Sewage sludge was mixed with fly ashes (70:30 to 80:20) and with Ca(OH)(2), granulated and analyzed for content of heavy metals after 5-step leaching and for bioavailability. The heavy metals (except for Zn) were strongly bonded with the granule matrix. The heavy metal contents did not exceed the allowable concns. (except for Pb) and the granulates can be recommended as additives to mineral fertilizers in agriculture.