Abstract: A method of treating wood-fiber pump, particularly wood-fiber pulp that contains recycled paper, comprises delivering the pulp to and advancing the pulp in a heating zone while delivering steam to the heating zone. The pulp is finely-divided in a disperser and the finely-divided pulp delivered to a screw press without separate departure of steam, so as to compact the pulp in the end of the screw press and therewith form a plug seal. At the same time, one or more bleaching chemicals is or are supplied during one or more treatment stages, and the temperature of the pulp is regulated to obtain an optimal bleaching process or optimal bleaching processes. The temperature of the pulp can be raised or lowered by supplying steam or water thereto respectively. The invention also relates to a plant for carrying out the method.