Enzymatic Removal of Stickie Contaminants, 1997 Pulping Conference Proceedings

Stickie contaminants are a costly problem for both recyclers of market pulp and the papermakers using it. Increased use of pressure sensitive adhesives (PSAs) has compounded this problem in recycled furnishes. Preliminary labora-tory experiments using commercially available enzyme preparations at the ambient pH of the paper furnish (neutral pH range) have resulted in a significant reduction of all residual contaminants, including stickies. We found in recent laboratory trials that pulping with either cellulase, lipase, or a mixture of both enzymes at the ambient pH of mixed office paper removed the adhesives more effectively than did conventional alkaline pulping at pH 10. To confirm these preliminary results, a pilot plant scale-up, including pressure screening, will be run at the USDA Forest Serv-ice, Forest Products Laboratory, and results will be presented at the 1997 TAPPI Pulping Conference. Comparative process water quality will be monitored and residual stickies quantified at various stages of recycling. Process water will also be analyzed for colloidal and dissolved micro-stickies.