The ANDRITZ drum drying system, DDS, dries and granulates different types of municipal, industrial, and agricultural sludges. The dewatered sludge is granulated in a mixer tailored to the application. It is then dried in the triple-pass drum (three concentric cylinders revolving around a joint axis) in a convective drying process to < 10% residual moisture. The sludge is conveyed pneumatically by the stream of hot gases, ensuring an evenly dried, pasteurized product.