METHOD OF PRODUCING BLEACHED PULP FOR PAPER MAKING

摘要

PROBLEM TO BE SOLVED: To provide an economical bleaching method in which chlorous acid is inexpensively reduced without use of environmentally troublesome chemicals such as formaldehyde and can efficiently carry out the chlorine dioxide bleaching and a method for producing pulp of high whiteness by using a reduced amount of chlorine dioxide. SOLUTION: The pulp using lignocellulose material as a starting material is subjected to (a) the alkaline oxygen bleaching step and (b) the enzyme treatment step, and then allowed to undergo (c) the ECF (element chlorine free) bleaching process that starts with the chlorine dioxide step. The reacted filtrate at the enzyme treatment step is allowed to pass through a membrane filter to obtain permeate. At least a part of the permeate is added to the chlorine dioxide bleaching step whereby the lignocellulose material is bleached. COPYRIGHT: (C)2004,JPO