Calizzano Caragnetta Wastewater Treatment Plant, Calizzano, Liguria

Calizzano Caragnetta is a municipal wastewater treatment plant located in Calizzano, a town in the Liguria region of northwestern Italy. The plant serves a population of approximately 4,000 residents and is situated in the inland area of the Savona province, near the Melogno Pass. It operates under Italy's implementation of the EU Urban Waste Water Treatment Directive (91/271/EEC), which requires secondary treatment for agglomerations of this scale. The plant provides secondary treatment, a biological process that removes organic matter and suspended solids. With a designed capacity of 9,000 m³/day and an average discharge volume of 791.86 m³/day, the facility operates well below its capacity, indicating room for future growth or seasonal variations. The treatment process meets the EU directive's standards for inland freshwater discharges. The treated effluent is discharged into local watercourses that flow toward the Ligurian Sea, part of the Mediterranean basin. The plant plays a key role in protecting the region's streams and downstream coastal waters from pollution, supporting aquatic life and recreational use of the marine environment.

The plant discharges into small streams in the Bormida di Millesimo or Tanaro river system, which eventually flows into the Po River and then the Adriatic Sea. Alternatively, the local drainage may flow directly to the Ligurian Sea via short coastal rivers. The surrounding watershed includes forested hills and agricultural areas, and the treated effluent helps maintain water quality in ecologically sensitive streams that support diverse aquatic life.