After the biological line, the water continues into secondary sedimentation tanks. Here, sludge settles at the bottom and is scraped into sumps to be sent for further processing. Treatment is then completed by two separate processes. In the first, called tertiary treatment, phosphorus is precipitated out of the water using ferric salts, and additional reduction of nitrogen and suspended solids is carried out. Then, at the very end, the water is irradiated with UV lamps to destroy the last remants of organic pollution.
And so, after about 20 hours, the murky and foul-smelling wastewater that entered the treatment process flows out into the Vltava river, clean. It can then peacefully set out on its long journey to Hamburg and the North Sea without posing any environmental risk.
...that excessive phosphorus in wastewater encourages unwanted growth of algae and cyanobacteria?
That’s why we eliminate phosphorus in the treatment process.
If you want to know more, continue to other parts of the treatment plant ...