Macerator

Abstract

A macerator comprising a maceration chamber and an impeller mounted in a base of the maceration chamber, the impeller having a rotor disc and a rotary axis is provided. The maceration chamber has a side wall having a plurality of cutting apertures extending around at least a portion of the periphery of the rotor disc, and the side wall having the plurality of cutting apertures extending in the direction of the rotary axis of the impeller. The maceration chamber has a collector having a collector volume, at least part of which is radially outwardly from an axis of rotation of the impeller and beyond a plurality of the cutting apertures. The collector volume is in fluid communication with at least one drain, and the collector is arranged to convey slurry passing through the cutting apertures to the at least one drain. The collector volume radially outwardly from the axis of rotation of the impeller beyond the cutting apertures defines a collector area which decreases in a circumferential direction about the axis of rotation of the impeller away from the at least one drain, and / or the collector has a surface whose distance from the axis of rotation of the impeller decreases in a circumferential direction about the axis of rotation of the impeller away from the at least one drain, and / or the collector volume radially outwardly beyond the cutting apertures extends over an arc of less than 360 degrees around the periphery of the rotor disc, and wherein the drain is located closer to one end of the arc than the other end of the arc and / or wherein the cutting apertures are unevenly arranged either side of the drain between the ends of the arc.

Description

MACERATORFIELD OF THE INVENTION

[0001] The present invention relates to a macerator and to a method of operating a macerator.BACKGROUND OF THE INVENTION

[0002] Macerators process solid waste products by reducing the solid product to a slurry in water, which can then be more readily disposed of through conventional drainage conduits. Clinical waste typically disposed of by maceration includes pulp fibre trays and containers contaminated by bodily waste or fluids. The macerator includes a chamber in which the solid product is shredded and mixed with water and an outlet through which the slurry produced passes to waste. A rinse step rinses the macerator chamber clean for the next cycle.

[0003] The outlet is typically provided in a base or pulveriser head of the macerator chamber. The base is typically formed with a generally frusto-conical shape to allow slurry to fall under gravity towards an annular gallery formed around an outer edge of the base. The base of the gallery inclines towards the outlet. The frusto-conical base has a central aperture through which the output shaft of a motor passes and engages and rotationally drives an impeller which sits at the bottom of the chamber. The chamber is formed generally conically with a wall which is thereby inclined towards the base of the chamber and has an annular lower rim.

[0004] The impeller is generally conical in form and includes a paddle on its upper surface to aid movement of materials to be macerated around the macerator chamber.

[0005] The lower rim of the impeller is associated with or formed with a cutter ring. Cutter ring and annular rim both include apertures or notches respectively. Thus, in use, fixed cutter ring cooperates with the rotating impeller, cooperating to divide materials introduced into the maceration chamber into a slurry.

[0006] The radial dimensions of notches and the relative axial position of the impeller with respect to rim define the maximum particle size which can be passed from the chamber to annular gallery and thus to outlet.

[0007] Whilst such constructions are very effective, there can be larger particles passing through the slots and this can have an impact on flow within the gallery. It is beneficial to reduce the solid waste as quickly and as efficiently as possible, and to reduce the likelihood of solid waste loaded into the macerator becoming trapped or otherwise not being macerated. Accordingly, there is a need to provide a macerator construction which overcomes this problem.SUMMARY OF THE INVENTION

[0008] A first aspect of the invention provides macerator comprising:a maceration chamber; andan impeller mounted in a base of the maceration chamber, the impeller having a rotor disc and a rotary axis,wherein the maceration chamber has a side wall, the side wall having a plurality of cutting apertures extending around at least a portion of the periphery of the rotor disc, andwherein the side wall having the plurality of cutting apertures extends in the direction of the rotary axis of the impeller, anda collector having a collector volume, at least part of which is radially outwardly from an axis of rotation of the impeller and beyond a plurality of the cutting apertures,wherein the collector volume is in fluid communication with at least one drain, and the collector is arranged to convey slurry passing through the cutting apertures to the at least one drain,wherein i) the collector volume radially outwardly from the axis of rotation of the impeller beyond the cutting apertures defines a collector area which decreases in a circumferential direction about the axis of rotation of the impeller away from the at least one drain, and / orii) the collector has a surface whose distance from the axis of rotation of the impeller decreases in a circumferential direction about the axis of rotation of the impeller away from the at least one drain, and / oriii) the collector volume radially outwardly beyond the cutting apertures extends over an arc of less than 360 degrees around the periphery of the rotor disc, and wherein the drain is located closer to one end of the arc than the other end of the arc and / or wherein the cutting apertures are unevenly arranged either side of the drain between the ends of the arc.

[0009] The collector here refers to a component of the macerator that defines a volume located between the cutting apertures and the drain. The collector is configured to manage the flow of slurry, either by facilitating a back pressure to retain the slurry within the maceration chamber or by allowing the slurry to drain efficiently.

