GB2616613A

GB2616613A - Obtaining fibrous material comprising cellulosic fibres

Info

Publication number: GB2616613A
Application number: GB2203503.4A
Authority: GB
Inventors: Stephen Price Paul
Original assignee: Biotech Services Ltd
Current assignee: Biotech Services Ltd
Priority date: 2022-03-14
Filing date: 2022-03-14
Publication date: 2023-09-20
Also published as: GB202203503D0

Abstract

A method of extracting fibrous material comprising cellulosic fibres from green waste material 13, the method comprising: a first stage comprising macerating green waste material 13 under conditions of continuous mixing in an aqueous environment to at least partially break down the green waste material into cellulosic fibres, lignin, hemicellulose, pectin and chlorophyll; a second stage comprising separating the macerated green waste 13 into liquid and solid components, the solid component comprising fibrous material comprising cellulosic fibres, and optionally hemicellulose and lignin; a third stage comprising diluting and washing the solid component from the second stage, thereby further separating non-fibrous components from the fibrous material comprising cellulosic fibres; and a fourth stage comprising obtaining fibrous material comprising cellulosic fibres, from the third stage. A seventh stage may comprise refining the fibrous material from the fourth stage, optionally by high shear homogenisation and cavitation techniques. The fibrous material may be treated to separate cellulosic fibres from lignin. The first or third stage may comprise enzymatic treatment to liberate the cellulosic fibres, lignin, hemicellulose, pectin, chlorophyll.

Description

OBTAINING FIBROUS MATERIAL COMPRISING CELLULOSIC FIBRES

TECHNICAL FIELD

The present invention is directed to a method of extracting fibrous material, for example cellulosic fibres, from green waste. The present invention is also directed to a system for performing the method.

BACKGROUND TO THE INVENTION

Waste plastic is a source of pollution and consumers are demanding greater environmental accountability. Plant based materials may offer an alternative to some plastics. Converting plant-based wastes into useful materials typically involves high temperatures and pressures, which demands a high energy input, and/or processing the plant material using harsh chemicals.

It is an aim of the present invention to provide an improved method of extracting fibres from plant waste.

SUMMARY OF THE INVENTION

According to a first aspect, the present invention is directed to a method of extracting fibrous material comprising cellulosic fibres from green waste material, the method comprising: a first stage comprising macerating green waste material under conditions of continuous mixing in an aqueous environment to at least partially break down the green waste material into cellulosic fibres, lignin, hemicellulose, pectin and chlorophyll; a second stage comprising separating the macerated green waste material into liquid and solid components, the solid component comprising fibrous material comprising cellulosic fibres, and optionally hemicellulose and lignin; a third stage comprising diluting and washing the solid component from the second stage, thereby further separating non-fibrous components from the fibrous material comprising cellulosic fibres and optionally lignin, optionally wherein the solid component is subjected to further maceration under conditions of continuous mixing, during or after diluting and washing; and a fourth stage comprising obtaining fibrous material comprising cellulosic fibres, and optionally lignin, from the third stage.

According to a second aspect, the present invention is directed to a system configured to extract fibrous material comprising cellulosic fibres from green waste material in accordance with the method of the first aspect.

According to a third aspect, the present invention is directed to a method of installing or retrofitting a system in accordance with the second aspect.

According to a fourth aspect, the present invention is directed to a composition comprising, consisting essentially of or consisting of cellulosic fibre obtainable by the method of the first aspect.

DETAILED DESCRIPTION OF THE INVENTION

The methods of the present invention enable the extraction of fibrous material comprising cellulosic fibres and optionally lignin from green waste material. Advantageously, this may be achieved without using high processing temperatures or pressures, or harsh chemicals.

Green waste Green waste is waste organic material which can be composted and which contains high concentrations of nitrogen. For example, green waste may include fresh crop waste or processing waste of fresh crop product, such as offcuts and/or trimmings. Green waste is different to brown waste, which contains high concentrations of carbon. Green waste may decay into brown waste, and so a particular material may be green waste or brown waste, depending on how fresh it is. For example, freshly cut grass cuttings are green waste, but will decay into brown waste.

Examples of green waste include leafy waste, grassy waste, crop waste, horticultural waste (e.g., plants and flora), or mixtures thereof. Green waste also includes agricultural waste (also known as agri-waste). Suitable agricultural wastes include crop residues, weeds, leaf litter, sawdust and forest waste. For present purposes, agricultural waste does not include wastes which do not contain extractable fibrous material comprising cellulosic fibre such as, for example, livestock waste, e.g., manure, or any other animal derived products or by-products. The cultivation of food products such as tomatoes, carrots, lettuce, cucumber, peppers, onions, potatoes, celery and courgette produces green waste, in that not all parts of these plants are intended for consumption. For example, the leaves of many of these vegetables are not intended for human consumption, and they have such low calorific content that they are not valuable as animal feed. Such leaves are therefore considered green waste. The cultivation of grass, oats, rice, wheat and barley also produces green waste, for example, in the form of chaff.

Green waste material comprises fibrous materials which include cellulosic fibres.

Cellulose molecules are typically arranged into microfibrils, microfibrils typically arrange into macrofibrils, and macrofibrils typically arrange into fibres.

Preliminary stage -mechanically treating the green waste The method may further comprise mechanically treating the green waste to reduce its volume prior to macerating in the first stage. The mechanical treatment may be done in a preliminary stage, before the first stage. The preliminary stage may comprise providing green waste material for use in the first stage. The method may comprise mechanically treating, for example, by grinding, the green waste in order to reduce the volume of the green waste. The mechanically treated, for example, grinded, green waste may sometimes be referred to as a pulp, or a green waste pulp. For example, the mechanically treated green waste may have a density of from about 100 to about 400 kg/m3, for example, from about 200 to about 300 kg/m3, for example, about 250 kg/m3. The method may comprise mechanically treating the green waste with a mechanical flail or grinder, or other appropriate apparatus known in the art.

First stage The first stage may comprise controlling the aqueous environment of the first stage, which may comprise adjusting the viscosity of the green waste material in the aqueous environment. The first stage may comprise adjusting the viscosity of the macerated green waste material, which may comprise lowering the viscosity to prevent the formation of Pectate. Controlling the aqueous environment of the first stage or adjusting the viscosity of the green waste material may comprise diluting the green waste material, which may comprise diluting the green waste material to a target viscosity and/or diluting the green waste material to a target dry matter. The target viscosity may be from about 20 cP to about 200 cP, for example, from about 30 cP to about 190 cP, from about 40 cP to about 170 cP, from about 50 cP to about 170 cP, or preferably from about 60 cP to about 160 cP. The target dry matter content may be from about 15 wt.% to about 55 wt.%, for example, from about 20 wt.% to about 50 wt.%, from about 25 wt.% to about 45 wt.%, or preferably from about 30 wt.% to about 40 wt.%, more preferably about 35 wt.%. At least 50 wt. % of the dry matter is fibrous material, for example, at least about 75 wt. % of the dry matter is fibrous material, or at least about 80 wt. %, or at least about 85 wt. %, or at least about 90 wt. %, or at least about 95 wt. %, or at least about 99 wt. %. In certain embodiments, from 50 to 99 wt. % of the dry matter is fibrous material, for example, from about 75 to 95 wt. % of the dry matter is fibrous material. Controlling the aqueous environment of the first stage or adjusting the viscosity of the green waste material may comprise, if necessary, diluting the green waste material to a target viscosity of from about 60 cP to about 160 cP and to a target dry matter content of from about 30 wt.% to about 40 wt.°/0 (e.g., about 35 wt.%). Macerating the green waste material under conditions of continuous mixing in an aqueous environment may advantageously be more efficient when the green waste material is within the target viscosity. The first stage may comprise controlling the viscosity of the green waste material such that the extracted fibrous material and/or the macerated green waste is held in suspension in the liquid. The extracted fibrous material and/or the macerated green waste may be held in suspension in the liquid when the green waste material (which may have been diluted) has the target viscosity and/or the target dry matter content.

The volume of diluent required to reach the target viscosity and/or the target dry matter content may depend upon the moisture content of the green waste material.

Green waste materials from different sources may naturally contain different volumes of moisture, thereby different levels of dilution may be required to achieve the target viscosity and/or the target dry matter content. For example, freshly cut tomato leaf has a typical water content of about 88 wt.%. Using green waste materials which inherently have a viscosity within the target viscosity is advantageous since it means less or no additional water needs to be added to the system to dilute the green waste material This in turn may enable the size of vessel which is utilised for the first stage to be reduced, both of which may reduce energy consumption and/or costs. The first stage may comprise pre-treating the green waste material with an enzyme to release water, such as organically bound water, from the green waste material. Organically bound water is water that is an essential component of various materials (such as animal and plant cells or soils) from which it cannot be removed without changing their structure or composition and distinguishable from free water in such ways as by its inability to dissolve sugar or to form ice crystals. The enzyme used for the pretreatment may comprise cellulase, pectinase, pectinesterase, protease, polygalacturonase, or combinations thereof. The enzyme used for the pre-treatment may additionally or alternatively comprise any other enzyme or enzymes known in the art suitable for releasing water, such as organically bound water, from green waste material. It will be understood that the particular enzyme or enzymes used may depend upon the green waste material used, as green waste material from different plants may have different chemical compositions and therefore may require different pre-treatments. The moisture content of green waste may also vary depending on how fresh the green waste material is (i.e., how recently the green waste material was removed from a growing plant), with fresher green waste materials typically having a higher moisture content.

