Zvuky Prahy / Sounds of Prague

The Central Sewage Treatment Plant (ÚČOV) on Císařský ostrov cleans approximately 93% of wastewater from the city's sewage system. It was opened in the years 1965–1967 as a replacement for the old sewage plant in nearby Bubenč. The water line is in the western part of Císařský ostrov. The sewage is mechanical-biological with chemical precipitation of phosphorus. The waste water is first roughly cleaned in the gravel trap, combs and sand traps. Then mechanical pre-cleaning takes place in eight sedimentation tanks. Sediments or the primary sludge is pumped from the bottom of the tanks into the sludge management. Mechanically pre-purified water flows into the biological sector, where nitrogen is biologically removed by a combination of denitrification and nitrification and phosphorus is chemically precipitated. The activation tank is divided into denitrification zones and nitrification zones with fine bubble aeration. The activated sludge is regenerated in the regeneration tank. Separation of activated sludge from purified water takes place in 12 circular settling tanks. The resulting excess sludge is pumped into the sludge management, and the cleaned wastewater then flows into the Vltava towards Troja.