Organic waste processing

Abstract

The present invention relates to methods of processing organic waste, in particular it relates to a method for making fertilizer from organic waste, especially slow release fertilizer. The present invention also relates to fertilizers made by the method of the invention, especially slow release fertilizer. The method of processing organic waste to provide a slow-release fertilizer may comprise at least one hydrolysis step to provide hydrolyzed organic waste and a setting step to provide a slow release fertilizer.

Claims

1. A method of processing organic waste to provide a slow-release fertiliser comprising at least one digesting step to provide dissolved organic waste and a setting step to provide a slow release fertiliser, wherein said digesting step comprises combining the organic waste with a metal catalyst, concentrated sulfuric acid and concentrated hydrogen peroxide and heating to a temperature between 70 ?C. and 200?C., wherein the sulfuric acid and hydrogen peroxide are added to the organic waste in a ratio of 5-20:5:1 organic waste:sulfuric acid:hydrogen peroxide, and wherein said catalyst is titanium dioxide, copper or a copper compound; and, wherein the setting step comprises combining the dissolved organic waste with a liming mixture that can form a lime mortar and comprises calcium carbonate.

2. The method according to claim 1, wherein said sulfuric acid has a concentration of to 50 to 100%.

3. The method according to claim 1, wherein the liming mixture further comprises lime, calcium sulphate, calcium oxide and/or calcium hydroxide.

4. The method according to claim 1, wherein the liming mixture further comprises clay base materials.

5. The method according to claim 1, wherein the liming mixture sets to provide a lime mortar with the acidified dissolved organic waste bonded to the lime mortar or set within the lime mortar to provide a slow release fertiliser.

6. The method according to claim 1, wherein the liming mixture is composed to provide a lime mortar that degrades, when left exposed to the elements or in the soil, over a period of 1 to 9 months.

7. The method according to claim 1, wherein the mass of liming mixture compared to the mass of acidified dissolved organic waste is adjusted to provide a fertiliser that degrades faster or slower and/or to provide a fertiliser with a higher or lower neutralising value.

8. The method according to claim 7, wherein the mass of said liming mixture is 10% to 50% of the mass of the acidified dissolved organic waste.

9. The method according to claim 1 further comprising the step of adding one or more minerals at any stage in the method to provide nutrients in the slow release fertiliser.

10. The method according to claim 1 further comprising the step of adding one or more fungicides, pesticides, herbicides or unpalatable compounds to provide desirable properties to the slow release fertiliser.

11. The method according to claim 1 further comprising the step of processing the slow release fertiliser by pelleting, granulating, press-forming or powderising the slow release fertiliser.

12. The method according to claim 1, further comprising the step of coating the fertiliser with a coating comprising one or more of bacteria, fungal spores, fungicides, pesticides, herbicides, pest control agents, or unpalatable compounds.

13. The method of claim 1, wherein said hydrogen peroxide has a concentration of 30-100%.

14. The method of claim 1, wherein the ratio of sulfuric acid to hydrogen peroxide is between 1:1 and 1:10.

15. The method of claim 1, wherein the copper II compound or titanium dioxide is added at 0.1%-0.01% of the weight of organic waste.

16. The method of claim 1, wherein the method comprises a sizing step wherein said organic material is crushed, ground or chopped before the digesting step.

17. The method of claim 1, wherein the method further comprises a step of concentrating the dissolved organic waste by evaporation where 10-40% of the water is removed by evaporation after the digesting step.

