GB2487990A

GB2487990A - Organic waste processing apparatus

Info

Publication number: GB2487990A
Application number: GB1102588.9A
Authority: GB
Inventors: Ga Ran Nylin
Original assignee: GG ECO SOLUTIONS Ltd
Current assignee: GG ECO SOLUTIONS Ltd
Priority date: 2011-02-14
Filing date: 2011-02-14
Publication date: 2012-08-15
Also published as: GB201102588D0

Abstract

An organic-waste processing apparatus 30 includes a housing having a series of compartments 32, 34, 36 wherein the first compartment 32 has an inlet 38 for receiving waste, at least one inlet 40 for supplying a liquid to one or more compartments 32, 34, 36, an outlet 51 in communication with the last compartment 36 for supplying processed organic waste to the outside wherein the waste is mixed with liquid and fragmented by increasing degrees as it is conveyed through each compartment before being delivered to the outlet as processed organic waste. The waste is ideally fragmented as it passes through openings in walls 44, 46 which divide the compartments. The fragmenting or shredding may be performed by macerating or chopping pumps 48, 50, or alternatively, the shredding may be performed by a cutter which is separate from the pump. Preferably, the waste is fragmented 42 while it is being introduced into the first compartment 32. The organic waste may be digestate, anaerobic processing residue, equine (horse), pig or cow manure. The apparatus may also comprise sensors 52, 54, 56, 57, which monitor the level of waste in each compartment. The processed waste may be subjected to further processing in a split box.

Description

ORGANIC-WASTE PROCESSING APPARATUS

A commonly used process for managing waste and, as a by-product, releasing useful energy is the anaerobic digestion process. In this process microorganisms are added to biodegradable material in the absence of oxygen. The material is thereby broken down, resulting in the production of gases -chiefly methane and carbon dioxide -and a nutrient-rich residue, called the digestate.

The biodegradable material may be various forms of waste, including human and food waste. In addition, it is now common for biofuels to be produced from crops grown specifically for this purpose. These crops therefore constitute the biodegradable material in this case, and the result is, again, biogas and a digestate.

It is necessary to dispose of these digestates. A recently developed method for doing this involves the use of a so-called "split box" -marketed as the GGEcoboxTM by means of which the digestate is processed to produce a number of different products.

This is illustrated in Fig. 1. In Fig. I the digestate 10 is introduced into a split box 12, where it is subjected to physico-chemical processing based on an ion-exchange principle. The result is three outputs: a fertilizer, which is kept in slurry form in a silo 14 and transported, as necessary, to fields and gardens requiring fertilization; clean water, which is kept in a reservoir 16 and, again, used as necessary for irrigation or some other suitable purpose (e.g. for topping up wetland areas); and a solid-fraction biofuel, which is kept in a further silo 18. The biofuel in the silo 18 is used either for agricultural or soil-improvement purposes or for the generation of heat and/or power.

This system has the advantage that it is able to reduce the volume of the digestate entering the system by at least 80%, which means that more land is available for other, more profitable, purposes. A second advantage is that the split box can capture more than 99% of the ammonia, that would otherwise be released if the digestate were merely stored for use as required, which was the conventional procedure before the split box was developed.

A drawback of the split box approach up to this point, however, is that it has, in practice, been of only limited effectiveness. This is because it has not been able to deal efficiently with all forms of digestate fed into it, mainly due to clogging in the split box itself.

Furthermore, it would be desirable to use the split box to deal directly with various forms of animal waste -e.g. horse, pig and cow manure -as an alternative to feeding it with digestates. Unfortunately, similar problems have been experienced in gethng the split box to work efficiently with this kind of waste also.

Since the split box is, at least in principle, extremely effective in preventing ammonia from entering the atmosphere, in saving space normally occupied by digestates and animal waste generally, and in providing biofuels, fertilizer and water for subsequent use in industry and agriculture, there is a need to increase its effectiveness in practice, so that these noteworthy advantages can be fully realised. Indeed, recent European Union directives (e.g. the Directive on National Emission Ceilings), which limit the allowable emission of ammonia and other potential contaminants, have rendered this need rather urgent.

In accordance with a first aspect of the present invention, an organic-waste processing apparatus is provided, comprising: a housing having a series of compartments including a first compartment, a last compartment and at least one intermediate compartment between the first and last compartments; a first inlet for receiving an organic waste product, the inlet communicating with the first compartment; a second inlet for receiving a liquid, the second inlet communicating with at least one of the series of compartments; and an outlet, the outlet communicating with the last compartment; the apparatus being configured, such that the waste product is mixed with the liquid and is fragmented by increasing degrees while being conveyed from one compartment to the next toward the outlet.

The apparatus is preferably configured, such that the waste product is fragmented while being introduced into the first compartment.

The apparatus may comprise: separating walls dividing adjacent compartments from each other, and openings in respective separating walls; a cutter mounted adjacent to each opening, and a pump disposed downstream of the cutter.

