Biotechnology in Dissolving Pulp Manufacture, 1999 Pulping Conference Proceedings

Lew Christov

Sappi Management Services: R&D

Sappi Biotechnology Laboratory

Dept. of Microbiology and Biochemistry

University of the Orange Free State

This presentation gives an overview of the recent research achievements in the field of use of biological methods in acid sulfite dissolving pulp manufacture. Extensive research work on effluent bioremediation, biopulping and biobleaching of dissolving pulp has been conducted. The aim is to develop a modern biotechnology which could aid the existing chemical processes in a cost-effective and environmentally friendly way. Biosulfite pulping of Eucalyptus grandis with selected strains of the white-rot fungus Ceriporiopsis subvermispora was shown to improve the selectivity of both pulping and bleaching of dissolving pulp. The use of xylanases in dissolving pulp bleaching was favorable in terms of boosting the final brightness. The brightness gain could be translated into savings of chlorine dioxide which in turn would reduce the AOX and chloride content of bleach plant effluents. The enzymatic degradation and removal of hemicellulose from dissolving pulp decreased the levels of alkali solubility S18 and S10. Pulping and bleaching effluents have been studied for their usability to serve as inexpensive inducers and carbon source in microbial production of xylanase. Bioremediation studies with selected fungi led to isolation of a Rhizomucor pusillus strain capable of decolorizing rapidly the bleach plant effluent. It has been demonstrated that the fungal biotreatment of effluent could result in significant reductions of AOX, toxicity and COD.