Environmentally Friendly Totally Chlorine Free Bleaching of Wheat Straw Pulp Using Novel Cellulase-poor Xylanases of Wild Strains of Coprinellus Disseminatus

Cellulase-poor crude xylanases of Coprinellus disseminatus, strains SH1 NTCC 1163 (enzyme-A) and SH-2 NTCC 1164 (enzyme-B) produced under optimum conditions of solid-state fermentation (SSF), were used in bio-bleaching of wheat straw soda-AQ pulp in totally chlorine free (TCF) bleaching sequences. Kappa number reductions of 56% and 58% with respect to oxygen-delignified pulps were obtained after the sequences OX A E and OX B E, respectively. Significant increases in pulp brightness of 6.07% (enzyme-A) and 3.34% (enzyme-B) with slight decreases in some strength properties (due to the removal of hemicelluloses) were observed. Removal of hemicelluloses was further validated by an increase in pulp viscosity (6.07%, and 4.58%), COD (40%, and 38%), and facilitation of lignin removal, as indicated by colour values (48% and 45%) for OX A EQPP and OX B EQPP bleached pulps, respectively, over the control. Crude xylanases from C. disseminatus SH-1 NTCC 1163 and SH-2 NTCC 1164 can successfully be used for TCF bleaching of pulps owing to their high temperature and pH toleranance, and cellulasepoor nature, thus adding to the search for environment-friendly bleaching solutions for the pulp and paper industry.