[0010] The collector and the cutting apertures are configured to convey the slurry out of the maceration chamber, and directly to the drain. The collector is configured such that the collector volume is rotationally asymmetric, extending around at least a portion of the periphery of the rotor disc about the axis of the impeller. Providing a collector volume that is rotationally asymmetric enables the collector to selectively operate, depending on the rotation direction of the impeller, as either:i) a resistance in the flow path and fill up the collector volume, causing a back pressure towards the maceration chamber which promotes backflow from the collector volume into the maceration chamber, turbulent flow within the collector volume, and self-rinsing of parts of the collector, orii) a funnel which conveys the slurry down towards the drain more effectively.

[0011] Accordingly, to reduce the solid materials to a slurry effectively, less water can be used and spun into a vortex inside the maceration chamber for catching and blending the slurry. Reducing the amount of water required for effective operation of the macerator may aid in reducing the required power to operate the macerator, thus lowering the energy usage and leading to savings in operational costs. This may also facilitate simplifying the structural requirements of the macerator due to reduced internal dynamic forces caused by the moving slurry inside the macerator, thus leading to savings in production cost of the macerator.

[0012] The collector area decreasing in the circumferential direction away from the drain enables the collector to define a collector volume that is rotationally asymmetric and decreasing away from the drain, facilitating the back pressure in the collectorvolume. This back pressure generates a force against the material passing through the cutting apertures, promoting a backflow into the maceration chamber. Accordingly, less slurry and therefore less water can exit the maceration chamber, reducing the required water for effective maceration. Alternatively, or additionally, the surface whose distance from the axis of rotation of the impeller decreases in a circumferential direction away from the drain provides the rotationally asymmetric structure within the collector volume that can facilitate the backpressure guiding the slurry away from the drain. Further alternatively, or additionally, uneven arrangement of the cutting apertures either side of the drain provides a rotational asymmetry of the fluid communication between at least one drain and the collector which is arranged to convey slurry passing through the cutting apertures, thus facilitating the backpressure guiding the slurry away from the drain. Extending the collector volume over an arc of less than 360 degrees enables the collector to convey the slurry towards the drain without looping around the full periphery of the rotor, thus facilitating removal of the collector when necessary. In this manner, the removal of the collector can be achieved without a need to remove or disassemble other components of the macerator that may in the way, such as a drive shaft of the impeller. Removing the drive shaft of the impeller may require specialist knowledge which may complicate and / or extend the maintenance activities as well as the downtime of the macerator. Having a collector volume over an arc of less than 360 degrees removes this requirement of specialist knowledge as well as the additional maintenance time and improve serviceability of the macerator. The impeller not only macerates the material but also accelerates the fluid towards the exit, ensuring a smooth and continuous flow out of the maceration chamber. This dual function of the impeller coupled with the asymmetric collector / cutter ring design enhances the overall draining performance, reduces blockages, and maintains a steady flow of slurry.

[0013] The decreasing collector area may be biased towards a first direction of rotation of the impeller as compared with an opposite, second direction of rotation of the impeller, preferably wherein the decreasing collector area may be in a direction substantially aligned with the impeller first direction of rotation. A desired operation mode of the macerator may determine the direction of rotation of the impeller.

[0014] During an outflow mode, the biased volume of the collector may allow for a more focused exiting of slurry, reducing drag and preserving momentum. This may aidin that the fluid exits the maceration chamber more efficiently, maintaining a steady flow and further reducing the likelihood of blockages. This asymmetric design of the collector may further aid in aligning the collector volume with the angle at which the slurry leaves the maceration chamber, thus preventing turbulence and preserving the slurry’s exit momentum.

[0015] In a retain mode, where the aim is to retain inside the maceration chamber as much of the slurry as possible, the collector may fill up more compared to the outflow mode, as the design of the collector generally guides the slurry away from the drain. This effect may be more pronounced at the tighter end opposite to the drain, where additional turbulence promotes backflow into the maceration chamber. This may encourage retention of the slurry and help clear remaining debris that may build up in the collector.

[0016] In this manner, the macerator can be operated between the outflow mode and the retain mode. During the outflow mode, the slurry may be conveyed to the drain passively with the force of gravity and / or actively, by preserving the momentum of slurry passing through the cutting apertures, which is generated by the rotation of the impeller impacting on the slurry inside the maceration chamber. In the retain mode, the slurry enters the collector at an angle such that the flow path of slurry misses the drain and impacts a sloped portion of the collector. This sloped portion may be a portion of the collector defining the collector volume and / or the surface the surface whose distance from the axis of rotation of the impeller decreases in a circumferential direction away from the drain. The impact causes turbulence within the stream of slurry which creates a back pressure in the collector, thus promoting backflow, which may also help clear debris in the collector.

[0017] The collector may have a collector inlet adjacent the cutting apertures and the collector surface may be a surface of an interior wall of the collector opposite the collector inlet.

[0018] The interior wall may be the sloped portion of the collector, defining the collector volume, providing a more compact collector arrangement. In retain mode, the slurry may enter the collector and impact the interior wall, causing turbulence within the slurry stream. The turbulence in the slurry stream generates the back pressure withinthe collector volume and promotes the backflow away from the drain and towards the maceration chamber.

