The present invention includes an apparatus and method for processing solid waste products. The invention features periodic removal of water preferably while the contents are under pressure. The apparatus comprises a rotatably mounted cylindrical vessel having a first end, a second end and an interior surface, at least one end terminating in a hatch that may be opened to allow access to the interior of the vessel and sealably closed to allow pressurization of the vessel; a steam inlet for injecting stem disposed at one or both ends; and one or more valves for exhausting water periodically as the waste mass is being processed.