18. The method of claim 1, further comprising a drying step to remove water after the setting step.

19. The method of claim 1, wherein the pH of the dissolved organic waste is increased by mixing it with chalk or lime.

20. The method according to claim 4, wherein the clay base materials include kaolin.

Description

(1) There now follows by way of example only a detailed description of the present invention with reference to the accompanying drawings, in which;

(2) FIG. 1 is a schematic view of an apparatus for processing organic waste;

(3) FIG. 2 is a cut-away side view of a heating vessel forming part of the plant of FIG. 1;

(4) FIG. 3 is a plan view of the vessel of FIG. 2;

(5) FIG. 4 is a cut-away side view of a heating vessel of FIG. 2 with further components shown; and

(6) FIG. 5 is a plan view of the vessel of FIG. 4;

(7) FIG. 6 shows a beaker containing 95 g of congealed frozen blood and 30 g of water;

(8) FIG. 7 shows a view of the hydrolysis and heating stage being performed on 95 g of blood with 30 g of water. 10 g of potassium Hydroxide pellets have been added and the mixture was stirred for two minutes to form a deep red solution. This reaction is very exothermic and so hydrolysis and heating happen at the same time;

(9) FIG. 8 shows the mixture of FIG. 7 with 8 g of 70% (1.42 specific gravity) nitric acid added to neutralize the potassium hydroxide this step is also very exothermic and is the neutralization step and a heating step at the same time. The resulting mixture is an alkaline solution of potassium nitrate containing dissolved hydrolysed blood;

(10) FIG. 9 shows a view of the solid set product that results when the mixture shown in FIG. 8 is combined with CaSO.sub.4. ?H.sub.2O (left hand side) or with CaO, CaCO.sub.3 and Ca(OH).sub.2;

(11) FIG. 10 shows a view of 63 g of chicken litter and bedding;

(12) FIG. 11 shows a view of the 63 g of chicken litter and bedding mixed with 150 ml and blended to form a workable paste;

(13) FIG. 12 shows a view of the blended mixture shown in FIG. 11 with 3 g (0.0306 mole) of H3PO4 (orthophosphoric acid (1.75 specific gravity) added and the mixture brought to the boil. This is the heating stage and a first hydrolysis stage (acid hydrolysis) done at the same time;

(14) FIG. 13 shows a view of the mixture in FIG. 12 with 0.0918 mol of potassium hydroxide (5.14 g) added to neutralize the acid, then 5 g more potassium hydroxide added to increase the pH to 14 and hydrolyse fat, proteins, lipids and nucleic acids, this stage is highly exothermic and is therefore a second hydrolysis step (base hydrolysis) performed at the same time as a heating step;

(15) FIG. 14 shows a view of the resulting mixture after pH of the mixture shown in FIG. 13 is neutralized using 8 g of 70% (1.42 specific gravity) nitric acid;

(16) FIG. 15 shows a view of the mixture shown in FIG. 14 after addition of calcium carbonate, calcium hydroxide and calcium oxide to produce a solid pellet; and

(17) FIG. 16 shows a pellet of fertiliser made from chicken litter using a process of the present invention.

(18) The method of the present invention may be carried out in an apparatus for processing organic waste, an example of which is set out below and in FIGS. 1 to 5.

(19) Referring to FIG. 1, an apparatus for processing organic waste comprises an inlet 10 which receives raw organic waste. A metal detector 12 is provided at the inlet 10 to detect any metal in the raw organic waste and to generate a control signal indicative of any metal content detected. The inlet 10 feeds into a particle sizing module, which in this case is a crushing module 14, arranged to reduce the raw product to pieces of a suitable size. In this embodiment the crushing module 14 comprises a first crusher arranged to crush the raw organic waste into pieces of less than a predetermined size, said size being 150 mm in this example, and a second crusher arranged to crush the raw organic waste into smaller pieces, of less than 40 mm in this example. A conveyor 16, which may be a screw conveyor, is arranged to transfer the crushed product from the outlet of the crushing module 14 to the first 18 of three heating vessels 18, 20, 22.

(20) The first heating vessel 18 comprises an enclosed steel container having an inlet 24 at the top through which the crushed product can be introduced, a further inlet 26, also at the top, which is connected to a water supply via a pump 28 so that water can be added to the product in the vessel 18, a further inlet 29 connected to a supply of steam, and an outlet 31 at the bottom. Flow control valves are provided in the water and steam inlets 26, 29, and the outlet 31. A heater 30 is provided around the wall of the vessel, and a temperature gauge 32 is arranged to measure the temperature in the vessel 18. A controller 34 is arranged to control the operation of the whole plant, including all the conveyors, pumps and heaters, and the inlet and outlet valves, as will be described in more detail below.