The green waste used in the first stage may not require dilution, as there may be a suitable volume of liquid released from the maceration and/or the pre-treatment of the green waste to achieve the desired viscosity. The first stage may therefore exclude a step of diluting the green waste.

The green waste material may be diluted with water (e.g. fresh or clean water, such as tap water or distilled water), with liquid from another stage of the method, with liquid from a bio-refinery (such as a multi-stage bio-refinery, for example, a multi-stage biodigestor), or mixtures thereof. The liquid from another stage of the method may comprise one or more green waste material breakdown products and/or one or more enzymes used in making the green waste breakdown products.

The green waste material breakdown products may be the result of biological breakdown of the green waste material (e.g., due to enzymatic treatment) and/or the result of mechanical breakdown of the green waste material (e.g., due to maceration).

Other than the cellulosic fibres and lignin, the green waste material breakdown products may comprise components such as, but not limited to: pectin; pectate or pectates and methanol, or mixtures thereof, for example, from broken down pectin; proteins; polypeptides and/or single amino acids, for example, from broken down proteins; shorter chain polysaccharides and/or sugars from broken down polysaccharides; chlorophyll; cellulose microfibrils; hemicellulose; and mixtures thereof. The liquid from the bio-refinery (such as a multi-stage bio-refinery, for example, a multi-stage bio-digestor) may comprise the likes of alcohol (such as ethanol), organic acids (such as acetic acid and/or propionic acid), bacteria and/or archaea (which may partially digest the green waste material, which may help extract the fibrous material).

Enzyme suitable for use in the process include cellulase, pectinase, pectinesterase, protease, polygalacturonase, and combinations thereof.

At least partially breaking down the green waste material into cellulosic fibres, lignin, hemicellulose, pectin and chlorophyll may comprise enzymatic treatment. The first stage may comprise enzymatic treatment to at least partially liberate cellulosic fibres, lignin, hemicellulose, pectin, chlorophyll, or combinations thereof, and optionally protein, nutrients, active components, or combination thereof, from the green waste material, for example, to partially breakdown pectin into shorter chain polysaccharides and/or sugars. The first stage may comprise enzymatic treatment to at least partially break down pectin, polysaccharides, proteins, or combinations thereof. The first stage may comprise enzymatic treatment to at least partially break down pectin, polysaccharides, proteins, or combinations thereof, to at least partially extract the fibrous material by at least partially breaking down the green waste material.

The enzyme used for the enzymatic treatment may comprise cellulase, pectinase, pectinesterase, protease, polygalacturonase, or combinations thereof. The enzyme used for the enzymatic treatment may additionally or alternatively comprise any other enzyme or enzymes known in the art suitable for extracting fibrous material comprising cellulosic fibres and lignin from green waste material. Suitable enzymes may be those which at least partially break down the green waste material. It will be understood that the particular enzyme or enzymes used may depend upon the green waste material used, as green waste material from different plants may have different chemical compositions and therefore may require different treatments.

For example, first stage may comprise enzymatic treatment with pectinase and/or polygalacturonase to at least partially break down pectin into shorter chain polysaccharides and/or sugars. The first stage may comprise enzymatic treatment with pectinesterase to at least partially break down pectin into one or more pectates and methanol. The first stage may comprise enzymatic treatment with protease to at least partially break down proteins into polypeptides and/or single amino acids. The first stage may comprise enzymatic treatment with cellulase to at least partially break down polysaccharides into shorter chain polysaccharides and/or sugars. The first stage may comprise enzymatic treatment with ferulic acid esterase to at least partially break down feruloyl-polysaccharide into ferulate and polysaccharides. The first stage may comprise the partial break down of cellulose to at least partially extract the fibrous material, but may exclude completely breaking down the cellulose. The partial break down of the cellulose may result in shorter average fibre lengths for the fibrous material as the method proceeds.

The first stage may comprise an enzyme concentration of less than 2 litres of concentrated enzyme solution per 1,000 kg of green waste material, for example, less than 1 litre of concentrated enzyme solution per 1,000 kg of green waste material, less than 500 ml of concentrated enzyme solution per 1,000 kg of green waste material, less than 300 ml of concentrated enzyme solution per 1,000 kg of green waste material, less than 200 ml of concentrated enzyme solution per 1,000 kg of green waste material, less than 100 ml of concentrated enzyme solution per 1,000 kg of green waste material, less than 80 ml of concentrated enzyme solution per 1,000 kg of green waste material, or preferably less than 60 ml of concentrated enzyme solution per 1,000 kg of green waste material, for example, about 50 ml of concentrated enzyme solution per 1,000 kg of green waste material.

The first stage may comprise controlling the enzyme concentration. The first stage may comprise measuring the temperature of the green waste material. The first stage may comprise using the temperature of the green waste material in the first vessel to determine the enzyme concentration. The temperature of green waste material may increase as the concentration of the enzyme used in the enzymatic treatment increases, because exothermic reactions will typically proceed more quickly with more enzyme. The temperature of the green waste material may therefore be used to determine if the exothermic reactions are proceeding too quickly, too slowly, or at an appropriate rate. If the reactions proceed too slowly, the system may not be able to process green waste material quickly enough to keep up with demand, for example, to utilize the source of green waste material at an appropriate rate or in a given period of time. If the reactions proceed too quickly, the enzymes may interact with the fibrous material in the green waste material, potentially reducing the quality and/or usefulness of the fibrous material once extracted. The enzyme concentration may be adjusted in order to maintain the temperature at a target temperature. For example, if the temperature is below the target temperature, enzyme concentration may be increased. If the temperature is above a target temperature, the enzyme concentration may be decreased. The target temperature may vary according to various process inputs including, for example, the type of green waste material, the amount of green waste material, the type of enzyme and the degree of breakdown required. For example, for any given enzyme a temperature below 70°C, such as below 65°C, 60°C, 55°C, 50°C, 45°C, 40°C, 35°C, or 30°C, may indicate that a higher concentration of enzyme is required and, thus, the method may comprising increasing the enzyme concentration. Conversely, for any given enzyme, a temperature above 30°C, such as above 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, or 65°C, may indicate a lower concentration of enzyme is required and, thus, the method may comprise lowering the enzyme concentration. The method may comprise maintaining the temperature within a target temperature range. This may require adjusting the enzyme concentration to maintain the temperature of the green waste between the lower limits and any of the upper limits described herein. For example, the method may comprise maintaining the temperature of the green waste material from 20°C to 70°C, such as from 20°C to 60°C, 20°C to 50°C, 20°C to 40°C, 20°C to 30°C, 30°C to 70°C, 30°C to 60°C, 30°C to 50°C, 30°C to 40°C, 40°C to 70°C, 40°C to 60°C, 40°C to 50°C, 50 °C to 70°C, or 50 °C to 60°C. If necessary, the enzyme concentration may be adjusted in order to maintain the temperature in any given range.

The first stage may be performed under ambient conditions, such as ambient temperature and/or pressure. The first stage may be performed at atmospheric pressure and/or room temperature, i.e., from 20-25 °C. The first stage may be performed within 10% (more or less) of the ambient temperature and/or pressure, such as within 8%, 5%, 4%, 3%, 2%, or 1%, of the ambient temperature and/or pressure. It is understood that the ambient pressure and temperature may change with the weather. Typically, the first stage process is performed in an open vessel.

The first stage may be performed at a temperature in a range from 10°C to 70°C, such as a temperature in a range from 10°C to 65°C, 10°C to 60°C, 10°C to 50°C, 10°C to 40°C, 10°C to 30°C, 10°C to 20°C, 20°C to 70°C, 20°C to 65°C, 20°C to 60°C, 20°C to 50°C, 20°C to 40°C, 20°C to 30°C, 30°C to 70°C, 30°C to 65°C, 30°C to 60°C, 30°C to 50°C, 30°C to 40°C, 40°C to 70°C, 40°C to 65°C, 40°C to 60°C, 40°C to 50°C, 50°C to 70°C, 50°C to 65°C, 50°C to 60°C, 60°C to 70°C, or 60°C to 65°C.

The first stage may not comprise raising the temperature of the green waste material, for example, using an external heat source. The first stage may exclude raising the temperature of the green waste. The first stage may therefore not require an external heat source. The first stage may exclude an external heat source. An external heat source is a dedicated source of heat, or a source which is used to deliberately generate heat, such as a heater. Incidental sources of heat, or sources which produce heat as a by-product of the process (e.g., from exothermic reactions), are not considered external heat sources. For example, heat generated through the use of a pump would be considered an incidental heat source.

In certain embodiments, the only source of heat (other than any incidental source of heat) during the first stage is heat generated by exothermic reactions, such as exothermic reactions of the enzyme with components of the green waste material.

