AU2001285595B2 - Method and apparatus for the treatment of waste - Google Patents

Description

WO 02/20429 PCT/AU01/01117 1 METHOD AND APPARATUS FOR THE TREATMENT OF WASTE Field of the Invention The present invention relates to a method and apparatus for the treatment and conversion of biodegradable waste and/or organic feed materials into other useable products.

The method and apparatus can be applied to improve the quality and usefulness of product produced from domestic or industrial waste sources and will primarily be described with reference to this context.

Background Art The treatment of waste and/or organic materials by vermiculture is known in the art. Worms of various species can be employed to convert materials such as effluent and organic waste into worm cast and worm biomass. Worm cast is the excreter from worms which has end uses in agriculture as a fertiliser, plant growth medium and a soil conditioner.

The worm biomass can be used for bait, animal fodder or for use in other composting systems.

Worms have the ability to convert a wide range of material such as sewage sludge, green (plant) wastes, organic wastes (fruit, vegetable material), and paper and cardboard. The materials that are included in the feed waste have an important bearing on the vendability of the products of vermiculture treatment. In vermiculture processes where sewage forms a portion of the feed some pathogens (disease producing organisms) and heavy metals present in that feed can find their way into the biomass and worm cast and thus limit the end uses of these products in more sensitive applications such as aquaculture, for example. In vermiculture processes where a general mixture of organic material is treated, potentially germinaceous WO 02/20429 PCT/AU01/01117 -2 material and pathogens in the process feed are often carried through to the end product worm cast. The presence of germinaceous material such as seeds, weeds etc can make such a product unsuitable for use in some agricultural applications. The presence of pathogens makes the handling of the product unsatisfactory from an occupational health standpoint. In order to avoid such problems with worm cast it would be preferable to remove the germinaceous material and pathogens from the chosen process feed material prior to use in a vermiculture process.

Composting processes are known in the art which selfheat and 'pasteurise' (sterilise, kill or purify) at least some of the germinaceous material and animal, human or plant pathogens present in an organic waste stream. In such composting processes, thermophilic bacteria operate principally between 45-65 0 C to decompose organic materials.

Maintenance of a pasteurisation temperature for a prolonged period of time is the usual way to ensure that the process is complete.

In static pile waste composting systems, material is piled up or buried in windrows etc for extended periods of time. However the temperature of such heaps will vary dramatically in response to the ambient temperature and moisture and to the moisture and oxygen levels within the pile itself. Unless the pile is turned, the outer portions of the pile will not experience a sufficient temperature rise leading to an uneven destruction of pathogens and germinaceous material etc. In RU2039029 (KASHCHI), long term composting in static windrows is described which would likely result in an incomplete pasteurisation prior to vermiculture, ultimately producing a casting mixture of limited value.

In mixed composting operations, for example, WO 02/20429 PCT/AU01/01117 3 pasteurisation can occur in around 4-16 weeks, which is still a relatively slow process from a production viewpoint.

Although the rate of decomposition or composting of organic feed materials can be increased by encouraging the development of higher temperatures in the mixtures, the effect on the carbon content of the composting material can be severe, and the carbon, nitrogen and phosphorous present are often converted to ash or volatilised and the product compost dried to low moisture levels. Although now decomposed, such materials are then rendered useless both as a food source for worms in a vermiculture operation and ultimately as a fertiliser or soil conditioner product. In RU2051137 (VOLKOV) sewage sediment is mixed and heated air is blown into the sediment prior to vermiculture. Such a process would most likely yield an uneven pasteurisation and would dry out the composted material, leading to decomposition of the values present into ash or volatilised products.

Summary of the Invention In a first aspect the present invention provides a method for the treatment and conversion into a product of a feed material of biodegradable waste and/or organic matter, the method including the steps of: heat treating the material with a heated fluid in a manner that substantially preserves feed content for a subsequent vermiculture process whilst sterilising a substantial portion of any pathogens and seeds, weeds and any other germinaceous matter in the material; and (ii) introducing the heat-treated material to a vermiculture process for converting at least some of the material to the product.

WO 02/20429 PCT/AU01/01117 4 When the phrase "heat treating the material with a heated fluid" is used, it refers to several possible ways of introducing liquids or gases as heated fluids to the feed material, either directly or indirectly, to enhance thermophilic decomposition. The feed material solids can be suspended in a liquid as a pulp and then have heated fluid introduced thereinto, or be added into a heated fluid. Furthermore the phrase anticipates the use of a combustible gas to produce a flame which heats a vessel in which the feed material is housed. In such an example, the heated fluid is the combustion gases which heat the vessel by conduction or radiation to effect the heat treatment.

The heat treatment stage functions to sterilise that organic matter present which is not dead, for example to kill pathogens and germinaceous matter such as seeds and weeds found in feed material. Importantly, the heat treatment stage substantially preserves the components of the feed material which are used in the subsequent vermiculture process, having little deliterious effect on the carbon, nitrogen and phosphorous content and moisture level of the composting material.

The vermiculture process step typically involves the use of several varieties of worms to consume all or part of the heat-treated material in an environment where the conditions of life of the worms are optimised for breeding, as described below. The soil conditioner and fertiliser products of the vermiculture process are commercially vendible in a variety of applications which are sensitive to the presence of seeds and weeds and pathogens. Preferably the heated fluid includes moisture for transfer to the material undergoing heat treatment to inhibit combustion of the feed material when heated. Most WO 02/20429 PCT/AU01/01117 5 preferably the heated fluid is steam or heated gas sparged into a pulp of the material.

Preferably the heat treatment step involves introducing a continuous flow of heated fluid into a continuous flow of feed material in a heat treatment vessel.

Preferably the feed material is caused to flow through a first region of the vessel where the material is heated from ambient temperature to a sterilisation temperature, and then to a second region of the vessel where the material is maintained at the sterilisation temperature for a period of time.