The pump is advantageously a chopper pump, in which a set of knife blades is attached to a rotor of the pump, the knife blades acting as the cutter. Alternatively, the cutter may be a set of knife blades separate from the pump.

The apparatus may comprise: an input-control device in the first inlet and a flow-control device in the second inlet; and a control device, which is connected to the pumps, cutters, input-control device and flow-control device and is configured to control the pumps, cutters, input-control device and flow-control device, such that: the waste product is introduced into the first compartment via the first inlet and the input-control device and is mixed with the liquid introduced via the second inlet and the flow-control device; the pump in the separating wall between the first compartment and its adjacent compartment is operated, so as to convey the waste product from the first compartment to the second compartment, the cutter allocated to that pump being operated at the same time, so as to fragment the waste product being conveyed; the remaining pumps in the other separating walls are similarly operated in sequence, so as to convey the waste product between the respective pairs of compartments, the cutters allocated to those pumps being operated at the same time as their respective pumps, so as to fragment the waste product being conveyed.

The control device may be configured, such that the waste product is not conveyed from one compartment to the next, until the one compartment is substantially full.

The second inlet will preferably communicate with at least the first compartment.

An embodiment is envisaged, in which an additional compartment is provided as the last compartment, and outlets are provided in both the additional and preceding compartments, the outlets being controlled by respective shut-off valves, the outputs of the shut-off valves forming the outlet of the apparatus, the shut-off valves allowing either the degree of fragmentation achieved in the additional compartment, or the degree of fragmentation achieved in the preceding compartment, to be selected for the output of the apparatus.

Each compartment may be constituted as a module, the module being adapted so as to allow the apparatus to be configured as either a vertical arrangement of compartments, or a horizontal arrangement of compartments. Advantageously, all the modules are identical.

In a second aspect of the present invention, an arrangement for processing an organic waste comprises: a split box, and a pre-processing apparatus upstream of the split box, the split box being configured to deliver at least a non-solid fertilizer product and a dry-fraction product, and the pre-processing apparatus being an organic-waste processing apparatus as defined in any one of the preceding claims.

The arrangement may comprise a first silo for storing the non-solid fertilizer product and a second silo for storing the dry-fraction product.

A pelletizer may be provided between the split box and the second silo for converting the dry-fraction product into pellet form.

The organic waste may be a digestate from an anaerobic digestion process, or horse manure. Where the digestate is horse manure, the arrangement may further comprise, upstream of the pre-processing apparatus: an auto-feeder for storing the horse manure and releasing it on demand, and an augur for conveying the released horse manure and supplying it to the pre-processing apparatus.

Alternatively, the organic waste may be pig manure or manure from a dairy farm.

In a third aspect of the present invention, a method of processing an organic waste product comprises: introducing the waste product into a first compartment of an organic-waste processing apparatus as described above and mixing it with a liquid; conveying the mixed waste product from the first compartment into a second compartment of the organic-waste processing apparatus adjacent to the first, while fragmenting the mixed waste product, and so on for further pairs of adjacent compartments in sequence; and outputting the fragmented waste product from the last compartment.

The waste product may also be fragmented while being introduced into the first compartment.

The fragmented waste product may be output to a split box for the production from the fragmented waste product of at least a non-solid fertilizer product and a dry-fraction product.

Embodiments of an organic-waste processing apparatus in accordance with the invention will now be described, by way of example only, with reference to the drawings, of which: Fig. I is a block diagram of a known split-box processing arrangement; Fig. 2 is a block diagram of a split-box processing arrangement incorporating an organic-waste processing apparatus in accordance with the present invention; Fig. 3 is a schematic diagram illustrating the concept of the organic-waste processing apparatus; Figs 4(a)-4(c) are sectional and perspective views of parts of a known chopper pump, which may be employed in an embodiment of the organic-waste processing apparatus according to the present invention; Figs. 5(a) and 5(b) are schematic views of exemplary pump mounting arrangements, which may be employed in an embodiment of the organic-waste processing apparatus of Fig. 3; Figs. 6(a) and 6(b) are plan and side views, respectively, of a horizontally disposed organic-waste processing apparatus according to the present invention; Fig. 7 is a further embodiment of an organic-waste processing apparatus in accordance with the present invention; Figs. 8(a) and 8(b) are isometric views of a module, which may be used as part of the organic-waste processing apparatus in accordance with the invention, and enables the apparatus to be configured vertically or horizontally Fig. 9 is a block diagram of a split-box processing arrangement incorporating an organic-waste processing apparatus in accordance with the present invention, as applied to the processing of horse manure; and Fig. 10 is a block diagram of a split-box processing arrangement incorporating an organic-waste processing apparatus in accordance with the present invention, as applied to the processing of pig or cow manure, An overview of an embodiment of the present invention is illustrated in Fig. 2. Fig. 2 is the same arrangement as Fig. 1, except that the digestate is fed first of all to an additional pre-processing apparatus 30 before being fed into the split box 12.

The basic concept of the apparatus 30 will now described with the aid of Fig. 3.

