ENVIRONMENTALLY FRIENDLY TOTALLY CHLORINE FREE BLEACHING OF WHEAT STRAW PULP USING NOVEL CELLULASE-POOR XYLANASES OF WILD STRAINS OF COPRINELLUS DISSEMINATUS

Shalini Singh, Dharm Dutt, C.H. Tyagi

Abstract


Cellulase-poor crude xylanases of Coprinellus disseminatus, strains SH-1 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 OXAE and OXBE, 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 OXAEQPP and OXBEQPP 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 cellulase-poor nature, thus adding to the search for environment-friendly bleaching solutions for the pulp and paper industry.

Keywords


Coprinellus disseminatus; Wheat straw; Pulp and paper; TCF bleaching

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