Preliminary Results of Enzyme-Enhanced Versus Conventional Deinking of Xerographic Printed Paper, 1993 Recycling Symposium Proceedings

T. Jeffries, J. H. Klungness, M. S. Sykes, K. Rutledge

Xerographic and laser printed papers are difficult to deink using conventional methods. The recycling rate for this paper is lower than that for other types of paper, and offices are using more laser printers and photocopiers every year. An alternative to conventional deinking is biological deinking, which uses enzymes to peel away cellulose fibrils, thus removing attached toner particles. The detached ink is then more readily removed by a flotation and washing processes. This study compares enzyme deinking to chemical deinking of xerographic printed paper. First, we optimized the enzyme treatment for temperature, time, and enzyme dosage. Then, we compared

the optimized enzyme method with a standard chemical method using identical steps of high-consistency pulping, flotation, and washing. The most effective deinking of our standard

styrene/acrylate toner stock was accomplished by pulping with cellulase. Based on these studies, we plan to evaluate enzymatic deinking with larger-scale equipment and with wastepaper that is more difficult to deink, as well as the effect of enzyme treatment on fiber and sheet strength properties.