Soure Wastewater Treatment Plant | Secondary Treatment in Coimbra, Portugal

The Soure wastewater treatment plant is located in the town of Soure, in the Coimbra district of central Portugal. It serves a population of approximately 3,900 residents, making it a small-scale municipal facility. The plant is situated inland, about 50 km from the Atlantic coast, and operates under Portuguese environmental regulations aligned with the EU Urban Waste Water Treatment Directive. The plant provides secondary treatment, which is the standard required by the EU Urban Waste Water Treatment Directive for agglomerations of this size (under 10,000 population equivalent). The designed capacity is 3,961 m³/day, with an average daily discharge volume of 650.25 m³, indicating a utilization rate well below capacity. Secondary treatment typically involves biological processes to reduce organic matter and suspended solids. The treated effluent is discharged into local watercourses that eventually drain into the Mondego River, one of the major rivers in central Portugal. The Mondego River flows westward to the Atlantic Ocean near Figueira da Foz. The plant plays a key role in protecting the water quality of the Mondego basin, which supports agricultural irrigation, aquatic ecosystems, and downstream communities.

The Soure plant discharges into the Mondego River basin, which flows approximately 234 km from the Serra da Estrela to the Atlantic Ocean. The lower Mondego is an ecologically sensitive area, supporting diverse aquatic life and serving as a migratory corridor for fish species. The plant's secondary treatment helps reduce nutrient loads that could otherwise contribute to eutrophication in the coastal zone.