SONEJA Wastewater Treatment Plant, Soneja, Comunitat Valenciana, Spain

SONEJA is a wastewater treatment plant located in Soneja, within the Comunitat Valenciana region of Spain. It serves a population of 2,457, classifying it as a small agglomeration under Spanish and EU regulations. The plant is situated inland, approximately 50 km from the Mediterranean coast. The plant provides secondary treatment, which is the standard required by the EU Urban Waste Water Treatment Directive (91/271/EEC) for freshwater discharges from agglomerations of this size. The designed capacity is 6,329 m³/day, with a current discharge volume of 409.41 m³/day, indicating operational headroom. As a Spanish facility, it operates under national water legislation transposing EU directives, with permits issued by the relevant regional authority (Confederación Hidrográfica del Júcar). The treated effluent is discharged into a local watercourse that ultimately drains into the Mediterranean Sea via the Palància River basin. This river supports diverse aquatic life and is an important ecological corridor in the region. The plant's secondary treatment helps protect downstream water quality and the coastal environment of the Valencian Community.

The plant discharges into the Palància River basin, which flows into the Mediterranean Sea near Sagunto. This coastal area supports seagrass meadows and fish nurseries, making nutrient and pollutant control critical. Secondary treatment reduces organic load and suspended solids, helping to maintain the ecological balance of the river and the marine environment.