[0019] The collector surface may be located between a collector inlet adjacent the cutting apertures and an interior wall of the collector opposite the collector inlet. In this manner the back pressure may be generated by a dedicated surface rather than solely relying on internal geometry of the collector. This may be preferable where design constraints prevent the collector surfaces from having the rotational asymmetry that is necessary for generating the back pressure.

[0020] A first portion of the collector surface may form a first angle with an adjacent cutting aperture at a first angular position with respect to the axis of the impeller, and a second portion of the collector surface may form a second angle with an adjacent cutting aperture at a second angular position with respect to the axis of the impeller closer to the drain than is the first angular location, and the second angle may be smaller than the first angle.

[0021] In retain mode, the collector may fill up more as the backpressure guides the slurry away from the drain. This effect may be more pronounced at an end of the collector surface that is furthest from the drain, by providing the collector surface forming varying angles with the adjacent cutting apertures. In this manner, the turbulence may be more pronounced at a tighter end of the collector, promoting further backpressure and therefore enhancing the backflow into the maceration chamber. Accordingly, varying angles of the collector surface may enhance the retention efficiency of the retain mode and help clear remaining debris in the slurry flow path.

[0022] The angle of the surface receiving the impact from the slurry entering the collector volume, with respect to the axis of the impeller, may also determine the collector volume

[0023] The uneven arrangement of the cutting apertures may comprise an uneven spacing of the cutting apertures. This uneven spacing may help to reduce drag during outflow mode by allowing the slurry to pass through with varying levels of resistance, thus preventing any one area from becoming a bottleneck. In retain mode, the same uneven spacing may increase resistance by creating turbulence within the slurry flow. As the slurry encounters apertures of different sizes and at different intervals, it may beforced to change direction and speed, resulting in a back pressure that pushes the slurry back into the maceration chamber, thus enhancing the efficiency of retain mode.

[0024] The uneven spacing of the cutting apertures may comprise progressively increasing or decreasing the spacing between the neighbouring cutting apertures over at least a portion of the arc. When neighbouring apertures progressively increase in spacing in the direction of the slurry flow, for example in retain mode, the slurry initially passes along the closely spaced apertures, experiencing higher resistance and more frequent cutting action between the impeller and the cutting apertures, creating more turbulence and back pressure. As the slurry moves along, the increased spacing reduces resistance, allowing the slurry to flow more smoothly within the maceration chamber. Conversely, when the spacing progressively decreases in the direction of the slurry flow, for example in outflow mode, the slurry starts with less resistance allowing the slurry to flow more smoothly through the cutting apertures. Furthermore, the slurry faces increasing resistance as it moves along the apertures, continuing maceration process even when the maceration chamber is being drained.

[0025] The uneven arrangement of the cutting apertures may comprise an uneven sizing of the cutting apertures. This uneven sizing may influence the resistance against the slurry flow. During outflow mode, the variation in aperture sizes may allow slurry to pass through with different levels of resistance, which can be configured based on required slurry outflow rate.

[0026] The uneven sizing of the cutting apertures may comprise progressively increasing or decreasing the size of neighbouring cutting apertures over at least a portion of the arc. This configuration may work by initially subjecting the slurry to higher resistance at the smaller apertures, effectively enhancing the cutting and maceration process. As the slurry moves along and encounters larger apertures, the resistance decreases, allowing for a smoother and more efficient flow. When neighbouring apertures progressively increase in size in the direction of the slurry flow, for example in retain mode, the slurry initially passes along the smaller apertures, experiencing higher resistance and more frequent cutting action between the impeller and the cutting apertures, creating more turbulence and back pressure. As the slurry moves along, the increased size of the apertures reduces resistance, allowing the slurry to flow more smoothly within the maceration chamber. Conversely, when the size progressivelydecreases in the direction of the slurry flow, for example in outflow mode, the slurry starts with less resistance due to larger apertures allowing the slurry to flow more smoothly through the cutting apertures. Furthermore, the slurry faces increasing resistance as it moves along the apertures, continuing maceration process even when the maceration chamber is being drained.

[0027] The uneven arrangement of the cutting apertures may comprise a different number of the cutting apertures on opposite sides of the drain. On the side with fewer cutting apertures, the slurry may experience less resistance, allowing for a more rapid flow towards the drain, for example during outflow mode. Conversely, on the side with more cutting apertures, there may be increased resistance, which generates more turbulence and back pressure, for example during retain mode. This back pressure may help to guide the slurry back into the maceration chamber, enhancing the efficiency of the maceration process. Accordingly, this configuration may help with further reducing drag during outflow mode and conversely increasing backflow during retain mode.

