Evaluation of selected white-rot fungi for biosulfite pulping

Biosulfite pulping of Eucalyptus grandis wood chips pretreated with ten strains of selected white-rot fungi was investigated. The biopulping efficiency was evaluated based on fungal pretreatment time (5, 7 and 10 days) and properties of biosulfite pulp (pulp yield, kappa number, brightness, alkali solubility S-10 and S-18, and viscosity) in comparison to the controls. Pretreatment of eucalyptus wood chips with Ceriporiopsis subvermispora SS-3 in the absence of an additional carbon source for 10 days resulted in a substantial decrease in kappa number (by 29%) and increase in brightness (by 12%). On the other hand 5% of the pulp yield was lost, and both viscosity and alkali solubility (S-10 and S-18) were retained at levels comparable to the control. When the fungal incubation time was reduced to 5 days, a 5% reduction of kappa number, 11% increase in brightness and no loss of pulp yield was observed. C. subvermispora SS-3 was therefore selected for further optimization studies of biosulfite pulping for dissolving pulp-directed manufacture. (C) 1998 Published by Elsevier Science Ltd. All rights reserved.