AUXI LE CHATEAU SE Wastewater Treatment Plant, Auxi-le-Château, France

AUXI LE CHATEAU SE is a wastewater treatment plant located in Auxi-le-Château, a commune in the Pas-de-Calais department of the Hauts-de-France region, northern France. The plant serves a population equivalent of 2,483, classifying it as a small agglomeration under French and EU regulations. The plant employs advanced treatment processes, which go beyond the secondary treatment standard required by the EU Urban Waste Water Treatment Directive (91/271/EEC) for agglomerations of this size. With a designed capacity of 3,600 m³/day and a reported discharge volume of 442.96 m³/day, the facility operates well within its capacity, ensuring effective treatment of municipal wastewater. The treated effluent is discharged into the local watershed, which ultimately drains into the Authie River and then into the English Channel. The plant plays a key role in protecting the water quality of the Authie estuary and the surrounding coastal environment, supporting aquatic life and recreational uses.

The plant discharges into the Authie River basin, which flows into the English Channel via the Authie estuary. This coastal zone supports diverse aquatic habitats, including migratory fish species and intertidal wetlands. The advanced treatment helps reduce nutrient loads and pollutants, safeguarding the ecological balance of the estuary and downstream marine environment.