[0028] The at least one drain may have a drain inlet, wherein the drain inlet may be located below a lowermost region of the base, and preferably wherein the drain inlet may always be open. In this manner a continuous drainage may be provided, for example with the aid of gravity, and possibility of blockages that may be caused by stagnation of the slurry may be further reduced, enhancing the efficiency of the macerator. The open drain inlet may also help to maintain a steady flow during outflow mode, even for example in the absence of a pumped drainage system coupled to the drain inlet. Compared to using a bung, plug, or valve, an always-open drain in retain mode may be preferrable. In this manner there may be no physical barrier to the slurry’s escape via the drain as in closed tank models. Instead, it may be the swirling motion of the contents and / or the collector / cutting aperture arrangement that prevents exiting of the slurry. This may facilitate a smaller volume of water exciting the maceration chamber on any given cycle, as the slurry drains slower, if at all. Consequently, the maceration chamber reaches a target volume faster. The target volume is the amount of liquid required in the hopper to catch all materials that may not naturally fall onto the impeller for maceration. The always-open drain may allow any pressure changes to equalize, preventing any build-up that could cause failure. This is not possible in closed tank systems except with a vent or similar components which may introduce additionalpoint of failure. This is because, bungs and valves require an additional system to operate or offer limited functionality. Furthermore, in a bunged system, the bung must occupy the lowest point in the hopper to be able to drain all contents. Thus, the blades are raised above the base. The water fluid level must rise to the height of the blades before full maceration can begin. This filling time is wasted. This waste may be avoided in retain mode due to the blades' positioning at the bottom of the maceration chamber.

[0029] The drain inlet may be gravity fed, and preferably may be solely gravity fed. In this manner the design may be simplified for the drainage process and thus reducing the need for additional components, improving the reliability of the macerator.

[0030] The collector may have an inlet diameter adjacent the cutting apertures that is at least twice the drain inlet diameter. This diameter refers to the defining measurement across the widest part of the collector inlet, which may have an irregular but generally circular or oblong shape. In this manner, the larger inlet diameter may aid in improved slurry collection and conveyance, reducing the risk of blockages.

[0031] The cutting apertures may extend over an arc of less than 270 degrees around the periphery of the rotor disc, and the remainder of the circumference around the periphery of the rotor disc may be without any cutting apertures, and the collector volume may be arranged around only the portion of the periphery of the rotor disc having the cutting apertures in the side wall. In this manner, the maceration process may be optimised by focusing the cutting action on a specific area. This may also allow for easier maintenance, as there is no longer a need to dis-assemble the components of the rotor disc to replace or service side wall having the plurality of cutting apertures.

[0032] The plurality of apertures may extend over an arc of less than 180 degrees, preferably less than 90 degrees, preferably approximately 60 degrees, around the periphery of the rotor disc.

[0033] By limiting the plurality of apertures to an arc of less than 180 degrees or 90 degrees, the design enables a more effective retain mode functionality. The water can be guided around and over the cutting apertures, ensuring that the slurry is adequately macerated without causing blockages. This optimal flow path reduces the likelihood of drag and promotes efficient backflow, enhancing the overall performance of the macerator.

[0034] By limiting the cutting holes to approximately one sixth of the circle, the liquid is directly captured and funnelled down to the drain. This short distance helps direct the momentum in the slurry as it passes through the cutting holes, effectively reducing the risk of debris build-up, particularly in outflow mode. This compactness not only saves space but also simplifies the maintenance process. The smaller collector volume allows for easier access to the cutting apertures, making it more convenient to service and replace components as needed, thereby reducing downtime and maintenance costs.

[0035] The base may have a recess and the rotor disc may be seated in the recess. The rotor disc may be fully within the recess. In this way, the stability and alignment of the rotor disc may be enhanced, ensuring that it operates smoothly and efficiently within the maceration chamber. The recessed rotor disc may also help to contain any splashing or turbulence within the chamber, minimising potential wear on other components. Additionally, this configuration can simplify maintenance and cleaning procedures, as the rotor disc can be easily accessed and removed when necessary.

[0036] The recess may have a recess side wall and a recess floor, and the recess side wall may be the side wall having the plurality of cutting apertures. This design may aid in the efficiency of the maceration process by ensuring that the cutting apertures are optimally positioned.

[0037] The recess floor may be inclined with respect to the base of the maceration chamber such that the recess side wall height varies around the rotor disc, and preferably the recess side wall height may be substantially zero at one edge. This inclination provides an asymmetry within the maceration chamber, thus enhancing the separation between retain and outflow modes. In retain mode, when the slurry moves non-tangentially with respect to the cutting apertures (e.g., flowing over and past the holes), the rotational movement of the impeller collides with the slurry. This action sweeps the slurry up and around the outer wall, away from and over the cutting apertures, effectively preventing slurry from exiting the maceration chamber. Conversely, in outflow mode, when the slurry moves tangentially with respect to the cutting apertures, the impeller impacts the slurry and pushes it tangentially across the face of the side wall. This movement exposes the slurry to more of the cutting apertures, promoting efficient discharge of slurry. Therefore, the inclined recess floor may facilitate more controlled and effective flow dynamics, supporting the desired operational modes. It enables thatduring retain mode, the fluid is redirected back into the maceration chamber, enhancing maceration efficiency. During outflow mode, it promotes the slurry discharge, optimizing the overall performance of the macerator.

[0038] The rotor disc may be inclined at substantially the same angle as the recess floor with respect to the base of the maceration chamber. This matching inclination may further aid in improving the efficiency of the macerator, by facilitating consistent and effective interaction between the rotor disc and the recess side wall having the plurality of cutting apertures.

