CUISE LA MOTTE Wastewater Treatment Plant, Trosly-Breuil, Hauts-de-France

CUISE LA MOTTE is a wastewater treatment plant located in Trosly-Breuil, within the Oise department of Hauts-de-France, France. The plant serves a population of 5,100 and has a designed capacity of 10,000 m³/day, with a current discharge volume of approximately 910 m³/day. As a secondary treatment facility, CUISE LA MOTTE provides biological treatment to reduce organic matter and suspended solids. Under the EU Urban Waste Water Treatment Directive (91/271/EEC), agglomerations of this size (5,100 population equivalent) are required to have secondary treatment, which the plant meets. The directive also mandates appropriate collection systems and treatment to protect receiving waters. The plant discharges treated effluent into the local watershed, which ultimately drains into the Aisne River, a tributary of the Oise River, and then into the Seine River before reaching the English Channel. This waterway supports diverse aquatic life and is important for regional water quality and downstream ecosystems.

The treated effluent from CUISE LA MOTTE enters the Aisne River, which flows into the Oise River and then the Seine River, eventually reaching the English Channel. The Seine basin is a major ecological corridor in northern France, supporting fish species such as Atlantic salmon and European eel. The plant's secondary treatment helps reduce nutrient loads that could contribute to eutrophication in downstream waters.