AU2023202455A1

AU2023202455A1 - An improved method for decomposing animal skin

Info

Publication number: AU2023202455A1
Application number: AU2023202455A
Authority: AU
Inventors: Fritz Michael Heinz QUINTERN
Original assignee: Noke Ltd
Current assignee: Noke Ltd
Priority date: 2022-04-22
Filing date: 2023-04-21
Publication date: 2023-11-09

Abstract

The invention is a method for decomposing animal skin, particularly sheep skin, through the use of vermicomposting in such a manner that may reduce the emission of undesirable gases and by products. The sheep skin to be processed is mechanically worked and combined with a carbon 5 based modifier. The resulting feedstock then undergoes a vermicomposting step involving the exposure of the feedstock to a population of earthworms producing vermicast or vermicompost. 18 FIGURE 2 A E Sheep Skins / Plts Modifiers B Combined prepamion Preparaim F Prep-wfian ~~ cattn indppkin&g.ti ipig C Pre-Treatrent e.g. fermentation, temperature, biological,others Ioptional GH 200 Vermicornposting (windrows, raised beds, others] Ver2iaSt 2/2

Description

FIGURE 2

A E Sheep Skins / Plts Modifiers

B

Combined prepamion Preparaim F Prep-wfian ~~ cattn indppkin&g.ti ipig

C Pre-Treatrent e.g. fermentation, temperature, biological,others Ioptional

GH

200 Vermicornposting (windrows, raised beds, others]

Ver2iaSt

2/2

James & Wells Ref: 317686AU

AN IMPROVED METHOD FOR DECOMPOSING ANIMAL SKIN

1. TECHNOLOGY FIELD

The present technology relates to an improved method for decomposing animal skin. The technology may find particular application in, but is not limited to, vermicomposting sheep skin.

2. BACKGROUND

Animal skin typically has a significant protein content, around 30% to 32% w/w. This percentage is even higher in the case of animals such as sheep.

Animal skins are a common waste product of agriculture and meat processing, and need to be disposed of.

One method of disposing of animal skins is to send them to landfill. However, there are various reasons to minimise landfill, including environmental concerns, ground water contamination, spread of disease, greenhouse gas emissions, etc.

Another method of disposing animal skins is to subject them to a decomposition process, such as vermicomposting. Vermicomposting is a process in which earthworms (such as compost

worms and soil dwelling earthworm species) are used to decompose waste to vermicompost or vermicast. The method is beneficial due to its relatively fast decomposition rate, and production of nutrient-rich vermicompost or vermicast.

However, animal skins frequently include high protein and fat which adversely affect earthworms

used in vermicomposting. When protein decomposes, foul and/or pungent substances, such as ammonia, are released. Also, nitrogen-based compounds substances may be released, such as by leaching into the soil and/or ground water or dispersing into air. Indiscriminate release of odorous and nitrogenous substances may be quite dangerous if the decomposing unit is located close to locations inhabited by humans and/or animals. In addition, the released substances may attract pests like flies, rodents, birds, insects, etc which deter use of decomposition to dispose of animal skins.

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As a result of, inter alia, these problems, animal skins are frequently disposed of in landfill or incineration, or are de-fractionised under high temperature, pressure or chemicals. However, as mentioned above, these methods all have adverse effects on humans, animals and the environment. Moreover, the ways in which animal skins are currently disposed also tend to be expensive and capital intensive.

3. OBJECTS OF THE TECHNOLOGY

Accordingly, it is an object of the present technology to address one or more of the foregoing shortcomings.

Accordingly, it is an object of the present technology to provide an improved solution for disposal of animal skins.

Accordingly, it is an object of the present technology to reduce disadvantages with vermicomposting of animal skins using known technologies.

Accordingly, it is an object of the present technology to provide a process for decomposing of animal skins which reduces or eliminates generation, or release, of undesirable substances

compared to existing techniques.

Accordingly, it is an object of the present technology to provide a process which reduces or eliminates adverse environmental effects of disposing animal skins.

Alternatively, it is an object of the present technology to at least provide the public with a useful

choice.

