The present invention is a method and apparatus for controlling the processing solid waste material in a vessel during a processing cycle, including: (1) loading the vessel with a charge of solid waste products, said vessel including: (a) a rotatably mounted cylindrical vessel having an interior surface and two ends, at least one end terminating in a hatch that may be opened to allow access to the interior of said vessel and sealably closed to allow pressurization of said vessel; (b) a vessel steam inlet for injecting steam into at least one of said ends so as to come into contact with waste material placed into said vessel; (c) a thermometer adapted to monitor the processing temperature of the waste material placed into said vessel during an operational cycle; (d) a timer adapted to monitor the processing time of an operational cycle for the waste material placed into said vessel; (e) a microprocessor having processing instructions adapted to calculate the required processing time by integrating the function of the said processing temperature versus the processing time so as to be able to determine whether a predetermined energy input to the waste material has been attained, and to issue a signal in response thereto; and (2) terminating said processing cycle in response to said signal.