Phosphorus is an essential plant nutrient and therefore integral component of many fertilizers. Due to
the exploitation of natural resources, a shortage is previsible for the near future and new resources
have to be found. Sewage sludge – a virtually infinitely available raw material – offers high contents of
phosphates, but is also heavily contaminated by organic and inorganic pollutants. A newly developed
process allows the complete removal of those substances, especially the heavy metal content, by the
use of highly chlorine-containing atmospheres at temperatures of up to 1000°C. However, there are
currently no materials commercially available which can withstand such conditions over longer periods
of time.