NOVELTY - Unit comprises (a) a base (2), (b) a member (3) for containing a dry mass (50) of organic wastes, emerging from the base along a vertical axis of extension (A) and comprising at least one perimeter wall (4), (c) units (7) for feeding the organic wastes operatively associated with the door and configured to gravity feed the organic wastes into the containment member through the door, (d) mixing units (9) accommodated at least partly inside the containment member and configured to move the dry mass to distribute it.    USE - The unit is useful for digestion of wastes (claimed), and recycling and eco-efficient transformation of urban wastes, of organic biomasses including energy crops and animal feces.    ADVANTAGE - The unit can be installed in small spaces. The method consumes less time and less energy, prevents blockage due to deposits and sediments, treats high volume of mass, avoids health risks, minimizes operator intervention, is capable of minimizing dissipation, reuses waste, and transfers heat uniformly throughout the mass.    DETAILED DESCRIPTION - Unit comprises (a) a base (2), (b) a member (3) for containing a dry mass (50) of organic wastes, emerging from the base along a vertical axis of extension (A) and comprising at least one perimeter wall (4) equipped, at its lower end adjacent to the base, with a reclosable mouth for picking up the dry mass, where the containment member also comprises a roof (5) having an openable door to allow organic wastes to be fed into the containment member, (c) units (7) for feeding the organic wastes operatively associated with the door and configured to gravity feed the organic wastes into the containment member through the door, (d) mixing units (9) accommodated at least partly inside the containment member and configured to move the dry mass to distribute it. INDEPENDENT CLAIMS are included for the following:    (1) plant for treating organic wastes; and    (2) method for treating organic wastes.    DESCRIPTION OF DRAWING(S) - The drawing shows perspective view of digestion unit.    Base (2)    Containment member (3)    Perimeter wall (4)    Roof (5)    Feeding unit (7)    Conveyor belt (8)    Mixing unit (9)    Elongate element (10)    Movement member (11)    Spiral blade (12)    Dry mass (50)