[0039] The recess may have a recess geometric centre, and the base may have a base geometric centre, and the recess geometric centre may be offset with respect to the base geometric centre.

[0040] Providing an impeller arranged to rotate about an impeller axis offset from the geometric centre of the base may create an asymmetry within the maceration chamber. This asymmetry may assist in the maceration of waste by creating an asymmetric orbit of liquid slurry within the maceration chamber and / or may reduce the likelihood of waste becoming trapped and not being macerated.

[0041] The recess may be located with respect to the base such that a portion of an edge of the recess is substantially coincident with a portion of an edge of the base. This configuration promotes more efficient flow dynamics within the maceration chamber, particularly in retain mode.

[0042] In retain mode, the impeller’s action, coupled with the asymmetric geometry of the maceration chamber, prevents the free release of a large proportion of the water. The impeller’s movement forces the slurry around the outer wall, over the edge of the recess towards the portion of the edge that is coincident with the base edge, and past the cutting apertures. This arrangement provides the retain benefits of a bung, plug, or valve without needing an additional system. This effect is observed when the fluid moves non-tangentially with respect to the cutting apertures (e.g., flowing over and past the cutting apertures). In this scenario, the rotational movement of the impeller collides with the slurry and sweeps it up and around the outer wall, away from and over the cutting apertures, towards the edge of the recess that coincides with the base edge. Thisconfiguration encourages the slurry away from exiting the maceration chamber, thereby enhancing the retain mode functionality

[0043] A portion of the base adjacent the recess may define a ridge above the plurality of cutting apertures. When the slurry moves non-tangentially (i.e. with a component radially inwardly or outwardly) with respect to the cutting apertures, it flows off the ridge and over the holes. In this scenario, the rotational movement of the impeller collides with the slurry, sweeping it up and around the outer wall, away from the cutting apertures, and directing it back onto the ridge. This action effectively prevents the slurry from exiting the maceration chamber, thus enhancing the retain mode functionality. Conversely, in outflow mode, the slurry moves tangentially with respect to the cutting apertures, flowing below the ridge within the maceration chamber. The impeller impacts the fluid and pushes it tangentially across the side wall, exposing the fluid to more cutting apertures and promoting slurry discharge from the chamber. This configuration, facilitated by the ridge, may aid in efficient fluid management by directing incoming fluid from various angles away from or back into the collector depending on the desired operational mode.

[0044] The collector may comprise an deflector configured to promote slurry retention. This deflector may be located closer to the drain and configured to capture the slurry entering the collector from collector inlet portion closer to the drain side. The deflector directs fluid entering from a wider range of angles back into the collector, ensuring efficient circulation and minimizing the risk of premature drainage. Behind the deflector, a back channel may be designed to facilitate slurry discharge during outflow mode. This configuration may enable the back channel to work in conjunction with the deflector, establishing a controlled and efficient flow path for the slurry. The back channel enables that the slurry is effectively directed towards the drain during outflow mode, while the deflector aids in retaining the fluid within the collector during retain mode.

[0045] The ridge may have a tapering width which tapers to substantially zero at one end of a row of the plurality of apertures. The tapering width of the ridge, which merges and seamlessly connects the base and the recess, thus reducing turbulence sources where it is not desirable within the maceration chamber. In this manner, asymmetric orbit ofliquid slurry within the maceration chamber can be brought back into symmetry with the impeller for further maceration..

[0046] The base may be substantially elliptical and the recess in the base may be substantially circular. The elliptical shape of the base may promote the asymmetry within the maceration chamber, which is advantageous for facilitating the asymmetric orbit of liquid slurry within the maceration chamber, promoting efficiency of retain mode. The substantially circular recess may be configured to house the impeller. In this manner, the impeller can rotate smoothly and efficiently within the chamber, aiding in the thorough maceration of the material. The circular shape of the recess may complement the impeller's movements, allowing for optimal interaction between the impeller and the slurry. This configuration may enhance the cutting and maceration efficiency by ensuring that the material is consistently exposed to the cutting apertures and cutting features on the rotor disc.

[0047] The rotor disc may form a gap with the plurality of cutting apertures, wherein the gap is less than 5mm, and preferably approximately 2mm. The gap may be substantially 0 mm. This gap may enhance the cutting efficiency by optimising the distance the macerated material has to travel before being processed and drained out. This may also reduce the likelihood of blockages and ensures a smoother flow of material through the maceration chamber, thereby improving overall performance and reducing maintenance needs.

[0048] The rotor disc may have one or more cut outs around its periphery for providing a cutting action by cooperating with the plurality of cutting apertures as the rotor disc rotates. These cut outs may cooperate with the plurality of cutting apertures to enhance the cutting action as the rotor disc rotates.

[0049] The rotor disc cut outs may be formed as scallops in a peripheral edge of the rotor disc. Scallop-shaped cutouts may provide a greater surface area for the cutting action compared to, for example, a simple slit as a cut out. This increased surface area may allow for a more effective and thorough maceration of the material.

[0050] Moreover, the scalloped design may create turbulent eddies as the rotor disc rotates, which helps in breaking down the material more finely and uniformly. Theunique shape promotes better circulation and mixing of the slurry, ensuring that even the tougher, more fibrous materials are adequately processed.

