Fragosela Wastewater Treatment Plant, Viseu, Portugal

Fragosela is a wastewater treatment plant located in the Fragosela area of Viseu, Portugal. It serves a population of approximately 2,900 residents, making it a small-scale municipal facility. The plant is situated inland, away from coastal areas, and operates under Portuguese and EU environmental regulations. 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. It has a designed capacity of 3,516 m³/day and currently discharges an average of 483.52 m³/day of treated effluent. Secondary treatment typically involves biological oxidation and sedimentation. The treated effluent is discharged into a local watercourse that eventually drains into the Vouga River basin, which flows into the Atlantic Ocean near Aveiro. The plant plays a key role in protecting the local watershed and downstream aquatic ecosystems from untreated wastewater pollution.

The plant discharges into a tributary of the Vouga River, which flows into the Ria de Aveiro coastal lagoon and then the Atlantic Ocean. The Vouga basin supports diverse aquatic life and is important for migratory fish species. The plant's secondary treatment helps reduce organic load and protect water quality in this ecologically sensitive region.