Phosphorus Precipitation at Water Surface

The eutrophication of the freshwater environment is based entirely on phosphorus compounds. The phosphorus precipitation method is used primarily to limit the availability of phosphorus compounds as a key nutrient for the development of cyanobacteria and algae populations in shallow lakes and lakes with long water residence times (more than 1 year). However, coagulation followed by sedimentation is also one of the most commonly used methods for the removal of humic substances and turbidity.  

For the mass growth of cyanobacteria in the reservoir, a phosphorus concentration (P total) of around 0.020 mg per liter is sufficient. This is very little in today's world of nutrient surpluses and highly nutritious waters. Therefore, it is often necessary to use the application of substances that very effectively remove phosphorus compounds from the water column or from the inflow water and lock the precipitated phosphorus firmly at the bottom, so that it is not available for primary production. In particular, coagulants based on aluminium and ferrous salts (aluminium sulphate, iron sulphate, PAX, PIX, ...) are used.