ALAEJOS Wastewater Treatment Plant, Alaejos, Castilla y León, Spain

ALAEJOS is a wastewater treatment plant located in Alaejos, a municipality in the province of Valladolid, within the autonomous community of Castilla y León, Spain. The plant serves a population of approximately 4,141 residents, reflecting its role in managing domestic wastewater for this inland community. The plant operates with secondary treatment, which is the standard biological treatment 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, ensuring effluent quality meets regulatory standards before discharge. The treated effluent from ALAEJOS is discharged into the local hydrological network, which ultimately drains into the Duero River basin. The Duero River flows westward through Spain and into Portugal, reaching the Atlantic Ocean near Porto. The plant's operations help protect the water quality of local streams and the downstream river ecosystem.

ALAEJOS discharges into the Duero River basin, which drains into the Atlantic Ocean via the Douro River in Portugal. The receiving waters support diverse aquatic life and are used for irrigation and recreation. The plant's secondary treatment helps reduce nutrient and organic loads, mitigating eutrophication risks in downstream water bodies.