SANTACARA MELIDA Wastewater Treatment Plant, Mélida, Navarra, Spain

SANTACARA MELIDA is a wastewater treatment plant located in Mélida, in the region of Navarra, Spain. It serves a population of approximately 1,637 people, classifying it as a small agglomeration under Spanish and 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 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 3,650 m³/day indicates the plant is built to handle peak flows, while the current discharge volume of 494 m³/day suggests ample capacity for the served population. Secondary treatment typically involves biological processes to reduce organic matter and suspended solids. The treated effluent is discharged into a local watercourse, which ultimately flows into the Ebro River basin, a major hydrological system in northeastern Spain. The Ebro River drains into the Mediterranean Sea, supporting diverse aquatic ecosystems and agricultural activities. The plant's operation helps protect local water quality and downstream environments from untreated wastewater pollution.

The plant discharges into a tributary of the Ebro River basin, which flows through the semi-arid landscape of Navarra. The Ebro River is a vital water source for irrigation and supports a variety of fish species, including the European eel. Downstream, the river forms the Ebro Delta, an ecologically sensitive wetland area that provides habitat for migratory birds and aquatic life. Proper treatment at this plant helps reduce nutrient and pollutant loads entering this important river system.