Process for completely or partially dissolving lignin in trees

Abstract

A method for completely or partially dissolving lignin in trees by supplying a chemical composition comprising a lignin-dissolving enzyme to living trees during a period of time prior to the tree dying. In a first embodiment of the method, the chemical composition is supplied during a period of time prior to felling. In a second embodiment, the chemical composition is supplied in connection with felling. In a third embodiment, the chemical composition is supplied to the tree or parts of the tree after the tree has been felled but before the tree has died.

Description

[0001] PROCESS FOR COMPLETELY OR PARTIALLY DISSOLVING LIGNIN IN TREES

[0002] Technical Field

[0003] The present invention relates to a method for completely or partially dissolving lignin in living trees, by supplying a chemical composition comprising a lignin-dissolving enzyme to the living trees during a period of time prior to the trees dying, in accordance with the patent claims.

[0004] Technical Background

[0005] In the production of pulp and biofuels from wood raw material, lignin and cellulose fibres in the wood are separated from one another. A problem with known methods for releasing lignin from the cellulose fibres of wood raw material is that these methods require a large amount of energy to be carried out. Another problem with many of the methods currently used to release lignin from cellulose fibres is that they employ environmentally harmful chemicals.

[0006] In summary, the global problems in cellulose and fibre production are that the techniques and methods used to release lignin from cellulose fibres are costly, timeconsuming, equipment-intensive, energy-inefficient, and environmentally burdensome.

[0007] Prior Art

[0008] Patent application SE9403961-7 describes a method and device for processing wood in living trees. To achieve desirable wood properties, the living trees are injected with chemicals. The treated trees are provoked by the chemicals to react, resulting inter alia in resin formation. According to the patent application, “high-value dry pine timber and impregnated wood” are created through the injection of the chemicals.

[0009] The patent application does not describe the use of lignin-dissolving substances in accordance with the present patent application.

[0010] Patent specification US952245 describes a technique for colouring wood by supplying liquid dyes to living trees. In that patent, the liquid dye is supplied by injection. The patent specification does not describe the supply of lignin-dissolving chemical substances in accordance with the present patent application.

[0011] Swedish patent SE453713 describes a method for combating unwanted trees. This is achieved by creating a hole in the tree to be eliminated, into which a plug containing an herbicide in an internal compartment is inserted. The herbicide is released from the plug, killing the tree. The method described in patent specification SE453713 does not use a chemical substance in accordance with the present patent application.

[0012] Patent specification US3706161 describes a variant of a capsule intended for introducing a substance (“medications”) into trees. The capsule is inserted into a drilled hole in the tree. The capsule comprises an internal space containing the substance. The capsule has a sleeve-like construction with barbs on the outside that allow easy insertion into the tree while preventing removal. The patent specification does not describe the use of chemical substances corresponding to those of the present patent application.

[0013] Techniques for injecting liquids into trees are previously known. For example, the injection of chemical substances into trees is described in the aforementioned Swedish patent application SE9403961-7, in U.S. patent US4144673, and in several other patent documents.

[0014] A compilation of techniques for injecting chemical substances into living trees is described, for example, in the article “The development and evolution of trunk injection mechanisms - a review” by Israel Ojo et al. The article does not describe injection of chemical substances in accordance with the present patent application.

[0015] Object of the Invention

[0016] The object of the present invention is to eliminate or substantially reduce at least one of the previously mentioned problems, or problems mentioned in the following description, associated with the prior art in the field. The object is achieved by a method using a chemical composition, alternatively a chemical substance, comprising a lignin-dissolving enzyme, in accordance with the present application. Brief Description of the Figures

[0017] In the following detailed description of the invention, references will be made to the figures. Each figure is briefly described in the following list of figures. Note that the figures are schematic and that details may therefore be omitted. The exemplary embodiments shown in the figures are thus not limiting to the scope of protection of the present patent application.

[0018] Figure 1 schematically shows a tree to which a chemical substance, alternatively a chemical composition according to the present patent application, is supplied.

[0019] Figure 2 schematically shows part of a cross-section of a tree according to Figure 1 , to which a chemical substance or chemical composition is supplied.

