A method of processing organic material

Abstract

Animal by-products and waste contain valuable elements, compounds and nutrients, which can be lost. Various processes are known for processing organic material to process the waste into a usable form. However, these processes have well-established drawbacks. For example, composting is slow and land-intensive, and incineration can produce large quantities of greenhouse gasses and airborne pollutants. The present invention provides a method of processing organic material, in which a catalyst (100) and a base (110) are mixed (120) with an organic material slurry within a pressure vessel; the pressure vessel is heated to at least (140) degrees Celsius and pressurised to at least 300kPa (130) for at least 15 minutes (160), and then an acid (170) is added to the pressure vessel (180). In this way, slow-release or controlled-release fertiliser may be produced (270), which may release nutrients to plants over a period of time, for example several months. This means that there is less danger of toxicity to plants and of fertiliser running off the land before it is taken up by plants.

Description

A METHOD OF PROCESSING ORGANIC MATERIAL

[0001] The present invention relates generally to a method of processing organic material and finds particular, although not exclusive, utility in processing animal by-products to produce slow-release or controlled-release fertiliser.

[0002] It is well established that various kinds of organic material are discarded. For example, in the production of meat from animals, various animal by-products (such as bone, blood, gut content, wool, fur and feathers) are discarded. In addition, animal waste (such as chicken-litter, cow slurry and pig and horse manure) is routinely discarded. Moreover, vegetable waste (such as kitchen waste, animal bedding, fruit or vegetable processing waste, for example, fruit peeling and sugar cane waste) is discarded.

[0003] This organic material contains valuable elements, compounds and nutrients, which can be lost. Various processes are known for processing organic material to process the waste into a usable form. However, these processes have well-established drawbacks. For example, composting is slow and land-intensive, and incineration can produce large quantities of greenhouse gasses and airborne pollutants.

[0004] According to a first aspect of the present invention, there is provided a method of processing organic material, the method comprising the steps of: mixing an organic material slurry with a catalyst and a base within a pressure vessel; heating the pressure vessel to at least 140 degrees Celsius and pressurising the pressure vessel to at least 300kPa; maintain the pressure vessel at at least 140 degrees Celsius and at least 300kPa for at least 15 minutes; adding an acid to the pressure vessel; and leaving the acid in the pressure vessel for at least 10 minutes.

[0005] The above method enables the decomposition of organic proteins, carbohydrates and fats, and may produce short-chain amino acids, soluble carbon and minerals.

[0006] In this way, slow-release or controlled-release fertiliser may be produced, which may release nutrients to plants over a period of time, for example several months. This means that there is less danger of toxicity to plants and of fertiliser running off the land before it is taken up by plants. Slow-release fertilisers can provide a sustained supply of nutrients through a longer period of the growing season compared to fertilisers that are easily soluble and release nutrients quickly.

[0007] The method of processing organic material may be a method of producing fertiliser.

[0008] The method may comprise the step of comminuting an organic material to produce a comminuted organic material. Comminuting may comprise particle reduction, for example mincing. This enables a larger surface area of the organic material to be available for reaction. Alternatively, comminuted organic material may be initially provided such that the step of comminuting is unnecessary.

[0009] The method may comprise the step of ensuring a minimum water content of the comminuted organic material to produce an organic material slurry. This may comprise adding water to the comminuted organic material, or merely testing to ensure that enough water is already present.

[0010] The method may comprise the step of heating the organic material slurry to at least 90 degrees Celsius. This enables certain constituents of the organic material slurry to melt. Heating the organic material slurry to at least 90 degrees Celsius may comprise heating the organic material slurry to at least 130 degrees Celsius. Heating the organic material slurry to at least 130 degrees Celsius may comprise heating the organic material slurry to at least 170 degrees Celsius.

[0011] The method may comprise the step of agitating the organic material slurry. The method may comprise the step of removing lipids from the organic material slurry. This is beneficial as lipids may be processed in a different and more efficient manner.

[0012] Removing lipids from the organic material slurry may comprise removing lipids with a density less than that of water from the organic material slurry; however, it is to be appreciated that some lipids have a density greater than that of water, and the method could include removing these instead or as well.