Advantageously, the pH of the green waste material (which may be diluted) may be maintained within a target range. For example, if enzymatic treatment is used in the first stage, the enzymes used for the enzymatic treatment may be most active within a target pH range. Therefore, the first stage may comprise controlling the pH of the green waste material, for example by adding a pH buffer. The pH of the green waste material during at least part of, preferably all of, the first stage may range from acidic to alkaline, for example, a pH of from: about 2.0 to about 9.0, for example, from about 4.0 to about 9.0, such as from about 5.0 to about 8.0, or from about 5.5 to about 7.5; or from about 2.0 to about 7.0, such as from about 2.0 to about 6.0, from about 3.0 to about 6.0, or from about 3.0 to about 5.5; or from about 2.0 to about 9.0, such as from about 3.0 to about 8.0, preferably from about 4.0 to about 7.0. In certain embodiments, the pH of the green waste material during at least part of, or all of, the first stage may be from about 7 to about 11, such as from about 7 to about 10, or from about 7 to about 9, or form about 7 to about 8, or from about 8 to about 11, or from about 8 to about 10, or from about 8 to about 9, or from about 9 to about 11, or from about 9 to about 10. The pH of the green waste material during at least part of, preferably all of, the first stage may depend on the enzyme being used. For example, if protease is used, the pH may be from about 4.0 to about 9.0, such as from about 5.0 to about 8.0, preferably from about 5.5 to about 7.5, optionally with a temperature of 55°C to 65°C. If pectinase is used, the pH may be from about 2.0 to about 7.0, such as from about 2.0 to about 6.0, from about 3.0 to about 6.0, preferably from about 3.0 to about 5.5, optionally with a temperature of 35°C to 55°C. If ferulic acid esterase is used, the pH may be from about 2.0 to about 9.0, such as from about 3.0 to about 8.0, preferably from about 4.0 to about 7.0, optionally with a temperature of 30°C to 60°C.

The fibrous material comprising cellulosic fibres of the green waste prior to the first stage may have an average length of about 250 mm to about 450 mm, such as an average length of about 250 mm to about 400 mm, about 250 mm to about 350 mm, about 250 mm to about 300 mm, about 300 mm to about 450 mm, about 300 mm to about 400 mm, or about 300 mm to about 350 mm.

The first stage may be conducted in a single vessel or in a series of different vessels.

Advantageously, the present method and system requires relatively low energy input to produce the cellulosic fibres from the green waste. For example, the energy consumed during the first stage (that is, from the point at which the green waste enters the first stage up until it enters the second stage) may be less than 1 kWh per kilogram of the as-received (i.e., undiluted) green waste material (1 kWh/kg), such as less than 0.8 kWh per kilogram of undiluted green waste material (0.8 kWh/kg), less than 0.6 kWh per kilogram of undiluted green waste material (0.6 kWh/kg), less than 0.4 kWh per kilogram of undiluted green waste material (0.4 kWh/kg), less than 0.10 kWh per kilogram of undiluted green waste material (0.10 kWh/kg), less than 0.08 kWh per kilogram of undiluted green waste material (0.08 kWh/kg), or less than 0.05 kW per kilogram of undiluted green waste material (0.05 kWh/kg). In certain embodiments, the energy consumed during the first stage is at least 0.001 kWh per kilogram of undiluted green waste material (0.001 kWh/kg), for example, at least 0.010 kWh per kilogram of undiluted green waste material (0.010 kWh/kg), or at least 0.025 kWh per kilogram of undiluted green waste material (0.025 kWh/kg).

The duration of the first stage will depend on, for example, the amount of green waste material to be processed. For example, the first stage may last up to 72 hours. The first stage may last up to 48 hours. The first stage may last up to 24 hours, such as from 12 hours to 24 hours, from 16 hour to 24 hour, or from 20 hours to 24 hours, from 12 hours to 20 hours, or from 16 hours to 20 hours.

The first stage may comprise leaving the green waste to stand. After macerating green waste material under conditions of continuous mixing in an aqueous environment, the first stage may comprise stopping the maceration of the green waste material and/or stopping the mixing of the green waste material, and allowing the green waste to stand. The first stage may comprise leaving the green waste material to stand for up to 90% of the total duration of the first stage, such as up to 80% of the total duration of the first stage, up to 70% of the total duration of the first stage, up to 60% of the total duration of the first stage, up to 50% of the total duration of the first stage, up to 40% of the total duration of the first stage, up to 30% of the total duration of the first stage, up to 20% of the total duration of the first stage, or up to 10% of the total duration of the first stage. A ratio of the duration of the maceration and mixing time to standing time may be more than 1:10, for example, more than 1:9, more than 2:8 (i.e. 1:4), more than 3:7, more than 4:6 (i.e. 2:3), more than 5:5 (i.e. 1:1), more than 6:4 (i.e. 3:2), more than 7:3, more than 8:2 (i.e. 4:1), more than 9:1, or more than 10:1. The enzymatic treatment may be initiated while the green waste is standing. Alternatively, the enzymatic treatment may be initiated during maceration and mixing and permitted to continue for a period of time during which the green waste is standing.

The first stage may comprise determining the average length of the fibrous material comprising cellulosic fibres. The first stage may comprise sampling the green waste material to determine the average fibre length of fibrous materials comprising cellulosic fibres. The method may comprise ending the first stage, and/or transitioning the macerated green waste material from the first stage to the second stage, once the average fibre length of the fibrous material comprising cellulosic fibres has been substantially reduced, for example, once the average fibre length of the fibrous material comprising cellulosic fibres is about 50 mm to about 150 mm, such as an average length of about 50 mm to about 125, about 50 mm to about 100 mm, about 50 mm to about 75 mm, about 75 mm to about 150 mm, about 75 mm to about 125 mm, about 75 mm to about 100 mm, about 100 mm to about 150 mm, or about 100 mm to about 125 mm.

Second stage The second stage may comprise separating the macerated green waste into liquid and solid components using a separator. Any suitable separator may be used. For example, the separator may be a mechanical separator, such as a screw press separator, a filter, a centrifugal separator, or a sieve.

The fibrous material comprising cellulosic fibres at the start of the second stage may have an average length of about 50 mm to about 150 mm, such as an average length 35 of about 50 mm to about 125, about 50 mm to about 100 mm, about 50 mm to about 75 mm, about 75 mm to about 150 mm, about 75 mm to about 125 mm, about 75 mm to about 100 mm, about 100 mm to about 150 mm, or about 100 mm to about 125 MM.

The separated liquid component may typically comprise one or more of cellulose microfibrils, hemicellulose, pectin, and/or chlorophyll. The separated liquid component may further comprise one or more of the green waste material breakdown products described above, and/or the enzyme(s) used in the first stage.

The separated solid component comprises the cellulosic fibres, and optionally lignin.

Third stage The third stage may comprise controlling the aqueous environment of the third stage, which may comprise adjusting the viscosity of the diluted solid component, for example, in any of the same ways that the aqueous environment is controlled in the first stage. The third stage may comprise adjusting the viscosity of the diluted solid component, which may comprise lowering the viscosity to prevent the formation of Pectate. Controlling the aqueous environment of the third stage or adjusting the viscosity of the diluted solid component may comprise diluting the solid component to a target viscosity and/or diluting the solid component to a target fibre content. The target viscosity may be from about 20 cP to about 200 cP, for example, from about 30 cP to about 190 cP, from about 40 cP to about 170 cP, from about 50 cP to about 170 cP, or preferably from about 60 cP to about 160 cP. The target dry matter content may be from about 15 wt.% to about 55 wt.%, for example, from about 20 wt.% to about 50 wt.%, from about 25 wt.% to about 45 wt.%, from about 30 wt.% to about 40 wt.%, or about 35 wt.%. Controlling the aqueous environment of the third stage or adjusting the viscosity of the diluted solid component may comprise diluting the solid component to a target viscosity of from about 60 cP to about 160 cP and to a target dry matter content of from about 30 wt.% to about 40 wt.% (e.g. about 35 wt.%).

The third stage may comprise diluting the solid component with water (e.g. fresh or clean water, such as tap water or distilled water). The third stage may comprise diluting the solid component to control the viscosity of the diluted solid component. The desired viscosity of the diluted solid component may depend upon a number of factors including, for example, the quantity and type of green waste material used in the first stage, the enzymatic treatment, the extent of maceration, etc. The third stage may comprise controlling the viscosity of the diluted solid component such that the extracted fibrous material and/or the solid component is held in suspension in the liquid. The extracted fibrous material and/or the solid component may be held in suspension in the liquid when the diluted solid component has the target viscosity and/or the target dry matter content.

Washing the fibrous material may comprise removing extraneous material from the fibrous material. The extraneous material may comprise dirt (e.g. soil), grit (e.g. gravel, or sand), particles from crop workers' gloves (which may be plastic, leather, or other materials from which gloves are typically made), fastenings for crops (which may be clips or fasteners, and may be made from plastic, string, or other suitable materials), or sheeting materials (e.g. plastic). It may also include plant proteins, foams, scum or other such material, or combinations thereof. Washing the fibrous material may be accompanied by further macerating and/or mixing of the diluted solid component. The third stage may therefore comprise macerating and or mixing, for example, continually mixing the diluted solid component as it is washed. The mixing and/or maceration of the diluted solid component may agitate the solid component, such that extraneous material is separated from the fibrous material.

