Process for treating sludge or ashes, especially clarified sludge sewage or clarified sewage ashes

摘要

1. A process for the decomposition of sludges or ashes, in particular clarifying sludges or clarifying sludge ash having a proportion of undecomposed mineral fertilizer components, in particular insoluble phosphate compounds, for fertilizer purposes, characterised in that the sludges or ashes, in particular the clarifying sludges or clarifying sludge ash, are treated at a high temperature up to 1200 degrees C, in the presence of one or more of the compounds Na2 CO3 , CaO, Ca(OH)2 , MgO and MgSO4 , whereby the difficultly-soluble phosphates are converted into phosphate compounds which are highly soluble in water and/or citric acid and which are usable by plants.