PURPOSE: To enable bleaching of high whiteness without decreasing its own quality of a paper pulp by a process for bleaching treatment contg. an oxygen treatment stage and free from chlorine.
CONSTITUTION: When bleaching a paper pulp, the pulp of high whiteness is obtained, while maintaining an excellent quality of the paper pulp, for example, at first by O stage contacting with gaseous oxygen, then preferably X stage using xylanase enzyme produced from a bacterium, Q stage by a metal ion- blocking agent (suitably diethylenetriamine pentaacetic acid), a bleaching stage (P stage) by hydrogen peroxide, a second bleaching stage by ozone and the bleaching stage(PI stage) by hydrogen peroxide in accordance with this order, by bleaching methods free from chlorine, and moreover by treatment stages including O, X and Z stage.
ERITSUKU DO BIYUI
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