SISSONNE Wastewater Treatment Plant, Sissonne, Hauts-de-France

The SISSONNE wastewater treatment plant is located in the commune of Sissonne, within the Aisne department of the Hauts-de-France region in northern France. It serves a population of approximately 1,248 residents, classifying it as a small agglomeration under French and EU regulations. The plant provides secondary treatment, which is the minimum standard required by the EU Urban Waste Water Treatment Directive (91/271/EEC) for discharges into freshwater. With a designed capacity of 4,000 m³/day and an average daily flow of about 223 m³, the plant operates well below its capacity, indicating potential for future growth or seasonal variations. The treated effluent is discharged into the local watershed, which ultimately drains into the Seine River basin. This region is part of the larger Seine-Normandy hydrographic system, supporting diverse aquatic life and agricultural water use. The plant's secondary treatment helps protect downstream water quality and ecosystems.

The SISSONNE plant discharges into the Marais de Montaigu area, which feeds into the Souche River, a tributary of the Aisne River. The Aisne flows into the Oise, then the Seine, and finally the English Channel. This watershed supports diverse freshwater habitats and is important for migratory fish species. The plant's secondary treatment reduces organic pollution and nutrients, helping to maintain the ecological balance of the receiving waters.