SERRADA Wastewater Treatment Plant, La Seca, Castilla y León, Spain

The SERRADA wastewater treatment plant is located in La Seca, a municipality in the province of Valladolid, within the autonomous community of Castilla y León, Spain. The plant serves a population of approximately 3,000 people, reflecting its role in managing domestic wastewater for this inland community. Its designed capacity is 3,000 cubic meters per day, and the current discharge volume is 440.02 cubic meters per day, indicating operational headroom. As a secondary treatment facility, SERRADA meets the minimum treatment standards required under the European Union's Urban Waste Water Treatment Directive (91/271/EEC) for agglomerations of this size. The directive mandates secondary treatment for populations between 2,000 and 10,000 in inland areas, ensuring effective removal of organic matter and suspended solids before discharge. The plant discharges treated effluent into the local hydrological network, which ultimately drains into the Duero River basin. The Duero River flows westward through Castilla y León into Portugal, reaching the Atlantic Ocean near Porto. This watershed supports agricultural irrigation and diverse aquatic habitats, making proper wastewater treatment essential for maintaining water quality and ecological balance in the region.

The SERRADA plant discharges into the Duero River basin, which drains into the Atlantic Ocean via the Douro River in Portugal. The Duero basin is a vital agricultural and ecological corridor in Castilla y León, supporting vineyards, wetlands, and migratory bird species. Secondary treatment helps reduce organic pollution and nutrient loads, protecting downstream water quality and aquatic life in this semi-arid region.