This paper presents the influence of different methods of sewage sludge conditioning on the effectiveness of dewatering. In the laboratory research, three conditioning methods were tested: (1) with the use of biomass ash, (2) chemical conditioning by means of polyelectrolyte and (3) dual conditioning with the application of biomass ash in conjunction with polyelectrolyte. The specific resistance to filtration, the moisture content and characteristics of filtrates were measured. The influence of sludge conditioning on capillary suction time and the initial pH was also examined. The obtained results showed that MC and SRF decreased after sludge conditioning. Among all tested methods, the dual conditioning influenced the sludge dewaterability to the highest extent. Due to their effectiveness, physical and dual conditioning methods might be a promising alternative for the application of polyelectrolytes. The reduction of polyelectrolyte consumption has also economic benefits, which was confirmed in a previous economic analysis. (C) 2018 Elsevier B.V. All rights reserved.