Santa Olalla del Cala Wastewater Treatment Plant | Secondary Treatment, Andalucía

The Santa Olalla del Cala wastewater treatment plant is located in the Sierra de Huelva region of Andalucía, Spain, serving the town of Santa Olalla del Cala. It is an inland facility designed to treat wastewater from a population of 3,197, with a designed capacity of 3,197 population equivalents. The plant provides secondary treatment, which is the standard level required under the EU Urban Waste Water Treatment Directive (91/271/EEC) for agglomerations of this size (under 10,000 population equivalent). The directive mandates secondary treatment for all discharges from agglomerations of over 2,000 population equivalent, ensuring organic matter and suspended solids are reduced. The treated effluent is discharged into the local watershed, which ultimately drains into the Atlantic Ocean via the Guadiana River basin. The plant plays a key role in protecting the region's water resources, particularly the sensitive ecosystems of the Sierra de Huelva, which support diverse aquatic life and are important for biodiversity.

The plant discharges into the Guadiana River basin, which flows into the Atlantic Ocean at the Gulf of Cádiz. The receiving waters support ecologically sensitive habitats, including riparian forests and wetlands that provide critical habitat for migratory birds and endemic fish species. The secondary treatment process helps reduce nutrient and organic pollution, safeguarding downstream water quality.