Barruelo de Santullán Wastewater Treatment Plant - Castilla y León, Spain

Barruelo de Santullán wastewater treatment plant is located in the municipality of Barruelo de Santullán, in the province of Palencia, within the autonomous community of Castilla y León, Spain. The plant serves a population of approximately 6,229 people, classifying it as a small to medium agglomeration under Spanish and EU regulations. The plant operates with secondary treatment, which is the minimum standard required by the EU Urban Waste Water Treatment Directive (91/271/EEC) for freshwater discharges from agglomerations of this size. The designed capacity of 6,229 population equivalents matches the served population, indicating adequate infrastructure for current loads. The daily discharge volume is 543.77 cubic meters. The treated effluent is discharged into a local watercourse, likely a tributary of the Pisuerga River, which flows into the Duero River and eventually reaches the Atlantic Ocean near Porto, Portugal. The plant plays a key role in protecting the local aquatic environment and downstream water quality in the Duero basin.

The plant discharges into a small river system within the Duero River basin, one of the largest watersheds on the Iberian Peninsula. The Duero River flows westward through Spain and Portugal, supporting diverse aquatic life and agricultural irrigation before reaching the Atlantic Ocean. The local watershed includes sensitive freshwater habitats that benefit from the plant's secondary treatment, which reduces organic pollutants and protects downstream ecosystems.