NOVELTY - A rotary cylindrical vessel is divided into infeed compartment, discharge compartment and multiple successive digesting compartments. Baffles with weirs are formed between adjacent compartments for retaining supply of microbial material. Air is forced through the vessel by a speed variable fan to selectively change the rate of air flow through vessel from discharge to infeed end.    USE - E.g. in rotary composters used for biological degradation of organic waste materials.    ADVANTAGE - The provision of dual air infeed fans enhances the flow of air through the rotatable cylindrical vessel. As the internal baffles retard the flow of material through the vessel, the flow rate is approximately three days from infeed to discharge operation.    DETAILED DESCRIPTION - A speed variable drive unit rotates the cylindrical vessel. The speed variable blower has an air infeed port (53) extending into discharge compartment for receiving volume of air from blower. A rotatable auger is positioned within the air infeed port. The baffle provided between the last digestive compartment and discharge compartment has a central opening such that a weir is formed between the central opening and the outer wall of vessel. The baffle provided between infeed compartment and the adjacent digesting compartment has an eccentric opening so as to form a weir between the eccentric opening and outer wall of vessel. Each baffle separating the adjacent digesting compartments has passageways which are at an offset of about 120degrees around the circumference of vessel. The access and discharge openings of infeed and discharge compartments are provided with separate movable doors for selectively retaining the material within the vessel. An electric motor having a variable output speed of rotation transfers rotational power to any one drive roller engaged with vessel. The auger which is of 1.5 inches positioned within the air infeed port has a motor operationally connected to drive chain which is connected to a sprocket (85). The sprocket is connected to a wire screw auger shaft (84). The wire screw auger is rotated at rate of one revolution per minute. Primary and secondary pipes are connected to tee portion attached to the air infeed port.    DESCRIPTION OF DRAWING(S) - The figure shows the enlarged view of rotary composter.    Air infeed port (53)    Wire screw auger shaft (84)    Sprocket (85)