Fontainhas Wastewater Treatment Plant, Grândola, Portugal

Fontainhas is a wastewater treatment plant located in Grândola, Setúbal District, Portugal. It serves a population of approximately 3,500 people, classifying it as a small agglomeration under EU standards. The plant is situated inland, more than 10 km from the coast, and operates under the regulatory framework of the European Union's Urban Waste Water Treatment Directive (91/271/EEC). The plant provides secondary treatment, which is the minimum required for agglomerations of this size under the EU directive. Its designed capacity is 6,750 m³/day, and it currently discharges 583.56 m³/day of treated wastewater. Secondary treatment typically involves biological processes to reduce organic matter and suspended solids. The treated effluent is discharged into a local water body, likely a river or stream within the Sado River basin, which flows into the Atlantic Ocean near Setúbal. The plant plays a key role in protecting the region's water quality and supporting the ecological health of downstream environments, including the Sado Estuary, a vital habitat for bird species and aquatic life.

The plant discharges into a tributary of the Sado River, which flows into the Sado Estuary and ultimately the Atlantic Ocean. The Sado Estuary is an ecologically sensitive area supporting diverse aquatic life, including migratory birds and fish species. The plant's secondary treatment helps reduce nutrient and organic pollution, contributing to the health of this downstream ecosystem.