Oxygen is increasingly used as an oxidant in pulp and paper mills.

Paper making typically generates significant streams of wastewater and energy containing by-products such as black liquor from the digestion process. Oxygen is increasingly used as an oxidant in pulp and paper mills within the delignification, bleaching, chemical and energy recovery, and wastewater treatment processes to increase capacity, meet environmental regulations, improve product quality and energy usage. Specific applications of oxygen include oxygen delignification, oxygen reinforced alkali extraction, ozone bleaching, black liquor oxidation, white liquor oxidation, and biochemical wastewater treatment.