The third stage may comprise enzymatic treatment, such as enzymatic treatment to help separate the fibrous material comprising cellulosic fibres, and optionally lignin, from non-fibrous components. The enzymatic treatment during the third stage may be the same as any of the enzymatic treatments described above in relation to the first stage.

The enzyme used for the enzymatic treatment may comprise cellulase, pectinase, pectinesterase, protease, polygalacturonase, or combinations thereof. The enzyme used for the enzymatic treatment may additionally or alternatively comprise any other enzyme or enzymes known in the art suitable for extracting fibrous material comprising cellulosic fibres from the solid component. It will be understood that the particular enzyme or enzymes used may depend on the composition of the solid component. The composition of the solid component may depend upon the green waste material, the enzymes used in making the green waste material breakdown products, and/or the green waste material breakdown products from the first stage.

For example, the third stage may comprise enzymatic treatment with pectinase and/or polygalacturonase to at least partially break down pectin into shorter chain polysaccharides and/or sugars. The third stage may comprise enzymatic treatment with pectinesterase to at least partially break down pectin into one or more pectates and methanol. The third stage may comprise enzymatic treatment with protease to at least partially break down proteins into polypeptides and/or single amino acids. The third stage may comprise enzymatic treatment with cellulase to at least partially break down polysaccharides into shorter chain polysaccharides and/or sugars. The third stage may comprise the partial break down of cellulose to at least partially extract the fibrous material, but excludes completely breaking down the cellulose. The partial break down of the cellulose may result in shorter average fibre lengths for the fibrous material as the method proceeds. The enzyme or enzymes used may depend on, for example, the extraneous material which needs to be separated from the fibrous material, and the composition of the extraneous material may depend upon the green waste used in the method, and/or on the processing of the first stage, which may affect the composition of the solid component in the third stage.

The third stage may comprise an enzyme concentration of less than 2 litres of concentrated enzyme solution per 1,000 kg of solid component, for example, less than 1 litre of concentrated enzyme solution per 1,000 kg of solid component, less than 500 ml of concentrated enzyme solution per 1,000 kg of solid component, less than 300 ml of concentrated enzyme solution per 1,000 kg of solid component, less than 200 ml of concentrated enzyme solution per 1,000 kg of solid component, less than ml of concentrated enzyme solution per 1,000 kg of solid component, less than 80 ml of concentrated enzyme solution per 1,000 kg of solid component, or preferably less than 60 ml of concentrated enzyme solution per 1,000 kg of solid component, for example, about 50 ml of concentrated enzyme solution per 1,000 kg of solid component.

The third stage may be performed under ambient conditions, such as ambient temperature and/or pressure. The third stage may be performed at atmospheric pressure and/or room temperature, i.e., from 20-25 °C. The third stage may be performed within 10% (more or less) of the ambient temperature and/or pressure, such as within 8%, 5%, 4%, 3%, 2%, or 1%, of the ambient temperature and/or pressure. It is understood that the ambient pressure and temperature may change with the weather.

Advantageously, the pH of the diluted solid component may be maintained within a target range. For example, if enzymatic treatment is used in the third stage, the enzymes used for the enzymatic treatment may be most active within a target pH range. Therefore, the third stage may comprise controlling the pH of the diluted solid component, for example by adding a pH buffer. The pH of the diluted solid component during at least part of, preferably all of, the third stage may range from acidic to alkaline, for example, a pH of from: about 2.0 to about 9.0, for example, from about 4.0 to about 9.0, such as from about 5.0 to about 8.0, or from about 5.5 to about 7.5; or from about 2.0 to about 7.0, such as from about 2.0 to about 6.0, from about 3.0 to about 6.0, or from about 3.0 to about 5.5; or from about 2.0 to about 9.0, such as from about 3.0 to about 8.0, preferably from about 4.0 to about 7.0. In certain embodiments, the pH of the diluted solid component during at least part of, or all of, the third stage may be from about 7 to about 11, such as from about 7 to about 10, or from about 7 to about 9, or form about 7 to about 8, or from about 8 to about 11, or from about 8 to about 10, or from about 8 to about 9, or from about 9 to about 11, or from about 9 to about 10. The pH of the diluted solid component during at least part of, or preferably all of, the third stage may depend on the enzyme being used. For example, if protease is used, the pH may be from about 4.0 to about 9.0, such as from about 5.0 to about 8.0, preferably from about 5.5 to about 7.5. If pectinase is used, the pH may be from about 2.0 to about 7.0, such as from about 2.0 to about 6.0, from about 3.0 to about 6.0, preferably from about 3.0 to about 5.5.

Advantageously, the third stage may proceed more quickly if the temperature of the diluted solid component is maintained within a target range. For example, if enzymatic treatment is used in the third stage, the enzymes used for the enzymatic treatment may be most active within a target temperature range. Therefore, the third stage may comprise maintaining the temperature of the diluted solid component. The temperature of the diluted solid component may be maintained by heating the diluted solid component and/or by controlling the enzyme concentration. For example, increasing enzyme concentration may result in increased exothermic reaction activity, thereby typically increasing the temperature, while conversely, decreasing enzyme concentration may result in decreased exothermic reaction activity, thereby typically decreasing the temperature. The third stage may comprise maintaining the temperature of the diluted solid component, for example by heating and/or controlling the enzyme concentration, between ambient temperatures and 70°C, for example, in the range of 20°C to 70°C, such as a temperature in the range of 20°C to 65°C, 20°C to 60°C, 20°C to 50°C, 20°C to 40°C, 20°C to 30°C, 30°C to 70°C, 30°C to 65°C, 30°C to 60°C, 30°C to 50°C, 30°C to 40°C, 40°C to 70°C, 40°C to 65°C, 40°C to 60°C, 40°C to 50°C, 35°C to 65°C, 35°C to 60°C, 35°C to 55°C, 35°C to 50°C, 35°C to 45°C, 35°C to 40°C, 40°C to 65°C, 40°C to 60°C, 40°C to 55°C, 40°C to 50°C, 40°C to 45°C, 45°C to 65°C, 45°C to 60°C, 45°C to 55°C, 45°C to 50°C, 50°C to 65°C, 50°C to 60°C, 50°C to 55°C, 55°C to 70C, 55°C to 65°C, or 55°C to 60°C. The temperature of the dilute solid component may depend on the enzyme used. For example, if protease is used, the temperature may be from about 55°C to about 65°C, optionally with a pH of 5.5 to 7.5. If pectinase is used, the temperature may be from about 35°C to about 55°C, optionally with a pH of 3.0 to 5.5. If ferulic acid esterase is used, the temperature may be from about 30°C to about 60°C, optionally with a pH of 4.0 to 7.0.

The duration of the third stage may depend, for example, on the composition of the solid component. For example, the third stage may last up to 72 hours. The third stage may last up to 48 hours. The third stage may last up to 24 hours, such as from 12 hours to 24 hours, from 16 hour to 24 hour, or from 20 hours to 24 hours, from 12 hours to 20 hours, or from 16 hours to 20 hours.

The third stage may comprise leaving the green waste to stand. For example, after macerating and/or mixing the diluted solid component, the third stage may comprise stopping the maceration of the solid component and/or stopping the mixing of the diluted solid component, and allowing the diluted solid component to stand. The third stage may comprise leaving the diluted solid component to stand for up to 90% of the total duration of the third stage, such as up to 80% of the total duration of the third stage, up to 70% of the total duration of the third stage, up to 60% of the total duration of the third stage, up to 50% of the total duration of the third stage, up to 40% of the total duration of the third stage, up to 30% of the total duration of the third stage, up to 20% of the total duration of the third stage, or up to 10% of the total duration of the third stage. The ratio of the duration of the maceration and/or mixing time to standing time may be more than 1:10, for example, more than 1:9, more than 2:8 (i.e. 1:4), more than 3:7, more than 4:6 (i.e. 2:3), more than 5:5 (i.e. 1:1), more than 6:4 (i.e. 3:2), more than 7:3, more than 8:2 (i.e. 4:1), more than 9:1, or more than 10:1 The third stage may comprise determining the average length of the fibrous material comprising cellulosic fibres. For example, the third stage may comprise sampling the solid component to determine the average fibre length of fibrous materials comprising cellulosic fibres. The method may comprise ending the third stage, and/or transitioning from the third stage to the fourth stage, once the average fibre length of the fibrous material comprising cellulosic fibres is about 10 mm to about 50 mm, such as an average length of about 10 mm to about 40 mm, about 10 mm to about 30 mm, about 10 mm to about 20 mm, about 20 mm to about 50 mm, about 20 mm to about mm, about 20 mm to about 30 mm, about 30 mm to about 50 mm, or about 30 mm to about 40 mm. The average length of the cellulosic fibres may be determined by sampling from the separation stages and measuring the length of individual fibres, for example, using a rule. An average length is then calculated by summing the length of each individual fibre and dividing by the number of fibres measured.