4. SUMMARY OF THE TECHNOLOGY

According to a first aspect of the present technology, there is provided a method of decomposing animal skin, the process comprising the steps of:

• preparing a feedstock by combining animal skin and a modifier which contains carbon containing compounds; and

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performing a vermicomposting step by exposing the feedstock to a population of earthworms for a period of time.

According to another aspect of the present technology, the method may include a preparation step.

In certain forms of the present technology, the preparation step may occur prior to combining the animal skin and the modifier. However, in another form, the preparation step may occur during the combining of the animal skin and the modifier. Combining of the animal skin and modifier prior to or during the preparation step helps with providing a more homogenous mixture and facilitates the modifier's adsorption of odours and liquids derived from the animal skin.

Throughout the present specification, reference to the term "preparation step" should be understood as a mechanical process to prepare the animal skin and which improves the efficacy of a subsequent vermicomposting step. The use of vermicomposting for decomposing animal skins and/or pelts is advantageous as it is not pH specific and potentially reduces output of, for example, nitrogen.

In a particularly preferred embodiment, the preparation step may involve reducing the size of the animal skin and / or increasing the surface area of the animal skin e.g. shredding, cutting

and/or broken down finely.

The inventor has surprisingly found that the use of a preparation step may provide further advantages for the present technology. For instance, decreasing the size of the animal skin may facilitate better mixing with the modifier having carbon-containing substances. This may provide

a more homogenous feedstock which is better suited to vermicomposting.

Further, by increasing the surface area of the animal skin, the surface area which may be exposed to the population of earthworms is increased. This may facilitate faster decomposition, and / or improve air circulation which reduces accumulation of odorous substances.

In certain forms of the technology, the present method may include a pre-treatment step.

James & Wells Ref: 317686AU

Throughout the present specification, reference to the term "pre-treatment" should be

understood as meaning a mechanical and / or chemical and / or microbial and / or biological treatment process to prepare the animal skin for a subsequent vermicomposting step.

In a preferred embodiment of the method, the pre-treatment step may involve the use of a fermentation process.

The process of fermentation may result in fermented skins with an increased pH and/or levels of ammonia. The increased pH and/or ammonia may be buffered subsequently in the vermicomposting process.

In a preferred form, the animal skin(s) may be decomposed partially by the process of fermentation. The animal skin(s) may be decomposed between substantially 1% and substantially 99%.

Preferably, the fermentation process may be carried out in conditions that are substantially anaerobic or aerobic.

Throughout the present specification, reference to the term "modifier"should be understood as

meaning a substance which contains carbon or carbon-containing compounds.

According to some forms of the technology, the modifier may comprise hemicellulose-based compounds. For instance, the carbon-based material may include one or more of plant fibres, pulp mill solids, cardboard, paper, hemicelluloses, plant materials and similar.

In some forms of the technology, the modifier may include, by-product from the building industry, in particular plasterboard which contains gypsum and is a source of calcium.

In certain forms of the technology, the hemicelluloses-based products may include fibrous material. Fibrous material tends to increase moisture holding capacity of the feedstock. This may reduce or prevent rain or irrigation water from leaching out of the vermicomposting beds. Thereby, ground water is not likely to be contaminated by nutrients such as nitrogen or phosphorous of the feedstock being carried by rain or irrigation water.

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According to some forms of the technology, the modifier(s) containing carbon-containing

compound(s) may be substantially free from lignin or at least has a reduced lignin content. The inventor has found that this can be beneficial as lignin is not easily decomposed using vermicomposting, and it requires an enzyme lignease for decomposition. Therefore, having a

/ the modifier(s) substantially free from lignin may provide an improved process for decomposing animal skins by vermicomposting. However, in other forms, lignin may be present in the modifier(s).

According to another form of the technology, the modifier may be sized before being mixed with the animal skin. For instance, the modifier may be cut or ground using techniques as should be known to those skilled in the art. In these embodiments, the method therefore may include a step of sizing the modifier to reduce its size or increase its surface area. This step may improve mixing of the modifier with the animal skin to provide a more even distribution of the carbon based material throughout the animal skin.