[0020] Figure 3 shows an alternative supply of a chemical substance or chemical composition in liquid form to a tree.

[0021] Detailed Description of the Invention

[0022] The present invention relates to a method that uses a chemical composition, alternatively a chemical substance, comprising a lignin-dissolving enzyme to completely or partially dissolve lignin in at least one tree 1, or alternatively in part or parts of a tree, during a period of time prior to the tree dying. Preferably, the technique is used on a large number of trees prior to felling, during felling, or after felling but before the trees and their parts die.

[0023] In preferred embodiments of the chemical composition or chemical substance comprising a lignin-dissolving enzyme, the lignin-dissolving enzyme consists of lignin peroxidase. However, the specified lignin-dissolving enzyme is not limiting to the inventive concept of the present patent application, and in alternative embodiments other lignin-dissolving enzymes may be used. Examples of other conceivable lignindissolving enzymes are provided later in this description.

[0024] In initial exemplary embodiments, the chemical composition comprises, in addition to lignin peroxidase, hydrogen peroxide, manganese, and citric acid. With reference to Figure 1 , the enzymatically lignin-dissolving composition, or alternatively the lignin-dissolving chemical substance, is supplied to the tree 1 in the form of a water-soluble capsule 2, tablet, ampoule, or the like. By capsule 2 it is understood that this may also consist of a tablet, ampoule, or similar. Alternatively, two or more capsules 2 may be supplied to the tree.

[0025] In an exemplary embodiment of the capsule 2, tablet, ampoule, or similar, the weight is approximately 7.5 grams. In this exemplary embodiment, the capsule weighing approximately 7.5 grams comprises the following chemical substances:

[0026] • Lignin peroxidase: 5-10 mg / ml

[0027] • Hydrogen peroxide (H2O2): 1-2 mM

[0028] • Manganese (Mn2+): 0,1-0, 2 mM

[0029] . Citric acid: 10-20 mM

[0030] It should be noted that the weight of the capsule 2 and the quantities of the respective chemical substances may vary within the scope of the inventive concept. When the weight of the capsule 2 is changed, the proportions between the different chemical substances contained in the capsule 2 are maintained.

[0031] At least one capsule 2, tablet, ampoule, or the like is inserted into the tree 1 via at least one hole 3, recess, or similar that extends through the bark 4 of the tree and a distance into the trunk 5 of the tree. The figure also shows a plug 6 or similar that seals the drilled hole 4 after the capsule 2, tablet, ampoule, or similar has been inserted into the tree 1.

[0032] The chemical composition or chemical substance is supplied to the tree in the form of at least one water-soluble capsule 2, tablet, ampoule, or similar during winter or spring. When the sap begins to rise, the capsule 2 or capsules 2 dissolve, after which the process begins. The capsule 2 or capsules 2 are preferably placed where the sap flow is greatest, near the root end of the tree, as shown for example in Figure 1 . The liquid tends to form reagents and is substantially taken up throughout all parts of the tree.

[0033] When the liquid encounters the tree’s natural binding substances for fibres, the supplied substance or chemical composition reacts, for example, with the tree’s lignin and renders it incapable of holding the tree’s fibres / cells together. This reaction continues for several weeks until the tree dies or is substantially dying. The tree is then felled, after which the primary function of the bark is to retain the cellulose during transport for further processing.

[0034] In an alternative embodiment, the chemical composition or chemical substance is a liquid comprising the lignin-dissolving composition or the lignin-dissolving chemical substance. In an exemplary but non-limiting embodiment, the chemical composition comprises lignin peroxidase, hydrogen peroxide, manganese, citric acid, and water. This may be achieved by producing a liquid comprising lignin peroxidase together with hydrogen peroxide, manganese, and citric acid. The liquid may also be created by dissolving the aforementioned capsule or capsules in a liquid (water) at the time of use.

[0035] Injecting liquid into trees is previously known, as described in the background. The following describes an example of how liquid may be injected into trees, which is not limiting as to how liquid may be injected. Injection may, for example, occur by supplying liquid from at least one liquid container as shown in Figure 3.

