Abstract: A method of bleaching recycled paper containing pulp wherein said pulp is contacted with ozone in an ozone stage (Z) treatment with a brightness stabilizing step during or at the end of said ozone stage (Z), said stabilizing step consisting of contacting a small amount of hydrogen peroxide with said pulp, the amount of hydrogen peroxide contacted with said pulp being small compared to the amount of hydrogen peroxide usually in an hydrogen peroxide stage, no washing step of the pulp being provided between the ozone contacting step with said pulp and the hydrogen peroxide contacting step. The pulp is first submitted to a test procedure to determine whether the pulp is more reactive to ozone in acidic or alkaline conditions, and if necessary the pH is accordingly adjusted.

Abstract: Provided herewith is a process for reducing the fluorescence of pulp fibers. The process comprises contacting the pulp fibers with ozone in two or more stages, with an intermediate washing stage or bleaching stage preferably being conducted in between the ozone contacting stages. It has been discovered that splitting the total ozone charge into two or more stages provides a much more efficient and effective process for reducing fluorescence.

Abstract: The invention relates to a method of bleaching waste paper pulp. The pulp is first treated to a reductive chemical followed by acidification and washing or dewatering. The pulp is then subjected to ozone and then to hydrogen peroxide. The reductive chemical used is either formamidine sulphinic acid or sodium hydrosulfite.