Preferably the heated fluid is introduced at a plurality of locations in the first and second regions.

Preferably the step of heat treating the material involves raising the temperature of the material to about 900°C or greater and maintaining it at that temperature for a period of time sufficient for sterilisation.

Preferably the time period for the feed to be heated from ambient temperature to 90 0 C is about fifteen minutes and the time period for the feed to be maintained at 90 0

C

or greater is about fifteen minutes.

Preferably the heat treatment additionally or alternatively involves conducting energy to the material from heated oil or other fluid circulating in coils which are located in a pulp of the material.

Preferably the material fed to the heat treatment step is shredded and blended prior to suspension in a fluid pulp. Preferably the feed material is blended from two or more sources of feed material to establish a predetermined carbon and nitrogen content therein.

WO 02/20429 PCT/AU01/01117 Preferably the feed material is dewatered after the heat treatment so that a pulp of lower moisture content is introduced to the vermiculture process.

Preferably the conditions of the vermiculture process are controlled to allow for continual breeding of worms.

Preferably the heat-treated material, together with water, are introduced at an upper surface of one or more treatment chambers, worms are harvested from that upper surface and worm casting products are removed from open portions of an underside of the or each chamber.

Preferably the vermiculture step is a continuous process. Preferably the product includes a solid product that is subsequently dried, and a liquid product that is collected and bottled.

In a second aspect the present invention provides a method for the pre-treatment of a feed material of biodegradable waste and/or organic matter for use in a vermiculture process, the method including the step of heat treating the material by introducing steam or heated fluid thereinto in a manner that substantially preserves feed content for a vermiculture process whilst sterilising a substantial portion of any pathogens and seeds, weeds and any other germinaceous matter in the material.

Preferably the pre-treated material is introduced into a vermiculture process for converting at least some of the material to a product.

Preferably the heat treatment of the second aspect is as defined in the first aspect.

In a third aspect the present invention provides an apparatus for the treatment and conversion into a product of a feed material of biodegradable waste and/or organic matter, the apparatus including: WO 02/20429 PCT/AU01/01117 7 a heating vessel for heat treating the material with a heated fluid; and (ii) a treatment chamber for treating the heattreated material by a vermiculture process to convert at least some of the material to the product.

Preferably the heating vessel includes an inlet and an outlet both capable of being opened and closed in use to allow the respective ingress and egress of the material, and wherein introduction means are provided separate to the inlet and outlet for introducing the heated fluid.

Preferably the heated fluid introduction means includes an inlet conduit arranged for introducing steam or other heated gas by sparging into a pulp of the material located in the vessel in use.

Preferably the inlet conduit penetrates a wall of the vessel. Preferably a plurality of spaced apart inlet conduits radially penetrate the wall. Most preferably each point of entry of the radial inlet conduits combine to define a spiral helical pattern extending from a position adjacent a top to a position adjacent a base of the vessel.

Preferably the vessel outlet includes at least one screw auger rotatable and in a U-shaped channel in a base portion of the vessel, in use the auger cooperating with the channel to remove a controlled amount of heat-treated pulp feed material from the vessel.

Preferably a coil for receiving heated oil or other fluid therethrough is additionally or alternatively arranged in the vessel for introducing heat by conduction into the material.

WO 02/20429 PCT/AU01/01117 8 Preferably a shredding device is located to shred the feed material prior to its introduction into the heating vessel.

Preferably the treatment chamber includes a base having a plurality of generally parallel support elements spaced apart from one another to define open portions in the underside of the chamber, and a perimetal side wall which extends up from and around the base to further define the chamber.

Preferably treatment chamber further includes a cutting device positionable between adjacent support elements in the base such that, when the device is moved along and between the support elements, it can cut product from within the chamber and/or that protrudes between the support elements.

Preferably the cutting device comprises a lower section, two generally parallel spaced apart flanges projecting up from the lower section and a cutting wire fastened to extend between the flanges in use wherein the cutting wire can cut the product in a plane parallel to the chamber base.

Preferably the flanges are pivotable at the lower section to enable regulation of depth of planar cutting of the product at the chamber base.

Preferably a plurality of like cutting devices are adjacently provided on a moveable trolley, each device for a respective open portion, and wherein the trolley can be moved along under the chamber in order to enable progressive cutting detachment of the product from the open portions.

Preferably the support elements are elongate bars or rods.

WO 02/20429 PCT/AU01/01117 9 In a fourth aspect the present invention provides apparatus for the pre-treatment of a feed material of biodegradable waste and/or organic matter for use in a vermiculture process, the apparatus including a vessel for heat treating the material and means for introducing steam or heated fluid thereinto in a manner that substantially preserves feed content for a vermiculture process whilst sterilising a substantial portion of any pathogens and seeds, weeds and any other germinaceous matter in the material.

Preferably the heat treatment vessel of the fourth aspect is as defined in the third aspect.

In a fifth aspect the present invention provides a cutting device for cutting product from a base of a vermiculture treatment chamber, the device positionable between adjacent chamber support elements that are located at the base of the chamber, such that when the device is moved along and between the support elements it can cut product from within the chamber and/or that protrudes between the support elements, the device including a lower section, two generally parallel spaced apart flanges projecting up from the lower section and a cutting wire fastened to extend between the flanges in use wherein the cutting wire can cut the product in a plane parallel to the chamber base.

Such a cutting device can cleanly slice or shave the worm cast product as the device is moved along the underside of the bed in one direction, without disturbing the structure of the cast located within the bed and reducing the incidence of any untreated feed and worms being dislodged and falling onto the floor or carriage rails below the bed, a common problem found in the more intrusive prior art cast harvesting devices. The use of 29/08 '02 THU 17:45 FAX 61 2 99255996 GRIFFITH HACK PCT/AU01/01117 Received 29 August 2002 10 knife edges or brushes in the prior art (eg. W099/51545 (VERMITECH)) frequently leads to sticking of the worm casting to the surface area of the cutter, and "drawing" or tearing of the worm cast out of the bed base occurs.