The energy consumed during the third stage (that is, from the point at which the solid component enters the third stage up until it enters the fourth stage) may be less than 1 kWh per kilogram of undiluted solid component (1 kWh/kg), such as less than 0.8 kWh per kilogram of undiluted solid component (0.8 kWh/kg), less than 0.6 kWh per kilogram of undiluted solid component (0.6 kWh/kg), less than 0.4 kWh per kilogram of undiluted solid component (0.4 kWh/kg), less than 0.10 kWh per kilogram of undiluted solid component (0.10 kWh/kg), less than 0.08 kWh per kilogram of undiluted solid component (0.08 kWh/kg), less than 0.06 kWh per kilogram of undiluted solid component (0.06 kWh/kg), or less than 0.05 kW per kilogram of undiluted solid component (0.05 kWh/kg, or 0.050 kWh/kg). In certain embodiments, the energy consumed during the third stage is at least 0.001 kWh per kilogram of undiluted solid component (0.001 kWh/kg), for example, at least 0.010 kWh per kilogram of undiluted solid component (0.010 kWh/kg), or at least 0.025 kWh per kilogram of undiluted solid component (0.025 kWh/kg).

Fourth stage The fourth stage may comprise obtaining fibrous material comprising cellulosic fibres by separating the washed fibrous material from the diluent, for example, using a separator. The separator may be a mechanical separator, such as a screw press separator, a filter, a centrifugal separator, a sieve, or any other suitable separator known in the art for separating liquid and solid components.

The fibrous material obtained in the fourth stage comprises cellulosic fibres. The obtained fibrous material may additionally comprise lignin. The obtained fibrous material may additionally comprise hemicellulose.

Advantageously, the method may result in fibrous material which is compositionally similar to the fibrous material in the green waste. For example, the proportion of cellulosic fibres and, when present, lignin and/or hemicellulose, in the obtained fibrous material may be approximately the same as the green waste material. For example, the relative proportions of cellulose, lignin and hemicellulose in the obtained fibrous material at the end of the fourth stage may be within 25 % of the relative proportions of the cellulose, lignin and hemicellulos in the green waste material at the start of the method, for example, within 20 %, or within 15 %, or within 10 %, or within 5 % or with 2 %. The obtained fibrous material may comprise at least 50 % of the cellulosic fibres present in the green waste material, for example, at least 60 %, or at least 70 %, or at least 80 %, or at least 90 %, or at least 95 %, or at least 98 %. The obtained fibrous material may comprise at least 50 % of the lignin present in the green waste material, for example, at least 60 %, or at least 70 %, or at least 80 %, or at least 90 °A), or at least 95 %, or at least 98 %. The obtained fibrous material may comprise at least 50 % of the hemicellulose present in the green waste material, for example, at least 60 %, or at least 70 %, or at least 80 %, or at least 90 %, or at least 95 %, or at least 98 %.

The fourth stage may further comprise drying and/or grading the fibrous material comprising cellulosic fibres. The method may comprise drying the fibrous material to less than 10% moisture content, such as less than 7%, less than 5%, less than 2%, or less than 1% moisture content. The moisture content may be determined using any suitable method known in the art. The method may comprise grading the fibrous material based on fibre length, diameter, and/or mass. The fourth stage may further comprise bagging the graded fibrous material.

Other products -fifth and sixth stages Advantageously, the method may further comprise obtaining by-products. The method may comprise a fifth stage, the fifth stage comprising obtaining by-products from the separated liquid component, and/or the method may comprise a sixth stage, the sixth stage comprising obtaining by-products from the diluent of the third stage. The by-products may comprise, for example, cellulose microfibrils, non-cellulose microfibrils, hemicellulose, pectin, and/or chlorophyll from the separated liquid component, and/or cellulose microfibrils, non-cellulose microfibrils, hemicellulose, pectin and/or chlorophyll from the separated liquid component or from the diluent. The by-products may comprise green waste breakdown products.

The by-products obtained in the fifth stage and/or in the sixth stage, such as the cellulose microfibrils, non-cellulose microfibrils, hemicellulose, pectin and/or chlorophyll obtained from the liquid component or from the diluent, may be obtained using one or more of filtration, such as membrane filtration, crossflow filtration, microfiltration and nanofiltration, distillation, solvent extraction, precipitation, flocculation, floatation, centrifugal separation, cyclonic separation, and/or ionic separation.

The method may further comprise a seventh stage. The seventh stage may comprise refining the fibrous material comprising cellulosic fibres obtained from the fourth stage, for example, using high shear homogenisation and/or cavitation techniques.

The method may advantageously provide chemicals for (e.g. feed chemicals to), and/or receive chemicals from, a bio-refinery, such as a multi-stage bio-refinery, for example, a multi-stage bio-digestor.

The method may comprise feeding one or more by-products, at least a portion of a liquid from any of the first, second, third or fourth stages, one or more of the green waste material breakdown products, one or more of the enzymes used in making the green waste material breakdown products, or combinations thereof, to a bio-refinery, such as a multi-stage bio-refinery, for example, a multi-stage bio-digestor.

The method may comprise receiving at least a portion of the liquid used in first stage and/or in the third stage from a bio-refinery, such as a multi-stage bio-refinery, for example, a multi-stage bio-digestor. The liquid received from the bio-refinery may comprise alcohols (such as ethanol) and/or organic acids (such as acetic acid and/or propionic acid). The method may advantageously comprise using liquid from a bio- refinery. For example, the method may comprise receiving ethanol from a bio-refinery, and may further comprise using the ethanol to clean the system used to perform the method.

Other features The total energy consumed during the method (that is, from the start of the preliminary stage, if there is one, or from the start of the first stage if there is no preliminary stage, up until the end of the fourth stage) may be less than 10 kWh per kilogram of as-received green waste material (10 kWh/kg), such as less than 5 kWh per kilogram of green waste material (5 kWh/kg), less than 2 kWh per kilogram of green waste material (2 kWh/kg), less than 1 kWh per kilogram of green waste material (1 kWh/kg), less than 0.8 kWh per kilogram of green waste material (0.8 kWh/kg), less than 0.6 kWh per kilogram of green waste material (0.6 kWh/kg), less than 0.5 kWh per kilogram of green waste material (0.5 kWh/kg), or less than 0.4 kWh per kilogram of green waste material (0.4 kWh/kg, or 0.40 kWh/kg). In certain embodiments, the total energy consumed during the method is at least 0.025 kWh per kilogram of green waste material (0.025 kWh/kg), for example, at least about 0.050 kWh/kg, or at least about 0.075 kWh/kg, or at least about 0.100 kWh/kg, or at least about 0.125 kWh/kg of green waste material.

In certain embodiments, the energy consumed by the first stage, second stage, third stage and fourth stage taken together (and excluding any preliminary stage) is less than about 0.400 kWh/kg of green waste material, for example, from 0.150 kWh/kg to 0.400 kWh/kg of green waste material, or from 0.150 kWh/kg to 0.350 kWh/kg, or from 0.150 kWh/kg to 0.350 kWh/kg, or from 0.200 kWh/kg to 0.350 kWh/kg, or from 0.150 kWh/kg to 0.350 kWh/kg, or from 0.200 kWh/kg to 0.300 kWh/kg, or from 0.250 kWh/kg to 0.300 kWh/kg of green waste material.

Pectin can form a gel, for example, by reacting with calcium ions. Such a gel can inhibit the method, for example, creating blockages in the system used to perform the method. The method may therefore comprise ion exchange, for example, to adjust the hardness of liquid used in any of the stages of the method, such as reducing the hardness of water that is used in the first and/or third stages in the method. The method may comprise ion exchange to remove one or more alkaline earth metals, such as calcium. Removing alkaline earth metals may prevent pectin from the green waste material reacting with the alkaline earth metal(s) to form a gel. The method may comprise preventing pectin gel formation by removing alkaline earth metals with ion exchange. The method may preferentially comprise ion exchange during the first stage. The method may comprise ion exchange during the third stage.

The method may comprise treating the fibrous material to separate cellulosic fibres from lignin. The method may comprise removing lignin from the fibrous material, such as the extracted fibrous material, by dissolving the lignin in a solvent which does not dissolve cellulose, for example, in the third stage or the fourth stage. The method may comprise separating cellulose and lignin, and optionally hemicellulose, from the extracted fibrous material by dissolving one of cellulose, lignin and hemicellulose in a solvent which does not dissolve some or all of the other components of the extracted fibrous material. The dissolved component or components may then be obtained by precipitation from the solvent.

Extracted fibrous material and further processing The extracted fibrous material may comprise cellulose fibres, and optionally lignin and hemicellulose. The extracted fibrous material may comprise cellulosic fibres and lignin in approximately the same relative quantities, for example, within 10 wt. %, as the green waste material from which they were separated.

The extracted fibrous material may be processed into packaging, such as food packaging. The extracted fibrous material may be processed into medical dressings.

Lignin in the extracted fibrous material and/or extracted during the method may be processed into plastic filament (or "ink") for 3D printing applications.

System for performing the method The system configured to extract fibrous material comprising cellulosic fibres from green waste material may be for retrofitting to pre-installed plant or machinery.

