To provide a method for producing a chemical pulp which can be formed into a closed system by simplifying chemicals used in a cooking step and a bleaching step, uniting waste liquids and wastewater in the cooking step and the bleaching step, and carrying out the recovery of energy by concentration and combustion, because, in a conventional method for producing the chemical pulp, an SP cooking method has a problem for selecting woody materials, an environmental problem in the recovery of cooking chemicals, and a problem of air pollution by sulfur dioxide gas, and a KP cooking method has a problem of the air pollution by a sulfur compound and a water pollution problem such as COD, BOD and chromaticity by bleaching waste water.

The same chemicals are used in both steps of the cooking and the bleaching, and one of chlorine dioxide, hydrogen peroxide, peracetic acid, performic acid and an agent for generating the peroxide is effectively used for aggressive delignification in the cooking step and the bleaching step as nuclear chemicals.

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