GB2406804A - Waste disposal and composting unit - Google Patents

Abstract

The invention provides apparatus for waste disposal comprising: <SL> <LI>(i) a waste disposal unit 2 having a grinding chamber 12 provided with a waste inlet 10, a waste outlet 18 and a recycling inlet 20; <LI>(ii) a composting container 8 linked to the waste outlet of the grinding chamber; and <LI>(iii) a diverter valve 26 having (a) an inlet linked to the waste outlet of the grinding chamber; (b) a first outlet linked to the composting container; and (c) a second outlet linked to the recycling inlet of the grinding chamber; and; <LI>(iv) means for controlling the diverter valve so that waste from the grinding chamber can be diverted to the composting container or to the recycling inlet as required, or into a sewer. Also disclosed is an apparatus comprising a unit having a comminuting mechanism that can be configured to provide different ranges of particle size of comminuted waste (see fig 2), and the inclusion of a control means so as to adjust/select the particle size accordingly depending on diversion to a composter or sewer. </SL>

Description

1 2406804

WASTE DISPOSAL UNIT

This invention relates to a waste disposal unit capable of either composting waste or discharging the waste to a main sewer depending on the nature of the waste. The invention also relates to methods of controlling the particle size and water content of comminuted waste produced by waste disposal units.

Background of the Invention

In the United Kingdom every year, many tens of millions of tonnes of domestic refuse are produced, most of which ends up in landfill sites. A very high proportion of domestic waste is organic in nature, consisting of, for example, vegetable peelings, teabags and food scraps. The decomposition of organic materials within....

landfill sites leads to the generation of large volumes of methane, a greenhouse gas that is considered to have a major effect on climate change. Such is the concern about the levels of methane produced by landfill sites that the reduction of the amount of organic waste going into landfill sites is now seen as a major priority. In .

Europe, the Landfill Directive (1999/31/EC) aims to reduce methane emissions...

from landfill by reducing biodegradable waste entering landfill to 75% of 1995 levels by 2010. .

The composting of domestic waste is seen as one of the potential solutions to the problem. Central composting schemes have been introduced and several hundred thousand tonnes of compost are processed annually in the UK. Local government schemes have been set up, in which composting bins are provided at low cost or free of charge, or in which separate waste bins are provided to domestic households that allow the separate collection of compostable domestic waste and non recyclable and noncompostable waste. However, such schemes do suffer from a number of problems. One problem is the difficulty in ensuring that significant cross contamination with non-compostable waste does not occur. At present there are restrictions on the spreading of such compost on land because of the possibility that it may have been contaminated with animal waste. Another problem concerns the energy consumed in collecting and handling the waste and the greenhouse gases generated as a consequence.

Domestic composting by householders of their own waste represents one solution to the above problems but, for a variety of reasons, is often viewed as being inconvenient. Although a large proportion of domestic kitchen waste (e.g. fish, meat, cheese, plate scrapings) is unsuitable for composting, food waste of plant origin such as vegetable and fruit peelings, stalks, leaves and spoiled fruit and vegetables, can be composted. However, the somewhat messy nature of such waste and the perceived inconvenience of taking the waste to an outside compost heap or compost bin often results in such waste simply being disposed of along with the non-compostable waste.

The present invention sets out to provide a system which makes the separation of food waste into compostable and non-compostable waste more convenient and avoids the need for inconvenient food waste trips to the garden composter or a compost bin outside the house. . .

It is well known to provide kitchen sinks with waste disposal units to enable solid..

or semi-solid wastes such as food waste to be disposed of down the sink. Waste. . . disposal units typically comprise a chamber or hopper connected to the drainage outlet of the sink into which waste materials from the sink can be flushed. Means are provided in the chamber or hopper for grinding or otherwise comminuting the .

waste to particles of a size small enough to be flushed through the waste pipes and into the sewage system. An example of a waste disposal unit is described in our earlier United Kingdom patent application number 0220527. 6, filed 4th September 2002, the contents of which are incorporated herein by reference.

It has been proposed to link domestic waste disposal units to a composter and one such arrangement is disclosed in US 5,971,303.