The system configured to extract fibrous material comprising cellulosic fibres from green waste material may comprise a homogeniser, a first separator, a washer, and a second separator. The homogeniser may be for macerating green waste material under conditions of continuous mixing in an aqueous environment; the first separator may be for separating liquid and solid components from the macerator; the washer may be for washing the separated solid component from the first separator; and the second separator may be for obtaining washed fibrous material from the washer.

The system may comprise a homogeniser, which may be for the first stage of the method. The homogeniser may comprise a first vessel, which may be for holding the green waste material during the first stage. The homogeniser may comprise a first mixer, for mixing, such as continuously mixing, macerated green waste material in and/or from the first vessel. The first mixer may be a pump, such as a centrifugal pump or chopper pump, or any other appropriate mixer known in the art. The first mixer may be configured to operate, such as operate most efficiently, when pumping a liquid or mixture with a viscosity of from about 60 cP to about 160 cP. The output from the first mixer may be directed or directable (for example, with a first valve) to provide a flow pattern in the first vessel, whereby the flow pattern causes mixing in the first vessel. The homogeniser may comprise a first macerator for macerating the green waste material in or from the first vessel. The first mixer may also be the first macerator -i.e. the first mixer and the first macerator may be the same piece of apparatus, such as a chopper pump.

The system and/or the homogeniser may comprise a first dosing apparatus and/or the homogeniser may be in fluid communication with, or fluidly connectable to, a first dosing apparatus. The first dosing apparatus may be in fluid communication with the first vessel. The first dosing apparatus may be configured or configurable to dose the macerated green waste material with enzyme, and/or with any other chemicals which may be desired in the macerated green waste material during the first stage of the method. The enzyme and/or any desired chemicals may depend upon the source of the macerated green waste material, as the composition of the macerated green waste material may depend upon the green waste material which is used.

The homogeniser may comprise a heat source, such as an external heat source. The heat source may be configured to heat the green waste material in the homogeniser, for example to maintain the temperature of the green waste material in a target temperature range during the first stage of the method. The heat source may be a heater.

The system and/or the homogeniser may comprise a first valve. The first valve may be configured to direct output from the first mixer to the first vessel and/or to a first separator. The first valve may be configured to control output from the first vessel to the first separator.

The first separator may be for the second stage of the method. The first separator may be for separating liquid and solid components in the second stage. The first separator may be a mechanical separator, such as a screw press separator, a filter, a centrifugal separator, a sieve, or any other suitable separator known in the art for separating liquid and solid components.

The system may comprise a washer, which may be for the third stage of the method. The washer may be configured to receive the separated solid component from the first separator. The washer may comprise a second vessel, which may be for holding the diluted solid component during the third stage. The washer may comprise a second mixer, for mixing, such as continuously mixing, diluted solid component from the second stage of the method in or from the second vessel. The second mixer may be a pump, such as a centrifugal pump or chopper pump, or any other appropriate mixer known in the art. The second mixer may be configured to operate, such as operate most efficiently, when pumping a liquid or mixture with a viscosity of from about 60 cP to about 160 cP. The output from the second mixer may be directed or directable (for example, with a second valve) to provide a flow pattern in the second vessel, whereby the flow pattern causes mixing in the second vessel. The washer may comprise a second macerator for macerating the green waste in or from the second vessel. The second mixer may also be the second macerator-i.e. the second mixer and the second macerator may be the same piece of apparatus, such as a chopper pump.

The system and/or the washer may comprise a second dosing apparatus and/or the washer may be in fluid communication with, or fluidly connectable to, a second dosing apparatus. The second dosing apparatus may be in fluid communication with the second vessel. The second dosing apparatus may be configured to dose the solid component with enzyme, and/or with any other chemicals which may be desired in the diluted solid component during the third stage. The enzyme or any desired chemicals may depend upon the green waste used, as the composition of the solid component may depend upon the various process inputs including, for example, the type of green waste, the amount of green waste, the type of enzyme and the degree of breakdown required.

Both the homogeniser and the washer may be in fluid communication with the same dosing apparatus. The dosing apparatus may be configurable to be in fluid communication with the homogeniser, the washer, the homogeniser and the washer separately, or the homogeniser and the washer simultaneously. The homogeniser and the washer may be in fluid communication with different dosing apparatus.

The washer may comprise a heat source, such as an external heat source. The heat source may be configured to heat the diluted solid component in the washer, for example to maintain the temperature of the diluted solid component in a target temperature range during the third stage of the method. The heat source may be a heater.

The system and/or the washer may comprise a second valve. The second valve may be configurable to direct output from the second mixer to the second vessel and/or to a second separator. The second valve may be configurable to control output from the second vessel to the second separator.

The second separator may be for the fourth stage of the method. The second separator may be for obtaining fibrous material comprising cellulosic fibres from the third stage of the method. The second separator may be a mechanical separator, such as a screw press separator, a filter, a centrifugal separator, a sieve, or any other suitable separator known in the art for obtaining fibrous material.

The system, and preferably the homogeniser, may comprise an ion exchange membrane. The first mixer may comprise and/or be fluidly connected to an ion exchange membrane. The ion exchange membrane may be to adjust, for example, reduce, the hardness of the water that is used in the method. The ion exchange membrane may be configured to remove alkaline earth metals, such as calcium, from liquid used in the method (e.g. from water).

The system may comprise a grinder, which may be for mechanically treating the green waste. The grinder may be a mechanical fail or anther appropriate apparatus known in the art.

The system may comprise a loader, which may be a hopper. The loader may be configured to transport green waste, such as grinded green waste, to the homogeniser, for example, from the grinder to the homogeniser.

The system may comprise a dryer. The dryer may be for drying fibrous material obtained in the fourth stage of the method.

The system may comprise a grader. The grader may be or comprise a fibre grader. The grader may be configured to grade fibres by size, for example by length, diameter, weight, mass, or any combination thereof. The grader may comprise a hammer mill and one or more screens.

The system may comprise or be connected or connectable to a bio-refinery, such as a multi-stage bio-refinery. A system comprising or connected to a bio-refinery may have an advantageous exchange of chemicals to and/or from the bio-refinery. For example, chemicals, such as by-products, from the system may be used in the bio-refinery, and/or chemicals from the bio-refinery may be used in the system. The system and the bio-refinery may therefore advantageously work together The homogeniser, the first separator, the washer, the second separator, or any combination thereof, may be connected or connectable to the bio-refinery. The system or the homogeniser, the first separator, the washer, the second separator, or any combination thereof may be connected or connectable to the bio-refinery by communication lines. The communication lines may be fluid communication lines, e.g. the communication lines may fluidly connect the system or the homogeniser, the first separator, the washer, the second separator, or any combination thereof to the bio-refinery. There may be multiple such communication lines.

The system may be configured to receive liquid and/or chemicals from the biorefinery, and/or feed liquid and/or chemicals, such as by-products, to the bio-refinery.

For example, the system, or part of the system, may be cleaned with ethanol from a bio-refinery. After cleaning the system, the ethanol from the bio-refinery may contain green waste material breakdown products and/or enzymes used in making the green waste material breakdown products. The ethanol which was used to clean the system or part of the system and which contains green waste material breakdown products and/or enzymes used in making the green waste material breakdown products may be fed back to the bio-refinery. The green waste material breakdown products and/or enzymes used in making the green waste material breakdown products may then be used in in the bio-refinery, for example in anaerobic digestion in the bio-refinery, for example to produce biogas in the bio-refinery.

The system may be configured to operate on a daily cycle, which may advantageously allow the system to process green waste at a rate which allows the system to process all green waste produced from a factory, farm, or other processing facility which produces green waste. For example, the system may be configured to extract fibrous material from a day's worth of waste material. For example, the system may be configured and sized to process in one day or less one day's worth of green waste material from a factory, farm, or other processing facility which produces green waste. Alternatively, different parts of the system may each be configured and sized to process one day's worth of green waste material from a factory, farm, or other processing facility which produces green waste, in one day or less. For example, each of the grinder (if present), the homogeniser, the washer and the dryer (if present) may be configured and sized to process one day's worth of green waste material from a factory, farm, or other processing facility which produces green waste, in one day or less. In this way, the system may advantageously process green waste material at the same rate that the green waste material is generated, or at a higher rate, while allowing a day's worth of green waste material to be processed in the system over multiple days, spending up to, for example, a day in each of the different stages, including the grinder (if present), the homogeniser, the washer and the dryer (if present). The method may therefore be a continuous process in which successive batches (e.g., a day's worth) of green waste material are continuous fed to the system with different batches being processed in different stages at the same time.

Alternatively, the method may be a batch process in which one batch (e.g., a day's worth) of green waste material is processed completely in the system before another batch is introduced.

Composition of the cellulosic fibres The composition comprising, consisting essentially of or consisting of cellulosic fibre may be obtained using the methods or systems described herein. The composition comprising, consisting essentially of or consisting of cellulosic fibre may further comprise lignin and/or hemicellulose.

