Son Serra de Marina Wastewater Treatment Plant, Santa Margalida, Mallorca

Son Serra de Marina is a wastewater treatment plant located in the coastal area of Santa Margalida on the island of Mallorca, in the Balearic Islands, Spain. It serves a small population of 1,040 residents, reflecting its role in a smaller coastal community. The plant is situated near the Mediterranean Sea, which influences its operational and environmental considerations. The plant operates with secondary treatment, which is the standard biological treatment required under the EU Urban Waste Water Treatment Directive (91/271/EEC) for discharges into coastal waters. Although designed capacity is 4,667 m³/day, the actual discharge volume is 184.88 m³/day, indicating that the plant is operating well below its capacity. The regulatory framework ensures that treatment levels are appropriate for the sensitive coastal environment. The treated effluent is discharged into the Mediterranean Sea, which is a semi-enclosed sea with limited water exchange, making it sensitive to nutrient pollution. The plant's secondary treatment helps reduce organic matter and nutrients, protecting local marine ecosystems and bathing water quality along the Mallorcan coast. The surrounding area includes beaches and coastal habitats that support diverse marine life.

The plant discharges into the Mediterranean Sea, a semi-enclosed sea with high ecological sensitivity. The coastal waters near Son Serra de Marina support seagrass meadows (Posidonia oceanica) and diverse marine fauna. Nutrient inputs from wastewater can lead to eutrophication, so secondary treatment is critical for maintaining water quality and protecting these habitats.