NOVELTY - Compost reactor for organic matter comprises support structure including horizontally disposed frame, an elongated hollow housing (44) having floor (52), pair of oppositely disposed side walls (48, 50), top wall, upper end, and lower end, where the upper end of housing being in communication with a source of organic matter, where housing being mounted on support structure where upper end is operatively vertically movably secured to upstanding frame and lower end is operatively movably secured to horizontally disposed frame.    USE - As compost reactor for organic matter (claimed).    ADVANTAGE - The compost reactor utilizes gravity and natural thermal convection to provide a compact, modular, plug-flow compost reactor which requires minimal aeration and agitation energy. The compost reactor is modular and is easily transported from place to place and can be installed in a side-by-side relationship with other identical reactors. The modularity of the system enables a compost facility to be quickly installed and readily expanded. The modularity of not only the reactor unit but also the support stand structure allows a facility to be readily disassembled and moved.    DETAILED DESCRIPTION - Compost reactor for organic matter comprises support structure including a horizontally disposed frame, having first and second ends, and upstanding frame, having upper and lower ends, extending upwardly from the horizontally disposed frame; an elongated hollow housing (44) having floor (52), pair of oppositely disposed side walls (48, 50), top wall, upper end, and lower end, where the upper end of housing being in communication with a source of organic matter, where the housing being mounted on support structure where the upper end is operatively vertically movably secured to the upstanding frame and the lower end is operatively movably secured to the horizontally disposed frame where the angle of the housing, with respect to horizontal, can be selectively varied, flow control and material agitator assemblies positioned in the housing in a longitudinally spaced-apart manner, each of the flow control and material agitator assemblies capable of controlling the flow of organic matter through it and capable of agitating the organic matter adjacent to it; the housing having of spaced-apart aeration zones, a process air supply which supplies process air to each of the aeration zones, a hood selectively closing the upper end of the housing, the hood having a process air exhaust outlet, and a discharge door selectively closing the lower end of the housing.    DESCRIPTION OF DRAWING(S) - The figure shows perspective view of container portion of reactor.    Elongated hollow housing (44)    Top wall (46)    Side walls (48, 50)    Floor of container (52)    Discharge end of container (56)    Elongated C-shaped channel members (84, 86)