A method for reducing the load of microbial contaminants in a pulp stock comprising a recycled fiber fraction

Abstract

The present invention relates to a method for reducing the load of microbial contaminants in a pulp stock comprising a recycled fiber fraction, said method comprising the following steps performed in sequence: a) providing a pulp stock comprising a recycled fiber fraction at a consistency in the range of 2-10 wt % in water; b) adding a basic oxide selected from the group consisting of calcium oxide (CaO) and sodium oxide (Na2O) to the pulp stock and allowing the basic oxide to react with water to form the corresponding hydroxide, wherein the amount of the basic oxide added is sufficient to raise the pH value of the pulp stock to above 12.5 and to maintain the pH value of the pulp stock above 12.5 for at least 60 minutes; c) allowing the pulp stock to remain at a pH value above 12.5 for at least 60 minutes; and d) adding an organic oxidative acid to the pulp stock, wherein the amount of the organic oxidative acid added is sufficient to reduce the pH value of the pulp stock to below 10.

Dependencies are inferred from the claim text.