Method for reducing AOX forming amount in chlorine dioxide bleaching process of bagasse pulp

Abstract

The invention relates to a method for reducing an AOX forming amount in a chlorine dioxide bleaching process of a bagasse pulp. The method is characterized by mainly including the following steps: (1) high temperature acid pretreatment section; (2) biological enzyme pretreatment section; and (3) chlorine dioxide bleaching section. According to the present invention, high temperature acid pretreatment on the unbleached bagasse pulp is mainly to remove the hexenuronic acid in theunbleached pulp, and the use of biological enzyme is to remove the semi-cellulose on the fiber surface and to expose more residual lignin, so as to ensure the less usage of chlorine dioxide in the chlorine dioxide bleaching process, and reduce the AOX generated in the bleaching process. After high temperature acid pretreatment and enzyme pretreatment on the bagasse pulp, the usage amount of chlorine dioxide is saved by 15%-30%, and the forming amount of AOX is reduced by 20%-40%.

Description

technical field [0001] The invention relates to a method for cleaning pulp bleaching in a pulp and papermaking enterprise, in particular to a method for reducing the amount of AOX formed during chlorine dioxide bleaching of bagasse pulp. Background technique [0002] Pulp and paper companies can achieve the unity of environmental, economic and social benefits by using chlorine dioxide-based elemental chlorine-free (ECF) technology to bleach pulp. North America has fully completed the process of converting from conventional chlorine bleaching to ECF bleaching, and other regions are also converting from elemental chlorine bleaching to ECF bleaching. However, the ECF bleaching process still generates a small amount of adsorbable organic halides (AOX). AOX is the main persistent organic pollutant (POPs) in the ECF bleaching process, which is toxic, bioaccumulative and semi-volatile, and is difficult to degrade. Long-distance migration can occur. With the improvement of society...

AI Technical Summary

Problems solved by technology

[0004] In recent years, there have been many methods at home and abroad to try to reduce the amount of chlorine dioxide used in the bleaching process by reducing hemicellulose and hexenuronic acid in pulp, thereby reducing AOX emissions in wastewater, such as dilute acid leaching before bleaching, wood polymerization before bleaching, etc. Carbohydrase and laccase treatment methods and high-temperature chlorine dioxide bleaching methods, etc., can all achieve the purpose of reducing the AOX content in wastewater, but these methods have increased a lot of additional input costs, and the input-output ratio is far from perfect Finding a way to increase the input-output ratio as much as possible and improving the general applicability in factories has become an urgent problem to be solved.