The apparatus 30 shown is a container, which is divided into three compartments 32, 34, 36. The compartment 32 receives the digestate via a conduit 38 and also receives a liquid, preferably water, via a conduit 40 and a shut-off valve (not shown). A paddle mixer is provided (not shown), which mixes the digestate and water together, thereby softening the digestate. Mounted either to an inside wall of the compartment 32 or in the conduit 38 is a chopper pump 42, while mounted in a separating wall 44 between the compartments 32 and 34 and in a separating wall 46 between the compartments 34 and 36 are further chopper pumps 48 and 50. Sensors 52, 54 and 56-which may take the form of, for example, float sensors -are provided near the top of the respective compartments for detecting a level of the digestate in the compartments, and a sensor 57, which may likewise be a float sensor, is located near the boftom of the last compartment, in order to sense when that compartment is virtually empty. An outlet 51 is provided for delivering the processed digestate to the next stage.

An example of a known chopper pump is shown in Figs. 4(a), 4(b) and 4(c).

The chopper pump is a centrifugal-type pump having (see Fig. 4(a)) a drive casing 60, a suction casing 62, a volute casing 64, an inlet 66 defined by the suction casing 62, an outlet 68, a drive shaft 70 mounted in the drive casing 60 and an impeller 72 fixed to the drive shaft 70. The impeller 72 (see Fig. 4(b)) comprises a series of vanes 74 extending out radially from a central hub. Each of the vanes 74 has, on a suction side of the impeller, a cuffing edge 76, which contacts a chopper plate 78, illustrated in greater detail in Fig. 4(c).

The chopper plate 78 has a first surface 80 facing toward the suction side of the pump and a second surface 82 facing toward the impeller. Defined in a central part of the chopper plate are openings 84, which allow fluids and solids to pass through the chopper plate toward the impeller.

It can be seen from this description of the chopper pump that this device combines the two functions of pumping liquids, in which solids are suspended, and fragmenting those solids before they reach the volute and are flung out through the outlet 68. Since some of the solids, which the chopper pump might be expected to deal with, will be quite tough, the impeller and its cutting edges are generally made of very hard steel.

Preferably all three of the pumps 42,48 and 50 are identically constructed, which makes for lower manufacturing costs.

A mode of operating the apparatus 30 will now be described.

Firstly, digestate is introduced into the conduit 38 and thence into the first pump 42, which fragments the digestate and delivers it into the first compartment 32. This fragmented digestate is mixed with water coming from the conduit 40, the mixing being achieved by means of the paddle mixer (not shown) mentioned earlier. Once the digestate has reached the level of the sensor 52, this sensor sends a signal to the controller controlling the operation of the apparatus 30, and the controller then starts the pump 48, while stopping the pump 42. The digestate in compartment 32 is then forced through the pump 48 into the compartment 34, but is at the same time fragmented even further due to the chopping action of the pump 48. Similar to compartment 32, once the digestate in compartment 34 has reached the level of the sensor 54, this likewise signals the controller to switch off the pump 48 and switch on the pump 50, which repeats the process, fragmenting the digestate in compartment 34 still further and delivering it under pressure into the compartment 36. Once filled to the level of the sensor 56, the controller then switches off the pump 50 and operates a final pump 58, which delivers the three-times fragmented digestate to the next processing stage.

In a preferred embodiment of the apparatus 30 the water in the conduit 40 is delivered not only to the first compartment, but also to the second and third compartments 34, 36 via respective further shut-off valves (not shown). However, as an alternative to, or in addition to, feeding water into the compartment 32 itself, it may be fed into the conduit 38, upstream of the first pump 42 (see dotted lines). This is to ensure that the digestate is suitably liquified, in order to be reliably passed through the pump 42. However, where the digestate is already in the form of a slurry, it may be sufficient to teed the water into the compartment 32, as shown in Fig. 3, and not into the conduit*38. Note that, where a water connection is made to the conduit 38, it may be necessary to employ some sort of check valve Upstream of the dotted-line connection to the conduit 38, to ensure that water flows in one direction only, namely toward the compartment 32.

As regards the flow of water into a compartment, water is preferably let in only during the time that compartment's pump is operating. Water flow is either continuous over that pump-operating period at a predetermined flow-rate, or it may occupy only a part of the pump's ON-cycle, in which case flow may be at a different rate, usually somewhat higher. The amount of water used will depend on the degree of blending and softening required by the stage downstream of the apparatus 30.

While this first mode of operating the apparatus 30 is possible, it is clearly, inefficient, since the compartments 32 and 34 (especially compartment 32) lie empty much of the time, while the initial amount of digestate works its way through the system. A second mode of operation removes this drawback, and will now be described.