Preferably the cutting device of the fifth aspect is moveable and pivotable as defined in the third aspect.

In a sixth aspect the present invention provides a vermiculture treatment apparatus including adjacent abutting elongate treatment chambers, each chamber including a base having a plurality of generally parallel longitudinal support elements spaced apart from one another to define elongate open portions in the underside of each chamber, wherein the open portions and the support elements of adjacent abutting chambers are aligned.

In the present apparatus, the elongate bed arrangement with the bars extending between opposing ends of the bed allows for the cutting devices to be provided on a moveable trolley which can harvest worm cast from along an entire row of aligned beds in a single, repeatable action.

Preferably the apparatus of the sixth aspect can operate with a cutting device as defined in the third aspect, the cutting device being capable of a unidirectional cutting movement between aligned support elements in adjacent aligned chambers.

In a seventh aspect the present invention provides a cutting device for cutting product from a base of a vermiculture treatment apparatus which includes two or more adjacent elongate treatment chambers, each chamber including a base having a plurality of generally parallel longitudinal support elements spaced apart from one another to define elongate open portions in the,underside of each chamber, the open portions and the support AMENDED

SHEET

;ePAIAU WO 02/20429 PCT/AU01/01117 11 elements of adjacent chambers aligned, wherein the cutting device including a transverse cutting element for cutting of the product from the open portions while being moved therealong and a downward displacement mechanism to allow the cutting device to be lowered below a wall which separates the adjacent chambers as the device is moved from one chamber to the next.

Preferably the downward displacement mechanism includes a guidance cam fitted to the base of each chamber which downwardly pivotally deflects an arm of the cutting device as the cutting device is caused to move past the cam thereby angling the cutting device sufficiently to pass below the wall.

Preferably the transverse cutting element is a cutting wire.

Brief Description of the Drawings Notwithstanding any other forms which may fall within the scope of the present invention, preferred forms of the invention will now be described, by way of example only, with reference to the accompanying drawings in which: Figure 1 shows a schematic view of one embodiment of a process for the treatment and conversion of biodegradable waste and/or organic feed materials into useable products, in accordance with the invention.

Figure 2 shows a schematic view of the heating vessel portion of the embodiment shown in Figure 1.

Figure 3 is a plan view of the embodiment shown in Figure 2.

Figure 4 is a detailed view of a portion of the embodiment shown in Figure 2.

Figure 5 shows a perspective view of a cutting device which is positionable between adjacent support elements in WO 02/20429 PCT/AU01/01117 12 the base of the treatment chamber such that when the device is moved along and between the support elements at the base of the chamber it can cut product from within the chamber and/or that protrudes between the support elements, in accordance with the invention.

Figure 6 shows a side sectional view of a portion of the embodiment shown in Figure 1 when a cutting device is provided on a moveable trolley beneath a treatment chamber.

Figure 6a shows a detailed side view of a portion of the embodiment of Figure 6.

Figure 6b shows a part-sectional end view of the embodiment shown in Figure 6 showing how the cutting devices arranged on a moveable trolley extend between the support elements in the base of the treatment chamber.

Figure 6c shows a detailed view of a portion of the embodiment of Figure 6b.

Figure 7 shows a side sectional view of a further embodiment of the apparatus shown in Figure 2 when the heating vessel has coils therewithin used to convey heated fluid.

Modes for Carrying out the Invention Referring to the drawings, an apparatus 10 is shown for the treatment and conversion of a feed material 12 of biodegradable waste and/or organic matter into vendible products such as soil conditioners, fertilisers, animal fodder and biomass. Typically the feed 12 to such a process is comprised of green wastes such as garden wastes, food scraps as well as paper and cardboard materials, although, depending upon the requirements, the process can also be used for sewage treatment.

WO 02/20429 PCT/AU01/01117 13 The apparatus principally includes a heating vessel in the form of a tank 14 for heat treating the raw feed material 12 and a treatment chamber in the form of worm bed 16 where the heat-treated material 18 is then decomposed by a vermiculture process and converted into the vendible products. The heat treatment stage functions to sterilise that organic matter present which is not dead, for example to kill pathogens and germinaceous matter such as seeds and weeds found in feed material 12.

Importantly, the heat treatment stage substantially preserves the components of the feed material which are used in the subsequent vermiculture process, having little deliterious effect on the carbon, nitrogen and phosphorous content and moisture level of the composting material.

The vermiculture process step typically involves the use of several varieties of worms to consume all or part of the heat-treated material 18 in an environment where the conditions of life of the worms are optimised for breeding, as described below. The soil conditioner and fertiliser products of the vermiculture process are commercially vendible in a variety of applications which are sensitive to the presence of seeds and weeds. In situations where the feed to the process is mainly nonsewage materials such as garden wastes, food scraps, paper and cardboard materials, the lack of any heavy metals or pathogens renders the animal fodder and biomass products vendible in sensitive applications such as pet foods or aquaculture. However the process is equally applicable for the treatment of municipal wastes and effluents, which often include such contaminants, and the end uses of the vendible products from such feed materials may be different.

WO 02/20429 PCT/AU01/01117 14 The process apparatus 10 is shown schematically in Figure 1. Feed material 12 is delivered into sorting bays wherein it is stored in separate areas depending upon the content of the feed. For example, paper and cardboard products are stored separately from organic wastes (food scraps) and separately from green wastes (such as tree, shrub and grass cuttings) or sewage wastes (including domestic or industrial effluent material, faeces, animal wastes etc.). This allows variable feed compositions to be arranged and fed through the process.