Accordingto one form of the technology, the modifier may be cut to an optimal size before being

mixed with the animal skin. In general, the smallerthe size of a modifier, the greater isthe surface area available for the earthworms. The increased surface area may also enhance certain properties like water and/or nutrient retention of the modifier. However, if the modifier is reduced to too small a size then the conditions of vermicomposting may become substantially

anaerobic. This may result in a reduction in worm population, and/or a significant increase in greenhouse gas emission from the process. Therefore, the modifier is preferably reduced to an optimal size which achieves a balance of all the influencing factors.

However, in other forms of the technology, the modifier may be mixed with the animal skin prior to cutting to an optimal size. As noted above, this helps with providing a more homogenous mixture and facilitates the modifier's adsorption of odours and liquids derived from the animal skin.

The optimal size may depend on a number of factors including, but not limited to, the percentage of protein content in the animal skin(s), the percentage of carbon-content in the modifier, nutrient absorption rate of the modifier, water retention rate of the modifier, etc.

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For instance, if the modifier can easily absorb nutrients like nitrogen and phosphorous then the

modifier need not be cut down to a fine size. In contrast, if the nutrient absorption rate of a modifier is substantially low and the same can be improved through increased surface area, then the modifier may be reduced to a relatively fine size.

Similarly, if a modifier has a high water-retention capacity, then the modifier may be optimally left at a large size. However, if increase in surface area can improve water-retention capacity, then the modifier may be cut to a smaller size.

In one form of the present technology, the modifier may comprise of complex carbon compounds. This may require the modifier to be reduced finely to improve availability to the worm population which in turn increases the rate of decomposition. In another form, the modifier may include relatively simple carbon-compounds. In such a case, the optimal size for the modifier may be substantially large.

The optimal size of the modifier may also depend on the relative size to which the animal skin(s) are reduced. This is because the ratio of carbon-based compounds and nitrogen-based

compounds may be important. This aspect is explained in more detail in the subsequent paragraphs.

In certain forms of the technology, the method may include an inoculation step.

Throughout the present specification, reference to the term "inoculation step" should be

understood as a process of combining semi-mature or mature vermicast, with or without earthworms or earthworm capsules, to the feedstock.

This addition of "inoculant", in the form of vermicast, may introduce microorganisms, such as bacteria and fungi, to the feedstock. This may reduce time required for vermicomposting, potentially mitigates losses of nitrogen and phosphate. This may also reduce greenhouse gas emissions.

In such forms, the inoculation step of combining the feedstock and the inoculant may produce a feedstock which contains animal skin and inoculant in a ratio between substantially 200:1 and

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substantially 1:4. In a preferred form, the volume percentage of the inoculant in a mixture of

feedstock and inoculant may be between substantially 0.5% and substantially 75%.

The inventor has surprisingly found that the technology described herein may provide a number of advantages. These may include one or more of the following:

• It may increase the ratio of carbon-based nutrients to nitrogen-based nutrients. This ratio tends to improve digestibility of the feedstock for the earthworms. • The addition of carbon-based organic material to the feedstock may increase surface area

of colonisation for the composting earthworms. This may improve access to the feedstock

for the earthworms.

• The ability of the feedstock to retain moisture may be improved. • The ability of the feedstock to retain nutrients such as nitrogen or phosphorous may be

improved.

Improving the ratio of carbon-based nutrients may reduce odour production during vermicomposting. This is because the earthworms would then be decomposing carbon-based

nutrients and nitrogen-based proteins. When carbon-based nutrients are decomposed, carbon dioxide is usually produced. When proteins are decomposed, ammonia and other odorous substances are the likely by-products. The improved ratio of carbon-based nutrients in the feedstock may lead to an increased release of carbon dioxide relative to methane from the vermicomposting earthworm beds. The mineralised nitrogen from decomposition of the skins may be digested by earthworms and released as a stable humus, like earthworm castings (vermicast or vermicompost) while the bulk nitrogen may be fixed in the earthworm protein tissue. Fixing the nitrogen in earthworm tissue (body mass) may mitigate nitrogen pollution, releasing of nitrogenous gases, ammonia volatisation, or nitrate leaching. Moreover, the presence of carbon-based nutrients in the feedstock may improve the overall digestibility of the feedstock for the composting earthworms. This is because proteins are generally more complex compounds than carbohydrates or other carbon-based organic material. Proteins are usually first decomposed into amino acids and then into ammonia. If the feedstock gets too acidic then the

James & Wells Ref: 317686AU

earthworms may die. By mixing carbon-based organic material into the feedstock, the overall pH

of the feedstock is likely to not get too low before the amino acids are converted to ammonia.