The second mode of operating the apparatus 30 is to fill the first compartment 32 up to the level of the sensor 52, as in the first mode of operation. This time, however, once the contents of the first compartment 32 have been emptied into the second compartment 34 by the operation of the pump 48 (the pump 42 still being stopped during this time), and once the pump 50 starts up, in order to transfer the contents of compartment 34 into compartment 36, pump 42 is made to start up again, thereby filling compartment 32 again (pump 48 being stopped at this time). Then, once compartment 36 is filled up to the level of the sensor 56 and compartment 32 is filled up to the level of the sensor 52, pump 50 is stopped, pump 58 is started and pump 48 is also started, so that the contents of compartment 36 are delivered to the next stage and the contents of compartment 32 are fed into compartment 34, and so on in cyclical manner.

This mode of operation is an improvement over the first mode, since it allows a greater throughput of digestate through the system.

These two modes of operation are summarized in Tables I and 2, which list the various stages in the fragmenting process and the ON/OFF states of the various chopper pumps and sensors.

The states marked "ON-÷ OFF" indicate a situation, in which a sensor is turned ON when the digestate level, reaches that sensor, then turns OFF when that level drops again. Furthermore, it can be seen that these modes go through a certain number of initial operations, then enter a loop. In the case of mode 1, the loop consists of steps 1- 8, while for mode 2 the loops are steps 6-9. The shorter loop in the second case is an indication of the greater throughput achieved by the second mode.

IASth1LMOQE1)

PUMP ---SENSOR -

STEP ______ _______ _______ _______

42 48 50 58 52 -54 -56 57 -0 OFF OFF OFF OFF OFF OFF -OFF -OFF 1 ON --OFF OFF OFF OFF -OFF OFF OFF -2 ON OFF OFF OFF ON OFF -OFF OFF 3 OFF ON OFF OFF ON-' OFF OFF OFF OFF 4 OFF ON OFF OFF -OFF ON -OFF OFF -OFF OFF ON OFF --OFF -ON-'OFF OFF OFF - 6 OFF OFF ON OFF OFF OFF ON OFF 7 -OFF OFF OFF ON OFF OFF ON-' OFF OFF 8 ON -OFF OFF OFF OFF OFF OFF -ON-'OFF

I ON OFF OFF OFF OFF OFF OFF OFF

TABLE 2 (MODE2J

PUMP SENSOR

STEP ____ --____ ____ ______ _____ _____ _____

42 48 50 58 52 54 56 57 0 OFF OFF OFF -OFF OFF OFF OFF OFF -1 ON OFF OFF -OFF OFF OFF OFF OFF 2 ON OFF OFF OFF ON OFF -OFF OFF - 3 OFF ON OFF -OFF ON-' OFF OFF OFF OFF 4 OFF -ON OFF OFF OFF ON OFF -OFF ON OFF ON OFF OFF ON-' OFF -OFF OFF 6 ON OFF ON OFF ON OFF ON OFF - 7 OFF ON OFF ON -ON-' OFF OFF ON-' OFF OFF 8 OFF ON OFF ON -OFF ON -OFF ON 9 ON OFF ON -OFF OFF OFF OFF ON-'OFF 6 ON OFF ON OFF ON OFF ON OFF It will be noted that sensor 57 operates in the opposite sense to sensors 52, 54, 56, since it is meant to output a signal when the digestate level is low, not when it is high.

Unfortunately, if sensor 57 is a float sensor like the other sensors, it will give a false reading while the last compartment is starting to fill with digestate. This can be prevented by gating the signal from the sensor 57 with signals from the pumps 50 and 58. More specifically, in electronic control terms, the signal from the sensor 57 would be inverted, then AND-ed with the ON signal from pump 58 and the OFF signal (i.e. inverted ON signal) from pump 50. Alternatively, and to use the more conventional NOR gating, the non-inverted signal from sensor 57 would be NOR-ed with the inverted pump 58 ON signal and the uninverted pump 50 ON signal A third mode of operation is also possible. This involves continuously pushing digestate through the system in an uninterrupted manner. Pumps 48, 50 and 58 will, as before, start up, once a signal has been outputted by sensors 52, 54 and 56, respectively.

However, this time the sensors 52, 54 and 56 will operate to keep the levels of the digestate in the respective compartments relatively constant -that is, at more or less their maximum levels, as defined by the positions of the sensors. Thus, as soon as sensor 52, for example, indicates a full level (sensor 52 ON signal), pump 42 will shut off. However, once sensor 52 outputs an OFF signal, which occurs when the level has dropped somewhat, pump 42 will operate again to let more digestate into the first compartment, and so on for the other sensors, pumps and compartments.

Note that in this mode of operation the degree of fragmentation in the digestate being output through the outlet 51 is not so well defined as in the first two modes. This is because there will be considerable mixing between the digestate already in a particular compartment, and the digestate being introduced into that compartment from the preceding compartment. Thus, there may be many different degrees of fragmentation present in the apparatus as a whole, which may not be desirable in some applications.

This third mode achieves the greatest throughput of all, since at all times all three compartments are essentially full, while digestate is continually being passed through.

