The objective of this study is to contribute to the evaluation of the relevance of using biosolids biochar as a fertilizing material. 6 different types of biosolids (biological and anaerobically digested origin), dried to over 90% solid content, collected from 6 WWTPs across 3 countries, were pyrolyzed in a heated screw at temperatures of 600 °C with a solid residence time ranging from 15 to 20 minutes. An extensive physicochemical and agronomic characterization of the biochars was conducted. The obtained results indicate that the pyrocarbonisation of biosolids at temperatures above 600°C leads to high removal rate of Contaminants of Emerging Concern (PFAS, Microplastics, Dioxins, Furans, PCBs, PAHs). The fraction of biochar-phosphorus that is soluble in ammonium citrate, characterizing phosphorus bioavailability in biochars, ranges from 8% to 52%. In excess of 70% of the nitrogen in the sludge was volatilized during pyrolysis. Moreover, above 90% of the remaining nitrogen fraction in the biochar appears to be poorly bioavailable. Although the majority of heavy metals (except for a few volatile species, e.g. Hg and As) are concentrated in the solid, these species remain much less bioavailable in the biochar compared to sludge.