(21) A first separation vessel 36 is arranged to receive the product from the outlet 31 from the first heating vessel, and is arranged to hold the solid product and allow liquid to drain into a collection tank 38 situated below it. A second conveyor 40 is arranged to transport the solid product from the separation vessel 36 to the inlet 42 of the second heating vessel 20.

(22) The second heating vessel 20 is pressurized, and has a pressure vent controlled by a vent valve 43 so that the pressure in the vessel 20 can be controlled. It also has a further inlet 44 for water, a further inlet 45 for steam, and an outlet 46 at its bottom end, each with a flow control valve controlled by the controller 34. It also has a heater 48 around its side walls, and a temperature gauge 50 and pressure gauge 52 arranged to measure the temperature and pressure of the contents of the second vessel 20. These are connected to the controller 34 which is arranged to control the temperature and pressure, as well as the quantities of water, steam, and product, in the second vessel 20 as required.

(23) A second separation vessel 56 is arranged to receive the product from the outlet 46 from the second heating vessel 20, and is arranged to hold the solid product and allow liquid to drain into a collection tank 58 situated below it. A third conveyor 60 is arranged to transport the solid product from the separation vessel 56 to a second crusher unit 62. The second crusher unit 62 is arranged to break down the solid product into pieces no larger than 2 mm.

(24) The outlet from the crusher unit 62 is arranged to output the product into a pan 64, which may be arranged to pre-heat the product prior to it being received in the third heating vessel 22. A further conveyor 66 is arranged to transport the product from the pan 64 to the inlet 68 of the third heating vessel 22.

(25) The third vessel 68 also has a further inlet 70 at its top end connected to a source 72 of acid via a pump 74, and a further inlet 76 connected to a source 78 of hydrogen peroxide, via pump 80. These are controlled by the controller 34 so that acid and hydrogen peroxide can be added into the vessel 22 in the required amounts and rates and at the required time. The third vessel also has a heater 82 and a temperature gauge 84 connected to the controller 34. An outlet 84 at the bottom end of the vessel 22 is connected to a neutralization vessel 86 which is arranged to receive the product from the third heating vessel 22, and also arranged to receive an alkaline additive, in this embodiment a lime mix, via a conveyor 88, from an alkaline additive source 90, under the control of the controller 34.

(26) The final neutralized product is in the form of a paste and an extruder 92 is arranged to receive this product from the neutralization vessel 86 and extrude it into pellets, and a packaging module 94 is arranged to receive the extruded pellets and package them for transport away from the plant.

(27) Each of the liquid collection vessels 38, 58 has an outlet that is connected to a separator in the form of a centrifuge 96 which is arranged to separate out the lighter and heavier components of the liquid. The lighter components will generally comprise fats, and the heavier components generally comprise gelatine, and these components are collected in separate collection vessels 98, 100.

(28) Operation of the plant will now be described with particular reference to the treatment of bone, although it will be appreciated that it can be used for a wide variety of other waste products.

(29) Raw bone is introduced into the crusher module 14 where it is crushed into pieces no larger than 40 mm. From there it is transferred into the first vessel 18.

(30) The controller 34 is arranged to monitor the amount of product entering the vessel 18, for example using a load cell to measure its weight, and to stop the transfer of product when a specified amount has entered the vessel. The controller 34 is also arranged to control the introduction of water and steam into the vessel 18, and to heat the vessel 18 to the required temperature. The bone and water mixture is heated to approximately 95? C. to form an organic waste slurry which is then transferred to the separation vessel 36.

(31) In the separation vessel 36, liquid drains from the slurry into the collection tank 38 while the slurry is transferred along the vessel. The drier slurry is then transferred via the conveyor 40 to the second heating vessel 20. The amount of slurry introduced into the second vessel 20 is controlled by the controller, for example using weighing cells to weigh the amount added, and then controlled amounts of water and steam are added by controlled operation of the inlet valves. The second vessel 20 is then heated up to about 135? C., and the vent valve 43 closed so that the pressure increases to about 5 bar. This temperature and pressure is maintained for about twenty minutes.

