GB2528848A

GB2528848A - Blending apparatus

Info

Publication number: GB2528848A
Application number: GB1413528.9A
Authority: GB
Inventors: James Lloyd; James Spruell; James Tyler; Simon Webb
Original assignee: OWE Ltd
Current assignee: OWE Ltd
Priority date: 2014-07-30
Filing date: 2014-07-30
Publication date: 2016-02-10
Also published as: GB201413528D0

Abstract

A composting apparatus 1 for composting material in the apparatus 1, comprising: a first and second elongate channel 3, 4 each with a substantially curved base; and a shaft 13, 14 located substantially along a length of each channel 3, 4. Each shaft 13, 14 comprises at least one mixing member 15 which extends radially outwardly from the shaft 13, 14 for mixing the material. The first and second channels 3, 4 are aligned alongside each other such that the curved bases of the first and second channels 3, 4: define an upstanding dividing portion 7 where they meet between the channels 3, 4, which has a height allowing material from one channel to pass into the other channel; and extend upwardly to form the lateral side walls 8 of the apparatus 1. The side walls 8 reach a height substantially above the at least one mixing member 15 such that the material is kept within the apparatus 1 whilst it is being mixed by the at least one mixing member 15. Also claimed is a method of composting material comprising feeding material into the composting apparatus 1.

Description

Blending apparatus The present invention relates to a blending apparatus and an associated method of blending material, particularly to an apparatus and method for composting organic material.

The processing of organic materials by both aerobic and anaerobic biological treatment is an increasing global trend as conservation and recycling of valuable organic matter becomes increasingly important. Traditional methods of aerobic and anaerobic digestion suffer from a number of limitations associated with poor quality management of heterogeneous feedstock.

It is usual for a variety of organic materials from different sources to be processed at the same location. This presents a problem for the operator of having to develop strategies for storing, pre-processing and blending feed stocks to enable the core processing operations to function properly. In addition, costly, inefficient, microbial seeding, recirculation or start-up phases are required within the core processing step to bring the system up to maximum operating efficiency wasting time, space and money.

Blending non-optimum heterogeneous material can have a deleterious effect on the core processing step by introducing "shocks" to the system thereby creating results of variable quality, or in other cases slowing (or in extreme circumstances halting) the biological process, with the consequent impact on final product quality and the ability to find a productive final end use.

Furthermore, there are odour nuisance problems associated with the processing of organic materials. These nuisances can be caused by the production of hydrogen sulphide, and/or other Volatile Organic Compounds (VOC), or by poor quality material management leading to uncontrolled releases of exhaust air.

It is an object of embodiments of the present invention to address all or some of the above problems. The present invention is set out in the appended claims.

An objective of embodiments of the present invention is to pre-condition a wide range of organic or mixed organic materials, that a processing plant may receive, into a homogenous, sanitized (from human, animal and plant pathogens) output that contains the maximum target microbial population for the core processing step. As a result the subsequent processing of the output material will be more efficient, economic and stable.

Another objective of embodiments of the present invention is to produce a sanitised output where these problem materials are volatilised within the apparatus, removed and treated. As a result the output lowers odour risk and the associated costs of managing noxious, nuisance or harmful gases.

According to an aspect of the present invention there is provided a composting apparatus for composting material in the apparatus, the apparatus comprising: a first elongate channel with a substantially curved base; a second elongate channel with a substantially curved base; and at least one shaft located substantially along a length of each channel, each shaft comprising at least one mixing member which extends radially outwardly from the shaft for mixing the material, wherein the first and second channels are aligned alongside each other such that the curved bases of the first and second channels: define an upstanding dividing portion where they meet between the channels, the upstanding dividing portion having a height which allows material from one channel to pass into the other channel; and extend upwardly to form the lateral side walls of the apparatus, the side walls reaching a height substantially above the mixing members such that the material is kept within the apparatus whilst it is being mixed by the mixing members.

The apparatus is used to mix, biologically degrade and/or pre-condition organic materials of varying characteristics into a sanitised (from human, animal and plant pathogens), homogenous consistency and quality for onward processing and/or finishing.

The apparatus maximises the mixing of a heterogeneous variety of input materials into a singular, consistent product for more efficient downstream processing. The shafts and at least one mixing member provide an efficient mixing mechanism which can mechanically reduce the average particle size of the input material, increasing the efficiency and amount of recoverable organics from the downstream processing.