[0051] Additionally, scallops may reduce the likelihood of clogging, as the rounded edges prevent material from getting stuck, unlike the sharp edges of, for example, a slit which can create blockages. This results in a smoother flow of macerated material towards the drain, enhancing the overall performance and reliability of the macerator.

[0052] The rotor disc may have a substantially conical form. The conical form of the rotor disc may aid in the effective draining of the slurry. The conical shape may facilitate effective conveyance of the slurry towards the drain, enhancing the overall flow dynamics within the maceration chamber. This design minimizes the risk of fluid retention and blockages inside the maceration chamber, thereby maintaining the performance of the macerator..

[0053] Moreover, the conical rotor disc may enhance the cutting action by providing a larger surface area for interaction with the cutting apertures or any other cutting features located on the rotor disc. The increased surface area allows for more effective maceration as the material is subjected to a greater cutting force.

[0054] Additionally, the conical design may create a centrifugal effect as the rotor disc rotates. This effect helps to distribute the macerated material more evenly, ensuring a consistent and uniform texture. The improved circulation also aids in preventing any material from settling and potentially causing blockages.

[0055] The plurality of apertures may be static with respect to the base of the maceration chamber. In this manner, the apertures may work harmoniously with the collector, promoting efficient maceration by preventing any unnecessary relative movement between the apertures and the collector that could disrupt the slurry retention or discharge depending on the desired operation mode. The stability provided by the static apertures may be preferrable in such an asymmetric design, as it may prevent the apertures from rotating and while maintaining the intended flow dynamics within the chamber as well as within the collector volume. As a result, the waste material may be processed consistently and efficiently.

[0056] In addition, static apertures may minimise wear and tear on the components, as there are fewer moving parts that can degrade over time. This can lead to a longerlifespan for the macerator and reduced maintenance requirements. The static nature of the apertures also simplifies the design and manufacturing process, thus lowering production costs of the macerator.

[0057] The impeller further comprises one or more blades extending from the rotor disc into the maceration chamber, preferably wherein the blades are fixed with respect to the rotor disc. As the rotor disc rotates, these blades may cut, shred, and macerate material more effectively by providing additional cutting surfaces that interact with the material within the chamber.

[0058] The macerator may further comprise a plurality of drains associated with the same impeller, each drain having a respective collector having a collector area which decreases in the direction away from the respective drain. In this manner, the macerated material may be evenly distributed and effectively channelled towards the drains.

[0059] As the material is processed, the decreasing collector area may facilitate a smoother flow, reducing the potential for blockages and ensuring a consistent discharge of the macerated slurry. This design may promote an optimal utilization of the impeller's cutting and shredding capabilities by maintaining a steady and uniform movement of material out of the maceration chamber.

[0060] Additionally, the multiple drains with their respective collectors may allow for a more balanced slurry distribution across the system. This may not only improve the overall reliability of the macerator but also extend its operational lifespan by minimising wear and tear on individual components.

[0061] The macerator may further comprise a plurality of the impellers, preferably wherein the plurality of impellers is two impellers each with respective sets of the cutting apertures, preferably wherein the sets of cutting apertures are arranged back-to-back. This may allow for a reduction in the size of each impellers, which in turn reduces the required motor torque for rotating the impellers. By attaching multiple impellers to a single motor via a sprocket, the mechanical efficiency of the system may be enhanced, allowing for smoother operation and reduced energy consumption.

[0062] In addition, having multiple impellers may help distribute the mechanical load more evenly across the system. This balanced load distribution may minimise wear and tear on individual components, thereby extending the operational lifespan of themacerator. The reduced strain on each impeller also means that the system can handle larger volumes of material without compromising performance.

[0063] The base may be inclined relative to the horizontal. Inclining the base relative to the horizontal provides the lowermost region of the base where liquid slurry in the maceration chamber will fall to under the effect of gravity. This may improve ease of draining liquid, optionally macerated waste, out of the maceration chamber, for example via a drain inlet..

[0064] The maceration chamber may have a side wall upstanding from the base, the maceration chamber sidewall defining a conical volume comprising an axis of rotational symmetry, and the impeller may have an axis of rotation offset from the axis of rotational symmetry of the maceration chamber, preferably the maceration chamber may be inclined relative to the vertical.

[0065] Providing a maceration chamber defined by a side wall having an axis of rotational symmetry may help to control and / or direct the movement of liquid slurry in the maceration chamber as the impeller rotates. Arranging the impeller to rotate about an impeller axis offset from the axis of rotational symmetry may create an asymmetry within the maceration chamber. This asymmetry may assist in the maceration of waste by creating an asymmetric orbit of liquid slurry within the maceration chamber and / or may reduce the likelihood of waste becoming trapped and not being macerated.

[0066] The macerator may further comprise an openable lid which together with the maceration chamber may define a maceration volume when the lid is in a closed position. The lid may be openable to provide user access to insert maceratable materials into the maceration chamber. The openable lid may have a pivotal connection to a body of the macerator..

