OISSERY St PATHUS Wastewater Treatment Plant, Oissery, France

OISSERY St PATHUS is an advanced wastewater treatment plant located in Oissery, a commune in the Seine-et-Marne department of north-central France. The plant serves a population of around 5,142 and is part of the municipal infrastructure managed by the local authority. Its designed capacity of 10,000 m³/day indicates it is sized for moderate flows, with an actual discharge volume of 917.32 m³/day. The plant employs advanced treatment processes, which go beyond secondary treatment to remove nutrients and other pollutants. This level of treatment is consistent with French and EU regulations under the Urban Waste Water Treatment Directive (91/271/EEC), which requires appropriate treatment for sensitive areas. The plant's performance is likely monitored by the French water agencies (Agences de l'eau) to ensure compliance with discharge standards. Treated effluent from the plant is discharged into local waterways that eventually drain into the Seine River basin. The Seine flows through Paris and into the English Channel, supporting diverse aquatic ecosystems and serving as a critical water resource. The advanced treatment helps protect downstream water quality and the ecological health of the Seine estuary.

The plant discharges into the Seine River basin, which drains northward through the Paris region and into the English Channel. The Seine supports a variety of fish species and is an important migratory corridor for eels and salmon. Advanced treatment reduces nutrient loading, helping to prevent eutrophication in the river and its estuary.