The appropriate quality system of production control of pre-treated sewage sludge and its characterization needs to be established in order to provide confidence in its constant quality as a raw material in the circular economy. Waste to energy procedure with increased energy efficiency in utilization of its residues is gaining an increased recognition. To manage waste to energy procedure the pre-treated (dried) sludge must be continuously assessed in accordance with the CEN/TC 343 technical standards and the European Union (EU) initiative for circular economy. In evaluation of the dried sewage sludge as an alternative solid recovered fuel (SRF), three parameters are important – net calorific value (NCV), chlorine (Cl) and mercury (Hg) content. The statement of the authorized contractor on the quality of sewage sludge as a SRF with the Class code NCV 3 to 4; Cl 1; Hg 3 creates confidence in its stable quality for energy production in cement kilns, power plants and dedicated sludge mono-incinerators. The removal of Hg from municipal wastewater, constant quality control of the dried sewage sludge, and tracking the mass balance of Hg during incineration make it possible to prevent the circulation of this critical pollutant in the environment.