When the apparatus is operating aerobically, the apparatus may be operable to maximise the exposure of material to oxygen to minimise the anaerobic activity. The shafts and at least one mixing member may help entrain oxygen in the flow of material, and the presence of oxygen is essential for the natural biological processes taking place.

Thus, the generation of heat is facilitated, which may help to sanitise the material and reduce the moisture content to an optimal level. Reducing the moisture content of the material may minimise the potential for issues relating to leachate produced by untreated waste, and may help achieve significant mass reduction of treated waste such that downstream handling treatment and/or transport of the material is reduced and mechanically easier to achieve. Under aerobic conditions, the apparatus may maximise the growth and create an environment that will encourage an even distribution of thermophilic microbial populations to aid the speed and efficiency of processing. The apparatus may rapidly volatilise VOCs and/or other compounds which may cause nuisance odours.

When the apparatus is operating anaerobically, the apparatus may capture the generated gases such as biogas (methane, ethane etc., carbon dioxide and/or other trace gases). The apparatus may maximise the growth and even distribution of thermophilic or mesophilic microbial populations to aid the speed and efficiency of processing.

Utilising separate shafts within separate channels means that the mixing may be programmed to achieve high levels of homogeneity in a short space of time. Compared with currently available composters, for a certain surface area, the mixing capacity of the apparatus, and thus volume of material that can be mixed, is dramatically increased.

The upstanding dividing portion may only partially separate and/or divide the channels. The upstanding dividing portion may reach a height that's approximately 10- 50% of the height of the side walls, preferably 20-40%, more preferably about 30%. The upstanding dividing portion and curved bases may allow for material to pass between the channels, and prevent a dead portion existing between the channels where material would otherwise sit and not mix. The curved bases may force material that would otherwise sit near the upstanding dividing portion, to fall down towards the deepest parts of the channels so that the material can be picked up by the at least one mixing member and thus be mixed. The side walls may prevent material being mixed from spilling out of the sides of the apparatus.

The apparatus may be made from a single skin of material. The material may be, but is not limited to, any one or more of stainless steel, steel (treated or otherwise), concrete, aluminium, or fibreglass. The material may be glass reinforced plastic. The material may be strong enough for use on ship hulls. Any other material suitable to provide structure and withstand organic acids and/or abrasion may be used. The apparatus may be made from two or more skins of material. The apparatus may be formed from a standard self-contained 40 foot shipping container. This may be useful for ease of transportation and/or installation. The apparatus may be sized such that it is easily transportable by road. The apparatus may be sized for use on an industrial scale.

The channels may be contained within one vessel. The vessel may define one volume. The vessel may be defined by the bases of the channels and the lateral side walls. The vessel may be further defined by a roof.

The base of each channel may be substantially semi-circular. The channel may be substantially 0-shaped. The lateral side walls may be substantially vertical. The lateral side walls may be substantially curved. The lateral side walls may make an angle of between about 30 degrees and about 90 degrees to the horizontal. The lateral side walls may make an angle of between about 45 degrees and about 75 degrees to the horizontal.

The apparatus may have an inlet at a first inlet end of the apparatus and an outlet at the opposite outlet end of the apparatus. The upstanding dividing portion may extend from the inlet end. It may extend along only a part of the length of the channels. It may extend along about 40-100% of the length of the channels. It may extend along about 50-95% of the length of the channels. It may extend along about 70-95% of the length of the channels. It may extend along approximately 80% of the length of the channels. In the remaining length of the channels, where there is no upstanding dividing portion, there may effectively be a single channel. This may mean there is one substantially curved base across the width of the apparatus along substantially this remaining length.

Additionally, or alternatively, along substantially this remaining length, there may be a dividing portion reaching a height substantially similar to that of the lateral side walls.

This may divide the two channels completely along substantially this remaining length.

The design of the at least one mixing member may vary depending on the prevailing characteristics of the material intended to be mixed and/or processed by the equipment. The at least one mixing member may extend continuously along substantially the length of the shaft. The at least one mixing member may extend along only a part of the shaft. There may be a plurality of mixing members. Each mixing member may extend along only a part of the shaft; the plurality of mixing members may extend along substantially the length of the shaft. The at least one mixing member may be a blade or a tine. The at least one mixing member may be of a length such that when in a substantially vertical downwards position, the at least one mixing member makes a clearance fit with the base of the channel. Alternatively, the gap between the end of the at least one mixing member and the base of the channel in this position may be wider.