It should be noted that the increasing fragmentation of the organic waste is achieved by virtue of the series of stages in the fragmentation process, i.e. the waste gets chopped into smaller and smaller pieces each time, because each successive cutter has smaller pieces to work on. Hence, it is sufficient if the cuffing action (as represented by the number of knife blades and the speed of rotation of the cutter) is the same for each stage. This is indeed the preferred situation since, as mentioned earlier, it is expedient to employ the same kind of chopper pump for all of the pumps 42, 48 and 50 for inventory purposes. However, an alternative arrangement is to have different cuffing rates for the different cutters. Thus, for example, the cutter associated with pump 50 in Fig. 3 may have more or fewer blades and operate at a higher or lower speed than the pump 48. Where a chopper pump is being used, such a difference in cuffing performance will normally involve a corresponding difference in pumping performance, since a chopper pump combines both functions. This may not be desirable.

Consequently, where it is desired to have different degrees of culling in the different compartments, it may be expedient to separate the pumping and culling functions.

Where the cuffing and pumping functions are separated, the separate cutter will normally be disposed upstream of its associated pump, in order to reduce the strain on that pump. However, it may be located downstream of the pump, if the performance of the pump is not affected. At all events, it will be necessary to ensure that the relative dispositions of the pump, cutter and separating wall are such that no pressure is lost as digestate goes from the preceding compartment and through the cutter and pump. This can be achieved by encasing the upstream cutter in a conduit, which then leads directly into the inlet of the pump -see Fig. 5, which will now be described.

As regards the method of mounting the chopper pumps in the compartments, Fig. 5(a) shows a simplified representation of part of the apparatus 30, in which an opening 90 is provided in the separating walls 44 and 46 and the pumps 48 and 50 are mounted by any suitable means adjacent to those openings. As an example, Fig. 5 shows a conduit portion 91 and flanges 92, which are attached to the lower end of the conduit portion, as a convenient mounting point for the pumps. A similar conduit portion and flange for the pump 42 may be provided on the opening of the first compartment 32 communicating with the conduit 38, unless, of course, it is decided to mount this pump in the conduit 38 itself.

Where a separate pump and cutter are used, the upstream cutter will be housed in the conduit portion 91, so that the suction of the pump can act directly on the digestate entering the cutter, without part of the suction being lost thiough gaps between the cutter and pump, or between the cutter and the separating wall.

Alternatively, where a chopper pump, such as the one shown in Figs. 4(a)-4(c), is employed, this may be mounted directly adjacent the opening 90, instead of via a flange 92 and conduit 91. Fig. 4(a) shows possible mounting points at the open ends of the suction casing 62, the outlet 68 and at the bottom end of the drive casing 60. Therefore the simplest way of mounting such a pump to the separating walls 42, 48 in Fig. 3 is to bolt the suction casing 62 to the separating wall via the mounting points of the suction casing. Referring again to Fig. 3, this would turn the chopper pump shown in Fig. 4(a) through 90°, so that the outlet 68 would eject digestate horizontally. It is because of this that the pumps in Fig. 3 are shown offset from a central position in the separating walls 42, 48.

This direct mounting of a chopper pump, such as the one shown in Figs. 4(a)-4(c), to the separating wall is shown in Fig. 5(b). Thus, in Fig. 5(b) the inlet 66 is bolted directly to the separating wall 44 or 46, so that it receives digestate vertically downwards, as shown by the arrow 87. The fragmented digestate is ejected from the outlet 68 in a horizontal direction, as shown by the arrow 89.

Whatever method of securing the pumps and cutters to the separating walls is chosen, the openings 90 in those walls will be approximately as large as the inlet opening of the cutter or pump -in the case of the chopper pump hereinbefore described, approximately as large as the open end of the inlet 66 in Fig. 4(a).

One practical aspect of this embodiment of the invention has not so far been mentioned.

This is that, where centrifugal pumps such as the illustrated chopper pump is employed, some form of shutter will be required either directly upstream or downstream of the pump, in order to prevent an undesired passage of digestate through the pump in its unoperated state. Such a shutter can, for example, be situated on the upper surface of the separating wall 44 or 46 in Fig. 5(b) and likewise in Fig. 5(a). Alternatively, in Fig. 5(b) the shutter may be located in the conduit portion 91. The shutter is conveniently operated by solenoid or motor, and will be operated either at the same time as its associated pump is started up, or slightly beforehand.

So far, the apparatus 30 has been shown as consisting of a series of compartments disposed on above the other. An alternative arrangement is shown in Figs. 6(a) and 6(b).

In Fig. 6(a), which is a plan view, the compartments 32, 34 and 36 are disposed side by side. Hence, digestate flows horizontally through the apparatus, rather than vertically.

This will, of course, negate the advantageous effect of gravity on the digestate flow.

However, the pressure created by the pumps far overrides the effect of gravity, so that digestate flow is negligibly impaired.

