Carrión de los Condes Wastewater Treatment Plant - Palencia, Castilla y León, Spain

The Carrión de los Condes wastewater treatment plant is located in the municipality of Carrión de los Condes, in the province of Palencia, Castilla y León, Spain. It serves a population of approximately 5,000 residents, classifying it as a small agglomeration under EU regulations. The plant is situated inland, away from coastal areas, and its operations are part of the regional water management infrastructure. The plant provides 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. Its designed capacity is 3,600 m³/day, and the reported discharge volume is 622 m³/day, indicating operational capacity well below design limits. Secondary treatment typically involves biological processes to reduce organic matter and suspended solids. The treated effluent is discharged into the local watershed, which ultimately drains into the Carrión River, a tributary of the Pisuerga River, part of the Duero River basin. The Duero River flows westward through Spain and into Portugal, emptying into the Atlantic Ocean at Porto. The plant plays a key role in protecting the water quality of the Carrión River and downstream ecosystems, supporting aquatic life and agricultural water use.

The plant discharges into the Carrión River, a tributary of the Pisuerga River, which joins the Duero River basin. The Duero River flows through Spain and Portugal to the Atlantic Ocean. The watershed supports diverse aquatic habitats and is important for irrigation and drinking water supply. Secondary treatment helps reduce nutrient loads, protecting downstream water quality and preventing eutrophication in sensitive river stretches.