PURPOSE: To obtain a highly white pulp in a high yield and close the drainage of bleached waste water by subjecting digested pulp or oxygen-bleached pulp to a multi-combination treatment using an enzyme, a chelating agent and a surfactant, and subsequently subjecting the treated pulp to a non-chlorine bleaching treatment.
CONSTITUTION: Digested pulp or oxygen-bleached pulp is subjected to a one stage treatment using an oxygen-resistant enzyme such as xylanase having the maximum xylane-decomposing activity at a pH of ≤4.5, a chelating agent such as a polyalkylenepolyamine acetate, and at least one kind of surfactant selected from the group consisting of anionic, cationic, nonionic and amphoteric polymeric surfactants or to a multi-stage treatment comprising the combination of the enzymatic treatment, the chelating treatment and the surfactant treatment in an arbitrary order at a pH of ≤5 at 10-80°C for 10-180min at an enzyme addition rate (based on absolute dry pulp) of 0.1-1000μg, a chelating agent-addition rate of 0.01-5wt.% and a surfactant addition rate (based on the absolute dry pulp) of 0.01-5wt.% and subsequently bleached in an oxidation system or a reducing system or in the combination of the oxidation system and the reduction system at one stage or the combination stage. The bleached waste is returned to the previous treatment stage countercurrently, and finally subjected to a black solution-recovering process.
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MATSUHASHI MITSUHIRO
MATSUURA AKIRA
UMEDA KOICHI
KITO KUNIYASU
AMANO PHARMA CO LTD
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