(32) At the end of the treatment in the second vessel 20, the vent valve 43 is opened to reduce the pressure in the vessel, and the outlet 46 is opened to allow the product, which is still in the form of a slurry, to empty into the second separation vessel 56. From that vessel 56, liquid drains into the second collection vessel 58, and the solid component of the slurry is transferred via conveyor 60 into the second crusher unit 62, where it is crushed to a particle size of about 2 mm and transferred to the pre-heating vessel 64, where it is pre-heated.

(33) From the pre-heating vessel 64 the solid product is transferred via conveyor 66 into the third heating vessel 22 via the conveyor 66 and the inlet 68. Again the amount of product introduced is controlled, and also sulphuric acid and hydrogen peroxide are added in controlled amounts via the inlets 70, 76. The reaction in the vessel 22 is exothermic and the temperature rises to about 95? C., and then falls off when the reaction is complete. This heat and the acid and hydrogen peroxide kills any disease or bacteria in the product, and also oxidises any carbon in the product resulting in an inorganic product which is suitable for use as a fertiliser.

(34) When the acidification step is complete, the outlet 22 from the third vessel 22 is opened and the product transferred to the neutralization vessel 86, to which lime mix is added in controlled quantities in order to increase the pH of the mixture to neutralize the product. The lime mix may comprise a mixture of chalk and lime, or quick lime for example. The lime mix may also comprise additives to alter the properties of the mix, such additives for example comprising selected macro/micro nutrients. The lime mix, and/or the additives, can be varied as required to deliver the required fertilizer properties. The lime mix causes an exothermic reaction. This serves to at least partially dry the acidified organic waste.

(35) The increased pH mixture, which is typically in the form of a paste, is then dried if necessary, and passed into the extruder 92, from which it is extruded as pellets or granules, and packaged at packaging module 94 for transport.

(36) The liquid from the collection vessels 38, 58 is separated in the centrifuge 96, with fat being transferred to fat storage tank 98 and gelatine to the gelatine storage tank 100.

(37) The third heating vessel 22 may also comprise additive inlets arranged to deliver further additives to the slurry. These additives can be of any suitable ingredient to adjust the mineral or nutritional content of the solid slurry particles to suit a particular use or location of use. Thus the additives can be controlled to alter the macro/micro nutrient bases of the solid slurry particles to suit different soil or ground conditions for example, or to provide optimum nutrition for a particular type of crop.

(38) Referring to FIGS. 2 and 3, the first heating vessel 18 comprises a cylindrical steel body 200, about 1.25 m high and 750 mm in diameter, arranged so that its central axis 202 and curved side walls 204 extend vertically. A pair of part-helical heat transfer blades 206 are mounted by means of cross members 208 on a central rotatable shaft 210 which is located on the central axis 202. Each of the heat transfer blades 206 is formed of a strip of sheet metal 209 about 15 mm wide, which is formed into a part-helix shape extending around the outer part of the vessel close to the side wall 204 but spaced slightly from it. The blades each extend from a point about two thirds of the way up the side of the vessel, down to close to the bottom of the vessel, and through half a turn around the central axis. The two blades 206 are diametrically opposite each other, so that they extend around opposite sides of the vessel.

(39) A pair of scrapers 212 are also supported on the cross members 208. Each scraper 212 comprises a flat scraper blade 214 extending vertically down the side wall 204 of the vessel with an outer scraping edge 216 just clear of the side wall 204. Each of the scraper blades 214 is supported on a set of support brackets 218, which in turn are supported on a vertical support pole 220 which extends vertically between the cross members 208 near their outer ends.

