CALLES Wastewater Treatment Plant, Calles, Comunitat Valenciana, Spain

The CALLES wastewater treatment plant is located in Calles, a municipality in the La Serranía comarca of Valencia, within the Comunitat Valenciana, Spain. This facility serves a population of approximately 1,291 residents, reflecting its role as a small-scale municipal treatment plant in a rural inland area. The plant employs secondary treatment, which is the standard biological treatment required under the EU Urban Waste Water Treatment Directive (91/271/EEC) for agglomerations of this size. With a designed capacity of 2,000 m³/day and a current discharge volume of 220.40 m³/day, the plant operates well below its capacity, indicating adequate headroom for future growth or seasonal variations. The treated effluent is discharged into a local watercourse, which ultimately drains into the Turia River basin and then into the Mediterranean Sea. The plant's inland location, more than 50 km from the coast, reduces direct marine impact, but its discharge contributes to the overall water quality of the Turia River, which supports agricultural irrigation and local ecosystems.

The CALLES plant discharges into a tributary of the Turia River, which flows eastward through the Comunitat Valenciana and empties into the Mediterranean Sea near Valencia. The Turia River basin supports diverse aquatic life and is used for irrigation, making nutrient removal from wastewater important to prevent eutrophication.