The feed material 12 is then passed onto an inspection conveyer 42 and large or foreign items are removed to reject bin 43. The conveyer 42 moves the feed 12 to a shredder 44 or similar device which reduces the coarse mixed waste feed material 12 to a fine particle size. The shredded feed is then moved from the stockpile by means of bucket elevator 46 or other suitable conveyor system to a delivery chute 48 or similar which is connected to heat treatment tank 14 at an uppermost inlet port In the embodiment shown in Figure 1, three identical heat treatment tanks 14 are shown, although any number of such devices is within the scope of the invention. The heat treatment tank 14 inlet port 20 is generally open to atmosphere and both feed material 12 and a liquid stream 21 of recycled or fresh water enters the tank 14 via this port 20. A pulp outlet is positioned in the base of the tank 14 and is capable of being opened and closed to allow the egress of heat treated pulp. Generally the tank 14 is operated on a continuous basis, although the operation of the tank 14 can be configured in batch, particularly if different feed types are being sequenced through parallel heat treatment tanks 14.

WO 02/20429 PCT/AU01/01117 15 In the preferred embodiment shown in Figure 2, the outlet by which the heat treated feed material 18 and heated liquid egress the tank 14 comprises three screw augers 22 each rotatably positioned in a U-shaped channel 23. In use each auger 22 cooperates with each channel 23 to allow the removal of a controlled amount of heattreated feed material 18 in a pulp from the tank 14, depending on the rotational speed of the auger 22.

The tank 14 has heated fluid such as steam (or other heated gas) added to it via a plurality of inlet conduits in the form of spargers 26 arranged for introducing the steam directly into the pulp of the feed material 12 when the pulp is located in the tank 14 in use. In the preferred embodiment shown in Figures 2, 3 and 4, the spargers 26 are radially arranged about the wall 29 of the tank 14 and penetrate that wall 29 via holes 31 so that the sparger 26 is positioned at a downward angle so that steam can be injected downwardly into the pulp. The steam spargers 26 extend some distance into the tank 14 from the interior wall 27 so that the injected steam can reach the centre of the pulp in the tank 14, and the spargers 26 can be retractable so that their location within the tank 14 can be adjusted. As shown in the drawings, the spargers 26 are arranged in a spiral helical pattern extending from a position adjacent the top of the tank 14 to a position adjacent to the base of the tank 14.

Typically the tank 14 is cylindrical and of a height of 6.0m, and the spiral pattern of spargers 26 extend from a position 1.5m from the top of the tank 14 to a position 1.5m from the base of the tank 14. Typically the tank is of. circular diameter and is fitted with internal wall mounted baffles to improve mixing of the pulp. In the present embodiment, it is preferred that the tank has a WO 02/20429 PCT/AU01/01117 16 diameter of 1.5m noting that the dimensions will all be dependent on the particular process capacity requirements.

The tank 14 is preferably made of a material that can withstand a heated aqueous environment for an extended period, such as stainless steel.

In general, any number of tanks 14 may be used in parallel with one another to treat batches of feed 12.

This allows for convenience of operation where, for example, a least one tank may be filling, one tank may be in heating mode and one tank may be emptying. For convenience, Figure 1 shows a three tank operation only.

In the prior art processes, while it is known the rate of pasteurisation composting of organic materials using thermophilic bacteria can be increased by using higher temperatures in intensive aerobic composting processes, the feed materials can be severely affected.

The carbon present in the composted material is often converted to ash or broken down into other degraded forms of carbon sugar sources. This leads to three disadvantages in regard to the subsequent use of such materials in vermiculture. Firstly, the material becomes biologically 'dead' and therefore cannot be effectively processed by worms. Secondly, the level of nutrients in the material is reduced, and not only are the worms unable to be sustained from carbon sources, but the available plant nutrients such as nitrogen and phosphorous are volatilised and therefore are not available in the product worm castings. Thirdly, the moisture levels in high temperature aerobic composting processes are also generally lower than that desirable in a feed to a vermiculture process, which is typically in the range wt%.

WO 02/20429 PCT/AU01/01117 17 In the preferred embodiment of the present invention, the steam, which is delivered from an external water heating system or boiler 37, is injected into the tank 14 to quickly raise the temperature of the pulp to a level at which seeds and weeds and any other non-dead or germinaceous organic material are killed. Pathogens (disease-producing organisms) are also killed when the pulp temperature is raised. However the inventor has determined that the moisture inherent in steam reduces the possibility of combustion of the feed materials at high pulp temperatures and maintains the moisture level of the feed materials in order to preserve the constituents of the feed from volatilisation. Steam sterilisation leaves the carbon sugar food sources undegraded, adds moisture to the pulp and has the added benefit that it destroys plant, human and animal pathogens and germinacous material at a much higher rate than found in standard composting systems.

Referring to Figure 2, in the preferred embodiment the feed material 12 flows continuously through a first region 33 of the tank 14 where the feed material 12 is heated from ambient temperature to a sterilisation temperature of about 90C. The fluid residence time in the first region 33 is about 15 minutes. The material then passes to a second region 35 of the tank 14 where the feed material 12 is maintained at the sterilisation temperature of about 90C for a further 15 minutes, a time found to be sufficient for sterilisation. The steam is introduced at a plurality of locations via spargers 26 located in the first 33 and second 35 regions, as described.

In further embodiments of the process the tank 14 can be operated in a batch mode whereby the tank is filled to the desired level and steam is then injected via spargers WO 02/20429 PCT/AU01/01117 18 to raise and hold the temperature in the preferred range for a sufficient residence time to achieve the desired sterilisation outcome.

In alternative embodiments of the invention the feed material in the tank can be heat-treated in a variety of ways with heated fluids, the fluids being either liquids or gases. In the preferred embodiment a gas and liquid mixture (steam) is introduced into the tank 14 directly into a pulp of feed material in water. In that instance the feed material 12 is suspended in a liquid as a pulp and then heated fluid is introduced thereinto. Equally the feed material can be added into a stream of liquid pre-heated by a heated fluid. The heated fluid can be the same as the liquid in which the feed material is suspended, for example if the heated fluid is hot water injected into an aqueous pulp of feed material. The heated fluid can also be other heated gases instead of steam, for example waste heat gases from combustion processes.

