This article examines the process of pressure agglomeration of garden waste compost mixed with sewage sludge ash (SSA) to produce granulated fertilizer material, using a flat die rotating compaction roller system. The study evaluated the effects of adding SSA at mass fractions of 0%, 10%, 20%, 30%, 40%, and 50% on the process of pelleting and the quality of pellets. Increasing the SSA content from 0% to 50% reduced the power demand of the pellet mill by 13.5% (from 4.92 kW to 4.25 kW), decreased the kinetic strength of the pellets by 0.7% (from 98.21% to 97.56%), and slightly increased the pellet density, by 2.6% (from 1641.17 kg·m