[0013] In any event, removing lipids with a density less than that of water from the organic material slurry may optionally comprise allowing the organic material slurry to settle; In this way, the lipids may rise to the top of the slurry. Allowing settling may involve waiting after agitation has subsided, or (for instance where agitation is not employed) merely heating the slurry over a finite time period. Said allowing to settle may comprise doing so over a period of at least five minutes, for example ten minutes, fifteen minutes or preferably at least twenty minutes.

[0014] Removing lipids with a density less than that of water from the organic material slurry comprises skimming the lipids with a density less than that of water from a surface of the organic material slurry.

[0015] Alternatively or additionally, removing lipids from the organic material slurry may comprise separating the organic material slurry with a centrifugal separator.

[0016] The method comprises the step of mixing the organic material slurry with a catalyst and a base within a pressure vessel.

[0017] The base may be a strong base; that is, the base completely dissociates in water. The base may comprise one or more of sodium hydroxide, potassium hydroxide, magnesium hydroxide, ammonium hydroxide and sodium borate. The base may comprise at least 50% Weight / Volume solution (that is, in water); in particular, the base may comprise at least 70%, more particularly at least 90%.

[0018] The base may be mixed with the organic material slurry in a quantity sufficient to bring a pH of the organic material slurry to at least 8, in particular at least 10, more particularly at least 12, preferably at least 14.

[0019] The base is mixed with the organic material slurry in a ratio of between 1:100 and 1:5 base to the organic material slurry, by volume; in particular between 1:80 and 1:10, more particularly between 1:60 and 1:20, preferably between 1:40 and 1:30.

[0020] The catalyst may comprise one or more of aluminium oxide, cerium oxide, ferrous oxide, magnesium oxide, strontium oxide, titanium dioxide and zinc oxide.

[0021] The catalyst may be added to the organic material slurry in a quantity of between 0.001% and 1% by mass of the organic material slurry; in particular between 0.01% and 0.1%.

[0022] The method comprises the step of heating the pressure vessel to at least 140 degrees Celsius (in particular at least 150 degrees Celsius) and / or pressurising the pressure vessel to at least 350kPa (in particular at least 380kPa, more particularly at least 400kPa).

[0023] The method comprises the step of maintain the pressure vessel at said pressure and at a temperature of at least 140 degrees Celsius (in particular at least 150 degrees Celsius) for at least 15 minutes, in particular at least 20 minutes, more particularly at least 25 minutes. During this time, alkaline hydrolysis occurs to break down the organic material. 15 minutes at 150 degrees Celsius and 400kPa is typically sufficient, though longer time periods may be employed.

[0024] To ensure biosecurity, the pressure vessel may be maintained at at least 140 degrees Celsius and at least 300kPa for at least 20 minutes. However, it is preferable to heat and maintain the pressure vessel at at least 150 degrees Celsius and at least 400kPa for at least 15 minutes (more preferably 20 minutes).

[0025] The method comprises the step of adding an acid to the pressure vessel.

[0026] Adding the acid to the pressure vessel may be carried out while the pressure vessel is still at said elevated pressure or at said elevated pressure. Adding the acid to the pressure vessel may be carried out after said maintaining step. This is explosive, and actually acts on the organic material to mechanically disassociate it.

[0027] The acid may be a strong acid (that is, it completely dissociates in water). The acid may comprise one or more of phosphoric acid, sulphuric acid, nitric acid, hydrochloric acid, citric acid and boric acid. The acid may comprise at least 50% Weight / Volume solution (that is, in water); in particular, the acid may comprise at least 70%, more particularly at least 90.

[0028] The acid may be added to the pressure vessel in a quantity sufficient to bring a pH within the pressure vessel to below pH 7, in particular between pH 4 and pH 7, more particularly between pH 5 and pH 7, for example between pH 6 and pH 6.9 or pH 6.3 to pH 6.9. In this way, the addition of the acid may go beyond mere neutralisation to conduct acid hydrolysis.