In some embodiments a heated liquid or gas can be indirectly introduced to heat the feed material. For example, as shown in Figure 7 (where like numerals indicate common parts described earlier) the steam injection system of the preferred embodiment can be supplemented with coils 30 fitted in tank 14, the coils arranged for receiving heatable oil, water, combustion gases or another fluid therethrough, to enable heat to be directly conducted into the feed pulp. In still further embodiments, the coils can replace the direct steam (or other gas) injection system described in the preferred embodiment as a complementary means of adding heat to pulp located in tank. The effect of the use of coils to deliver heat indirectly into the feed material within the WO 02/20429 PCT/AU01/01117 19 tank can also be achieved if the tank is jacketed or includes a heating mantle located on the tank exterior.

In still further embodiments a pulp of the feed material can be heat treated with a heated fluid such as combustion gases produced by a flame which is used to heat the vessel in which the feed material is housed. In such an example, the combustion gases which heat the vessel by conduction or radiation to effect the heat treatment.

The steam enters the feed material pulp in slugs via the sparger 26 creating mixing of the tank contents. In some embodiments the tank can be agitated by a motor driven impeller arrangement to improve the effectiveness of mixing of the pulp and steam to facilitate the killing of the germinaceous material present in feed material 12.

In alternative embodiments, the tank may be of any shape and such features as the motor, agitator and baffles may be of any size or orientation to facilitate mixing.

In alternative embodiments the tank 14 can be replaced by an autoclave or other heated and/or pressurised vessel to achieve the required level of sterilisation of the germinaceous and pathogenic material as long as the feed content is substantially preserved for use in vermiculture, for example by adding water in a vapour etc.

In further alternative embodiments heat and pressure can be supplied by ultrasound applied directly into the tank containing feed material.

Heat-treated pulp material 18 exits the tank 14 via auger 22 when the sterilisation interval is concluded.

The pulp 18 flows into feed hopper or sump 50 which allows for gravity separation of some of the water from the heattreated 18 material. The separated, heated water 52 is substantially recycled as process water to the vermiculture treatment part of the process to moisten the WO 02/20429 PCT/AU01/01117 20 worm beds 16. Damp, heat-treated, sterilised organic solid material 18 having a moisture content of 70-85wt% water is then either stockpiled or fed directly to the vermiculture process.

Typically a feed trailer 54 and auger 55 is then used to deliver the heat treated feed solids at the required rate to the upper surface of worm bed 16. The worm bed 16 includes a base having a plurality of generally parallel support elements in the form of bars 56 spaced apart from one another to define open portions in the underside of the bed 16, and a side wall 58 typically in the form of woven mesh or wire which extends upwards from the base to define the bed 16. Typically the bed is an elongate rectangular structure with the bars 56 extending between opposing ends of the bed 16. The space between the bars is both sufficient to provide support for the organic matter and worm cast to be contained in the bed while still allowing a quantity of the worm cast to be removed from the space between the bars 56 as it passes downward in the worm bed 16 under the action of gravity.

Typically the worm beds 16 have four walls 58, fastened at adjoining corners. Typically the space between the bars 56 is 75mm, although this spacing will depend on the viscosity, particle size and moisture content of the worm cast product in any given situation.

Typically the basal support bars are located within and not below the base edge 80 of the bed. Thus the worm cast does not protrude from the bed itself but is supported within the confines of the bed side walls 58 and the upper edge of the bars 56. As shown in Figures 6 and 6a, the support bars 56 at their lower edge 82 are at least flush or level with the base edge 80 of the bed. This arrangement permits a more even and readily controlled WO 02/20429 PCT/AU01/01117 21 removal of worm cast with less spillage than occurs using the known vermiculture beds, as will be described below.

The typical startup operation of a vermiculture process will now be outlined. Depending upon the desired properties of the final worm cast product, the heat treated organic feed material 18 can be augmented by the addition of other feed materials such as lime, zeolite and mineral additives into worm bed 16. The process feed may also be tailored in terms of the carbon and nitrogen content by varying the amount of paper and cardboard (sources of carbon) and organic (fruit, vegetable), and green (plant) waste streams (both being sources of nitrogen) that are mixed in the waste feed material stream 12. This has an important bearing on the vendibility of the process products that are produced. For example, cardboard is a good source of boron, which, when carried into worm cast will be of benefit to avocado farmers whose crops benefit from the presence of such a trace mineral.

Typically the feed materials are blended within the range 25-30% carbon and 65-70% nitrogen content, although any combination can be useful depending on the end use of the vermiculture products. The feed is most desirable to worms at a slightly acidic pH of around 6.5-7.0 although any pH in the range 5-9 is acceptable.

At the commencement of use of worm bed 16, cardboard or other degradable material is placed over the base bars or rods 56 of the bed 16 and a 200-300mm deep layer of organic feed is introduced onto the cardboard. Worms are also added to the feed solids and the worms commence digesting the solids and breeding. Among the varieties of highly efficient composting worms are the African crawler, ring blue and red varieties. Incremental layers of freshly heat treated organic feed are then added above WO 02/20429 PCT/AU01/01117 22 this initial layer until the bed is filled, with a typical bed depth of 600mm. The worms breed to greater numbers and as they do so their demand for food increases. The worms thus eat in an upward direction toward the fresh source of food being added to the upper surface of bed 16.

After a lengthy interval in the order of 60-90 days, all of the material at the base and in the lower half of the bed is worm cast and the initial layer of cardboard has rotted away, allowing any cast which then protrudes into the space between the base bars 56 to be removed from the bed.

Typically the vermiculture operation in the worm bed 16 resembles a countercurrent process where worms rise upward and cast is extruded downward. The preferred temperature of operation of the bed is in the range 0-40°C although the ideal range from a worm breeding point of view is 22-28 0 C. In order to maintain the worm beds in the preferred temperature operating range of 22-28 0 C, the entire apparatus may be enclosed in a climate-controlled building or other structure.

