Pre-treatment of spruce chips by fungi with aim to improve the pulp properties

Spruce chips applied for a pulp production are in the first place stored, usually 1 or 2 months. In this time their molecular structure can be changed due to atmospheric and biodeterioration processes, and some of the occurring changes may have a positive effect on the pulp quality. To estimate some principles of the biotic effects in a natural pile, in the presented work, spruce chips have been subjected to model degradation processes caused by selected white-rot fungi: Phanerochaete chrysosporium, Heterobasidion annosum, Onnia circinata or Climaeocystis borealis, and the brown-rot fungus Fomitopsis pinicola, under laboratory conditions during 3 or 6 weeks. The aim of our experiment was to find advisable storage conditions of chips to achieve satisfactory acid sulphite pulp quality. 3-week degradation of chips by Phanerochaete chrysosporium did not influence the yield and strength of pulps markedly, and brought a benefit of reduced Kappa number, reduced contents of lipophilic compounds and diminished the amount of rejects.