Authors: MD. NAZRUL ISLAM, MD. REZAUL KARIM, RAIMO O. MALINEN
Abstract: Three white-rot fungi (Ceriporiopsis subvermispora (Pilát) Gilb. & Ryvarden, Phanerochate chrysosporium Burds, and Trametes (Coriolus) versicolor (L.) Lloyd) were tested for their ability to modify/degrade lignin in cooking and bleaching. Both chips and pulps of Acacia mangium Willd. and Eucalyptus camaldulensis Dehn. were pretreated with these white-rot fungi for different time periods (8, 12, and 16 days for chips; and 4, 8, and 12 days for pulps). For chip pretreatment, Kappa number decreased with the increase of fungal treatment time, and the maximum reduction in Kappa number was 28% and 25% for acacia and eucalyptus, respectively, after 16 days of fungi inoculation. The variation in Kappa reduction was also found for different fungi species when inoculated in the same wood species. Fungi treated pulps were also easy to delignify in oxygen delignification stage compared to the control pulp without serious viscosity loss. In bleaching, the final brightness was higher in the case of FD_0ED_1 bleached pulps (as much as 8 ISO units) than OD_0ED_1 bleached pulps for both species. By FD_0ED_1 bleaching sequence, it was also possible to reach the full brightness of pulp. Hand sheet properties were also improved significantly by fungi treatment prior to bleaching. Strength properties of hand sheets increased up to 20% by fungi treatment. Considering all the pulping and papermaking properties, the performance of C. subvermispora was better compared to other fungi tested, and the response of fungi to eucalyptus was better compared to acacia.
Keywords: Fungi, biopulping, biobleaching, acacia, eucalyptus, inoculation
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