XYLANASE-AND MANNANASE-AIDED ECF AND TCF BLEACHING

This work studies the effects of T. reesei xylanase and mannanase trea tments on the bleaching of radiata pine and northern pine sulfate pulp s in three-stage peroxide- and chlorine dioxide-based DED bleaching se quences. The xylanase treatment was more effective in enhancing pulp b leaching than the mannanase treatment. Pulp origin, method of pulping, and the sequence used in bleaching influenced the effectiveness of en zymatic treatment. Enzymatic treatment affected bleaching of northern pine kraft pulp more than radiata pine kraft with a similar kappa numb er. Radiata pine kraft pulp responded more readily to the xylanase and less readily to the mannanase treatment than the radiata pine modifie d continuous cooking pulp. Application:Progress toward more environmen tally friendly bleaching sequences has created a need for easily bleac hed kraft pulps. This work suggests that using a suitable combination of enzyme treatment and bleaching sequence can enhance the bleachabili ty of low kappa number pulps produced by modified or new kraft pulping methods.