[0029] The acid may be added to the pressure vessel in a in a ratio of between 1:5 and 1:0.2 acid to base, by volume; in particular between 1:2 and 1:0.5, more particularly between 1:1.5 and 1:0.7, preferably between 1:1.1 and 1:0.9.

[0030] The method may comprise the step of burning the lipids to provide energy for use in at least one step in the method of processing organic material. The energy provided may be heat that is used to heat the organic material slurry, at the heating the organic material slurry step, and / or at the heating the pressure vessel step. Alternatively or additionally, the energy provided may be electricity (for instance via a generator).

[0031] Energy released by exothermic neutralisation of the acid and base may be provided for use in at least one step in the method of processing organic material, as above. Alternatively or additionally, the energy provided is potential energy due to an elevated pressure within the pressure vessel, and / or the energy provided is kinetic energy. For example, a piston may be driven by the exothermic neutralisation to pressurise the pressure vessel at an earlier step.

[0032] Leaving the acid in the pressure vessel for at least 10 minutes may comprise leaving the acid in the pressure vessel for at least 15 minutes, in particular at least 20 minutes, more particularly at least 25 minutes. During this time, the base may be neutralised and acid hydrolysis may occur to further break down the organic material.

[0033] Leaving the acid in the pressure vessel may comprise maintaining the pressure vessel at at least 130 degrees Celsius and at least 300kPa (or at another exemplary temperature and / or pressure recited herein, mutatis mutandis) for at least 10 minutes.

[0034] The method may comprise the step of venting off gas from pressure vessel. The venting off the gas from pressure vessel may occur at least 5 minutes after the acid is added to the pressure vessel, in particular at least 10 minutes, more particularly at least 15 minutes.

[0035] The method may comprise the step of condensing water from vented gas.

[0036] The method may comprise the step of filtering water from a resultant mixture within the pressure vessel.

[0037] The method may comprise the step of using the water (from either condensing or filtering steps) in the step of adding water to the comminuted organic material.

[0038] In particular, the method may be a continuous or batch process, and so feedback of energy and / or water into an earlier step would constitute feedback of energy in relation to a subsequently-introduced organic material parcel and / or subsequent batch, respectively.

[0039] The method may comprise the step of adding a neutralising dry material to the resultant mixture to form a paste. The neutralising dry material may comprise clay, chalk and / or ash.

[0040] The method may comprise the step of granulating the paste to form granules.

[0041] The method may comprise the step of drying the granules. Drying the granules may comprise holding the granules at a temperature of at least 30 degrees Celsius, in particular at least 40 degrees Celsius, more particularly at least 50 degrees Celsius. Drying the granules may comprise reducing a moisture content of the granules to at most 12% water by mass, in particular 10%, more particularly 5%.

[0042] The method may comprise the step of passing the dried granules through at least one screen to grade the granules.

[0043] The above and other characteristics, features and advantages of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of the invention. This description is given for the sake of example only, without limiting the scope of the invention. The reference figures quoted below refer to the attached drawings.

[0044] is a flow diagram illustrating a method of processing organic material.

[0045] The present invention will be described with respect to certain drawings but the invention is not limited thereto but only by the claims. The drawings described are only schematic and are non-limiting. Each drawing may not include all of the features of the invention and therefore should not necessarily be considered to be an embodiment of the invention. In the drawings, the size of some of the elements may be exaggerated and not drawn to scale for illustrative purposes. The dimensions and the relative dimensions do not correspond to actual reductions to practice of the invention.

[0046] Furthermore, the terms first, second, third and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a sequence, either temporally, spatially, in ranking or in any other manner. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that operation is capable in other sequences than described or illustrated herein. Likewise, method steps described or claimed in a particular sequence may be understood to operate in a different sequence.

[0047] Moreover, the terms top, bottom, over, under and the like in the description and the claims are used for descriptive purposes and not necessarily for describing relative positions. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that operation is capable in other orientations than described or illustrated herein.

[0048] It is to be noticed that the term “comprising”, used in the claims, should not be interpreted as being restricted to the means listed thereafter; it does not exclude other elements or steps. It is thus to be interpreted as specifying the presence of the stated features, integers, steps or components as referred to, but does not preclude the presence or addition of one or more other features, integers, steps or components, or groups thereof. Thus, the scope of the expression “a device comprising means A and B” should not be limited to devices consisting only of components A and B. It means that with respect to the present invention, the only relevant components of the device are A and B.