(40) Referring to FIGS. 4 and 5, an inner helical lifting flight 222 is also mounted on the shaft 210. The lifting flight 222 is formed of a flat strip of metal 224 about 100 mm wide, formed into a helix centred on the shaft 210, and turning through about seven turns. The top of the lifting flight 222 is about level with the top of the heat transfer blades 206 and the bottom of the lifting flight 222 is slightly above the bottom of the heat transfer blades 206. The turning sense of the lifting flight 222 is the same as both of the heat transfer blades 206. A motor 224 is arranged to rotate the shaft 210, so that the lower end of the lifting flight forms a leading end and the upper end of the lifting flight forms a trailing end, and the lifting flight provides lift in the central part of the vessel 18 close to the central axis 202. At the same time, the lower ends of the heat transfer blades 206 form leading ends and the upper ends of the heat transfer blades form trailing ends, and the heat transfer blades also provide a small amount of lift, or in fact resistance to downward flow, in the outer part of the vessel closer to the outer wall 204. As the shaft rotates, the scrapers 212 move around the wall 204 of the vessel, scraping from the wall any of the by-product or other contents of the vessel that may have accumulated on the wall.

(41) The central shaft 210 is rotated as the product is introduced into the vessel 18 through the inlet 24, the water is introduced through the inlet 26, this forms a slurry, and the steam is introduced through the inlet 29 which helps to heat the slurry. As the heater 30 heats up the contents of the vessel 18 and the steam is injected into it, the central lifting flight 222 causes a general upward flow of the mixture in the central area of the vessel. The mixture then moves outwards at the top of the vessel 18 and cascades downwards in the outer region of the vessel 18 close to the wall 204. The rotating heat exchange blades 206 provide some resistance to the downward flow, and therefore mix the mixture, but also help to conduct heat through the mixture quickly allowing it to be heated quickly to the required temperature. This helps to reduce the time required for the heating step carried out in the first heating vessel 18.

(42) The second vessel 20 has the same mixing and heat exchange mechanism as the first vessel 18 as shown in FIGS. 2 to 5. In this vessel the heating process is similar to the first vessel, though at increased pressure, and the heat exchange coils and the lifting flight serve to distribute heat from the heater and steam throughout the vessel in a similar way. Similarly the third vessel 22 also has the same mixing and heat exchange mechanisms as shown in FIGS. 2 to 5. In this case the heat is generated by the exothermic reaction in the vessel. However, rapid heat dissipation is still helpful to ensure that the temperature remains approximately equal throughout the vessel, and that the reaction proceeds at about the same rate throughout the vessel.

(43) It will be appreciated that various modifications can be made to the embodiment described above, and that the design of the heating vessel or vessels can be varied as appropriate for the process and products to be treated. For example, the two heat transfer blades could be replaced by one continuous helical coil, or more than two blades. Also the blades may not be strictly part-helical. For example the angle of the blade or blades to the vertical may vary along its length. Similarly the lifting flight may be of a different shape, or may be rotated independently of the heat transfer coils. Indeed a different type of lifting mechanism may be provided which is not a helical flight.

(44) A number of pilot studies, described in the examples below, were performed to assess the effectiveness of different compositions for use in the hydrolysis step of the present method. The hydrolysis step may take place in one of the reaction vessels, for example vessel (22) in FIG. 1. The pilot studies were mostly done on a small scale but may be scaled up and the method may be performed on large quantities of organic waste, for example in an apparatus as shown in FIG. 1. The inlets for acid and hydrogen peroxide described in relation to FIG. 1 may alternatively be used to add other ingredients for the hydrolysis and neutralization steps.

Example 1 Acid and Hydrogen Peroxide

Bone Paste

(45) The preferred ranges of the temperature and reaction times.

(46) Operating temperature range: Start temp of bone paste 10? C. to 100? C. giving an end temp after the hydrolysis step of 100? C. to 200? C.

(47) Preferred temp for process: Start temperature 50-90? C.-end temp 130-170? C.

(48) Ratio of wet bone paste to acid to hydrogen peroxide by mass 5-20:5:1 (wet bone:acid:peroxide), for example 13.5:5:1 (wet bone:acid:peroxide).

