Milly-sur-Thérain Wastewater Treatment Plant, Hauts-de-France, France

The Milly-sur-Thérain wastewater treatment plant is located in the commune of Milly-sur-Thérain, within the Oise department of Hauts-de-France, France. It serves a population of approximately 3,094 residents, classifying it as a small agglomeration under French and EU regulations. The plant is situated near the Pont des Bœufs area, reflecting its role in managing local domestic wastewater. The facility 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 7,000 m³/day and a current discharge volume of 551.96 m³/day, the plant operates well below its capacity, indicating room for future growth or seasonal variations. The advanced treatment likely includes nutrient removal to protect sensitive receiving waters. The treated effluent is discharged into local watercourses that ultimately drain into the Thérain River, a tributary of the Oise River, which flows into the Seine River and eventually the English Channel. This downstream pathway highlights the plant's role in safeguarding the Seine basin ecosystem, supporting aquatic biodiversity and water quality for downstream communities.

The plant discharges into the Thérain River, a tributary of the Oise River, which flows into the Seine River and reaches the English Channel. This watershed supports diverse aquatic life and is part of a densely populated region with agricultural and industrial activities. Advanced treatment helps reduce nutrient loads, protecting downstream water bodies from eutrophication and maintaining ecological balance.