A sludge treatment plant includes an extended floor with a work surface for receiving a mass of spread-out sludge and a movable carriage positioned transversely above the work surface. The movable carriage includes a displacement tool designed to carry the sludge towards a terminal part of the work surface. A withdrawal tool transfers the sludge towards an outlet channel. The outlet channel includes a screw conveyor associated with a rotational drive system and equipped with a heating element. A controller adjusts the temperature in this screw conveyor to a predetermined value between 90° C. and 100° C., while adjusting the rotational drive of the screw conveyor in order to obtain a residence time of the sludge within this screw conveyor to a predetermined value of greater than 4 hours.