A side view of this arrangement is illustrated in Fig. 6(b). This view is a view through the apparatus itself. Thus, the view shows the pump 42 adjacent the side 94 of the apparatus (see Fig. 6(a)), the pumps 48 and 50 mounted inside the compartments 34 and 36 adjacent the separating walls 44 and 46, and the conduit 51 mounted on the wall 96 of the apparatus. Also shown in Fig. 6(b) are the branches 40-1, 40-2, 40-3 of the water conduit 40, which communicate with the wall 96, and the sensors 52, 54 and 56, which are mounted in that same wall.

In this Fig. 6 arrangement, it may be necessary to provide a sensor similar to the sensor 57, which is shown in Fig. 3, near the bottom end of each of the compartments 32, 34 and 36. This is because digestate is being drawn off horizontally, rather than vertically, through the pumps, and this is a situation similar to that of the last compartment in Fig. 3, which required the sensor 57.

A further embodiment of the organic-waste processing apparatus 30 is shown in Fig. 7.

In Fig. 7 four compartments are provided, both of which have conduits 51 mounted to them. The conduits 51 each have a shut-off valve 100, the outlets of which are connected together to form a single outlet 102. The final pump 58 is mounted in the outlet 102.

In this embodiment it is possible to choose between two degrees of fragmentation. A first, coarser degree of fragmentation is achieved in the compartment 36, while a finer degree of fragmentation is achieved in the additional compartment 104. Depending on the next stage of processing downstream of the apparatus 30, either of these degrees can be selected by corresponding opening of the appropriate valve 100.

Instead of a single pump in the conduit 102, two pumps may be used, one per conduit 51.

In a preferred embodiment of the organic-waste processing apparatus, the apparatus is modular in design. Thus, each compartment forms a module and all modules are the same. Consequently, as many compartments as desired can readily be assembled into the complete apparatus. In this embodiment each modular compartment will have openings in the walls corresponding to the inlet 38, outlet 51 and the sensors 52, 54, 56 and 57, as well as openings for the water supply. However, those compartments below the first compartment will have their inlet openings blanked off, and those compartments above the last compartment will have their outlet openings blanked off. (This does not apply to the Fig. 7 embodiment, since then the outlets of last two compartments will be in use.) Similarly, those compartments above the last compartment will have their lower sensor (57) openings blanked off, In addition, the top and bottom walls of each compartment (assuming a vertical disposition of the compartments) will each have an opening corresponding to the cutter/pump. In that case, the first compartment will have its top cutter/pump opening blanked off, and likewise the last compartment will have its bottom cutter/pump opening blanked off. The first and second compartments will be mounted adjacent to each other, so that the bottom cutter/pump opening of the first compartment registers with the top cutter/pump opening of the second compartment, and so on for the remaining compartments. Thus, the adjacent top wall of one compartment and bottom wall of the preceding compartment will together form the separating wall 44, 46 of Fig. 3.

Such a modular design can be employed for, at the same time, both the vertically configured embodiment of Fig. 3 and the horizontally configured embodiment of Figs. 6(a) and 6(b). An example of this is shown in Figs. 8(a) and 8(b).

Fig. 8(a) is an isometric view of a module, as deployed in a vertically configured organic-waste processing apparatus. The module has its top wall removed for convenience. Comparing this with, e.g., the first (top) compartment of Fig. 3, the wall defined by the thick lines 150 corresponds to the left-hand wall, looking at Fig. 3, while the wall 152 corresponds to the right-hand wall, looking at Fig. 3. Reference numeral 154 is the opening in the left-hand wall for the pump 42, while reference numeral 156 represents the opening in the bottom wall of the first compartment corresponding to the separating waIl 44 in Fig. 3. This opening communicates with the pump 48. Finally, reference numeral 158 is the opening in the right-hand wall 152 for the sensor 52.

Sensor 158 is near the top of the module, and therefore defines an upper level limit for the digestate.

Turning now to Fig. 8(b), which again has its top wall removed, this is the same module, but lying in a position suitable for a horizontal disposition of the apparatus. Comparing this now with Figs. 6(a) and 6(b), the thick lines in Fig. 8(b) (which are the same as the thick lines in Fig. 8(a)) correspond to the wall 94 in Fig. 6(a), while wall 152 in Fig. 8(b) corresponds to the wall 96 in Fig. 6(a). The right-hand opening 156 in Fig. 8(b) communicates with the pump 48 in Fig. 6(a) and the opening 158 communicates with the sensor 52 in Fig. 6(a). It should be noted that there are two openings 156 in Fig. 8(b). This is because, as mentioned earlier, the module can be used in any position in the apparatus, not only the first position. When the module is used in an intermediate position, both of the openings 156 will be in use. When used in the first position, however, only the right-hand opening 156 will be used, the other being blanked off, and conversely, when the module is used in the last position, only the left-hand opening 156 will be used, while the other is blanked off.

It should be noted that the opening 158 in Fig. 8(b) defines also for this horizontal disposition of the module an upper level limit for the digestate, just as it did for the vertical disposition. Hence it is not necessary to provide different sensor opening positions for the horizontal and vertical configurations. Similarly, the opening 154 lies at the top of the compartment in both dispositions, since it is preferred that the digestate be fed in from the top.

