Enzymatic Peroxide Enhancer for Chemithermal Mechanical Pulp, 1996 Pulping Conference Proceedings

Dr. Chip B. Hill

Buckman Laboratories International, Inc.

A new biobleach boosting enzyme effectively lowers peroxide and caustic soda use levels required for bleaching CTMP. Buzyme® 2511 is a stabilized form of bacterial xylanase with endo- 1,4-beta-D-xylanase activity without cellulase activity. This enzyme is substantially more stable at both higher temperatures and at higher alkalinity than other commercial xylanase products. The commercial application of 0.5kg/ton of Buzyme to the blend chest before the repulper followed by three hours in a medium consistency tower prior to peroxide bleaching resulted in the sustained peroxide savings of 25-30% coupled with a sodium hydroxide reduction of 15-20% while maintaining the same target IS0 brightness of 65%. The formulated xylanase also allowed the incorporation of lower quality chips while maintaining final target brightness. Final brightness between 74-76% ISO were achieved at moderate enzyme dosages (0.5kgAon) with a moderate increase in peroxide (from 4.5 to 5.5%).