In addition, the present technology may have a relatively slower rate of production of ammonia compared to prior technology. This may improve the ability of the earthworm population to decompose and correspondingly retard the rate of production of odorous substances.

Reducing the amount and the rate at which odorous and/or nitrogenous substances are released from the feedstock may also provide other advantages. For instance, reduction in the release of odorous compounds may allow vermicomposting of animal skins closer to an area which may not otherwise be acceptable.

In certain forms of the technology, the method of combining the animal skin and the modifier may produce a feedstock which contains animal skin and modifier in a ratio between substantially 1:20 and substantially 7:3. In a preferred form, the volume percentage of the modifier in a mixture of animal skin and modifier may be between substantially 5% and substantially 70%.

According to certain forms of the technology, the ratio of the modifier in the feedstock may be

tailored based on the amount of fat and/or protein content present in the animal skin. Higher content of fat or protein will lead to lower animal skin to modifier ratio, preferably towards 20:80.Throughout the present specification, reference to the term "vermicomposting step" should be understood as meaning decomposition using earthworms. This involves

decomposition of organic matter, the resulting product being worm castings (vermicast) and/or residual vermicompost.

Throughoutthe present specification, referenceto theterm "earthworms" should be understood to include epigeic, endogeic, and anecic earthworm species.

Further aspects of the technology, which should be considered in all its novel aspects, will

become apparent to those skilled in the art upon reading of the following description which provides at least one example of a practical application of the technology.

James & Wells Ref: 317686AU

5. BRIEF DESCRIPTION OF THE DRAWINGS

One or more embodiments of the technology will be described below by way of example only, and without intending to be limiting, with reference to the following drawings, in which:

Figure 1 shows a schematic representation of a decomposing unit containing a feedstock in accordance with the present technology;

Figure 2 shows a flow-chart illustrating steps of a process of decomposing animal skins in accordance with the present technology.

6. BRIEF DESCRIPTION OF PREFERRED EMBODIMENTS OF THE TECHNOLOGY

6.1. DECOMPOSING SYSTEM

Referring now to Figure 1 which shows one example of a decomposing system 100 for use in a method according to the present technology.

A decomposing vessel 110 is provided in which a feedstock of animal skins and modifier can be added.

The decomposing system 100 further includes a first hopper 120 which can receive and hold

animal skins (not illustrated in Figure 1). The animal skins may be sized before addition to the first hopper 120 e.g. using a shredding, cutting or grinding unit (not illustrated in Figure 1).

The first hopper 120 is configured to provide e.g. tip or otherwise deposit the animal skins into the decomposing vessel 110.

A second hopper 140 can receive and hold a store of a modifier (not illustrated in Figure 1).

In preferred embodiments, the modifier may comprise relatively chopped fibres. In another embodiment, the modifier may comprise substantially finely chopped fibres.

The second hopper 140 is configured to provide e.g. tip or otherwise deposit the modifier into the decomposing unit 100.

James & Wells Ref: 317686AU

It is also envisaged that a feedstock of animal skin and modifier can be prepared outside of the

decomposing vessel 110, and subsequently added to the vessel 110. For instance, an auger (not illustrated) may be used to combine the animal skins and modifier to form a feedstock, which is then added into the decomposing vessel 110.

6.2. METHOD

Referring now to Figure 2 which illustrates steps of a method or process 200 of decomposing animal skins and/or pelts, such as, for example, sheep skin, to produce a feedstock for vermicomposting. The following discussion refers to skins and pelts of sheep, but it will be understood that the process may be used to process skins and pelts of other animal species.

