sewage sludge has different calorific values depending on water content and loss on ignition. These can range from negative (high water content) values to about 18,000 kJ / kg. Due to new regulations, to use sewage sludge as fertilizer will be limited in the future. Which is why the focus in sewage sludge utilization now lies in sewage sludge incineration. A major challenge for the thermal utilization of sewage sludge lies in the decision to recover phosphorus from sewage sludge. Due to this new requirement, currently used methods of sewage sludge incineration in waste incineration plants or sewage sludge as additional fuel in cement or coal fired power plants can no longer be practiced. Since no process has proven to be sufficiently efficient in the field of phosphorus recovery, both before and after the incineration of sewage sludge, sewage sludge can currently only be utilized in designated mono-incineration plants in order to avoid a loss of phosphorus in mixed ash. In addition to the combustion processes in different variants (fluidized bed process, grate firing) there are other thermal processes such as pyrolysis or thermolysis process available. The ash and slag residues resulting from the different processes and the phosphor contained therein can then be stored temporarily and fed to a suitable recovery process at a later time.


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