Biobleaching of pulp from agricultural residues with enzymes

Pulp from agricultural residues (wheat straw) was bleached with the DE_PD (chlorine dioxide-extraction with soda and hydrogen peroxide-chlorine dioxide) or P sequence (hydrogen peroxide) after enzymatic pretreatment with cartazyme HS.The enzymatic pretreatment increases the final brightness of the pulp after bleaching with the P and DE_PD sequences (+3.7%) and saves bleaching reagents (from 3.5 to 5.2%); however, it also decreases the pulp yield (from 9.3 to 14.1%) and breaking length (from 20.2 to 13.2%), burst index (from 13.1 to 8.2%) and tear index (from 4.2% to 16.8%) of the paper sheets formed from the pulp.The authors wish to express their gratitude to DGICyT, Spanish Ministry of Education and Science, for financial support granted for the realization of this work as part of Project PB 91-0841.