Using Biotechnology to Improve the Nature of Trees

Using biotechnology to improve the properties of trees: The University of Michigan Technology, USA recently reported that modification of trees through the biosynthesis of lignin, including lignin, can reduce the lignin content in poplars by 45%, while the high cellulose content can reach 75%. This modified poplar wood is advantageous for pulping and papermaking, and the growth rate of trees is significantly increased.

Enzymatic removal of resin from wood: Early application of enzymes to remove resin from wood is preceded by pulping. Treating wood with enzymes can reduce the resin content. In the wood stored for one month after being treated with enzymes in a factory, the resin content was 0.72%, and it was 0.35% after 7 months of storage. However, the whiteness of the wood is reduced, the whiteness of the wood stored for one month is 57.5% (ISO), the whiteness of the wood stored for seven months is reduced to 52.5% (ISO), the yield of the wood is reduced, and the storage space is required to increase the investment. cost.

Bio-mechanical pulping: Enzymatic treatment of wood chips before refining can save energy consumption from preheated wood chips. Finland uses enzymes to treat the coarse pulp obtained from the first stage of refining, and uses cellulase to treat the brown slurry for 2-4 hours, which can save energy consumption of 15%-20% for the second stage of refining.

Enzymes are used in bleaching: The pretreatment of kraft pulp with enzymes can reduce chlorine consumption and the amount of AOX that can be adsorbed. In addition, pulp whiteness can be increased. Conditions for treatment with xylanase are generally pH 8 and temperature 65[deg.]C. University of Georgia, USA uses xylanase to pretreat hardwood kraft pulp after oxygen delignification (pH10 and temperature of 90°C), bleaching the pulp with DoED1ED2 sequence, the final whiteness can reach 90.5% (ISO) instead of wood aggregation. Carbohydrase pretreatment, pulp final whiteness was 86.7% (ISO). Although the dosage of xylanase was 55 IU/g dry pulp, it was higher than the normal amount used in the factory. However, the xylanase pretreated pulp could reduce the amount of chlorine dioxide by 25%. Treatment of Northern Softwood Kraft pulp with a pH of 10-10.3 and a temperature of 65°C was carried out in Finland with xylanase.

Deinking of waste paper with enzymes: A European plant uses a mixture of enzymes (including xylanase, mannanase, amylase and lipase) in combination with non-ionic surfactants, and 100% chemical wood pulp coated paper waste Deinking paper is more effective than conventional methods of chemical deinking. The deinking of waste paper using enzymes can significantly reduce the dust and fiber bundles of the deinked pulp and improve the whiteness of the pulp.

Treatment of factory wastewater with enzymes: Recent studies reported that the use of enzymes to treat dissolved and colloidal substances in wastewater is effective. Finnish studies have found that four types of enzymes (lipase, mannanase, laccase, and pectinase) can exert significant effects on the extracts and lignin present in the water used for wood mechanical pulping processes. (1) Lipase can change the chemical composition of the extract, making the fiber surface more hydrophilic, so that the pulp strength is higher, and can increase the solubility of the resin in the circulating process water. (2) Mannanase can cause instability and adhesion of fibers to fibers, resulting in lower pulp strength and affecting the utility of lipases. The hydrophilicity and localization of extracts are important for pulp strength. (3) Laccase polymerizes the low molecular weight lignin present in the water used in the preheated wood chips mill wood pulp and can partially oxidize lipophilic extracts. (4) Pectinase can reduce the amount of cationic polymer required when treating process water.