One of the problems in using kitchen waste from a domestic waste disposal unit for composting is the high level of water in the ground waste emerging from a typical waste disposal unit. Prior to being processed in a waste disposal unit, vegetable and fruit waste typically has an average water content of about 70%. However, by the time water has been added during the grinding operation, the water content of comminuted waste leaving the waste disposal unit typically rises to over 95%. By contrast, a water content (by weight) of 40% to 60% is required for optimum comporting.

Another problem with using a waste disposal unit is that the particle size of the ground waste may be too small for efficient aerobic composting. With very small particle sizes, if the water content is reduced to the levels necessary for composting, the articles of waste will agglomerate and take on a sludge or glue-like consistency which precludes efficient aeration and results in anaerobic decomposition taking place.

Thus, there is a conflict between the physical characteristics of the waste required to enable waste to be disposed of into a sewer and the characteristics of the waste desirable for efficient comporting. On the one hand, a high water content and small....

particle size are required for disposal to the sewer and, on the other hand, composting requires a much lower water content and a larger particle size. :e.:.

Summary of the Invention.. . .

The present invention sets out to resolve or at least alleviate the problem of the....

conflicting requirements with regard to water content and particle size between.

waste destined for the sewer and waste destined for a composter.

The invention also sets out to provide a more convenient means of sorting non- compostable waste from compostable waste and conveying waste from a waste disposal unit to a composter.

In one aspect, the invention provides a combination of a waste disposal unit and a composter that allows comminuted waste to be sent to a main sewer, or to the composter, or recycled back through the waste disposal unit depending on the nature of the waste. By recycling the waste so that it is subjected to a second, or further, grinding cycle before being directed to the composter, the water content of the waste can be controlled much more closely to give waste having the water content required for more efficient comporting.

Accordingly, in one embodiment, the invention provides apparatus for waste disposal comprising: (i) a waste disposal unit having a grinding chamber provided with a waste inlet, a waste outlet and a recycling inlet; (ii) a composting container linked to the waste outlet of the grinding chamber; and (iii) a diverter valve having (a) an inlet linked to the waste outlet of the grinding chamber; (b) a first outlet linked to the composting container; and (c) a second outlet linked to the recycling inlet of the grinding chamber; and; (iv) means for controlling the diverter valve so that waste from the grinding chamber can be diverted to the composting container or to the recycling inlet as 1 0 required.

Typically the diverter valve (iii) is provided with a third outlet for connection to a sewer, the means for controlling the diverter valve being controllable to allow the waste from the grinding chamber to be directed to the composting container or to .

the recycling inlet or to the sewer as required. . . --- . . The waste disposal unit of the invention allows waste from the grinding chamber to. .

be recycled via a diverter valve back through an inlet into the grinding chamber so that it is subjected to a further grinding operation. The additional grinding step renders the waste more fluid as water is released from the disrupted cells of the waste material. By recycling the waste and subjecting it to one or more repeat grinding cycles, the waste can be transformed into a state where it is sufficiently fluid to be pumped along pipe work to the composter whilst substantially reducing the proportion of water in the ground waste thereby reducing the dewatering requirement prior to composting. In this way, the water content can be reduced by a factor of 2 to 5, for example.

Although recycling of the waste through the waste disposal unit will give comminuted waste having a relatively low water content, means may nevertheless be provided for permitting further removal of water from the waste. Thus, for example, a separator may be disposed between the diverter valve and the composting container to allow any excess water present in the waste to be removed prior to entering the composting container. The separator can, for example, take the form of a settling tank, or a filter, or a cyclonic separator or a compressive mechanism such as a mangle.

A simple compressive mechanism such as a mangle, comprising one or more pairs of rollers between which the waste is passed on route to the composter, is currently preferred.

Where water is removed by filtration, this may be achieved by means of a filter comprising a filtering paper or other fabric optionally in combination with a particulate material such as ground glass.

Alternatively, the compositing container can be constructed so that excess water simply drains from the container.

::::.

in another aspect, the invention provides a waste disposal unit for connecting to a A. . composter in which the need for external diverting valves to divert waste selectively to either the sewer or the composter is avoided. Accordingly, the invention also provides apparatus for waste disposal comprising a waste disposal unit having a grinding chamber containing means for comminuting waste, the chamber being provided with a waste inlet upstream of the comminuting.. means and a plurality of waste outlets downstream of the comminuting means; one of the waste outlets being connectable to a sewer and another of the waste outlets being connectable to a composter.

