains into the Atlantic Ocean via the Blavet River or nearby coastal waters. The plant's location in rural Bretagne means it plays a key role in protecting the region's rivers and estuaries, which support diverse aquatic life and are important for agriculture and tourism.

The plant discharges into a small river system in the Blavet basin, which flows into the Atlantic Ocean near Lorient. The downstream environment includes estuarine and coastal habitats that support migratory fish species and marine biodiversity. Advanced treatment helps reduce nutrient loading, which is critical for preventing eutrophication in sensitive coastal waters.