The method for producing the feedstock involves two starting products: the sheep skin and/or pelt and a modifier. Dealing first with the skin and/or pelts that are to be decomposed, in step A, these are collected. These need to be prepared for use in the method.

The preparation is in the form of step B, in which the skins and/or pelts may be sized or otherwise mechanically worked e.g. thoroughly cut, shred and/or ripped to reduce the size of the skins

and/or pelts by reducing it to pieces and fragments. The optimal size to which the skins and/or pelts are to be cut may depend, amongst other factors, on the desired rate of decomposition. If, for instance, the skins and/or pelts contain a substantial percentage of fat and/or protein, then the rate of decomposition may inherently be slow. Alternatively, or in addition, the rate of

decomposition may also be slow if the skins and/or pelts are quite tough. In order to increase the rate of decomposition, the skins and/or pelts may be shred and/or cut down to a small size.

The size of the pieces and fragments of the skins and/or pelts may influence the rate of decomposition. When the size is small, the surface area available for the earthworms tends to be larger, thereby increasing the rate of decomposition. Similarly, when the size is large, relatively less surface area may be exposed to the earthworms, thereby retarding the rate of decomposition. The size of the fragmented and shredded skins and/or pelts may be determined in combination with the size to which the compounds of the modifier are shred to. This is discussed in further detail in step E.

James & Wells Ref: 317686AU

In some examples, an alternative preparation step C may be employed instead of step B as

described above. This involves, prior or during to the mechanical working of the skins and/or pelts, combining it with the selected modifiers. As discussed later, this may alleviate or minimise the amount of work and/or time involved in following steps of the method.

The simultaneous working of the skin and/or pelt together with the modifier is useful, since this allows liquids and odours from the former to be adsorbed by the latter. In some examples, the modifier may include waste plasterboard from the building industry; this serves as a source of calcium and sulphur, which may be important for later in the method. _

As per step D, the method 200 may involve an optional pre-treatment step for the sized skins and/or pelts, prior to being combined with the modifier in following step G. For instance, the skins and/or pelts may be fermented or temporarily thermal composted. Alternatively, the skins and/or pelts may be biologically or mechanically treated. This may increase the rate of decomposition, especially when the animal skins and/or pelts are tough due to the presence of connective or muscle tissue.

Biological treatment may include, but is not limited to, digestion by anaerobic microbes, enzyme catalysed biological fermenting, heat-induced microbial decomposition, etc.

Turning now to step E, this deals with the other starting product, the modifier. An amount of modifier to be mixed with the sized animal skins and/or pelts may be calculated based on the

composition of the animal skins and modifier(s). Based on the calculations, the requisite volume of modifier may be procured.

For instance, the amount of modifier required may depend on the composition of the skins and / or pelts to be vermicomposted. If the animal skins and/or pelts contain a high percentage of fats and/or protein, then a greater amount of modifier will be required to achieve the desired outcomes of the present technology. Similarly, if the animal skins and/or pelts are quite lean with little fat and/or protein content, then a relatively lesser volume of modifier may be required.

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Depending upon the percentage of fat and/or protein in the animal skin and / or pelts, sufficient modifier may be added. The animal skins and/or pelts comprise between substantially 5% and substantially 70% by volume of the feedstock.

In a specific, non-limiting, example, the amount of skins and/or pelts that are to be decomposed is 1M 3 . A plant-based product, such as pulp mill solids, cardboard, paper, other hemicelluloses containing fibres, may be used as a modifier. If the percentage of fat and protein in the skins and/or pelts is relatively low, then the amount of modifier that is required may be approximately 0.7 M 3 . On the other hand, if the skins and/or pelts have a high percentage of fat and/or protein, then the amount of modifier required may be approximately 4 m3

. Other factors may affect the volume of modifier required. For instance, if the modifier has a high water retention rate, then a lower volume of modifier may be optimal. This is because if the modifier absorbs moisture excessively, then the availability of water for the worm population may be reduced, thereby retarding decomposition. If, however, the modifier has a low water retention rate, then a greater volume of modifier may be useful.