The at least one mixing member may be arranged helically along substantially the length of the shaft. This may help to keep the material moving along the channel towards the outlet. The at least one mixing member may have a non-helical configuration along substantially the length of the shaft. A non-helical configuration may prevent the pushing or pulling of material so that the movement of material towards the outlet end is by displacement of the material, so by the input of fresh material and extraction of the product, and/or by fluidisation of the material, so by the reduction of particle size through the mixing action and mechanical blending. The at least one mixing member may have a variety of configurations to achieve rapid and effective mixing of the material.

The shaft and its associated at least one mixing member may form a single unit; the shaft and its associated at least one mixing member may be integrally formed or may be interconnected. Alternatively, the shafts and their associated at least one mixing members may form a single unit. Either arrangement may allow for the entire unit to be lifted in and out of the apparatus easily for the purpose of maintenance and replacement.

The apparatus may further comprise a driving mechanism, wherein both shafts are connected to the driving mechanism to drive the shafts together. The shafts may be driven together interlocked or they may be driven together via one driving mechanism.

The shafts may be rotationally driven by direct drive motors. Each shaft may be separately controlled to perform the desired speed, direction, time and intervals of rotation. The shafts may be operated to rotate synchronously or asynchronously, and/or clockwise or counter clockwise and/or forward or back independently and/or dependently. One shaft may be operated to rotate clockwise and the other counter clockwise. Alternatively, one of the shafts may remain stationary. The apparatus may comprise two or more driving mechanisms, wherein each driving mechanism is operable to drive each shaft separately. The shafts may be driven from the inlet end, the outlet end and/or both ends of the apparatus. An operator adjustable programmable logic control system may be used to control these specific settings.

The one or more driving mechanisms may be, but are not limited to, a direct drive motor, a gearbox, an offset gearbox arrangement. The one or more driving mechanisms may take any other form suitable of driving a shaft rotationally. The one or more driving mechanisms may generate the required torque to rotate the one or more shafts at speeds of approximately 0.01-25 RPM, preferably about 0.05-20 RPM or preferably about 0.1-10 RPM. The one or more driving mechanisms may generate the required torque to rotate the one or more shafts at speeds of approximately 0.25-5 RPM. The one or more driving mechanisms may generate the required torque to rotate the one or more shafts at speeds slower or faster than those mentioned. An operator adjustable, or factory pre-set, programmable logic control system may be used to control the specific settings of the speed, time, rotational direction and interval for the one or more shafts.

Each shaft may be located substantially centrally along the length of each channel. Alternatively, there may be two or more shafts located substantially along a length of one or more of the channels. The two or more shafts within a single channel may be positioned substantially end to end length ways and/or alongside one another, along a length of the channel. Preferably, each shaft is identical to the first shaft located substantially along a length of one or more of the channels.

The apparatus may further comprise a framework. The framework may allow for the channels to be raised above the base of the apparatus. The framework may allow for the channels to be raised by between 10cm and 1 m above the base. The framework may allow for the channels to be raised by between about 30cm and 80 cm above the base, preferably between about 40cm and 60cm above the base, preferably about 50cm above the base. The framework may be an open framework. This allows for easy access to the channels and/or sensors, air injection units for maintenance or otherwise. The framework may be closed, or "boxed-in", to create an air cavity between the box and the frame; this air cavity may be filled with insulating material. The framework may be rigid enough to resist the torque of the shafts and/or to be structurally stable when the vessel is moved.

At each end of the framework may be one or more load bearing end plates. The one or more load bearing end plates may provide a cover for an end of the channels. The shafts may be held in position and supported by the one or more end plates.

The upstanding dividing portion may comprise a temperature sensing means. The temperature sensing means may be a probe. The upstanding dividing portion may comprise a pH monitoring means. The upstanding dividing portion may comprise a means for detecting the moisture level. This may enable the efficient regulation of pH and moisture content of the different feedstocks. The apparatus may comprise means for monitoring the level of carbon dioxide and/or the level of oxygen in the apparatus. Any or all of these means may sit flush within the upstanding dividing portion so as to provide accurate measurement but so as not to cause an obstruction to the mixing of the material. Any or all of these means may comprise one or more sensors. These sensors may operate continuously or intermittently.

The apparatus may be constantly monitored and data logged for any one or more of carbon dioxide level, oxygen level, moisture content, headspace temperature, material temperature and/or exhaust gas temperature.

