IDL_MERCATALE Wastewater Treatment Plant, San Casciano in Val di Pesa, Tuscany

IDL_MERCATALE is a municipal wastewater treatment plant located in Mercatale in Val di Pesa, a frazione of San Casciano in Val di Pesa in the Tuscany region of Italy. The plant serves a population of 1,413 and 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 plant has a designed capacity of 1,300 m³/day and currently discharges 279.72 m³/day of treated wastewater. As a secondary treatment facility, IDL_MERCATALE provides biological treatment to reduce organic matter and suspended solids, meeting the effluent quality standards set by Italian regulations implementing the EU directive. For small agglomerations like this, secondary treatment is typically sufficient to protect the receiving water body, unless the area is designated as sensitive under the directive. The treated effluent from IDL_MERCATALE is discharged into a local watercourse that flows through the Val di Pesa valley, eventually joining the Pesa River and then the Arno River, which drains into the Tyrrhenian Sea near Pisa. The Arno basin is ecologically significant, supporting diverse aquatic life and providing water for agriculture and urban areas in Tuscany.

The plant discharges into a tributary of the Pesa River, which flows into the Arno River and ultimately reaches the Tyrrhenian Sea. The Arno basin is a densely populated and agriculturally important region, and its water quality is critical for both human use and ecosystem health. Secondary treatment helps reduce nutrient loads that could contribute to eutrophication in downstream coastal waters.