Method to preserve native starch present in pulp in a papermaking process

摘要

Methods to preserve starch present in pulp are provided and also methods to control calcium precipitation and/or scaling in digesters or BOD systems. The methods can be performed as part of a papermaking process. Process water containing pulp can be treated with a chloramine. Process water containing pulp with native starch can receive a double treatment with at least one biocide, such as chloramine, and at least one oxidant, such as sodium hypochlorite. The treatment can be performed in any suitable manner. The treatment can be performed at one or more stages or locations in a papermaking system. A target residual chloramine value or range can be achieved by the treatment. Packaging sheets/boards and other paper products manufactured using the methods provided exhibit superior strength and other desirable characteristics.

主权项

1. A method to preserve native starch present in pulp comprising:
in a papermaking process that includes an anaerobic digester, or an aerobic digester, or both, that processes process water, treating process water containing pulp comprising complexes or aggregates of cellulose and native starch, wherein said treating comprises separately adding at different locations chloramine and oxidant to said process water, wherein starch-degrading enzyme content in the treated process water is reduced compared to treatment of the process water without the oxidant, wherein the adding of said oxidant is at sub-demand concentrations such that oxidant is added at from about 10 wt % to about 50 wt % of the actual demand of said process water, wherein actual demand is total amount of chlorine that would be used up in reactions with all chloride-reactable compounds in the process water without leaving residual chlorine therein.