Method of Removing Color from Kraft Wood Pulps

Agency:

Forest Service

Technology Description:

The invention comprises a method of removing color from kraft wood pulps by treating the pulp with enzymes, specifically xylanases, obtained from Streptomyces species. These xylanases have a high specificity for releasing chromophores and increasing the brightness of wood pulps. The chromophores are extracted from the xylanase-treated pulp and the pulp is subsequently bleached with oxygen, rather than chlorine. Chlorine bleaching is the current industry standard to increase the brightness of wood pulps. However, the use of chlorine compounds results in the release of environmentally-harmful compounds, such as dioxin, into rivers and streams. Due to increasing regulatory pressures and consumer demand, new non-chlorine bleaching technologies are urgently needed by manufacturers of paper-grade chemical pulps. Xylanase treatment of wood pulp followed by oxygen bleaching represents such an environmentally-friendly technology. This invention significantly reduces the amount of bleaching that is necessary in the production of paper-grade pulp and, thus, presents an environmentally-friendly alternative to chlorine bleaching.

Reference:

Patent Number 5,834,301, issued November 10, 1998.

Inventor:

Thomas W. Jeffries
USDA/Forest Service
Forest Products Laboratory
One Gifford Pinchot Drive
Madison, WI 53705
(608) 231-9453