The apparatus may comprise means for heating the material within the apparatus.

This may help to ensure that the material is kept at an optimum temperature. Monitoring the temperature of the material, and/or heating the material when necessary, may be automatically controlled.

The apparatus may be operated under aerobic or anaerobic conditions. The apparatus may be hermetically sealed in order to operate under anaerobic conditions and to manage the mix of contained gases.

The apparatus may be an enclosed vessel. The apparatus may comprise a roof.

The framework may extend over the top of the vessel to support the roof of the vessel.

The roof may comprise one or more roof panels. The roof may comprise one or more vented roof panels. The panels may be sized and utilise materials that may be structurally sound and sufficiently load bearing for access and mounting of equipment.

The panels may also be small and light enough for an individual to lift without assistance in order to gain access to the process material.

The apparatus may comprise an integrated feed conveyor and/or an integrated discharge conveyor. This enables material to be fed into and from the apparatus in a controlled manner. The material feeding and/or mixing and/or discharging may be discrete programmable logic controlled operations.

The apparatus may comprise means for extracting the air from the apparatus. Air from the apparatus may be exhausted. This may create a negative pressure and hence prevent fugitive odour emissions from the process. Alternatively, this may create a controlled positive pressure state within the apparatus which can be maintained for the purpose of recovering process gas.

The apparatus may comprise an air injection means for injecting air into the material. The air may be injected through the side walls of the apparatus. The air may be injected whilst the shafts are rotating to maximise air entrainment in the material. Air may be injected when one or more of the shafts are stationary.

The apparatus may further comprise one or more additional channels being positioned alongside, and preferably being identical to each of the first and second channels. The one or more further channels may comprise any or all of the features as described above, or pictured, for the first and second channels.

The apparatus may be operated by a project specific software program operable to control every electronic component of the apparatus individually. Each component may be set and adjusted by an operator. The program may include the functionality to create saved pre-set operational parameters. This may mean that specific programs can be selected for particular operating conditions such as commissioning, night time running, day time running, holiday running and emptying. The apparatus may be programmed to follow operator set process performance targets.

The apparatus may be connected to the internet, by a hard and/or wireless connection. The apparatus may be controlled remotely and/or on site. The apparatus may be controlled by an automated system. This may allow the apparatus to work continuously.

Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, of which: Figure 1 is a side view of a composting apparatus of the present invention; Figure 2 is a plan view of a composting apparatus of the present invention; Figure 3 shows cross-sections through the width of a composting apparatus of the present invention, showing different configurations for rotation of the shafts, the direction of rotation of each shaft being indicated by the arrows (no rotation indicated by no arrow).

In the following, the terms upper, lower, top, bottom, front and back/rear are used to refer to the apparatus in the orientation as shown in the accompanying drawings, which is the orientation in which the apparatus is intended to be used. These terms should not be taken as otherwise limiting.

Referring to the drawings, a composting apparatus I is intended to blend organic materials of varying physical characteristics into a singular quality of feedstock for the onward processing by biological, chemical and/or mechanical treatment methods. The apparatus 1 comprises an enclosed vessel 2, which defines two horizontal channels 3, 4.

The vessel 2 has an inlet end 5 and an outlet end 6. Organic material is fed into and discharged from the vessel 2 by means of integrated feed and discharge conveyors.

The vessel 2 is approximately 12m in length, 2.3m in width and 1.8m in height, and is constructed from a single skin of stainless steel material..

The two horizontal channels 3, 4 are elongate and arranged alongside one another. Each channel has a curved base, with a substantially semi-circular shaped cross section across its width. The curved bases of the two channels meet between the channels to define an upstanding dividing portion 7 along approximately 80% of the length of the channels from the inlet end. This upstanding dividing portion 7 has a height which allows material from one channel to pass into the other channel and the curved bases allow for material residing on the edges of the channels to fall down towards the substantially deepest pad of the respective channel. In some embodiments, the upstanding dividing portion 7 comprises sensors to measure any or all of temperature, PH, moisture, carbon dioxide level, oxygen level. The sensors sit flush within the upstanding dividing portion. The curved bases also extend upwardly to form lateral side walls B for the vessel. As such, the cross section of the apparatus across its entire width is a substantially curved W shape.

