El Arenal Wastewater Treatment Plant, Ávila, Castilla y León, Spain

El Arenal wastewater treatment plant is located in the town of El Arenal, within the province of Ávila in the autonomous community of Castilla y León, Spain. The facility serves a population of approximately 6,000 residents and has a designed capacity of 6,000 m³ per day, with a reported discharge volume of 855.34 m³/day. The plant operates with secondary treatment, which is the standard level required under the EU Urban Waste Water Treatment Directive (91/271/EEC) for agglomerations of this size. The directive mandates secondary treatment for populations between 2,000 and 10,000 in inland areas, ensuring effective removal of organic matter and suspended solids before discharge. The treated effluent is discharged into the local watershed, which ultimately drains into the Alberche River, a tributary of the Tagus River. The Tagus River flows westward through Spain and Portugal, emptying into the Atlantic Ocean near Lisbon. The plant plays a key role in protecting the water quality of the Alberche and Tagus rivers, supporting aquatic ecosystems and downstream water uses.

The plant discharges into the Alberche River basin, which feeds into the Tagus River, one of the longest rivers in the Iberian Peninsula. The Tagus River supports diverse aquatic life and provides water for agriculture, industry, and drinking water for millions of people. The plant's secondary treatment helps reduce organic pollution and protect the ecological health of these water bodies, which are important for biodiversity and regional water resources.