Pulp bleaching process comprising oxygen delignification and xylanase enzyme treatment

Abstract

Process for bleaching lignocellulosic material comprising an oxygen bleaching treatment and an enzymatic treatment with a substantially cellulase-free xylanase, which process is compatible with, and can be incorporated into, conventional bleaching sequences. The process provides a delignified and bleached pulp using lower amounts of chlorine-containing compounds, and the opportunity of eliminating the use of elemental chlorine, thereby reducing the polluting effluent from a pulp mill employing the process. Also, a greater extent of delignification can be achieved while retaining acceptable pulp strength properties. The oxygen bleaching treatment and the enzynmatic treatment are done in series.

Dependencies are inferred from the claim text.