Villacastín Wastewater Treatment Plant - Advanced Treatment in Castilla y León, Spain

The Villacastín wastewater treatment plant is located in the municipality of Villacastín, in the province of Segovia, within the autonomous community of Castilla y León, Spain. It serves a population of approximately 4,268 people, classifying it as a small agglomeration under Spanish and EU regulations. The plant employs advanced treatment processes, which go beyond the secondary treatment required by the EU Urban Waste Water Treatment Directive (91/271/EEC) for agglomerations of this size. This level of treatment ensures a high quality of effluent, reducing nutrients and pollutants before discharge. The plant has a designed capacity of 4,268 m³/day and currently discharges 725 m³/day of treated wastewater. The treated effluent is discharged into a local watercourse, which eventually drains into the Duero River basin. The Duero River flows westward through Spain and Portugal, emptying into the Atlantic Ocean at Porto. The advanced treatment helps protect the ecological health of the receiving waters, supporting aquatic life and downstream water quality.

The plant discharges into a tributary of the Duero River basin, which flows through the Castilla y León region and into Portugal. The Duero basin supports diverse aquatic ecosystems and is important for irrigation and drinking water supply. The advanced treatment at Villacastín reduces nutrient loading, helping to prevent eutrophication in downstream reservoirs and the river's estuary.