[0067] The maceration chamber may define a maceration zone in a lower part of chamber volume, and in which the impeller may cause maceration of maceratable materials. In this manner, the maceratable materials may be guided towards the area where the cutting action is most effective, leading to a more thorough and efficient maceration process.

[0068] The macerator may be configured to process maceratable materials including incontinence briefs, pads, pans, wipes, food waste or dog waste. This may allow themacerator to handle a wide range of materials, making it suitable for various applications. The ability to process different types of materials may enable the macerator to be used in diverse settings, enhancing its utility and value across different technical fields and application environments.

[0069] A second aspect of the invention provides a method of operating a macerator according to first aspect, comprising driving the impeller in a first direction of rotation to cause material within the maceration chamber to flow in a first orbit, and driving the impeller in a second direction of rotation opposite the first direction to cause material within the maceration chamber to flow in a second orbit, whereby preferably, wherein the collector is shaped to resist the flow of slurry from passing through the cutting apertures to the at least one drain when the impeller rotates in the second direction as compared with when the impeller rotates in the first direction.

[0070] By driving the impeller in both a first and second direction of rotation, a bidirectional flow may be provided within the maceration chamber. In this manner, the desired operation mode may be set by changing the direction of rotation of the impeller.

[0071] The maceration chamber may have an openable lid, the method may comprise introducing maceratable materials into the maceration chamber when the lid is open, then closing the lid of the maceration chamber, then driving the impeller in a first direction of rotation, then driving the impeller in the second direction of rotation, then opening the lid; preferably wherein the at least one drain has a drain inlet which is always open. The lid may be openable to provide user access to insert maceratable materials into the maceration chamber. The openable lid may have a pivotal connection to a body of the macerator.BRIEF DESCRIPTION OF THE DRAWINGS

[0072] Embodiments of the invention will now be described with reference to the accompanying drawings, in which:Figure 1 shows a macerator;Figure 2 shows a sideview of the macerator of Figure 1;Figure 3 shows a schematic representation of a macerator according to a first example;Figure 4 a schematic representation of a macerator according to a second example;Figure 5 shows a schematic representation of a macerator according to a third example;Figure 6 shows a schematic representation of a macerator according to a fourth example;Figure 7 shows a schematic representation of a macerator according to a fifth example;Figure 8 shows a cross-sectional view of a portion of a macerator;Figure 9 shows a schematic representation of a portion of a macerator;Figure 10 shows a top view of a macerator base of a macerator;Figure 11 shows a schematic representation of a macerator according to a sixth example;Figure 12 shows a schematic representation of the method of operating the macerator of Figure 1.DETAILED DESCRIPTION OF EMBODIMENT(S)

[0073] Figure 1 shows a macerator 1 for macerating solids with water to produce macerated waste (which may be referred to as a slurry) which may more easily be distributed through drainage systems such as waste pipes, for example in a hospital. This process of maceration may also be referred to as processing waste. Specifically, the macerator 1 may be configured to process materials such as incontinence briefs, pads, pans, wipes or dog waste.

[0074] The maceration chamber 10, as shown in Figure 3 and Figure 4, is the primary processing area where the material is macerated. An impeller 20 is mounted in the base 12 of the maceration chamber 10. The impeller 20 includes a rotor disc 30 that rotates to macerate the material. The side wall 40 of the maceration chamber 10 includes a plurality of cutting apertures 50 extending around at least a portion of the periphery of the rotor disc 30. The maceration chamber 10 may have at least one water inlet 90. Thewater inlet 90 facilitates the entry of water into the maceration chamber 10, ensuring that the maceration process is supported by an adequate water supply.

[0075] A collector 60 is located radially outwardly from the impeller axis of rotation 22, as shown in Figure 3. The collector 60 is located beyond a plurality of the cutting apertures 50. The collector 60 has a collector volume 62 that is in fluid communication with at least one drain 70. The collector 60 is designed to convey slurry passing through the cutting apertures 50 to the drain 70. Figures 4 to 7 show different configurations of the maceration chamber 10 and its components within the macerator 1.

[0076] The collector volume 62 beyond the cutting apertures 50 defines a collector area decreasing in a circumferential direction about the impeller axis of rotation 22 away from the drain 70. In this manner, the rotational motion of the impeller 20 may actively push the slurry towards the outlet, rather than relying solely on gravity. The collector 60 may have a surface whose distance from the impeller axis of rotation 22 decreases in a circumferential direction. The collector volume 62 may extend over an arc of less than 360 degrees around the periphery of the rotor disc 30, with the drain 70 located closer to one end of the arc, as illustrated in Figures 7 and 9.

[0077] The impeller 20 is rotatable about the impeller axis of rotation 22. The impeller may be rotatable in two directions. The collector volume 62 may be configured such that the collector area decreasing in the circumferential direction about the impeller axis of rotation 22 may be biased towards a first direction of rotation of the impeller 24. The impeller may rotate in a second direction of rotation of impeller 26, opposite the first direction of rotation of the impeller 24. The decreasing collector area may be in a direction substantially aligned with the first direction of rotation of the impeller 24.

