NOVELTY - The comprises: a base (2); a pair of side walls (3, 4) facing each other and extending perpendicularly to the base; a roof (5) that is movable relative to the base between a raised position, where access by mechanical waste handling unit is allowed, and a lowered position; unit for blowing air into a containment space to allow the wastes to be aerobically digested; a frame designed to support the roof; and unit of actuating the roof between its open and closed positions.    USE - The unit is useful for aerobic digestion of wastes such as solid organic wastes and sludges and making compost from wastes, where the anaerobic digestors are useful for producing biogas by an anaerobic fermentation of the wastes inside the chamber.    ADVANTAGE - The unit is capable of simply and economically producing aerobic digestion with good durability in an efficient manner.    DETAILED DESCRIPTION - The comprises: a base (2); a pair of side walls (3, 4) facing each other and extending perpendicularly to the base; a roof (5) that is movable relative to the base between a raised position, where access by mechanical waste handling unit is allowed, and a lowered position; unit for blowing air into a containment space to allow the wastes to be aerobically digested; a frame designed to support the roof; and unit of actuating the roof between its open and closed positions. The roof together with the base and a first lower load-bearing portion (31, 41) of the side walls forms a waste containment space (6). Each of the side walls facing each other comprises a lower load-bearing portion. The first lower load-bearing portion is made of masonry. The first portion of the side walls comprises a prefabricated cement element. Each of the side walls facing each other comprise a second upper screening portion made of a plastic material. The second portion of the side walls is made of a plastic honeycomb material. The roof at the open position is higher than the base, whilst at the second closed position it is lower than the base. The roof is made of fiberglass. The roof is made of flexible material and in the open position is partly retracted to leave uncovered a part of the waste containment space, whilst in the second closed position it is extended to substantially cover all the containment space. The actuating unit comprises a linear actuator, and a device for winding/unwinding the roof. The blowing unit comprises an air treatment unit designed to produce air flow and a pipe connected to the air treatment unit for transferring the air flow into the containment space. The pipe is provided with nozzles for distributing air at the base. An INDEPENDENT CLAIM is included for a plant for treating solid organic wastes and sludges.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic view of an unit for an aerobic digestion of wastes.    Base (2)    Pair of side walls (3, 4)    Roof (5)    Waste containment space (6)    First lower load-bearing portion. (31, 41)