The composition may comprise cellulosic fibres and lignin, cellulosic fibres and hemicellulose, or cellulosic fibres, lignin and hemicellulose, in approximately the same relative quantities, for example, within 10 wt. %, as the green waste material from which they were separated.

The composition may be in powder form, for example, after drying and/or grading.

FIGURES

Embodiments will now be described by way of example only, with reference to the Figures, in which: Figure 1 is a system suitable for extracting fibrous material from green waste; Figure 2 is another system suitable for extracting fibrous material from green waste. and

Figure 1 shows a system 1. The system 1 comprises a homogeniser 10, a washer 30, a first screw press separator 22 and a second screw press separator 42.

The homogeniser 10 comprises a first vessel 12, a first centrifugal pump 14 and a first valve 16. The first vessel 12 contains macerated green waste material 13. The first vessel 12 is fluidly connected to the first centrifugal pump 14, and the first centrifugal pump 14 is then fluidly connected to the first valve 16. The first valve 16 has an output 17 which directs fluid from the first valve 16 back into the first vessel 12.

When the system 1 is in use during the first stage of the method, the macerated green waste material 13 is pumped from the first vessel 12 by the first centrifugal pump 14. The first centrifugal pump 14 contains a series of blades which further macerate the green waste 13 as it passes through the first centrifugal pump 14. This maceration helps homogenises the green waste material 13, and also helps expose the fibrous material including cellulosic fibres in the green waste material 13. During the first stage of the method, the macerated green waste material 13 is directed by the first valve 16 and the output 17 back into the first vessel 12. The output 17 is directed to provide a flow pattern of the macerated green waste material 13 in the first vessel 12, thereby mixing the macerated green waste material 13 in the first vessel 12. The first centrifugal pump 14 and directed output 17 provide maceration of the green waste material 13 under conditions of continuous mixing. Enzymes are added to the first vessel 12 to partially break down the green waste material 13, thereby partially exposing the fibrous material.

The macerated green waste material 13 is sampled, and the average fibre length of the fibrous material in the macerated green waste material 13 is determined. If the average fibre length is within a target range, then this shows that the green waste material 13 has been sufficiently homogenised in the homogeniser 10. The first valve 16 then directs the macerated green waste material 13 from the first vessel 12 to the first screw press separator 22 along pipe 18. The first screw press separator 22 separates the solid component of the macerated green waste material 13 and the liquid component of the macerated green waste material 13, thereby performing the second stage of the method. The separated solid component is directed by output 28 to the washer 30, for the third stage of the method. The separated solid component contains the fibrous material comprising cellulosic fibres from the green waste material. The separated liquid component can be collected from the output 27, sent back to the first vessel 12 to dilute further green waste, or sent for use in another process, such as in a bio-refinery.

The washer 30 has similar components to the homogeniser 10 and operates in a similar fashion. The washer 30 comprises a second vessel 32, a second centrifugal pump 34 and a second valve 36. The second vessel 32 contains diluted solid component 33, which contains the solid component from the first screw press separator 22 which has been diluted using clean water which is added to the second vessel 32. The second vessel 32 is fluidly connected to the second centrifugal pump 34, and the second centrifugal pump 34 is then fluidly connected to the second valve 36. The second valve 36 has an output 37 which directs fluid from the second valve 36 back into the second vessel 32.

When the washer 30 is in use during the third stage of the method, the diluted solid component 33 is pumped from the second vessel 32 by the second centrifugal pump 34. The second centrifugal pump 34 contains a series of blades which further macerate the solid component as it passes through the second centrifugal pump 34. This maceration further reduces the size of the fibres in the solid component and further exposes the fibrous material including the cellulosic fibres in the solid component. During the third stage of the method, the diluted solid component 33 is directed by the second valve 36 and the output 37 back into the second vessel 32. The output 37 is directed to provide a flow pattern of the diluted solid component in the first vessel 32, thereby mixing the diluted solid component 33 in the second vessel 32. Enzymes can be added to the second vessel 32 to partially break down the solid component, to further expose the fibrous material, and separate the fibrous material from extraneous green waste material in the solid component.

The diluted solid component 33 is sampled, and the average fibre length of the fibrous material in the diluted solid component 33 is determined. If the fibres in the diluted solid component 33 have been exposed and reduced in size to the desired length, the second valve 36 directs the diluted solid component 33 from the second vessel 33 to the second screw press separator 42 along pipe 38. The second screw press separator 42 separates the fibrous material including the cellulosic fibres of the diluted solid component 33 and the liquid component of the diluted solid component 33. The fibrous material is obtained from output 48. The separated liquid component can be collected from the output 47, sent back to the first vessel 12 to dilute further green waste, or sent for use in another process, such as in a bio-refinery.

Figure 2 shows a system 2. System 2 is an extension of system 1, and system 2 comprises the same homogeniser 10, washer 30, first screw press separator 22 and second screw press separator 42 as system 1. Reference is made to the description of these components in relation in system 1 above.

System 2 additionally includes a grinder 4, a dryer 50, a grader 60 and a bio-refinery 70. System 2 includes all of these components, but it is understood that any combination of the grinder 4, the dryer 50 and the grader 60, and the bio-refinery 70, can be added to system 1.

The grinder 4 grinds green waste material (such as tomato leaves) in a preliminary stage to reduce the volume of the green waste material. The grinded green waste material is denser than the unground green waste material, which may make it easier to handle, as smaller volumes are used. The grinded green waste material is added to the homogeniser 10 from the grinder 4 along loader 6, which may be a hopper.

The green waste material is processed by, and moves through, the homogeniser 10, the first screw press separator 22, the washer 30 and the second screw press separator 42 in the same manner as described above in relation to system 1.

After the fibrous material comprising cellulosic fibres are obtained from the second screw press separator 42, the fibrous material can be dried using dryer 50. Drying the fibrous material removes most residual liquid from the fibrous material which is not removed by the second screw press separator 42. The dried fibrous material have a moisture content of less than 2%.

The dried fibrous material can be graded by grader 60. Grading the fibrous material results in a more homogenous fibrous material products, which can be useful when handling the fibrous material or further processing the fibrous material into new products.

The system 2 can be connected to a bio-refinery 70. Chemicals, such as green waste material breakdown products, can be extracted from different parts of the system 2, and chemicals can be added to different parts of the system 2 from the bio-refinery 70. For example, liquid can be added to the bio-refinery 70 from the first vessel 13 along communication line 19, from the second vessel 33 along communication line 39, from the first screw press separator 22 from output 27, and/or from the second screw press separator 42 from output 47. The liquid added to the bio-refinery 70 from any of the first vessel 13, the first screw press separator 22, the second vessel 33 or the second screw press separator 42 will contain chemicals. The specific chemicals added to the bio-refinery 70 in the liquid will typically depend on the part of the system 2 from which the liquid is extracted, the green waste used, and the enzymes used to process the green waste material.

Chemicals can be added from the bio-refinery 70 to the system 2. For example, liquid can be added from the bio-refinery 70 to the first vessel 13 along communication line 71, and/or liquid can be added to the second vessel along communication line 73. Liquid from the bio-refinery 70 can be used to dilute the macerated green waste 13 in the first vessel 12 and/or to dilute the solid component tin the second vessel 33. Adding liquid from the bio-refinery 70 to the first vessel 13 may provide bacteria and/or archaea to the first vessel 12, which may partially digest the macerated green waste material 13, thereby helping to expose the fibrous material in the macerated green waste material 13. Ethanol can also be added to the system 2 from the bio-refinery 70, which can be used to clean the system 2. The ethanol will then contain residual material from the system 2, such as green waste material breakdown products, which can be fed back to the bio-refinery 70 for use in the bio-refinery 70.

Example 1

Example 1 describes a method for extracting fibrous material comprising cellulosic fibres from 2,000 kg of tomato leaf material. The tomato leaf has a fibre content of approximately 240 kg, which equates to a dry matter content of about 12%.

In the preliminary stage, 2,000 kg of tomato leaf material is transported by a loader to a grinder. The grinder reduces the volume of the tomato leaf, with the bulk density of the tomato leaf increasing to approximately 250 kg/m3. The grinded tomato leaf is then transferred to the homogeniser.

In the first stage, water is added to dilute the grinded tomato leaf in the homogeniser. 50 ml of concentrated pectinase solution and 50 ml of concentrated polygalacturonase solution are added to release organically bound water in the tomato leaf by breaking down pectin in a pre-treatment step. Pectinase and polygalacturonase are added to the homogeniser. The first centrifugal pump is then turned on, and the diluted tomato leaf is mixed and macerated. The temperature and pH is controlled. The combination of the pumping, macerating and enzymatic treatment causes pectin in the tomato leaf to down into shorter chain polysaccharides and/or sugars, and the fibrous material being at least partially liberated. After the pumping, the mixture from the homogeniser is sent to the first centrifugal separator for the second stage.

In the second stage, the liquid and solid components from the homogeniser are separated using the first centrifugal separator. The liquid component includes water, the enzymes used in the first stage. The liquid component also includes individual cellulose microfibrils which have been separated from the rest of the fibrous material and which are suspended in the water.

The solid component contains the fibrous material comprising the cellulosic fibres.

The solid component falls from the first centrifugal separator in to the washer.

