COBISA Wastewater Treatment Plant, Cobisa, Castilla-La Mancha, Spain

COBISA is a wastewater treatment plant located in Cobisa, a municipality in the province of Toledo, Castilla-La Mancha, Spain. The facility serves a population of approximately 9,000 residents, making it a small to medium-sized agglomeration under Spanish and EU classifications. The plant operates with secondary treatment, which is the standard required by the EU Urban Waste Water Treatment Directive (91/271/EEC) for agglomerations of this size discharging into freshwater or estuaries. The plant processes an average daily wastewater volume of 765 cubic meters, reflecting the local domestic and light industrial contributions. Treated effluent from COBISA is discharged into the local hydrological network, which ultimately drains into the Tagus River basin. The Tagus River is the longest river in the Iberian Peninsula and supports diverse aquatic ecosystems, as well as providing water for agriculture and urban use downstream. The plant's secondary treatment helps protect water quality in this sensitive basin.

The COBISA plant discharges into the Tagus River basin, which flows westward through Spain and Portugal to the Atlantic Ocean near Lisbon. The Tagus supports a variety of fish species, including the endangered European eel, and its estuary is an important migratory corridor for birds. The plant's secondary treatment reduces organic load and suspended solids, contributing to the ecological health of this transboundary river system.