Fungal pretreatment of Eucalyptus wood can strongly decrease the amount oflipophilic extractives during chlorine free graft pulping

Modern environmentally sound trends in manufacturing of bleached paper pulp involve development of totally chlorine free (TCF) bleaching and zero liqu id affluent (ZLE) processes. Lipophilic extractives are among the most prob lematic wood constituents for both TCF and ZLE processes, since they tend t o accumulate in circuits resulting in new manufacturing ("pitch" deposits) and environmental troubles. The extractive-degrading fungi Bjerkandera adus ta, Phlebia radiata, Pleurotus pulmonarius and Poria subvermispora were ass ayed to remove these compounds from Eucalyptus globulus wood using solid-st ate fermentation conditions. The pretreated chips were subjected to laborat ory kraft pulping to assess the effectiveness of the treatment. Evaluation of extractive removal was carried out by gas chromatography-mass spectromet ry of extracts from the pretreated wood and the pulps and black liquors aft er cooking. As a result of the fungal pretreatment, up to 75% decreased lev els of problematic compounds (including free and esterified sitosterol) wer e found in pulps and liquors. Moreover, a significant reduction of potentia l acute toxicity was found in black liquors from wood pretreated with three of the fungi. The bio-pulps were TCF-bleached, refined and handsheet prope rties evaluated to select the most advantageous fungi from the point of vie w of their industrial applicability in environmentally sound pulp manufactu ring processes.