A material drying apparatus for substantially eliminating the liquid content of a sludge, the apparatus including a first stage operating at ambient pressure for heating the sludge; a second stage operating with partial vacuum for receiving heated sludge from the first stage for further heating and for drying the sludge by evaporation of substantially all liquid therefrom leaving a dry particulate material; and an evacuated cyclonic stage for applying sufficient centrifugal force to the dry particulate material to render this material odorless.

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