ALARO Wastewater Treatment Plant, Alaró, Illes Balears, Spain

ALARO is a wastewater treatment plant located in Alaró, a municipality in the Raiguer region of Mallorca, Illes Balears, Spain. The plant serves a population of approximately 4,600 people, making it a small to medium agglomeration under Spanish and EU classifications. The plant provides secondary treatment, which is the standard required by the EU Urban Waste Water Treatment Directive (91/271/EEC) for inland freshwater discharges from agglomerations of this size. With a designed capacity of 9,000 m³/day and an average discharge volume of 778.29 m³/day, the plant operates well below its capacity, indicating room for future growth or seasonal variations. The treated effluent is discharged into the local watershed, which ultimately drains into the Mediterranean Sea. As part of the Balearic Islands' water infrastructure, the plant plays a key role in protecting the island's groundwater and coastal waters from nutrient pollution, supporting both local ecosystems and tourism-dependent water quality.

The plant discharges into the inland drainage network of Mallorca, which flows through ephemeral streams and eventually reaches the Mediterranean Sea. The Balearic Islands' coastal waters are ecologically sensitive, supporting seagrass meadows (Posidonia oceanica) and diverse marine life. Secondary treatment helps reduce organic load and nutrients, mitigating eutrophication risks in the coastal zone.