(49) For example the ratio may be: 1000 kg bone paste (wet) to 370 kg of 95% sulphuric acid to 74 kg of 30% hydrogen peroxide.

(50) Treatment time Broad range1 min to 30 mins, for example, the treatment time may be 5-10 mins.

(51) The amounts of acid and hydrogen peroxideBroad Range1:1 to 1:10 Concentrated sulphuric acid to hydrogen peroxide solution.

(52) Preferred ratio is 1:5 concentrated sulphuric acid to hydrogen peroxide for bone digestion but will vary for other waste streams.

(53) Concentrated sulphuric acid used is 95% (1.83 g/ml) but this could work over a range of 50-100%.

(54) Concentrated hydrogen peroxide used is 30% w/v (weight to volume) but concentrations between 5-100% w/v although greater than 30% can carries an explosion risk.

Example 2 Base and Hydrogen Peroxide

(55) Base Peroxide

(56) Broad range of concentrated ammonium hydroxide, and/or potassium hydroxide and/or sodium with hydrogen peroxide from 1:1 to 1:10 using 0.880 sg (specific gravity) ammonium hydroxide (ammonia solution) and 30% hydrogen peroxide solution.

(57) Preferred mixture 3:1 of 0.880 sg ammonia solution to 30% hydrogen peroxide solution for the purpose of dissolving for example poultry litter, pig manure, cow slurry, cow manure, horse manure, contents of intestinal tract material from abattoir waste etc.

Example 3 Hydrolysis of Blood

(58) Overviewblood contents are hydrolysed using sodium hydroxide or potassium hydroxide. The resulting solution is neutralized using nitric acid or sulfuric acid forming a potassium nitrate, sodium nitrate, sodium sulphate or potassium sulphate solution depending on the acid and base used solution containing the dissolved, heat treated, hydrolysed blood components.

(59) Method:

(60) To 100 g of congealed blood add 30 g of water and bring to the boil (water not required if blood is fresh and uncongealed). NBfrozen blood used can be seen melting in FIG. 1.

(61) Hydrolysis: Add 10 g of Potassium Hydroxide pellets KOH (solid, form preferred) or 7 g of sodium hydroxide (solid form preferred) and stir for two minutes until deep red solution formsvery exothermic reaction. The product of this reaction is shown in FIG. 2.

(62) Neutralisation: Add 16 g of 70% 1.42 specific gravity nitric acid to neutralize the potassium hydroxide (concentrated) although a dilute nitric acid solution would sufficevery exothermic. The resulting mixture is shown in FIG. 3.

(63) The resultant mixture is then treated with further nitric acid to achieve the desired pH for granulatingthis could be acidic or alkaline.

(64) Solution of potassium nitrate containing dissolved, hydrolysed blood. If a small amount of solid precipitates from the blood it may be separated and hydrolysed/oxidised by a small, additional dose of nitric (or sulphuric) acid and hydrogen peroxide in a ratio of 5:1 before recombining with original solution for pasting or setting.

(65) The neutralized hydrolysed blood may be blended with other soluble ingredients and the resultant solution sold as a liquid fertiliser or the neutralized hydrolysed blood may be granulated and sold as a solid granular form after setting using plaster of paris (CaSO4.?H2O) FIG. 4 left or Calcium carbonate/oxide/hydroxide CaCO3/CaO/Ca(OH)2 FIG. 4 right.

Example 4

(66) Acid hydrolysis using phosphoric acid (other acids could be usednitric acid or sulphuric acid) followed by alkaline hydrolysis using potassium hydroxide or sodium hydroxideresultant mixture neutralized using nitric acid or sulphuric acid.

(67) Phosphoric acid increases the phosphorus content (P) and hydrolyses cellulose content. Nitric acid increases the N content.

(68) Potassium hydroxide increases the K content and hydrolyses bulk content. Nitric acid neutralizes the potassium hydroxide or sodium hydroxide forming potassium nitrate or sodium nitrate and increases the N content.