The operation may continue for a lengthy period without any change to the routine of adding fresh heattreated feed 18 to the upper surface and removing worm cast from the base. Water is usually sprayed onto the upper surface of the worm beds 16 via sprayers 51 to continually moisten the feed material therein. Typically at intervals of 40-60 days thereafter, the top half of the contents of a particular bed 16 may be manually removed and the worms and uneaten feed material separated. The feed material is then returned to the worm bed 16 and the harvested worms are processed for vending as biomass and protein material for pet food, fodder and fishmeal for aquaculture purposes. Significantly such products are WO 02/20429 PCT/AU01/01117 23 free of any pathogens because of the prior heat treatment step. Another of the problems of prior art vermiculture processes is that seeds and weeds often propagate in the damp beds containing fertiliser products. This problem has been overcome by the heat treatment step since the seeds and weeds are sterilised and unable to germinate.

Typically the worm beds 16 are arranged in longitudinal rows. Any number of beds may be positioned end to end. The bars 56 which extend between opposing ends of the bed may be aligned in a general longitudinal direction along the row. Typically each bed is 2m in width and 6m in length. Rather than provide access space between individual rows, typically the beds are arranged so that one row lies back to back with another, to allow single side access for the beds in each row only. This represents a considerable saving in floor space. An end view of adjacent bed rows is shown in Figure 6B.

A cutting device 59 is provided at the base of bed 16 which is positionable between adjacent bars 56 such that, when the device is moved along and between the bars, it can cut worm cast either from within the base of the bed 16 or cast which protrudes downwardly in between the bars 56. The cutting device comprises a lower section in the form of a plate 60 having two generally parallel and spaced apart flanges 62 projecting up from the plate The flanges are spaced apart at a distance less than the distance between the bars 56. A transverse cutting element in the form of cutting wire 64 is fastened to extend between the flanges 62 in use to cut the worm cast product in a plane parallel to the base of the worm bed 16 as the device 59 is drawn along the underside of the bed.

The cutting device is shown in Figure 5, and an end view of the cutter when located within the base of the bed 16 WO 02/20429 PCT/AU01/01117 24 is shown in Figures 6B and 6C. The flanges shown in the preferred embodiment are elongate plates each with a hole or fastening point between which the cutting wire 64 is strung. In other embodiments of the invention the flanges and the lower section can also be attached rods or bars.

In another embodiment the flanges and the lower section can be formed in one piece, such as a curved or U-shaped support for the wire, for example in a horseshoe shape.

The cutting device 59 is pivotable at the plate 60 to enable regulation of the depth of planar cutting of the product at the bed base. When angled upward, the wire 64 can cut higher into the cast at the bed base. Typically a plurality of cutting devices 59 are provided on a moveable harvester trolley 66 with each device 59 being for a respective space between the bars 56. If the row of beds 16 is floor-mounted, the harvester trolley 66 can be moved within a channel cut into a floor beneath the beds 16 to detach the product. If the row of beds 16 is positioned on legs with a space between the supporting floor and the base of the beds 16, the harvester trolley 66 can be moved along the floor.

More than one device 59 can be fitted to the harvester trolley 66 for cutting product from a respective space between the bars 56, and each such device can be pivoted at a different angle to the device immediately in front of it to enable a more gradual planar shaving of the product at the bed base as the harvester trolley 66 is moved in one direction. The wire 64 may be made of any suitable thin gauge material such as metal wire or synthetic materials such nylon or plastics.

Typically the wire 64 projects into a region of the worm bed 16 near the upper edge of bars 56 (themselves located within and not below the base edge 80 of the worm WO 02/20429 PCT/AU01/01117 25 bed 16, as described earlier), although the device 59 may be angled so that the wire can cut higher into the cast than this. When the harvester trolley 66 traverses the length of a single bed 16, the device 59 encounters a barrier in the form of a bed lateral side wall 61 which is supported by a bed leg 63. The bed lateral side walls 61 generally separate the contents of individual beds 16.

The pivoting mechanism of the cutting device 59 allows the device to be lowered below the lower edge of the side wall 61 under the action of a guidance arm 63A which is joined thereto. A projection in the form of a cam 65 located at the bed base is arranged to deflect the guidance arm 63A as it moves past the cam 65 and cause the cutting device 59 to move into a lowered position to enable its passage past the side wall 61 obstruction (as shown in Figure 6).

Subsequently when the device 59 is located below the next consecutive bed, it resiliently pivots back into a cutting mode position into the region of the bed near the upper edge of bars 56, and dislodgement of worm cast can continue.

As the worm cast is dislodged it is collected in the harvester trolley 66, and when the harvesting trolley 66 has completed a single pass underneath the row of worm beds 16, it is moved out of the space underneath the worm beds and emptied at the delivery point of the cast conveyer 68. This conveyer 68 delivers worm castings via a series of secondary conveyers 69 where liquid can drain from the worm cast solids and be collected in tanks 71.

The drained worm castings are then dried in a drier 70 and then sieved and bagged 73 or delivered directly to trucks from hopper 74. The liquid held in tanks 71 containing dissolved fertilising materials may then be combined with fresh dilution water and bottled 75 for sale. The solid WO 02/20429 PCT/AU01/01117 26 product is sold for use as a soil conditioner and fertiliser. The product can find a use in situations in the marketplace where sensitivities exist to the presence of seeds and weeds etc being introduced via soil additives, for example, domestic gardens and plant nurseries.

There are considerable advantages of such a mechanised cast harvesting system over those systems known in the prior art. The known methods involve accessing the worm bed from either side and utilising a mechanical rake or cutting device to dislodge worm cast material from the space between the supporting bars of the base. This becomes a labour intensive task, since the rake or cutter must be inserted from the side into the space below each bed, the worm cast dislodged, and then the rake repositioned at the side of the consecutive bed, and so on. In the prior art apparatus the bed base bars in a row of vermiculture beds are arranged laterally rather than extending longitudinally as shown in the present invention, thus necessitating that the harvesting apparatus be arranged for side access.