While the split box is commonly used to process digestate from an anaerobic digestion process, the inventors have found that it can also be used to efficiently process raw animal waste directly, provided the fragmenting apparatus 30 (see Figs. 2 and 3) is inserted upstream of the split box.

An example of this is shown in Fig. 9, in which horse manure 110 is used as the input.

In this case, the manure is first fed into an auto feeder 112, which is arranged to store the manure and release it, according to demand. The released manure is taken to an auger 114, and from there to a pre-processing apparatus 116 similar to the apparatus in Figs. 2 and 3. The apparatus 116 supplies fragmented horse manure to a split box 118, which supplies three outputs, as in Fig. 2 -namely, water, which is stored in reservoir 120, a fertilizer for spreading on fields and a dry fraction for heat and power generation and other agricultural use. The third output is, however, first converted to pellet form in a pelletizer 122, and the pellets then stored in a silo 124 for eventual use in agriculture or the supply of heat and power.

As well as horse manure, pig and dairy manure may be similarly processed. Such a processing system is illustrated in Fig. 10, in which the manure 130 is taken directly to a pre-processing apparatus 132, similar to the apparatus 30 and 116 in Figs. 2 and 9, and from there to a split box 134. Pelletization occurs in a pelletizer 136, similar to the embodiment of Fig. 9, and fertilizer and dry-fraction pellets are stored in respective silos 138 and 140. Finally, purified water is produced and stored in a reservoir 142, from which it can be taken for use in irrigation or other applications, where clean water is required.

In both the Fig. 9 and Fig. 10 cases, the pelletization stage may be omitted.

Conversely, such a stage may be included in the Fig. 2 embodiment upstream of the silo 18, if desired. Furthermore, in Figs. 9 and 10 the pre-processing component may be employed in isolation without the subsequent components of the split box, etc.,. This is useful where the manure is merely required to be fragmented and then disposed of in some other way -for example, by burning in the case of stable waste.

While the processing carried out by the organic-waste processing apparatus has been described as involving the softening of the waste in all three compartments, the water in the conduit 40 may be supplied to only one or two of the compartments. This will normally include the first compartment.

More or less than three compartments may be employed in the apparatus. This number will be not less than two, and preferably not more than four. The embodiment of Fig. 7 will, of course, require one more than this number.

Although it has been assumed that a final separate pump 58 will be used to convey the digestate in the compartment 36 under pressure to the next stage, this may instead be achieved by operating the pumps 42, 44 and 46, so that the apparatus 30 undergoes another cycle, whereby more digestate is introduced into the compartment 32, while the digestate already present in compartments 32 and 34 moves down, forcing the digestate in the compartment 36 through the conduit 51 and into the next stage.

Where a separate pump 58 is employed, this has been assumed to be a conventional non-chopper type pump. However, a chopper pump may be used in this position, in which case it will perform a final fragmenting action before the digestate is fed to the next stage. This may be especially useful where the apparatus 30 is used as a pre-processing stage to a split box. This chopper pump would be most easily mounted directly to the outlet wall of the last compartment. The direction of the exiting digestate would, of course, be into or out of the page, looking at Fig. 3, since a chopper pump is centrifugal and has orthogonally disposed inlet and outlet, as shown in Figs. 4(a)-4(c).

Where the digestate was required to flow out of the apparatus 30 in the direction shown in Fig. 3, then the conduit 51 should be mounted in either the front wall or back wall of the last compartment, instead of in its side wall, as shown in Fig. 3. As with the other chopper pumps, pump 58 may also require its own shutter.

in place of the sensor 57, shown in Fig. 3, it is possible to sense when digestate is no longer being pumped through the pump 58, and to use this sensed event to switch off this pump and switch on the pump 42.

In Figs. 3, 6(a) and 6(b), it has been assumed that the water inlets to the individual compartments will be disposed lower than the sensors 52, 54, 56, which would mean that, when the digestate was at its maximum level, it would cover these water inlets. In that event it may be expedient to employ a check valve in each water inlet, to ensure that flow in these inlets can only be one way, namely into the compartment.

Alternatively, these inlets may be located higher than the sensors, in which case a check valve may be dispensed with.

Instead of a chopper pump, in which the cutter is formed in the impeller of the pump, a pump may be used, in which the cutter is still an integral part of the pump, but is provided separate from, and preferably upstream of, the impeller and driven by the drive shaft of the pump.

As regards suitable materials for the apparatus 30, any metal or plastics material may be used, which can withstand the aggressiveness of the material being fragmented.

Although the various openings have been shown to be formed in specific walls of the compartments, in practice they may be formed in any convenient wall (although the possibilities of the location of the sensor openings in the afore-described modules, which serve both a vertical and a horizontal configuration of the apparatus, will be limited). The openings for the pumps will, of course, always be formed in the separating wall.

