SANCHONUNO Wastewater Treatment Plant, Sanchonuño, Segovia, Spain

SANCHONUNO is a wastewater treatment plant located in Sanchonuño, Segovia, within the autonomous community of Castilla y León, Spain. The facility serves a population of approximately 11,700 people, classifying it as a medium-sized agglomeration under Spanish and European Union regulations. The plant operates with secondary treatment, which is the standard required by the EU Urban Waste Water Treatment Directive (91/271/EEC) for inland freshwater discharges from agglomerations of this size. The designed capacity is 11,700 cubic meters per day, matching the population served, and the reported discharge volume is 493.15 cubic meters per day. The treated effluent is discharged into local watercourses that ultimately drain into the Duero River basin. This river system flows westward through Portugal, reaching the Atlantic Ocean at Porto. The plant plays a key role in protecting the water quality of the Duero basin, which supports agricultural irrigation and diverse aquatic habitats.

The plant discharges into the Duero River basin, one of the major river systems in the Iberian Peninsula. The Duero flows through Castilla y León and into Portugal, emptying into the Atlantic Ocean. The basin supports extensive agriculture and is ecologically important for fish species such as the Iberian barbel and nase. Secondary treatment helps reduce organic pollution and nutrient loads, safeguarding downstream water quality.