In the present apparatus, the elongate bed arrangement with the bars 56 extending between opposing ends of the bed 16 allows for the cutting devices 59 to be provided on a moveable harvester trolley 66 which can harvest worm cast from along an entire row of aligned beds in a single, repeatable action removing the complexity of the previously known techniques. Figure 6B shows an end view of the aligned support bars 56 when viewed from the end of a row of aligned beds.

Furthermore, the present apparatus can cleanly slice or shave the worm cast product in a plane parallel to the bed base as the device 59 is drawn along the underside of WO 02/20429 PCT/AU01/01117 27 the bed in one direction, without unnecessarily disturbing the structure of the cast located within the bed and reducing the incidence of any untreated feed and worms being dislodged, a common problem found in the more intrusive prior art cast harvesting devices. In the prior art apparatus, such dislodged material can fall randomly onto the floor below the bed, presenting a hygiene and safety problem. The use of knife edges or brushes in the prior art (eg. W099/51545 (VERMITECH)) frequently leads to sticking of the worm casting to the surface area of the cutter, and "drawing" or tearing of the worm cast out of the bed base occurs. No such "drawing" can occur with the use of a cutting wire which presents a very limited surface area to cut and dislodge the worm castings.

Additionally, the very even cut provided by the wire can "seal" the base of the worm bed to prevent unnecessary moisture evaporation which often occurs with a roughly cut castings base which can have a higher surface of castings presented to the atmosphere. A further advantage of the present technique is that the cutting is a low noise, low vibration operation, which is good from an occupational health standpoint.

Whilst the invention has been described with reference to a number of preferred embodiments it should be appreciated that the invention can be embodied in many other forms.

It is to be understood that, if any prior art information is referred to herein, such reference does not constitute an admission that the information forms a part of the common general knowledge in the art, in Australia or any other country.

Claims (42)

1. A method for the treatment and conversion into a product of a feed material of biodegradable waste and/or organic matter, the method including the steps of: heat treating the material with a heated fluid in a manner that substantially preserves feed content for a subsequent vermiculture process whilst sterilising a substantial portion of any pathogens and seeds, weeds and any other germinaceous matter in the material; and (ii) introducing the heat-treated material to a vermiculture process for converting at least some of the material to the product.

2. A method as claimed in claim 1 wherein the heated fluid includes moisture for transfer to the material undergoing heat treatment to inhibit combustion of the feed material when heated.

3. A method as claimed in claim 1 or claim 2 wherein the heated fluid is steam or heated gas sparged into a pulp of the material.

4. A method as claimed in any one of the preceding claims wherein the heat treatment step involves introducing a continuous flow of heated fluid into a continuous flow of feed material in a heat treatment vessel. A method as claimed in claim 4 wherein the feed material is caused to flow through a first region of the vessel where the material is heated from ambient temperature to a sterilisation temperature, and then to a second region of the vessel where the material is maintained at the sterilisation temperature for a period of time. WO 02/20429 PCT/AU01/01117 29

6. A method as claimed in claim 5 wherein the heated fluid is introduced at a plurality of.locations in the first and second regions.

7. A method as claimed in any one of the preceding claims wherein the step of heat treating the material involves raising the temperature of the material to about 90 0 C or greater and maintaining it at that temperature for a period of time sufficient for sterilisation.

8. A method as claimed in claim 7 wherein the time period for the feed to be heated from ambient temperature to is about fifteen minutes and the time period for the feed to be maintained at 90 0 C or greater is about fifteen minutes.

9. A method as claimed in any one of the preceding claims wherein the heat treatment additionally or alternatively involves conducting energy to the material from heated oil or other fluid circulating in coils which are located in a pulp of the material. A method as claimed in any one the preceding claims wherein the material'fed to the heat treatment step is shredded and blended prior to suspension in a fluid pulp.

11. A method as claimed in any one the preceding claims wherein the feed material is blended from two or more sources of feed material to establish a pre-determined carbon and nitrogen content therein.

12. A method as claimed in any one the preceding claims wherein the feed material is dewatered after the heat treatment so that a pulp of lower moisture content is introduced to the vermiculture process.

13. A method as claimed in any one the preceding claims wherein the conditions of the vermiculture process are controlled to allow for continual breeding of worms. 30

14. A method as claimed in claim 13 wherein the heat- treated material, together with water, are introduced at an upper surface of one or more treatment chambers, worms are harvested from that upper surface and worm casting products are removed from open portions of an underside of the or each chamber. A method as claimed in claim 14 wherein the vermiculture step is a continuous process.

16. A method as claimed in any one of the preceding claims wherein the product includes a solid product that is subsequently dried, and a liquid product that is collected and bottled.

17. A method for the pre-treatment of a feed material of biodegradable waste and/or organic matter for use in a vermiculture process, the method including the step of heat treating the material by introducing steam or heated fluid thereinto in a manner that substantially preserves feed content for a vermiculture process whilst sterilising a substantial portion of any pathogens and seeds, weeds and any other germinaceous matter in the material.

18. A method as claimed in claim 17 wherein the pre-treated material is introduced into a vermiculture process for converting at least some of the material to a product.

19. A method as claimed in claim 17 or claim 18 wherein the heat treatment is as defined in any one of claims 2 to 9. Apparatus for the treatment and conversion into a product of a feed material of biodegradable waste and/or organic matter, the apparatus including: a heating vessel for heat treating the material with a heated fluid; and 31 (ii) a treatment chamber for treating the heat-treated material by a vermiculture process to convert at least some of the material to the product.

21. Apparatus as claimed in claim 20 wherein the heating vessel includes an inlet and an outlet both capable of being opened and closed in use to allow the respective ingress and egress of the material, and wherein introduction means are provided separate to the inlet and outlet for introducing the heated fluid.