Finally, on a purely practical level, it may be necessary to provide one or move vents in the organic-waste processing apparatus, in order to allow air within the apparatus to be dispelled, as the digestate or other organic waste is pumped into the various compartments. Such a vent may be conveniently provided in each compartment (or module), at a level above the sensors 52, 54, 56.

Claims

CLAIMS1. An organic-waste processing apparatus, the apparatus comprising: a housing having a series of compartments including a first compartment, a last compartment and at least one intermediate compartment between the first and last compartments; a first inlet for receiving an organic waste product, the inlet communicating with the first compartment; a second inlet for receiving a liquid, the second inlet communicating with at least one of the series of compartments; and an outlet, the outlet communicating with the last compartment; the apparatus being configured, such that the waste product is mixed with the liquid and is fragmented by increasing degrees while being conveyed from one compartment to the next toward the outlet.
2. The apparatus of claim 1, wherein: the apparatus is configured, such that the waste product is fragmented while being introduced into the first compartment.
3. The apparatus of claim 1, comprising: separating walls dividing adjacent compartments from each other, and openings in respective separating walls; a cutter mounted adjacent to each opening, and a pump disposed downstream of the cutter.
4. The apparatus of claim 3, wherein: the pump is a chopper pump, in which a set of knife blades is attached to a rotor of the pump, the knife blades acting as the cutter.
5. The apparatus of claim 3, wherein: the cutter is a set of knife blades separate from the pump.
6. The apparatus of any one of claims 3 to 5, comprising: an input-control device in the first inlet and a flow-control device in the second inlet; and a control device, which is connected to the pumps, cutters, input-control device and flow-control device and is configured to control the pumps, cutters, input-control device and flow-control device, such that: the waste product is introduced into the first compartment via the first inlet and the input-control device and is mixed with the liquid introduced via the second inlet and the flow-control device; the pump in the separating wall between the first compartment and its adjacent compartment is operated, so as to convey the waste product from the first compartment to the second compartment, the cutter allocated to that pump being operated at the same time, so as to fragment the waste product being conveyed; the remaining pumps in the other separating walls are similarly operated in sequence, so as to convey the waste product between the respective pairs of compartments, the cutters allocated to those pumps being operated at the same time as their respective pumps, so as to fragment the waste product being conveyed.
7. The apparatus of claim 6, wherein: the control device is configured, such that the waste product is not conveyed from one compartment to the next, until the one compartment is substantially full.
8. The apparatus of any one of the preceding claims, wherein: the second inlet communicates with at least the first compartment.
9. The apparatus of any one of the preceding claims, wherein: an additional compartment is provided as the last compartment, and outlets are provided in both the additional and preceding compartments, the outlets being controlled by respective shut-off valves, the outputs of the shut-off valves forming the outlet of the apparatus, the shut-off valves allowing either the degree of fragmentation achieved in the additional compartment, or the degree of fragmentation achieved in the preceding compartment, to be selected for the output of the apparatus.
10. The apparatus of any one of the preceding claims, wherein: each compartment is constituted as a module, the module being adapted so as to allow the apparatus to be configured as either a vertical arrangement of compartments, or a horizontal arrangement of compartments.
11. The apparatus of claim 10, wherein: all the modules are identical.
12. An arrangement for processing an organic waste, comprising: a split box, and a pre-processing apparatus upstream of the split box, the split box being configured to deliver at least a non-solid fertilizer product and a dry-fraction product, and the pre-processing apparatus being an organic-waste processing apparatus as defined in any one of the preceding claims.
13. The arrangement of claim 12, wherein: the split box is configured to deliver water as a further product.
14. The arrangement of claim 12 or claim 13, comprising: a first silo for storing the non-solid fertilizer product and a second silo for storing the dry-fraction product.
15. The arrangement of claim 14, comprising a pelletizer between the split box and the second silo for converting the dry-fraction product into pellet form.
16. The arrangement of any one of claims 12 to 15, wherein: the organic waste is a digestate from an anaerobic digestion process.
17. The arrangement of any one of claims 12 to 15, wherein: the organic waste is one or more of horse manure, pig manure or cow manure.
18. The arrangement of claim 17, wherein: the organic waste is horse manure, the arrangement further comprising, upstream of the pre-processing apparatus: an auto-feeder for storing the horse manure and releasing it on demand, and an augur for conveying the released horse manure and supplying it to the pre-processing apparatus.
19. A method of processing an organic waste product, comprising: introducing the waste product into a first compartment of an organic-waste processing apparatus as defined in claim I and mixing it with a liquid; conveying the mixed waste product from the first compartment into a second compartment of the organic-waste processing apparatus adjacent to the first, while fragmenting the mixed waste product, and so on for further pairs of adjacent compartments in sequence; outputting the fragmented waste product from the last compartment.
20. The method of claim 19, wherein: the waste product is fragmented while being introduced into the first compartment.
21. The method of claim 19 or claim 20, wherein the fragmented waste product is output to a split box for the production from the fragmented waste product of at least a non-solid fertilizer product and a dry-fraction product.