DICASTILLO ALLO Wastewater Treatment Plant, Allo, Navarra, Spain

DICASTILLO ALLO is a wastewater treatment plant located in Allo, a municipality in the province of Navarra, northern Spain. The plant serves a population of approximately 1,077 people, classifying it as a small agglomeration under the EU Urban Waste Water Treatment Directive (UWWTD). It is situated inland, away from coastal areas, and its operations are part of the regional water management infrastructure managed by the Government of Navarra. The plant provides secondary treatment, which is the minimum required by the EU UWWTD for freshwater discharges from agglomerations of this size. Secondary treatment typically involves biological processes to reduce organic matter and suspended solids. The plant has a designed capacity of 7,283 m³/day, and the current discharge volume is 633 m³/day, indicating it operates well below its design capacity. The treated effluent from DICASTILLO ALLO is discharged into a local watercourse that eventually flows into the Ebro River basin, one of Spain's major river systems. The Ebro River drains into the Mediterranean Sea, supporting diverse aquatic ecosystems and agricultural activities along its course. The plant's secondary treatment helps protect the local watershed from pollution, contributing to the ecological health of the Ebro basin.

The plant discharges into a tributary of the Ebro River, which flows through northeastern Spain before emptying into the Mediterranean Sea via the Ebro Delta. The Ebro basin supports a variety of aquatic life and is an important agricultural region. The secondary treatment provided by the plant reduces organic pollutants and suspended solids, helping to maintain water quality in the river system and downstream coastal environment.