Xylanase Treatment of D0 Pulp to Enhance Bleaching

Xylanase treatment is used to enhance the bleaching of kraft pulp. This technology is used in 15 mills in North America and enables the mills to bleach pulp while using 10% to 20% less chlorine dioxide or other oxidative chemicals. Xylanase treatment is carried out on brownstock prior to the bleach plant. This treatment location is satisfactory for most mills, but there is an interest in improving the benefits a mill can obtain from xylanase and in treating pulp in mills not amenable to brownstock treatments. This paper describes the xylanase treatment of pulp after the first chlorine dioxide (Do) bleaching stage. Such treatments can take place in neutral wash stages or in the first alkaline extraction stages. There is significant opportunity using xylanase treatments in these stages to obtain a greater benefit than in conventional xylanase treatments of brownstock.