In a preferred embodiment, the grinding chamber has a further waste outlet downstream of the comminuting means whereby comminuted waste can be recycled back into the grinding chamber upstream of the comminuting means.

The waste disposal unit preferably has means for selectively diverting waste through a selected waste outlet to permit waste to be routed either to the sewer or to the composter, or for recycling back to the grinding chamber as required.

By "selectively diverting" is meant that more than 50% by volume of the waste is diverted through a particular outlet. More usually at least 60%, for example at least 80%, e.g. at least 90%, of the waste is diverted through the selected outlet.

A variety of methods may be employed to divert waste selectively through one outlet or another. In one embodiment, the outlets can be arranged so that rotation of a comminuting element such as a rotor in one direction moves waste through one outlet whereas rotation in the other direction moves waste through another outlet.

In such an arrangement, a pair of outlets may be arranged in an opposed manner, each outlet being tangential to the grinding chamber. Baffles and/or flaps may be employed to prevent or hinder passage through a particular outlet during rotation of the comminuting element in a particular direction.

The outlets can be provided with means for selectively opening and closing them.

For example, a sliding internal blanking plate can be provided that can slide over and cover a selected one or more of the plurality of outlets to prevent waste from passing through the outlet. The plate can be configured so that the movement of ground waste in one direction over the plate causes the plate to slide around the .

interior of the grinding chamber so that it covers a particular outlet. Movement of.

the waste in the opposite direction causes the plate to slide in the reverse direction so that one outlet is unblocked and another becomes blocked. . a.

In another embodiment, the outlets may have associated hinged flaps that are displaced so as to cover an outlet when the waste moves in one direction but not in .

the reverse direction.

In a further embodiment, the outlets or their associated pipe work may each have separately adjustable width restrictions so that movement of the waste through a selected outlet may be hindered or prevented by reducing the width of the outlet or its associated pipe work. For example, each outlet may be connected to a flexible pipe or hose to which a clamping device (which may be e.g. solenoid controlled) is attached, selective activation of the clamping device serving to restrict the width of the hose or pipe. Alternatively, a solenoid-valve may be attached to each outlet so that a given outlet can be opened or closed as required.

The term "grinding chamber" as used herein refers to a chamber in which waste is ground, chopped, shredded or otherwise comminuted. The grinding chamber may comprise a hopper or housing for receiving waste from a sink, a comminuting mechanism such as a rotating blade for grinding, chopping or shredding waste material and a drainage chamber downstream (e.g. beneath) of the comminuting mechanism. The outlets are typically located in the drainage chamber.

Control of the particle size of the waste is also of importance to the efficiency of the composting process. Particles of waste that are too small may adhere together with the result that they are not properly oxygenated and undesirable anaerobic decomposition occurs.

In another aspect, the invention provides a waste disposal unit having a comminuting mechanism that can be configured to provide different ranges of particle sizes of comminuted waste.

In a further aspect, the invention provides a waste disposal unit that is capable of comminuting waste to several different ranges of particle sizes, for example to give .

either waste of a particle size suitable for flushing into a sewer, or waste of a particle size suitable for comporting. ..

In a still further aspect, the invention provides a waste disposal unit containing....

means for comminuting waste material, wherein the comminuting means can be; . controlled so that waste is comminuted either to a first range of particle sizes suitable for disposal to a sewer or to a second range of particle sizes suitable for comporting.

The comminuting means typically comprises a pair (or more) of comminuting elements that cooperate to shred, chop or grind waste material. An example of such a mechanism is described in our UK patent application number 0220527.6 and comprises a rotating disc-like element ("rotor") mounted on a spindle which is driven by an electric motor. The rotor may have an upstanding stub blade or impeller to assist movement of the waste and typically the outer edge of the rotor disc is provided with one or more cut-outs or slots. The rotor rotates within the circumference of a cutter ring which typically has one or more cutting edges formed in its inner surface. As the rotor is rotated, the cutting edges on the inner surface of the cutting ring cooperate with the outer edge of the rotor to provide exert a shearing motion on waste matter passing through the clearance between the rotor and cutting ring.

