S Joao da Pesqueira Wastewater Treatment Plant - São João da Pesqueira, Portugal

S Joao da Pesqueira is a wastewater treatment plant located in São João da Pesqueira, Viseu District, Portugal. The plant serves the local municipality, treating wastewater from a population of around 2,900 residents. It is situated inland, away from coastal areas, and discharges treated effluent into the local watershed. The plant operates with secondary treatment, which is the standard level required under the EU Urban Waste Water Treatment Directive (91/271/EEC) for agglomerations of this size. Secondary treatment typically involves biological processes to reduce organic matter and suspended solids. The plant has a designed capacity of 3,346 cubic meters per day and currently treats an average daily flow of 483.52 cubic meters, indicating it operates well below its capacity. The treated effluent is discharged into a receiving water body that ultimately drains into the Douro River basin, which flows westward to the Atlantic Ocean near Porto. The plant plays a key role in protecting local water quality and supporting the ecological health of the Douro River system, which is important for agriculture, biodiversity, and downstream communities.

The plant discharges into a tributary of the Douro River, which flows through the Douro Valley and empties into the Atlantic Ocean at Porto. The Douro basin supports diverse aquatic life and is an important migratory corridor for fish species. The region's Mediterranean climate with seasonal rainfall means that maintaining water quality is critical for both ecological balance and human uses such as irrigation and recreation.