TECHNOLOGY FOCUS - INSTRUMENTATION AND TESTING - Preferred Method: The method of composting a whole object (A1), includes: providing a horizontal base plate at the bottom of the composting chamber which supports the lug on it and locating the rigid member directly adjacent the base plate such that the rigid member and the base plate are rotatable relative to one another; providing many lugs supported on the base plate so as to be arranged to be received in the slot as the first and second grinding elements are rotated relative to one another; rotating the first grinding element relative to the housing and fixing the second grinding element such that the second grinding element is stationary relative to the housing; providing the lug with a leading edge which extends upwardly at an inclination in a direction of rotation of the grinding element towards the slot of the other grinding element to confront the other grinding element as the grinding elements are rotated relative to one another; providing the rigid member with at least one guide tooth above the slot which projects into a direction of relative rotation of the rigid member in which the guide tooth comprises a leading edge extending downwardly and inwardly towards the slot; fully supporting the sweep arm relative to the housing at the bottom end by axially spaced apart bearings such that the top end of the sweep arm comprises a free unsupported end; providing the composting chamber with a conical wall tapering downwardly and inwardly towards the grinder at the bottom end of the chamber and providing the sweep arm with an increasing diameter with increasing distance from the bottom end to the top end such that the sweep arm is in proximity to the conical wall throughout the full length of the sweep arm; providing a fixed member supported on a wall of the composting chamber at an intermediate location along the length of the sweep arm in alignment with a slot on the sweep arm such that the fixed member passes through the slot as the mixing member is rotated; providing many fixed members supported on the wall of the composting chamber in alignment with the slot on the sweep arm; providing the sweep arm of the mixing member with an upper ramped surface extending along a length of the sweep arm and spanning horizontally in a radial direction across a width of the sweep arm and urging the ground material in the composting chamber upwardly at a periphery of the chamber along the ramp surface of the mixing member as the mixing member is rotated; providing a gearbox having gearbox housing and a gearbox output shaft supported for rotation relative to the gearbox housing by respective gearbox bearings, providing the mixing member with a drive shaft extending through the bottom end of the composting chamber for rotation relative to the housing of the composting chamber with the mixing member about the upright axis, and supporting the drive shaft of the mixing member for rotation relative to the housing of the composting chamber by a pair of bearings spaced apart from one another in an axial direction at a location below the bottom end of the composting chamber and spaced above the gearbox bearings in the gearbox housing; providing a fixed member supported on a wall of the composting chamber at an intermediate location along the length of the sweep arm, where the fixed member has a thickness which is arranged to substantially fully span a gap between the sweep arm and the peripheral wall as the sweep arm is rotated past the fixed member; inserting a whole livestock carcass into the composting chamber along the unobstructed upright axis of the mixing member to the grinder at the bottom end of the composting chamber, grinding the whole livestock carcass into ground material at the bottom end of the composting chamber, and composting the ground material in the composting chamber; and rotating the first grinding element past the second grinding element so as to produce a scissor-like cutting action which grinds the whole object into the ground material. The method of composting a whole object (A2), includes: supporting the drive shaft of the mixing member for rotation relative to the housing of the composting chamber by a pair of bearings spaced apart from one another in an axial direction at a location below the bottom end of the composting chamber and spaced above the gearbox housing; and supporting the gearbox housing to resist rotation relative to the housing of the composting chamber by providing two torque members coupled between the gearbox housing and the housing of the composting chamber at diametrically opposed locations about the upright axis. Preferred Components: The rigid member extends radially out from the upright axis of the mixing member, where the lug is arranged to pass through the slot in the rigid member in a circumferential direction from the first side to the second side of the rigid member in relation to the upright axis. The slot in the rigid member is open to a bottom side of the rigid member, where the lug is supported on a bottom wall of the composting chamber. EXAMPLE - No suitable example given.