The rotor and cutting may be constructed so as to be capable of comminuting waste matter to several different ranges of particle sizes. For example, in one embodiment, variations in the particle size may be achieved by providing means for varying the clearance between the rotor and the cutter ring. As the clearance between the rotor and cutter is increased, so too are the sizes of the particles of waste that are produced.

In one embodiment, the cooperating comminuting elements comprise a frustoconical cutting ring and a rotor disposed within the cutting ring. The size of the particles of waste produced by the shearing action of the rotor and cutting ring....

can be varied by moving the rotor in an axial direction (e.g. up or down) relative to the frustoconical cutting ring thereby varying the clearance therebetween. Thus, for example, the rotor may be constructed so that it can be indexed axially along (e.g. .

up or down) its drive shaft, or the rotor may be fixedly mounted on the drive shaft. . and the drive shaft may be axially movable (e.g. up and down). The outer surface of the rotor can be frustoconical, or it can have a cylindrical outer surface. As an alternative to varying the clearance between cooperating comminuting elements, variation in size of the particles produced may be achieved by configuring the rotor such that rotation in one direction produces particles of one size and rotation in the reverse direction produces particles of another size. For example, the rotor may be configured to provide a shredding action in one direction and a grinding action in the other direction.

In a further alternative, variation on particle size of the comminuted waste can be varied by varying the speed of rotation of the rotor.

In a further embodiment, either the cutting ring or the rotor or both can be provided with two or more (but preferably two) annular arrays of cutting edges or teeth, the rotor being axially movable with respect to the cutting ring between two or more positions so that in one position, the rotor and cutting ring cooperate to comminute waste to one range of particle sizes whereas in another position, the rotor and cutting ring cooperate to comminute waste to another range of particle sizes.

In another embodiment, control of the particle size may be achieved by providing the rotor with one or more holes of a defined size whereby particles of waste of a desired size may pass through the holes. For example, the hole or holes may have a diameter of 2 mm to 20 mm, more usually 5 mm to 15 mm, and such holes will allow the passage of relatively coarse particles that are suited to comporting.

The rotor may be provided with means for closing the holes thereby allowing the waste disposal unit to operate in two modes. In a first mode, the holes in the rotor are open and the waste is coarsely chopped or shredded to a size particularly suitable for comporting. In a second mode, the holes are closed and hence the....

particles of waste can only pass through the clearance between the rotor and the cutter and hence are of a much smaller size and are suitable for disposal into a sewer. * :. a.

In one embodiment, the rotor comprises two axially mounted discs, each having one or more holes whereby relative rotation of the discs can bring the hole or holes in. . one disc into register with the hole or holes of the other disc thereby allowing waste.

to pass through the rotor. Relative rotation of the discs in the opposite direction moves the hole or holes of one disc out of register with the hole or holes of the other disc thereby preventing waste from passing through the rotor.

The waste disposal units can be constructed so as to allow the particle size of the comminuted waste be chosen by the user and to provide a facility for selecting the particle size before each comminuting operation depending on the nature of the waste.

In each of the foregoing aspects and embodiments of the invention, the grinding chamber may be provided with a second inlet into which a source of recycled water may be introduced. The recycled water may be "grey water" recycled from domestic appliances and installations such as washing machines, dishwashers, baths and showers, but more preferably the recycled water is water recycled from the composter or a separator linked to the composter. An advantage of recycling excess water from the composter is that it reduces the local drainage requirement at the composter.

The waste disposal unit is provided with a controller and associated circuitry to allow control of the motor driving the comminuting means, any solenoids and diverter valves or closures to inlets and outlets, and the pump for pumping the comminuted waste from the waste disposal unit to the composter.

The waste disposal unit may be activated by means of, for example, a wall mounted switch or by means of a sink plug or adaptor incorporating a switching mechanism (e.g. a magnetic proximity-switch) as described in our earlier UK patent application number 0220527.6. Several different sink plugs or adaptors may be provided for a given waste disposal unit, each one being configured to activate a different grinding ëe and/or waste disposal mode. For example, one plug or adaptor may be configured to activate the waste disposal unit so that it chops the waste relatively coarsely and directs the waste to the composter whereas another plug or adaptor can be ..

configured to activate the unit so that it produces waste of a relatively small particle.

size and directs the waste into the sewer.

