Sequential precipitation of phosphorus (SEPHOS Process) seems to be promising. The generated product, an “aluminium phosphate”, is a valuable raw material for the phosphorus industry. After alkaline treatment of the “aluminium phosphate”, it is possible to precipitate phosphorus as calcium phosphate (advanced SEPHOS Process). Following acidic elution of the ash, nano-filtration can also be used to separate phosphorus.
SCHAUM, C. CORNEL, P. NORBERT, J. (n.y): Phosphorus Recovery from Sewage Sludge Ash – A Wet Chemical Approach. Darmstadt/Essen: Technische Universität Darmstadt/Ruhrverband URL [Accessed: 10.06.2019]