Abstract: A process for increasing a degree of whiteness of paper pulp may include bring paper fiber pulp, which may at least partially include printed waste paper, into a suspension with water. The suspension may be mixed with bleaching aids and bleaching chemicals. The bleaching chemicals may preferably contain molecular oxygen. Intensely mechanically treating the pulp, e.g., at at least 20 kWh/to, prior to bleaching the pulp suspension. The bleaching period may take at least 10 minutes, with a pressure above the atmospheric pressure being exerted during the bleaching. After bleaching, a major portion of remaining color print particles may be removed from the bleached pulp.