The article presents the research on optimization of sewage sludge capsulation in the hydrogel carrier. Sewage sludge was derived from a municipal wastewater treatment plant. The aim of the research was to determine an optimum concentration of sodium alginate and the crosslinking solution. Another aim was to determine the influence of the reagent concentration on the mechanical stability of the obtained capsules. It was determined that the using of 2% sodium alginate results in obtaining capsules with desired mechanical stability. The crosslinking solution concentration has not been affected on the capsulation process. The encapsulation of sewage sludge capsules with additional wall of sodium alginate has been improved their mechanical stability.