The plugs and adaptors may be configured to provide different modes of activation. . .' by virtue of having different strengths of magnets, or differently positioned magnets arranged to interact differently with different strengths of proximity switch.

The plugs and adaptors may be colour coded or otherwise marked to indicate whether they direct the waste to the sewer or to the composter Brief Descrintion of the Drawines Figure I is a schematic view showing a waste disposal unit linked to a composter according to one embodiment of the invention.

Figure 2 is a schematic side sectional view of a variable clearance rotor and cutter ring assembly.

Detailed Descrintion of the Invention The invention will now be illustrated, but not limited, by reference to the specific embodiment shown in the drawings.

Figure 1 is a schematic illustration of a waste disposal unit coupled to a composter.

As shown on Figure 1, a waste disposal unit in accordance with one embodiment of S the invention comprises a waste disposa] unit 2, a pump 4, a water separator 6 and a composter 8 together with interconnecting pipe work and control valves.

The waste disposal unit 2 may be of the type typically used in domestic kitchen sinks or in catering establishments. Thus it has an opening 10 through which food waste and water are introduced, the opening 10 leading into a grinding or macerating chamber 12. At the bottom of the chamber 12 is a rotating blade 14 which is driven by the motor 16 underlying the grinding chamber and which cooperates with the wall of the chamber 12 to chop, grind or comminute food. '.

waste. Comminuted food waste exits the chamber 12 through outlet 18. , ...

At the upper end of the chamber 12 is located an inlet 20 which can be connected to: , . e an additional supply of water, for example "grey" water that has been recycled from.

domestic appliances and installations such as baths, showers and washing machines. . , The inlet 20 can be closed by a solenoid operated valve which can be activated to introduce additional water into the grinding chamber when the waste is intended to be discharged into the sewer.

Also at the upper end of the chamber 12 is a further inlet 22 for receiving recycled water from the water separator or the grinding chamber as described in more detail below.

The outlet 18 is connected via a short length of pipe or tube 24 to a three-way valve 26. The operation of the valve can be controlled manually but more preferably is controlled remotely from a switch or controller (not shown). One outlet from the valve 26 extends into pipe 28 which connects to the sewer. A second outlet from the valve is linked via pipe 30 to the pumping chamber 32 of pump 4. The third outlet of the valve 26 is linked via pipe 34 to the inlet 22 at the top of the grinding chamber 12.

At the bottom of the pumping chamber 32 is an outlet 36 which is linked via pipe 38 to the water separator 6. The pipe work is completed by a water return pipe which extends between the water separator 6 and the inlet 22 of the grinding chamber.

The composter 8 and water separator 6 are typically located outdoors and may be situated a considerable distance from the waste disposal unit, for example 15 metres or more. The pump 32 must therefore be powerful enough to be able to pump waste slurry through pipes over such distances. In addition, the waste must be ground or chopped to a size where it can be pumped easily thorough the pipes to the 1 0 composter.

In use, food waste enters the grinding chamber 12 through inlet 10 and is ground or. - chopped to form small particles. If additional water is required, this can be introduced into the chamber 12 from the inlet 20 connected to a supply of grey water. The ground food waste exits the chamber 12 through outlet 18 and passes I S through valve 26. If the food waste is of a type (e.g. meat or fish waste) that is not. . suitable for comporting, the position of the valve 26 is set so that the waste passes, . Out along pipe 28 to the sewer. If the waste is plant based, e.g. vegetable and fruit 2.

peelings, and is suitable for comporting, the valve can be set so that the ground '.

waste is diverted into the pumping chamber 32 from which it is pumped to the water separator 6 on top of the composter 8. In the water separator, the waste settles and any excess water is decanted off and returned to the grinding chamber along return pipe 40 which feeds into pipe 34 and enters the grinding chamber through inlet 22.

A large proportion of the weight of vegetable matter is due to its water content. By subjecting waste vegetable matter to several grinding cycles, the waste can be reduced to a state in which it is sufficiently fluid to be capable of being pumped along the pipe work to the composter without the addition of extraneous water.

