The study for the mechanism of enzymatic deinking Part 3. -Deveropment of optimized flow based on the mechanism of enzymatic deinking-

Abstract:

It is important to elucidate the mechanism of enzymatic deinking and establish the optimized enzymatic deinking flow to realize enzymatic deinking method. We have already reported that the combination of mechanical action and enzyme activity is very important and that enzyme reduce mechanical energy to get the same residual toner level of the control pulp. In this paper, we compared several treatment flows to establish the optimized enzymatic deinking flow. Kneading is very effective for the clean-toner conversion and reduction of residual toner area. And to get the same residual toner area of final pulp as control, kneading energy could be reduced by enzyme as 30% while it was added at pulper. Concerning the optimized enzymatic flow, we compared pulper addition with kneader addition. Consequently kneader addition with agitated soaking gave the best result. Hairy toner ratio of the optimized enzymatic deinking flow was smaller than conventional pulper addition method. Moreover to get the same residual toner area of final pulp as control, kneading energy could be reduced by enzyme as 50% in the case of kneader addition. As a result of that, the damage of fiber by kneading could be decreased and sheet strength was improved. New process gave 10% reduction of kneading energy to get the same residual toner area as by usual alkaline deinking. Therefore it could be concluded that the optimized enzymatic deinking flow was superior to not only reported enzymatic deinking but also conventional alkaline deinking