COV Cierna nad Tisou Wastewater Treatment Plant, Čierna nad Tisou, Slovakia

COV Cierna nad Tisou is a municipal wastewater treatment plant located in the village of Čierna nad Tisou, in the Košický kraj of eastern Slovakia. The plant serves a population of approximately 2,840, classifying it as a small agglomeration under EU standards. It is situated near the border with Ukraine and Hungary, in a region characterized by the Tisza River floodplain. The plant provides secondary treatment, which is the minimum required by the EU Urban Waste Water Treatment Directive (91/271/EEC) for freshwater discharges from agglomerations of this size. With a designed capacity of 5,500 m³/day and an average discharge volume of 581 m³/day, the facility operates well below its capacity, indicating room for future growth or seasonal variations. The treatment process likely involves biological treatment followed by sedimentation. Treated effluent from the plant is discharged into local watercourses that ultimately drain into the Tisza River, a major tributary of the Danube. The Tisza River basin supports diverse aquatic ecosystems and is an important migratory corridor for fish. The plant's operations help protect downstream water quality in this transboundary river system, which flows through several Central and Eastern European countries before reaching the Black Sea.

The plant discharges into the Tisza River basin, which drains into the Danube River and ultimately the Black Sea. The Tisza is a large river supporting diverse aquatic life, including fish species such as pike and catfish, and provides habitat for migratory birds. The region's floodplain ecosystems are ecologically sensitive, and the plant's secondary treatment helps reduce nutrient loads that could contribute to eutrophication downstream.