Sousel Wastewater Treatment Plant - Sousel, Portalegre, Portugal

The Sousel wastewater treatment plant is located in the town of Sousel, in the Portalegre district of Portugal. It serves a population of approximately 2,000 people, making it a small-scale municipal facility. The plant is situated inland, away from coastal areas, and its operations are part of the region's water management infrastructure. The plant provides secondary treatment, which is the standard biological treatment required under the EU Urban Waste Water Treatment Directive (91/271/EEC) for agglomerations of this size. The directive mandates secondary treatment for all discharges from agglomerations with a population equivalent (PE) between 2,000 and 10,000, unless the receiving waters are designated as sensitive areas requiring more advanced treatment. The plant's designed capacity is 2,219 cubic meters per day, and it currently treats an average daily volume of 333.46 cubic meters, indicating ample capacity for current loads. The treated effluent from Sousel is discharged into local streams that eventually drain into the Sado River basin, which flows westward to the Atlantic Ocean near Setubal. The region's water bodies support diverse aquatic life and are important for agriculture and local ecosystems. Proper treatment helps protect water quality in this inland watershed.

The Sousel plant discharges into small watercourses that are part of the Sado River basin. The Sado River flows through the Alentejo region and empties into the Atlantic Ocean via the Sado Estuary, a ecologically sensitive area that supports diverse birdlife and fish species. The plant's secondary treatment helps reduce organic pollution and nutrient loads, protecting downstream aquatic habitats and maintaining water quality for agricultural and recreational uses.