This can be achieved by switching the valve so that comminuted waste exiting the grinding chamber 12 through outlet 30 passes along the short length of pipe 34 and re-enters the grinding chamber 12 through inlet 22 at the upper end of the chamber.

In this manner the waste can be subjected to several grinding cycles until it has achieved the necessary consistency to be pumped along the longer length of pipe 38 to the composter. An advantage of recycling the waste in this way is that it reduces the water requirement of the waste disposal operation. In addition, although sufficiently fluid to be pumped through pipes, the overall water content of the waste is lower which assists in the subsequent composting process.

The size of the particles of waste produced by the waste disposal unit can be controlled in a number of ways. Figure 2 illustrates a comminuting mechanism that in which the clearance between a pair of comminuting elements can be varied to alter the particle size distribution.

Figure 2 is an exploded view of part of a waste disposal unit. The unit has a bell shaped housinglO2, only the lower part of which is shown in Figure 2. The bell- ..

shaped housing 102, which is coupled at its upper end (not shown) to a sink boss.

assembly through which waste is introduced into the unit, defines the upper part or upstream portion of the grinding chamber. The lower part or downstream portion of.

the grinding chamber is defined by drainage chamber 104, only a part of which is. . shown in Figure 2.

Mounted within the bottom of bell shaped housing 102 is a comminuting. mechanism comprising a cutter ring 106 and a rotor 1 10. A sealing ring 103 provides a seal between the upper edge of the cutter ring 106 and the housing 102.

The rotor 1 10, which is mounted on a spindle (not shown) extending upwardly from an electric motor at the base of the unit is formed from cast stainless steel. The rotor 110 is generally disc-shaped and has an upstanding stub blade or impeller 1 12 that tapers from the centre outwardly to the periphery of the rotor. A number (in this case 6) of small cut-outs or slots 114 are formed in the outer edge of the rotor disc 110.

The cutter ring 106, which is frustoconical in shape, is formed from cast stainless steel. Extending around the inner surface of the lower part ofthe cutter wheel is an array of ribs or lands 108 which taper slightly in a downwards direction. The ribs 108 have flat milled surfaces and have edges that, together with the peripheral edge of the rotor I 10, cooperate in use to grind waste in to small particles. Above the array of ribs, at 90 intervals around the inner surface of the cutter ring, are raised areas 1 16 that also cooperate with the stub blade 18 to comminute the waste. One opposed pair (not shown) of the raised areas are generally rectangular in shape whereas the other opposed pair 1 16 of raised areas take the form of downwardly pointing arrowheads. In use, the sloping edges of the arrowhead shape 1 16 assist in moving waste materials downwards towards the clearance between the ribs 108 on the cutter ring 106 and the outer periphery of the rotor 16, to assist grinding.

The lower edge of the cutter ring is seated in a stepped recess in an upper edge of the annular wall of the drainage chamber 104. The drainage chamber 104 contains one or more waste outlets for directing ground waste to the composter or to the sewer, or via a short length of pipe into the upstream portion of the grinding chamber to recycle the waste. .

In use, waste entering the chamber is comminuted by the shearing action exerted by the cooperating comminuting elements, i.e. the edge of the rotor 1 10 and the ribs 108 of the cutter ring. The comminuted waste passes through the clearance. .

between the rotor 1 10 and the cutter ring 106 into the drainage chamber from where..

it is directed into one or more of the waste outlets. In order to alter the size of the ...

particles of waste produced by the comminuting mechanism shown in Figure 2, the clearance between the two comminuting elements can be increased or decreased by raising or lowering the rotor 1 10 relative to the fixed cutter ring 106.

As an alternative, or in addition to, raising and lowering the rotor, the rotor can be provided with an array of holes (not shown) through which particles of a particular size can fall. In this way, larger particle sizes can be produced for waste intended to be directed to the composter.

Equivalents It will readily be apparent that numerous modifications and alterations may be made to the specific embodiments of the invention described above without departing from the principles underlying the invention. All such modifications and alterations are intended to be embraced by this application.