In step F, the modifier may be cut and/or shred, if necessary. If the modifier is already small in size, i.e., proportional to the sized skins and/or pelts that have been prepared in accordance with step B, then further cutting and/or shredding may be unnecessary, and the modifier may then be introduced to sized skin and/or pelt in step G. Otherwise, the modifier may need to be cut

and/or shredded, as per step F, or possibly in combination with the skin and/or pelt in step C.

The size to which the skins and/or pelts may be shredded in step B and/or the size to which the modifier may be shredded in step F (or the combination of the skins and/or pelts with the modifier in step C) may depend upon a number of factors. As mentioned earlier, the smaller the size, the greater is the surface area to expose the substances to the earthworm population.

The size of the modifier may be calculated to facilitate the use of optimum amount of modifier to maintain the desired rate of decomposition of the animal skins and/or pelts.

The optimal size to which the modifier is shred may also depend on the complexity and/or stability of the carbon compounds which comprise the modifier. For instance, relatively long

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chain, complex carbon-compounds may take longer to decompose than relatively simple carbon

based compounds. Similarly, carbon-compounds which are relatively stable and/or unreactive may also take longer to decompose. If the carbon compounds contained in the modifier are complex and/or stable, then they may be shred substantially finely. If the carbon-compounds are relatively less complex and/or relatively reactive, and therefore easy to decompose, then they may be shred to a substantially larger size to slow down their rate of decomposition.

If not already mixed and blended (by virtue of optional step C), the sized skin and/or pelt is combined with the sized modifier in step G. This mixes and thoroughly blended to form a feedstock. This mixing and blending step may still be required even for a feedstock produced from step C as it could further include addition of a pH adjuster which ensures that the pH of the resulting feedstock is within a desired range e.g. that which promotes vermicomposting. The desired range of pH may be substantially from 5.5 to 7.9.

For instance, lime or wood ash may be used as a pH adjuster if the feedstock is acidic. Alternatively, if the feedstock turns alkaline, then acidic food wastes (like citrus wastes) or

Dissolved Air Flotation (DAF) sludge with a low pH may be used. Alternatively, the modifier may have been selected such that the feedstock may have the optimal pH value substantially throughout the decomposition process.

In some examples, another additive added during the mixing and blending step G could be a

source of calcium and/or sulphate, in the form of gypsum-containing plasterboard, often a waste product from the building industry, or wood ash. This can improve the presence of nutrients in the resulting feedstock and could be conducive for earthworms during the vermicomposting step discussed further below.

In other examples, shown here as step H, vermicast, in either mature or semi-mature form (or a mixture of same) may be added to the feedstock of step G. This can add microorganisms, in the form of bacteria and fungi, to the feedstock. The presence of such microorganisms may be beneficial in reducing overall vermicomposting time in step I as well as potentially reduce losses of nutrients, and eliminate or reduce greenhouse gas emissions.

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In step I, the feedstock may be subject to vermicomposting either in an indoor or outdoor

environment. For instance, the feedstock may be laid out in windrows outdoors and earthworms may be added to start vermicomposting.

Alternatively, the feedstock may be laid out indoors in vermicomposting units such as raised beds, trays, bins, and the like. The earthworms may be added to start vermicomposting. In this step, the pH, temperature and pressure may be set to values which are most conducive for the earthworms to grow.

In an alternative embodiment, in step 1, the pH adjuster may be arranged to drip into the windrow at predetermined intervals and at a predetermined quantity. This arrangement is advantageous in adjusting the pH of the feedstock continuously. With production of compounds such as ammonia, the pH of the feedstock may vary continuously. The pH adjuster may be useful in correcting this change constantly, thereby ensuring that the earthworms can have optimal conditions.

Similarly, the values of temperature, moisture and pressure may also vary as the process of

decomposition progresses. In an alternative embodiment, device(s) to adjust the temperature and/or moisture and/or pressure may be provided.

Step I may also include a step of monitoring the values of the pH, temperature, moisture and pressure. Sensors may be provided to the windrow for this purpose. Alternatively, or in addition,

the values of the pH, temperature, moisture and/or the pressure may be controlled. The control may be done manually or by a control device.