In the third stage, water is added to the solid component in the washer together with enzyme. The second centrifugal pump is then turned on, and the diluted solid component is mixed and macerated. While the mixture is being pumped, the temperature and pH is controlled. The pump is run for 24 hours. The combination of the pumping, macerating and enzymatic treatment results in additional breakdown of the solid component, liberating the fibrous material. After the pumping, the mixture from the washer is then sent to the second centrifugal separator for the fourth stage.

In the fourth stage, the fibrous material is separated from most of the water which was used in the washer with the second centrifugal separator. The fibrous material includes cellulosic fibres. The liquid from the second centrifugal separator contains breakdown products and cellulose microfibrils which have been separated from the rest of the fibrous material and which are suspended in the water.

At this stage, there is approximately 320 kg of wet fibrous material, which includes approximately 240 kg of fibrous material and approximately 80 kg of water. The fibrous material is transferred to the dryer to remove this water. The fibrous material is dried to less than 2% moisture.

Following treatment in a vacuum separator, the fibrous material is fed with a manual hopper to a mechanical sieve, where the fibrous material is sieved. The sieved fibrous material is then fed with a manual feed to a hammer mill, where the fibrous material is graded. Finally, the fibrous material is manually fed to a vacuum bagger, where it is bagged.

Table 1

Stage Description Duration (hours) Input power Energy Used (kWh) kWh / kg' (kW) Preliminary stage Loader-tomato leaf material is transported to a grinder 1 75 75.00 0.038 Grinder-tomato leaf material is grinded 24 5.5 132.00 0.066 Transfer -grinded tomato leaf is transported to the homogeniser 0.5 5.5 2.75 0.0014 First stage Homogeniser-green waste is mixed and macerated 24 3.3 79.20 0.040 Second stage First separator -liquid and solid components are separated 2 2.2 4.40 0.002 Fibre Transfer 1 -solid component falls into the washer -0 0 0 0 Third stage Washer -solid component is diluted and washed 24 4 96.00 0.048 Fourth stage Second separator-washed fibrous material is separated from liquid 2 2.2 4.40 0.002 Fibre transfer 2 -fibrous material is transferred to the dryer 2 0.3 0.60 0.0003 Dryer fan 24 0.3 7.20 0.004 Dryer drive 24 1.5 36.00 0.018 Dryer Heater 1 259.6 259.6 0.130 Third separator -vacuum separator 24 0.3 7.20 0.004 Sieving -mechanical sieve fed by manual hopper sieves fibres 4 2.2 8.80 0.004 Grading -hammermill fed my manual feed hopper grades fibres 4 3.3 13.20 0.007 Bagging -vacuum bagger fed by manual feed bags fibres 4 4 16.00 0.008 Total energy used 742.39 0.371 kWh / kg is the amount of energy used per kg of initial green waste material.

As Table 1 shows, the total energy used for extracting 240 kg of fibrous material from 2,000 kg of tomato leaf material is only 742.39 kWh, or just 0.371 kWh for each kg of tomato leaf material. This covers the whole method, from transporting the tomato leaf to the grinder in the preliminary stage, through to finally bagging the extracted fibrous materials. Advantageously, the method described herein can therefore produce fibrous material comprising cellulosic fibres with a relatively low energy input, and without using any harsh or dangerous chemicals. The method also advantageously makes use of green waste material which may otherwise be disposed of in landfill.

It will be understood that the invention is not limited to the embodiments described above and various modifications and improvements can be made without departing from the concepts described herein. Except where mutually exclusive, any of the features may be employed separately or in combination with any other features and the disclosure extends to and includes all combinations and sub-combinations of one or more features described herein.

Claims

CLAIMSA method of extracting fibrous material comprising cellulosic fibres from green waste material, the method comprising: a first stage comprising macerating green waste material under conditions of continuous mixing in an aqueous environment to at least partially break down the green waste material into cellulosic fibres, lignin, hemicellulose, pectin and chlorophyll; a second stage comprising separating the macerated green waste into liquid and solid components, the solid component comprising fibrous material comprising cellulosic fibres, and optionally hemicellulose and lignin; a third stage comprising diluting and washing the solid component from the second stage, thereby further separating non-fibrous components from the fibrous material comprising cellulosic fibres, and optionally lignin, optionally wherein the solid component is subjected to further maceration under conditions of continuous mixing, during or after diluting and washing; and a fourth stage comprising obtaining fibrous material comprising cellulosic fibres, and optionally lignin, from the third stage.
2. The method of claim 1, further comprising mechanically treating the green waste to reduce its volume prior to macerating in the first stage.
3. The method of claim 1 or 2, wherein the first stage is conducted in a series of different vessels.
4. The method of any preceding claim, further comprising a fifth stage, the fifth stage comprising obtaining cellulose microfibrils, non-cellulose microfibrils, hemicellulose, pectin, and/or chlorophyll from the separated liquid component.
5. The method of any preceding claim, further comprising a sixth stage, the sixth stage comprising obtaining cellulose microfibrils, non-cellulose microfibrils, hemicellulose, pectin and/or chlorophyll from the diluent of the third stage.
6. The method of claim 4 or 5, wherein the cellulose microfibrils, non-cellulose microfibrils, hemicellulose, pectin and/or chlorophyll obtained from the liquid component or from the diluent are obtained using one or more of filtration, for example, membrane filtration, crossflow filtration, microfiltration and nanofiltration, distillation, solvent extraction, precipitation, flocculation, floatation, centrifugal separation, cyclonic separation, and/or ionic separation.
7. The method of any preceding claim, further comprising a seventh stage, the seventh stage comprising refining the fibrous material comprising cellulosic fibres obtained from the fourth stage, optionally using high shear homogenisation and cavitation techniques.
8. The method of any preceding claim, the fourth stage further comprising drying and/or grading the fibrous material comprising cellulosic fibres.
9. The method of any preceding claim, comprising treating the fibrous material to separate cellulosic fibres from lignin.
10. The method of any preceding claim, wherein the first stage does not comprise using an external heat source.
11. The method of any preceding claim, wherein the first and/or third stage comprises enzymatic treatment to at least partially liberate the cellulosic fibres, lignin, hemicellulose, pectin, chlorophyll, or combinations thereof, and optionally protein, nutrients, active components, or combinations thereof, from the green waste material, for example, to partially breakdown pectin into shorter chain polysaccharides and/or sugars.
12. The method of claim 11, wherein the enzyme is cellulase, pectinase, pectinesterase, protease, polygalacturonase, ferulic acid esterase, or combinations thereof
13. The method of claims 11 or 12, wherein the only source of heat during the first stage is heat generated by exothermic reaction of the enzyme with components of the green waste material.
14. The method of any preceding claim, wherein the first and/or third stage is performed under ambient temperatures and pressures.
15. The method of any preceding claim, wherein the first and/or third stage comprises an enzyme concentration of less than 100 ml of concentrated enzyme solution per 1,000 kg of green waste material or solid component.
16. The method of any preceding claim, further comprising adjusting the viscosity of the macerated green waste material or diluted solid component, for example, lowering the viscosity to prevent the formation of Pectate.
17. The method of any preceding claim, wherein the first stage and/or the third stage comprise ion exchange to adjust, for example, reduce, the hardness of the water that is used in the method.
18. The method of any preceding claim, wherein the third stage comprises further maceration of the diluted solid component.
19. The method of any preceding claim, wherein the fibrous material comprising cellulosic fibres has an average length of from about 250-450 mm prior to the first stage, and/or an average length of from about 50-150 mm at the start of the second stage, and an average length of from about 10-50 mm at the end of the third stage.
20. The method of any preceding claim, wherein the green waste material comprises or is leafy waste, grassy waste, crop waste, agricultural waste, horticultural waste, or mixtures thereof.
21. The method of any preceding claim, wherein at least a portion of the liquid used or separated during the method is fed to a bio-refinery, for example, a multi-stage bio-refinery.
22. The method of any preceding claim, wherein at least a portion of the liquid used in the method is fed from a multi-stage bio-refinery such as, for example, a multi-stage bio-digestor, and the liquid fed from the multistage bio-refinery, for example, bio-digestor, comprises alcohol, such as ethanol, and organic acids, such as acetic acid and/or propionic acid.
23. A system configured to extract fibrous material comprising cellulosic fibres from green waste material in accordance with any one of the preceding method claims, optionally wherein the system is for retrofitting to pre-installed plant or machinery, further optionally wherein the system comprises: a homogeniser for macerating green waste material under conditions of continuous mixing in an aqueous environment; a first separator for separating liquid and solid components from the macerator; a washer for washing the separated solid component from the first separator; and a second separator for obtaining washed fibrous material from the washer.
24. A method of installing or retrofitting a system according to any of claims 23-25.
25. A composition comprising, consisting essentially of or consisting of cellulosic fibre obtainable by the method according to any of claims 1-22, optionally comprising lignin and/or hemicellulose, further optionally wherein the composition comprises cellulosic fibres and lignin in approximately the same relative quantities, for example, within 10 wt. %, as the green waste material from which they were separated, and further optionally wherein the composition is in powder form.