22. Apparatus as claimed in claim 21 wherein the heated fluid introduction means includes an inlet conduit arranged for introducing steam or other heated gas by sparging into a pulp of the material located in the vessel in use.

23. Apparatus as claimed in claim 22 wherein the inlet conduit penetrates a wall of the vessel.

24. Apparatus as claimed in claim 23 wherein a plurality of spaced apart inlet conduits radially penetrate the wall.

25. Apparatus as claimed in claim 24 wherein each point of entry of the radial inlet conduits combine to define a spiral helical pattern extending from a position adjacent a top to a position adjacent a base of the vessel.

26. Apparatus as claimed in an one of claim 21 to claim wherein the vessel outlet includes at least one screw auger rotatable and in a U-shaped channel in a base portion of the vessel, in use the auger cooperating with the channel to remove a controlled amount of heat- treated pulp feed material from the vessel.

27. Apparatus as claimed in any one of claim 20 to claim 26 wherein a coil for receiving heated oil or other WO 02/20429 PCT/AU01/01117 32 fluid therethrough is additionally or alternatively arranged in the vessel for introducing heat by conduction into the material.

28. Apparatus as claimed in any one of claims 20 to 27 wherein a shredding device is located to shred the feed material prior to its introduction into the heating vessel.

29. Apparatus as claimed in any one of claims 20 to 28 wherein the treatment chamber includes a base having a plurality of generally parallel support elements spaced apart from one another to define open portions in the underside of the chamber, and a perimetal side wall which extends up from and around the base to further define the chamber.

30. Apparatus as claimed in claim 29 further including a cutting device positionable between adjacent support elements in the base such that, when the device is moved along and between the support elements, it can cut product from within the chamber and/or that protrudes between the support elements.

31. Apparatus as claimed in claim 30 wherein the cutting device comprises a lower section, two generally parallel spaced apart flanges projecting up from the lower section and a cutting wire fastened to extend between the flanges in use wherein the cutting wire can cut the product in a plane parallel to the chamber base.

32. Apparatus as claimed in claim 31 wherein the flanges are pivotable at the lower section to enable regulation of depth of planar cutting of the product at the chamber base.

33. Apparatus as claimed in any one of claims 29 to 32 wherein a plurality of like cutting devices are adjacently provided on a moveable trolley, each device 33 for a respective open portion, and wherein the trolley can be moved along under the chamber in order to enable progressive cutting detachment of the product from the open portions.

34. Apparatus as claimed in any one of claims 29 to 33 wherein the support elements are elongate bars or rods. Apparatus for the pre-treatment of a feed material of biodegradable waste and/or organic matter for use in a vermiculture process, the apparatus including a vessel for heat treating the material and means for introducing steam or heated fluid thereinto in a manner that substantially preserves feed content for a vermiculture process whilst sterilising a substantial portion of any pathogens and seeds, weeds and any other germinaceous matter in the material.

36. Apparatus as claimed in claim 35 wherein the heat treatment vessel is as defined in any one of claims 21 to 27.

37. A cutting device for cutting product from a base of a vermiculture treatment chamber, the device positionable between adjacent chamber support elements that are located at the base of the chamber, such that when the device is moved along and between the support elements it can cut product from within the chamber and/or that protrudes between the support elements, the device including a lower section, two generally parallel spaced apart flanges projecting up from the lower section and a cutting wire fastened to extend between the flanges in use wherein the cutting wire can cut the product in a plane parallel to the chamber base.

38. A device as claimed in claim 37 that is moveable and pivotable as defined in any one of claims 32 or 33. gainp nq THIT 17:46 FAX 61 2 99255996 GRIFFITH RACK C PCT/AUO1/O1 117 Received 29 August 2002 -34

39. A vermiculture treatment apparatus including adjacent abutting elongate treatment chambers, each chamber including a base having a plurality of generally parallrel longitudinal support elements spaced apart from one another to define elongate open portions in the *underside of each chamber, wherein the open portions and the support elements of adjacent abutting chambers are aligned. Apparatus as claimed in claim 39 wherein the apparatus can operate with a cutting device as defined in any one of claims 30 to 33, the cutting device being capable of a unidirectional cutting movement between aligned support elements in adjacent aligned chambers.

41. A cutting device for cutting product from a base of a vermiculture treatment apparatus which includes two or more adjacent elongate treatment chambers, each chamber including a base having a plurality of generally parallel longitudinal support elements spaced apart from one another to define elongate open portions in the underside of each chamber, the open portions and the support elements of adjacent chambers being aligned, wherein the cutting device including a transverse cutting element for cutting of the product from the open portions while being moved therealong and a downward displacement mechanism to allow the cutting device to be lowered below a wall which separates the adjacent chambers as the device is moved from one chamber to the next.

42. A cutting device as claimed in claim 41 wherein the downward displacement mechanism includes a guidance cam fitted to the base of each chamber which downwardly pivotally deflects an arm of the cutting device as the cutting device is caused to move past the cam thereby WO 02/20429 PCT/AU01/01117 35 angling the cutting device sufficiently to pass below the wall.

43. A cutting device as claimed in claim 41 or claim 42 wherein the transverse cutting element is a cutting wire.

44. A method for the treatment and conversion of biodegradable waste and/or organic matter as herein described with reference to the accompanying drawings. A method for the pre-treatment of a feed material of biodegradable waste and/or organic matter as herein described with reference to the accompanying drawings.

46. Apparatus for the treatment and conversion of biodegradable waste and/or organic matter as herein described with reference to the accompanying drawings.

47. Apparatus for the pre-treatment of a feed material of biodegradable waste and/or organic matter as herein described with reference to the accompanying drawings.

48. A cutting device as herein described with reference to the accompanying drawings.

49. A vermiculture treatment apparatus including adjacent elongate treatment chambers as herein described with reference to the accompanying drawings.