Claims (21)

1. Apparatus for waste disposal comprising: (i) a waste disposal unit having a grinding chamber provided with a waste inlet, a waste outlet and a recycling inlet; (ii) a composting container linked to the waste outlet of the grinding chamber; and (iii) a diverter valve having (a) an inlet linked to the waste outlet of the grinding chamber; (b) a first outlet linked to the composting container; and (c) a second outlet linked to the recycling inlet of the grinding chamber; I O and; (iv) means for controlling the diverter valve so that waste from the grinding chamber can be diverted to the composting container or to the recycling inlet as required. .

2. Apparatus according to claim 1 wherein the diverter valve (iii) is provided .

with a third outlet for connection to a sewer, the means for controlling the .

diverter valve being controllable to allow the waste from the grinding....

chamber to be directed to the composting container or to the recycling inlet or to the sewer as required.

3. Apparatus for waste disposal comprising a waste disposal unit having a grinding chamber containing means for comminuting waste, the chamber being provided with a waste inlet upstream of the comminuting means and a plurality of waste outlets downstream of the comminuting means; one of the waste outlets being connectable to a sewer and another of the waste outlets being connectable to a composter.

4. Apparatus according to claim 3 wherein the grinding chamber has a further waste outlet downstream of the comminuting means whereby comminuted waste can be recycled back into the grinding chamber upstream of the comminuting means.

5. Apparatus according to claim 4 having means for selectively diverting waste through a selected waste outlet to permit waste to be routed either to the sewer or to the composter, or for recycling back to the grinding chamber as required.

6. Apparatus according to claim 5 wherein the outlets are arranged so that rotation of a comminuting element such as a rotor in one direction moves waste through one outlet whereas rotation in the other direction moves waste through another outlet.

7. Apparatus according to claim 6 wherein a pair of outlets is arranged in an opposed manner, each outlet being tangential to the grinding chamber.

8. Apparatus according to claim 5 wherein the outlets are provided with means for selectively opening and closing them.

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9. Apparatus according to claim 8 wherein a sliding internal blanking plate is A. . provided that can slide over and cover a selected one or more of the plurality of outlets to prevent waste from passing through the outlet. :.

10. Apparatus according to claim 5 wherein the outlets or their associated pipe work each have separately adjustable width restrictions so that movement of I. .

the waste through a selected outlet may be hindered or prevented by.. :.

reducing the width of the outlet or its associated pipe work.

1 1. Apparatus according to claim 10 wherein each outlet is connected to a flexible pipe or hose to which a clamping device (which may be e.g. solenoid controlled) is attached, selective activation of the clamping device serving to restrict the width of the hose or pipe.

12. Apparatus for waste disposal comprising a waste disposal unit having a comminuting mechanism that can be configured to provide different ranges of particle sizes of comminuted waste.

13. Apparatus for waste disposal comprising a waste disposal unit containing means for comminuting waste material, wherein the comminuting means can be controlled so that waste is comminuted either to a first range of particle sizes suitable for disposal to a sewer or to a second range of particle sizes suitable for composting.

14. Apparatus according to claim 13 wherein the comminuting means comprises a pair (or more) of comminuting elements that cooperate to shred, chop or grind waste material.

15. Apparatus according to claim 14 wherein the comminuting elements comprise a rotor which rotates within the circumference of a cutter ring, the inner surface of the cutter ring having cutting edges which cooperate with the outer edge of the rotor to exert a shearing motion on waste matter passing through the clearance between the rotor and cutter ring. me

16. Apparatus according to claim 15 having means for varying the clearance between the rotor and the cutter ring. .

17. Apparatus according to claim 16 comprising a frustoconical cutting ring and a rotor disposed within the cutting ring, the size of the particles of waste produced by the shearing action of the rotor and cutter ring being variable. . by moving the rotor in an axial direction (e.g. up or down) relative to the.

frustoconical cutting ring thereby varying the clearance therebetween.

18. Apparatus according to claim 15 wherein the rotor and/or cutter ring is or are configured such that rotation in one direction produces particles of one size and rotation in the reverse direction produces particles of another size.

19. Apparatus according to claim 15 wherein the rotor has one or more holes of a defined size whereby particles of waste of a desired size may pass through the holes

20. Apparatus according to claim 19 wherein the hole or holes have a diameter of 2 mm to 20 mm, more usually 5 mm to 15 mm.

21. Apparatus according to any one of the preceding claims wherein the grinding chamber is provided with a second inlet into which a source of recycled water may be introduced.