The bachelor thesis deals with the issue of phosphorus in sewage sludge. It characterizes the treatment process at all stages of the WWTP, sludge management and sludge production in the Slovak Republic. It emphasizes the importance of phosphorus as a strategic raw material and its possibility of recovery from sewage sludge and wastewater. The aim of the work is to compare five different sewage sludges, in the parameters of combustion heat, ash and the total amount of phosphorus. The importance of the work is in the EU's justified request to recycle phosphorus, with an emphasis on wastewater and sewage sludge.