NIEBLA Wastewater Treatment Plant, Niebla, Andalucía, Spain

The NIEBLA wastewater treatment plant is located in Niebla, a municipality in the province of Huelva, Andalucía, Spain. The plant serves a population of approximately 3,923 people, classifying it as a small agglomeration under Spanish and EU regulations. It is situated inland, more than 10 km from the coast, and operates within the region's municipal wastewater infrastructure. The plant employs advanced treatment processes, which go beyond the secondary treatment standard required by the EU Urban Waste Water Treatment Directive (91/271/EEC) for agglomerations of this size. Advanced treatment typically includes nutrient removal (nitrogen and phosphorus) to protect sensitive water bodies. The plant's designed capacity is 3,923 cubic meters per day, and it currently discharges 711.03 cubic meters of treated wastewater daily, indicating a utilization rate well below capacity. The treated effluent is discharged into a local watercourse that ultimately drains into the Atlantic Ocean via the Tinto River basin. The plant's advanced treatment helps protect the ecologically sensitive Doñana region and the Gulf of Cádiz, which support diverse aquatic life and important migratory bird populations. By reducing nutrient loads, the plant contributes to the health of downstream ecosystems.

The NIEBLA plant discharges into a tributary of the Tinto River, which flows into the Atlantic Ocean near the Gulf of Cádiz. This coastal area is ecologically sensitive, supporting diverse marine life and serving as a critical habitat for migratory birds. The advanced treatment at the plant helps minimize nutrient pollution, protecting the downstream estuary and coastal waters from eutrophication.