[0049] Reference throughout this specification to “an embodiment” or “an aspect” means that a particular feature, structure or characteristic described in connection with the embodiment or aspect is included in at least one embodiment or aspect of the present invention. Thus, appearances of the phrases “in one embodiment”, “in an embodiment”, or “in an aspect” in various places throughout this specification are not necessarily all referring to the same embodiment or aspect, but may refer to different embodiments or aspects. Furthermore, the particular features, structures or characteristics of any one embodiment or aspect of the invention may be combined in any suitable manner with any other particular feature, structure or characteristic of another embodiment or aspect of the invention, as would be apparent to one of ordinary skill in the art from this disclosure, in one or more embodiments or aspects.

[0050] Similarly, it should be appreciated that in the description various features of the invention are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure and aiding in the understanding of one or more of the various inventive aspects. This method of disclosure, however, is not to be interpreted as reflecting an intention that the claimed invention requires more features than are expressly recited in each claim. Moreover, the description of any individual drawing or aspect should not necessarily be considered to be an embodiment of the invention. Rather, as the following claims reflect, inventive aspects lie in fewer than all features of a single foregoing disclosed embodiment. Thus, the claims following the detailed description are hereby expressly incorporated into this detailed description, with each claim standing on its own as a separate embodiment of this invention.

[0051] Furthermore, while some embodiments described herein include some features included in other embodiments, combinations of features of different embodiments are meant to be within the scope of the invention, and form yet further embodiments, as will be understood by those skilled in the art. For example, in the following claims, any of the claimed embodiments can be used in any combination.

[0052] In the description provided herein, numerous specific details are set forth. However, it is understood that embodiments of the invention may be practised without these specific details. In other instances, well-known methods, structures and techniques have not been shown in detail in order not to obscure an understanding of this description.

[0053] In the discussion of the invention, unless stated to the contrary, the disclosure of alternative values for the upper or lower limit of the permitted range of a parameter, coupled with an indication that one of said values is more highly preferred than the other, is to be construed as an implied statement that each intermediate value of said parameter, lying between the more preferred and the less preferred of said alternatives, is itself preferred to said less preferred value and also to each value lying between said less preferred value and said intermediate value.

[0054] The use of the term “at least one” may mean only one in certain circumstances. The use of the term “any” may mean “all” and / or “each” in certain circumstances.

[0055] The principles of the invention will now be described by a detailed description of at least one drawing relating to exemplary features. It is clear that other arrangements can be configured according to the knowledge of persons skilled in the art without departing from the underlying concept or technical teaching, the invention being limited only by the terms of the appended claims.

[0056] shows a method of processing organic material, in which organic material 10 is comminuted 20 to produce a comminuted organic material. Water 30 is added 40 to ensure a minimum water content of the comminuted organic material to produce an organic material slurry. The organic material slurry is then heated 50 to at least 90 degrees Celsius, and then agitated 60.

[0057] To remove lipids 70 from the organic material slurry, the organic material slurry is allowed to settle 80, and then the lipids 70 are skimmed from a surface of the organic material slurry 90. As an alternative, the lipids 70 can instead be separated using a centrifugal separator.

[0058] A catalyst 100 and a base 110 are then mixed 120 with the organic material slurry in a pressure vessel, which is then heated to at least 150 degrees Celsius and pressurised to at least 400kPa 130.

[0059] The lipids are burned 140 to provide heat that is used to heat the organic material slurry 50 and / or to heat the pressure vessel 130. Optionally, heat from the burning 140 may be used in a generator to provide electricity 150 that may be used at any point during the process; however, for clarity only use at the first step of comminuting the organic material is shown in this figure.

[0060] The pressure vessel is maintained at at least 150 degrees Celsius and at least 400kPa for at least 15 minutes 160, during which period alkaline hydrolysis takes place.

[0061] Subsequently, an acid 170 is added 180 to the pressure vessel to neutralise the contents in an exothermic reaction.

