Process for bleaching lignocellulosic pulp

摘要

Lignocellulose pulp is bleached by bleaching a pulp in aqueous alkali solution with oxygen and treating the pulp with an enzyme, while a liquid fraction delivered from the enzyme treatment step is subjected to a penetration treatment through a separation membrane, for example, reverse osmosis membrane, to separate a permeated fraction from a non-permeated fraction; the permeated fraction is fed to the alkali-oxygen bleaching (oxygen delignification) step and is used as a liquid medium of the bleaching system; and non-permeated fraction is subjected to a xylooligosaccharide-collecting procedure. <IMAGE>