Biodebarking

Chapter

Abstract

The removal of tree bark is the first step in all processing of wood. This step consumes a substantial amount of energy. Extensive debarking is needed for high-quality mechanical and chemical pulps because even a small amount of bark residue causes the darkening of the product. In addition to its high energy demand, complete debarking leads to losses of raw material due to prolonged treatment in the mechanical drums. The border between the wood and bark is the cambium, which consists of only one layer of cells. This living cell layer produces xylem cells toward the inside of the stem and phloem cells toward the outside. In all the wood species, the common characteristics of the cambium include a high content of pectins and the absence or low content of lignin. The content of pectins in cambium cells varies among the wood species but may be as high as 40% dry weight. The content of pectic and hemicellulosic compounds is very high in the phloem. Pectinases are found to be key enzymes in the process but xylanases may also play a role because of the high hemicellulose content in the phloem of the cambium. Enzymatic treatments cause significant decreases in energy consumption during debarking. The energy consumed in debarking is decreased as much as 80% after pretreatment with pectinolytic enzymes. The enzymatic treatment also leads to substantial savings in raw material. Enzymes may be able not only to increase existing debarking capacity, thus saving capital investment but may be also available as an aid to be used when debarking is difficult.

Keywords

Bark Debarking Mechanical pulp Chemical pulp Mechanical drum Cambium Pectins Phloem Pectinases Enzymatic treatment Hemicellulases Cellulases  

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Copyright information

© Springer Nature Singapore Pte Ltd. 2018

Authors and Affiliations

  1. 1.Pulp and Paper ConsultantKanpurIndia

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