[0062] Heat energy released by the exothermic neutralisation of the acid and base is used to heat the organic material slurry 50 and / or to heat the pressure vessel 130; however, only heating of the pressure vessel 130 is shown in the figure for clarity.

[0063] Similarly, potential energy due to an elevated pressure within the pressure vessel, and / or kinetic energy due to its release may be used to pressurise the pressure vessel 130 or to drive the electrical generator 150.

[0064] Gas from pressure vessel is vented off 190, and water 30 from the vented gas is condensed therefrom 200. Additionally, water 30 may be filtered 210 from the resultant mixture within the pressure vessel. Such water may be reintroduced at adding step 40 to ensure a minimum water content of the comminuted organic material.

[0065] A neutralising dry material 220 is added to the resultant mixture to form a paste 230. The paste is then granulated 240 to form granules, the granules are dried 250, and then the dried granules are passed through at least one screen to grade the granules 260 to produce a final product 270.

Claims

A method of processing organic material, the method comprising the steps of:mixing an organic material slurry with a catalyst and a base within a pressure vessel;heating the pressure vessel to at least 140 degrees Celsius and pressurising the pressure vessel to at least 300kPa;maintain the pressure vessel at at least 140 degrees Celsius and at least 300kPa for at least 15 minutes;adding an acid to the pressure vessel; andleaving the acid in the pressure vessel for at least 10 minutes.The method of processing organic material of claim 1, wherein the base is a strong base.The method of processing organic material of claim 1 or claim 2, wherein the base comprises one or more of sodium hydroxide, potassium hydroxide, magnesium hydroxide, ammonium hydroxide and sodium borate.The method of processing organic material of any preceding claim, wherein the base is mixed with the organic material slurry in a quantity sufficient to bring a pH of the organic material slurry to at least 8.The method of processing organic material of any preceding claim, wherein the catalyst comprises one or more of aluminium oxide, cerium oxide, ferrous oxide, magnesium oxide, strontium oxide, titanium dioxide and zinc oxide.The method of processing organic material of any preceding claim, wherein the acid is a strong acid.The method of processing organic material of any preceding claim, wherein the acid comprises one or more of phosphoric acid, sulphuric acid, nitric acid, hydrochloric acid, citric acid and boric acid.The method of processing organic material of any preceding claim, wherein the acid is added to the pressure vessel in a quantity sufficient to bring a pH within the pressure vessel to below pH 7.The method of processing organic material of any preceding claim, wherein adding the acid to the pressure vessel is carried out while the pressure vessel is still at a pressure of at least 300kPa.The method of processing organic material of any preceding claim, further comprising comminuting an organic material to produce a comminuted organic material for use in the organic material slurry.The method of processing organic material of claim 10, further comprising ensuring a minimum water content of the comminuted organic material to produce the organic material slurry.The method of processing organic material of claim 11, wherein ensuring a minimum water content of the comminuted organic material comprises adding water to the comminuted organic material.The method of processing organic material of any preceding claim, further comprising heating the organic material slurry to at least 90 degrees Celsius prior to the mixing.The method of processing organic material of any preceding claim, further comprising removing lipids from the organic material slurry prior to the mixing.The method of processing organic material of claim 14, wherein removing lipids from the organic material slurry comprises removing lipids with a density less than that of water from the organic material slurry by allowing the organic material slurry to settle and skimming the lipids with a density less than that of water from a surface of the organic material slurry.The method of processing organic material of claim 14 or claim 15, further comprising burning the lipids to provide energy for use in at least one step in the method of processing organic material.The method of processing organic material of any preceding claim, wherein energy released by an exothermic neutralisation of the acid and base is provided for use in at least one step in the method of processing organic material.The method of processing organic material of any preceding claim, further comprising venting off gas from pressure vessel, wherein said venting off the gas from pressure vessel occurs at least 10 minutes after the acid is added to the pressure vessel.The method of processing organic material of any preceding claim, further comprising adding a neutralising dry material to a resultant mixture from the pressure vessel to form a paste.The method of processing organic material of claim 19, further comprising granulating the paste to form granules; drying the granules.

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