[0036] Figure 3 shows a tree 1 to which at least one connected liquid container 7 is supplied, containing a liquid comprising the chemical substance or chemical composition in liquid form. In the exemplary embodiment, the liquid container 7 is located at a higher vertical position than the point at which the liquid is introduced into the tree 1. In this embodiment, the liquid is conveyed from at least one liquid container 7 via at least one hose 8 to at least one cannula 9 and further into the tree 1 . In alternative embodiments, injection of liquid into the tree may be carried out using other previously known techniques. The number of containers 7, hoses 8, and cannulas 9 is adapted to the size of the tree.

[0037] In alternative embodiments of the method, the chemical composition comprising a lignin-dissolving enzyme is supplied to the tree or parts of the tree in connection with felling, or during the period of time in which parts of the felled tree remain alive after felling. Since a tree remains alive for a period after felling, a corresponding technical effect is achieved if the composition comprising a lignin-dissolving enzyme is supplied to the tree or parts of the tree in connection with felling or during the period after felling while parts of the felled tree remain alive.

[0038] The supply of the chemical composition comprising a lignin-dissolving enzyme occurs by injection or by supplying the lignin-dissolving enzyme to the cut surfaces of cut tree parts. In alternative embodiments, other previously known techniques may be used to supply the composition to the trees.

[0039] In addition to the previously specified lignin-dissolving enzyme lignin peroxidase, the lignin-dissolving enzyme may consist of one of the following lignin-dissolving chemical substances or lignin-dissolving chemical compositions:

[0040] • Lignin peroxidase

[0041] • Manganese peroxidase

[0042] • Versatile peroxidase

[0043] • Laccase

[0044] • Dye-decolorizing peroxidase

[0045] • Glycoside hydrolases

[0046] • Lytic polysaccharide monooxygenases

[0047] • Cellobiose dehydrogenase

[0048] • Hemicellulases

[0049] • Lignin-degrading auxiliary enzymes

[0050] For injection, the following chemical composition may be used. For example, the following chemical composition may be used:

[0051] Injection Base Solution Recipe:

[0052] • Birch sap: 85% by volume

[0053] Additives:

[0054] • Surfactant reducing surface tension (Tween 80): 2% by volume

[0055] • Manganese(ll) sulfate (MnS04): 1 ,5% w / v

[0056] • Citric acid: 1% w / v

[0057] • Potassium carbonate (K2CO3): 0,5% w / v • Enzyme preparation comprising a lignin-dissolving enzyme: 10% by volume

[0058] It should be noted that the specified amounts and / or volumes of the constituent chemical substances and chemical compositions may vary within the scope of the inventive concept.

[0059] Advantages of the Invention

[0060] With the invention according to the present patent application, several advantages are achieved. The most apparent is that at least one of the problems identified in the background has been eliminated or substantially reduced.

Claims

Claims1 . A method for completely or partially dissolving lignin in trees, characterized in that a chemical composition comprising a lignin-dissolving enzyme is supplied to living trees during a period of time prior to the tree dying.

2. A method for completely or partially dissolving lignin in trees according to claim 1 , characterized in that the chemical composition comprising a lignindissolving enzyme is supplied to living trees during a period of time prior to the trees being felled.

3. A method for completely or partially dissolving lignin in trees according to claim 1, characterized in that the chemical composition comprising a lignindissolving enzyme is supplied to living trees at the time the tree is felled.

4. A method for completely or partially dissolving lignin in trees according to claim 1, characterized in that the chemical composition comprising a lignindissolving enzyme is supplied to the living tree or to part or parts of the tree after the tree has been felled but before the tree or part or parts of the tree have died.

5. The method according to any one of the preceding claims, characterized in that the lignin-dissolving enzyme is enclosed in at least one water-soluble capsule (2), tablet, or ampoule that is inserted into at least one drilled hole in the tree.

6. The method according to at least one of claims 1-4, characterized in that the lignin-dissolving enzyme is supplied to the tree, or parts of the tree, by injection.

7. The method according to any one of the preceding claims, characterized in that the lignin-dissolving enzyme consists of lignin peroxidase.

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