The two channels 3, 4 are supported by an open metal frame 9 that keeps the bases of the channels raised above the floor by approximately 0.5m. The frame 9 is rigid enough to resist the torque of the shafts but the open structure allows for easy access to the channels 3, 4, sensors and air injection units for maintenance or otherwise. At each end of the frame 9, and secured to the frame 9, is a load bearing end plate 10 substantially covering each end of both channels 3, 4. The end plate 10 at the inlet end 5 of the apparatus comprises an inlet 11 for inputting material to be composted, and the end plate at the opposite end of the apparatus comprises an outlet 12 for outputting the composted material. The open frame 9 and remaining 20% of the length of the channels 3, 4 without an upstanding dividing portion 7, provides enough space for both the inlet 11 and outlet 12 to comprise a screw conveyor system (not shown).

The outlet 12 comprises a discharge auger (not shown) which extends from outside of the vessel and from the outlet end to approximately halfway down the length of the channels. Product is conveyed along the auger and through the outlet end of the vessel. The discharge auger discharges onto a longer inclined, or declined, auger, a belt or radial belt which sits outside of the vessel and is affixed in position to transport processed material into a storage bay. In the case of a radial belt the position will be automated to enable the discharge position to move when required or to move after a 24 hour period to enable effective tracking of material batches.

There is a shaft 13, 14 located within each channel 3, 4, each shaft 13, 14 being located substantially centrally along the length of its channel 3, 4. The shafts 13, 14 are held in position and supported by the end plates 10. A plurality of mixing blades 15 extend radially outwardly from each shaft 13, 14, and follow a helical pattern along the length of each shaft 13, 14. The lengths of the blades 15 are such that the blades 15 make a clearance fit with the curved bases of the channels 3, 4 as the shaft 13, 14 rotates. Thus, material contained within each channel 3, 4 can be mixed by rotation of the shaft 13, 14 and the attached mixing blades 15 within that channel. The side walls 8 reach a height substantially above the top of the mixing blades 15, when the mixing blades are in the vertically upwards position, so that material being mixed by the mixing blades 15 is kept within the apparatus I and does not spill over the sides. This creates a large headspace above the material in the vessel 2. As the material is lifted and turned by the mixing blades 15, the headspace prevents damage occurring to a roof of the vessel and also prevents the material from being compacted. The shaft 13, 14 and supported mixing blades 15 form a unit. The method of attaching this unit to the vessel is such that the entire unit can be lifted in and out of the vessel easily for the purpose of maintenance and replacement.

The shafts 13, 14 are rotationally driven by direct drive motors, such that each shaft 3, 4 can be separately controlled to perform the desired speed, direction, time and intervals of rotation. With reference to Figure 3, the shafts 13, 14 can be operated to rotate synchronously or asynchronously, clockwise or counter clockwise, or alternatively one can be operated to rotate clockwise and the other counter clockwise. Alternatively, one of the shafts can remain stationary. An operator adjustable programmable logic control system is used to control these specific settings.

In some embodiments, the vessel 2 has a roof 16 which comprises one or more roof panels. The roof 16 is substantially flat to allow inspection hatches and other monitoring apparatus to be easily installed.

In some embodiments, one or more of the roof panels are vented roof panels. Air can be actively extracted from the vessel through the vented roof panels using an electric fan. The electric fan is controlled via the programmable logic control system. The processing of material will constantly produce VOC, moisture and bio aerosol laden air, which requires removal to avoid undermining the process. The vented roof panels are positioned so as to minimise, as much as is possible, saturation levels of the exhaust air being reached within the vessel. This would give rise to condensation and would impact the composting process. Once extracted from the vessel 2, the exhaust air can be treated by any one, or combination, of the various known methods available. The vessel 2 may be actively exhausted with the exhaust gases treated by appropriate third party technology solutions.

In some embodiments, the apparatus 1 comprises means for injecting air from outside of the vessel 2, through the side walls 8 and into the vessel 2 and the material being mixed. This is beneficial when the apparatus 1 is working in an aerobic mode. The air injection means can be controlled alongside the shaft 13, 14 rotation to maximise air entrainment in the material. Alternatively, whilst the blades 15 are not moving and the material is not being mixed, the air can be injected into the static material and left to sit for extended periods. The lack of mechanical agitation minimises the potential for evaporative cooling losses and allows uninterrupted growth of the microbial populations, reducing electrical use, wear and cost.

