ILE AUX MOINES Wastewater Treatment Plant, Île-aux-Moines, Brittany

The ILE AUX MOINES wastewater treatment plant is located on the island of Île-aux-Moines in the Morbihan department of Brittany, France. The plant serves a small island community of approximately 2,873 residents, providing essential sanitation infrastructure for this coastal settlement. Its location on an island presents unique operational challenges, including proximity to sensitive marine environments. 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. With a designed capacity of 2,500 cubic meters per day and a current discharge volume of 512.54 cubic meters per day, the facility operates well within its capacity. The advanced treatment level ensures high-quality effluent suitable for discharge into the surrounding coastal waters. The treated wastewater is discharged into the Gulf of Morbihan, a semi-enclosed coastal basin that connects to the Atlantic Ocean. This area is ecologically significant, supporting diverse marine life including seagrass beds, shellfish populations, and migratory bird species. The advanced treatment helps protect this sensitive coastal ecosystem from nutrient pollution and other contaminants.

The plant discharges into the Gulf of Morbihan, a shallow coastal inlet in southern Brittany that opens into the Atlantic Ocean. This marine environment supports extensive seagrass meadows, oyster farming, and important bird populations. The advanced treatment level is critical for minimizing nutrient inputs that could lead to eutrophication in the semi-enclosed gulf, which has limited water exchange with the open ocean.