HINOJOS Wastewater Treatment Plant, Hinojos, Andalucía, Spain

The HINOJOS wastewater treatment plant is located in Hinojos, a municipality in the province of Huelva, Andalucía, Spain. It serves a population of 5,223 and operates under secondary treatment, which is the standard biological treatment required by the EU Urban Waste Water Treatment Directive (91/271/EEC) for agglomerations of this size. The plant has a designed capacity of 5,300 m³/day and currently discharges 946.65 m³/day of treated effluent. As a secondary treatment facility, HINOJOS removes organic matter and suspended solids through biological processes, meeting the EU directive's requirements for inland discharges. The plant's capacity utilization is well below its design capacity, indicating it has room to accommodate future population growth or increased flows. The regulatory framework for this plant is governed by Spanish national legislation transposing the EU directive, with oversight from the regional government of Andalucía. The treated effluent from HINOJOS is discharged into a local watercourse that eventually drains into the Guadalquivir River basin and then into the Gulf of Cádiz (Atlantic Ocean). The surrounding area is part of the Doñana region, an ecologically sensitive area that supports diverse aquatic life and migratory birds. The plant plays a key role in protecting the local watershed and downstream ecosystems from untreated wastewater pollution.

The HINOJOS plant discharges into a local stream that flows into the Guadalquivir River basin, which ultimately reaches the Gulf of Cádiz in the Atlantic Ocean. The region includes the Doñana wetlands, an ecologically sensitive area that supports a rich diversity of bird species and aquatic life. Secondary treatment helps reduce nutrient loads and organic pollution, protecting the downstream environment from eutrophication and habitat degradation.