In some embodiments, the apparatus 1 comprises a power sieve at the outlet 12, which can be used to refine the end product. In circumstances where a bulking medium is incorporated into the material to be composted, the power sieve is also used to automatically separate the composted material from the bulking medium. In some embodiments, the apparatus comprises a bulking medium recirculation system l7so that the bulking medium can be automatically fed back into the system at the inlet end 5 for re-use. Where a power sieve and recirculation system 17 are both employed, the bulking medium is automatically separated from the end product and then fed straight back into the system.

In use, material is fed into the vessel 2 via the inlet 11. Depending on the properties of the material being blended, either one or both of the shafts 13, 14 are rotationally driven in a certain direction (the shafts 13, 14 may be rotationally driven in the same or opposite directions to each other). The mixing blades 15 are thus torced to pick the material up, to aerate it and blend it. The motion of the mixing blades 15 reduces the particle size and thus makes the material more fluid. As the material becomes more fluid, it can start to advance along the length of the vessel 2 whilst still being mixed by the mixing blades 15. Material may pass from one channel 13, 14 and into the other channel 14, 13. If the material falls off the mixing blades 15 and into the region of the upstanding dividing portion 7, the curved bases of the channels 13, 14 forming the upstanding dividing portion 7 will force the material to fall down towards the deepest part of the respective channel 13, 14. Material entering the other channel 14, 13 and/or falling down toward the deepest part of the respective channel 13, 14 will be picked up by the mixing blades 15 within that channel 13, 14. The material will keep advancing along the length of the vessel 2 towards the outlet end 6. Once the material has reached the outlet end 6 it will have been suitably processed. The processed material is then extracted via the outlet 12 for onward processing.

The above embodiments are described by way of example only. Many variations are possible without departing from the scope of the invention as defined in the appended claims.

Claims

CLAIMS1. A composting apparatus for composting material in the apparatus, the apparatus comprising: a first elongate channel with a substantially curved base; a second elongate channel with a substantially curved base; and a shaft located substantially along a length of each channel, each shaft comprising at least one mixing member which extends radially outwardly from the shaft for mixing the material, wherein the first and second channels are aligned alongside each other such that the curved bases of the first and second channels: define an upstanding dividing portion where they meet between the channels, the upstanding dividing portion having a height which allows material from one channel to pass into the other channel; and extend upwardly to torn the lateral side walls ot the apparatus, the side walls reaching a height substantially above the at least one mixing member such that the material is kept within the apparatus whilst it is being mixed by the at least one mixing member.
2. A composting apparatus as claimed in claim 1, wherein the shaft is located substantially centrally along the length of each channel.
3. A composting apparatus as claimed in claim 1, wherein there are two or more shafts located substantially along the length of each channel.
4. A composting apparatus as claimed in any preceding claim, wherein the base of each channel is substantially semi-circular.
5. A composting apparatus as claimed in any preceding claim, wherein the at least one mixing member is a tine.
6. A composting apparatus as claimed in any one of claims 1 to 4, wherein the at least one mixing member is a helical blade extending substantially continuously along the length of the shaft.
7. A composting apparatus as claimed in any of claims 1 to 3, wherein each shaft comprises a plurality of mixing members.
8. A composting apparatus as claimed in any preceding claim, the apparatus further comprising a driving mechanism, wherein both shafts are connected to the driving mechanism to drive the shafts together.
9. A composting apparatus as claimed in any of claims 1 to 5, the apparatus further comprising two driving mechanisms, wherein each driving mechanism is operable to drive each shaft separately.
10.A composting apparatus as claimed in any preceding claim, wherein the upstanding dividing portion comprises a temperature sensing means.
11. A composting apparatus as claimed in any preceding claim, wherein the apparatus further comprises means for injecting air into the apparatus.
12.A composting apparatus as claimed in any preceding claim, the apparatus further comprising a roof comprising one or more vented roof panels.
13.A composting apparatus as claimed in any preceding claim, wherein the apparatus further comprises one or more elongate channels, the one or more elongate channels each having a substantially curved base and a shaft located substantially centrally along a length of the channel, the one or more elongate channels being aligned alongside the first and second channels to define one or more upstanding dividing portions between the channels respectively.
14.A composting apparatus substantially as herein described with reference to any of the accompanying drawings.
15. A method of composting material comprising the steps of: feeding material into the composting apparatus of any preceding claim; rotating at least one shaft located substantially along a length of a channel of the composting apparatus to blend the material; and outputting the blended material.
16. A method substantially as herein described with reference to any of the accompanying drawings.