【Q&A】How is VPSA Oxygen System Applied in Pulp Bleaching? Oxygen is primarily used in the oxygen #delignification stage of the #pulpbleaching process to remove lignin, utilizing oxygen as a bleaching agent that reacts with pulp in an alkaline environment provided by magnesium compounds. Due to environmental protection demands, #oxygenbleaching has gained significant interest globally. Oxygen is non-toxic and reduces pollution. Oxygen delignification not only decreases decolorizer use and sewage