After the vermicomposting of the feedstock is substantially complete, vermicast (and/or the remains of vermicompost which may be incompletely decomposed) may be harvested in step J.

6.3. DISCLAIMER

Unless the context clearly requires otherwise, throughout the description and the claims, the words "comprise", "comprising", and the like, are to be construed in an inclusive sense as

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opposed to an exclusive or exhaustive sense, that is to say, in the sense of "including, but not limited to".

The entire disclosures of all applications, patents and publications cited above and below, if any, are herein incorporated by reference.

Reference to any prior art in this specification is not, and should not be taken as, an acknowledgement oranyform of suggestion that that prior artforms part of the common general knowledge in the field of endeavour in any country in the world.

The invention may also be said broadly to consist in the parts, elements, characteristics and features referred to or indicated in the specification of the application, individually or collectively, in any or all combinations of two or more of said parts, elements, characteristics or features.

Aspects of the present invention have been described by way of example only and it should be appreciated that modifications and additions may be made thereto without departing from the scope thereof as defined herein.

Where in the foregoing description reference has been made to integers or components having

known equivalents thereof, those integers are herein incorporated as if individually set forth.

It should be noted that various changes and modifications to the presently preferred embodiments described herein will be apparent to those skilled in the art. Such changes and modifications may be made without departing from the spirit and scope of the invention as

defined in the appended claims and without diminishing its attendant advantages. It is therefore intended that such changes and modifications be included within the present invention.

Claims

7. CLAIMS

1. A method of decomposing animal skin/pelt, the process comprising the steps of:

• preparing a feedstock by combining animal skin/pelt and a modifier which

contains carbon-containing compounds; and

• performing a vermicomposting step by exposing the feedstock to a population of

earthworms for a period of time. 2. The method as claimed in claim 1, wherein the method includes a preparation step.

3. The method of claim 2, wherein the preparation step includes mechanically working the

animal skin/pelt to break it down into fragments. 4. The method of either claim 2 or claim 3, wherein the preparation step is performed prior

to or during the step of combining the animal skin/pelt with the modifier. 5. The method as claimed in any one of claims 1 to 4, wherein the method includes a pre

treatment step. 6. The method as claimed in claim 5, wherein the pre-treatment step is a fermentation

process applied to the animal skin/pelt. 7. The method as claimed in either claim 5 or claim 6, wherein the fermentation process is

carried out in a substantial anaerobic environment.

8. The method as claimed in any one of claims 1 to 7, wherein the modifier is or includes hemicellulose-based compounds.

9. The method as claimed in claim 8, wherein the hemicellulose compounds is derived from one or more of plant fibres, pulp mill solids, cardboard, paper, hemicelluloses or plant

materials. 10. The method as claimed in any one of claims 1 to 9, wherein the modifier also includes a

fibrous material. 11. The method as claimed in any one of claim 1 to 10, wherein the modifier has a reduced

or substantially no lignin content. 12. The method as claimed in any one of claims 1 to 11, wherein the method includes a step

of mechanically working the modifier to break it down into fragments prior to being combined with the animal skin/pelt.

13. The method as claimed in any one of claims 1 to 11, wherein the method includes a step of mechanically working the modifier to break it down into fragments as it is combined

with the animal skin/pelt. 14. The method as claimed in any one of claims 1 to 13, wherein the modifier forms between

5% to 70% by volume of the feedstock.

15. The method as claimed in any one of claims 1 to 14, wherein the method includes a step of adding gypsum-containing material to the feedstock prior to the vermicomposting

step. 16. The method as claimed in any one of claims 1 to 15, wherein the method includes a step

of adding semi- or mature vermicast to the feedstock prior to the vermicomposting step. 17. The method as claimed in any of claims 1 to 16, wherein the method includes a further step of harvesting vermicast after a period of time has elapsed for the vermicomposting step.

18. The method as claimed in any one of claims 1 to 16, wherein the animal skin/pelt is that

ofsheep. 19. A vermicast formed from animal skin/pelt that has been decomposed by the method of

any one of claims 1 to 17.

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FIGURE 1 2023202455

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FIGURE 2 2023202455

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