Characterization of Residual Wood Components in Samples Biotreated by the Biopulping Fungus Ceriporiopsis Subvermispora, 2000 Pulping / Process & Product Quality Conference Proceedings

A. Ferraz, A. Guerra, R. Mendonca--Biopulping is the fungal pretreatment of wood chips, designed as a solid-state fermentation process, for production of mechanical or chemical pulps. Although promising results have been obtained by combining biopulping and chemical or mechanical pulping methods, there is no clear relationship between the pattern of biodegradation of the wood components and the increase in efficiency of the pulping method subsequently adopted. Selective lignin biodegradation is necessary to prevent cellulose loss or depolymerization. However, the extent of lignin removal during fungal pretreatment is not related to energy savings in biomechanical pulping or to the increase in delignification rates observed in chemical pulping. This study presents some new efforts to evaluate the chemical mechanisms involved in biopulping. Pinus taeda wood chips biotreated by C. subvermispora were characterized as to their residual lignin. The same wood chips were also cooked by kraft liquor to produce high-yield pulps with kappa numbers from 40 to 120 (low severity cooking). Aril-ether linkages, as measured by DRFC degradation, diminished from 10.6% (based on the klason lignin content) to 3.7% as a function of biodegradation time. The compiled data suggested that lignin breakdown starts at the early biodegradation stages when the biopulping benefits are commonly observed (wood weight losses up to 2-3 %). A possible relationship between the extent of lignin depolymerization in the biopulping treatment and the increase in efficiency of the pulping method subsequently adopted is discussed.