(69) Approximate ratios by mass42 (chicken litter):100 (water):2 (phosphoric acid):6.6 (potassium hydroxide) or 4.7 sodium hydroxide:8.0 (nitric acid).

(70) Overview 63 g of chicken litter and bedding is shown in FIG. 5.

(71) Addition of 150 ml of water followed by blending to form a suitable, workable paste shown in FIG. 6.

(72) Acid hydrolysis: high-heat stage of process. 3 g (0.0306 mole) of H3PO4 (Orthophosphoric acid 1.75 specific gravity) or 2.75 g 70% nitric acid is added to drop pH to pH 3-4 and mixture brought to the boil (high heat stage of process).

(73) Alkaline hydrolysisin heliotherm stage. First the phosphoric acid is neutralized by potassium hydroxide:
H3PO4+3KOH.fwdarw.Na3PO4+3H2O

(74) 3.00 g of phosphoric acid (0.0306 mol) requires 0.0918 mol of potassium hydroxide=5.14 g then an addition 5 g of KOH is required to facilitate the increase in pH to 14 and hydrolyse fat/protein/lipids/nucleic acids etc (total 10 g of KOH)lots of heat evolved NaOH could also be used (less required7.14 g).

(75) Neutralisationstill in heliotherm stage.

(76) Neutralisation using 17 g of 70% (1.42 specific gravity) nitric acid.

(77) Resultant mixture is an alkaline, sweet (molasses type smell) brown paste containing potassium nitrate, potassium phosphate and all the components of chicken litter suitable for plant uptake.

(78) Addition of calcium carbonate/hydroxide/oxide/calcium sulphate heptahydrate mix to produce the solid pellet form is shown in FIG. 10.

(79) Sodium hydroxide is useful for the hydrolysis of blood or chicken litter followed by neutralization using sulphuric acid. For example 100 g of blood requires 5 g of sodium hydroxide at around 90? C. to hydrolyse, followed by neutralization using concentrated sulphuric acid 3.6 ml (6.63 g) and then adjustment of pH to desired level.

(80) The present invention may be further described in the following numbered paragraphs: 1. A method of processing organic waste comprising one or more step of combining the organic waste with a hydrolysing composition. 2. The method according to paragraph 1 further comprising a heating step. 3. The method according to paragraph 2 wherein the organic waste is heated to between 70? C. and 200? C. 4. The method according to paragraph 2 or paragraph 3 wherein the organic waste is heated for between 10 and 60 minutes. 5. The method according to any one of the preceding paragraphs further comprising the step of removing liquid comprising fat and/or gelatine from the organic waste. 6. The method according to any one of the preceding paragraphs wherein the hydrolysing composition comprises: an acid and hydrogen peroxide; a strong base and hydrogen peroxide; a base; an acid; or hydrogen peroxide. 7. The method according to any one of the preceding paragraphs further comprising a sizing step wherein the organic waste is sized to pieces less than 50 mm. 8. The method according to any one of the preceding paragraphs further comprising a neutralization step, wherein acid or base is added to the mixture to bring the pH near to neutral. 9. The method according to any one of the preceding paragraphs further comprising a step of adding minerals or nutrients to the mixture. 10. The method according to any one of the preceding paragraphs further comprising drying the organic waste mixture. 11. The method according to any one of the preceding paragraphs further comprising adding a setting agent such as calcium carbonate, calcium hydroxide, calcium sulphate hemihydrate and/or calcium oxide to the organic waste in a quantity suitable to set the mixture. 12. The method according to any one of the preceding paragraphs further comprising the step of re-sizing the set organic waste into pieces of less than 40 mm. 13. The method according to any one of the preceding paragraphs further comprising adding one or more unpalatable ingredients to the organic waste mixture. 14. The method according to any one of the preceding paragraphs further comprising a step of pelleting or granulating the organic waste mixture. 15. The method according to any one of the preceding paragraphs wherein the method of processing organic waste is a method of producing fertiliser. 16. An organic waste composition obtained by the method according to any one of the preceding paragraphs. 17. A fertiliser composition obtained by the method of any one of the preceding paragraphs.