[0078] The collector 60 may have a collector inlet 66 adjacent to the cutting apertures 50. The collector may have an interior wall 68 of the collector 60 opposite the collector inlet 66. In this manner, the slurry entering from the collector inlet 66 may impact the interior wall 68 and may be guided towards the drain 70.

[0079] The collector may have a collector surface 64 located between the collector inlet 66 and the interior wall 68 of the collector 60 opposite the collector inlet 66. In this manner the slurry entering from the collector inlet 66 may impact the collector surface 64 and may be guided towards the drain 70. The collector surface 64 may be configuredfor optimum slurry transfer and with less dependency on the other design considerations that dictate the design of the collector volume 62.

[0080] The collector surface 64 or the interior wall 68 may comprise a first portion 80 at a first angular location with respect to the axis of rotation the impeller 22. The first portion 80 may form a first angle with an adjacent cutting aperture at a first angular position with respect to the axis of rotation of the impeller 22.

[0081] The interior wall or the collector surface may comprise a second portion 82. The second portion 82 may form a second angle with an adjacent cutting aperture at a second angular position with respect to the axis of the rotation of the impeller 22. The angular position of the second portion 82 may be closer to the drain 70 than the angular position of the first portion 80. The second angle may be smaller than the first angle.

[0082] As illustrated in Figure 9, the cutting apertures 50 may be unevenly arranged. The cutting apertures 50 may be uneven spaced. The uneven spacing of the cutting apertures may comprise progressively increasing or decreasing the space between the neighbouring cutting apertures over at least a portion of the arc. The cutting apertures 50 may be unevenly sized. The uneven sizing of the cutting apertures may comprise progressively increasing or decreasing the size between the neighbouring cutting apertures over at least a portion of the arc. The cutting apertures 50 may be arranged such that there is a different number of cutting apertures 50 on opposite sides of the drain 70, as illustrated in Figure 9.

[0083] As shown in Figure 6, the drain 70 may have a drain inlet 72 located below the lowermost region of the base 12. The drain inlet 72 may be always open. The drain inlet 72 may be gravity-fed. The drain inlet 72 may solely gravity fed. The collector 60 may have an inlet diameter 67 adjacent to the cutting apertures 50 that is at least twice the drain inlet diameter 73.

[0084] The cutting apertures 50 may extend over an arc of less than 270 degrees around the periphery of the rotor disc 30. The cutting apertures 50 may extend over an arc of less than 180 degrees around the periphery of the rotor disc 30. The cutting apertures 50 may extend over an arc of less than 90 degrees around the periphery of the rotor disc 30. The cutting apertures 50 may extend over an arc of approximately 60 degrees around the periphery of the rotor disc 30. The remainder of the circumference of the rotor disc30 may be without cutting apertures 50. The collector volume 62 may be arranged around only the portion of the periphery of the rotor disc 30 having the cutting apertures 50 in the side wall 40.

[0085] The base 12 of the maceration chamber 10 may have a recess 120. The rotor disc 30 may be seated in the recess 120, as shown in Figure 8. The rotor disc 30 may be fully within the recess 120. The recess 120 may have a side wall 122 with cutting apertures 50. The recess 120 may comprise a recess floor 124 which is inclined with respect to the base 12. This inclined design may help to direct macerated material towards the drain 70.

[0086] The recess floor 124 may be inclined with respect to the base 12 of the maceration chamber 10 such that recess side wall 122 may be arranged such that the height 123 of the recess side wall 122 varies around the rotor disc 30. The recess side wall 122 may have a height of substantially zero around at least a portion of the rotor disc 30.

[0087] The rotor disc 30 may be inclined at the same angle as the recess floor 124. As shown in Figure 10, the recess 120 may have a recess geometric centre 130 and the base may have a base geometric centre 140. The recess geometric centre 130 may be offset from the base geometric centre 140. This may help with creating a controlled and efficient flow path for the macerated material.

[0088] The recess 120 may be located with respect to the base 12 such that a portion of an edge of the recess 120 is substantially coincident with a portion of an edge 220 of the base 12.

[0089] Referring to Figure 8, a portion of the base 12 adjacent to the recess 120 may define a ridge 200 above the cutting apertures 50. This ridge 200 directs fluid back into the maceration zone 14, ensuring thorough maceration. Behind the ridge 200, a back channel 210 facilitates slurry exit during outflow mode. The ridge 200 may have a tapering width. The tapering width of the ridge 200 may taper to substantially zero at one end of a row of the plurality of apertures 50.

[0090] The base 12 may be substantially elliptical, i.e. up to edge 220. The recess 120 may be substantially circular. The elliptical shape of the base 12 may promote the asymmetry within the maceration chamber 10, which is advantageous for facilitatingthe asymmetric orbit of liquid slurry within the maceration chamber 10 for smooth movement and minimum turbulence.

[0091] The rotor disc 30 may form a gap 230 with the cutting apertures 50 of less than 5mm. The gap 230 may be approximately 2mm. This may facilitate a more controlled and consistent cutting action. The gap 230 may be approximately 0mm. Additionally, the gap 230 helps to maintain a smooth flow of material through the maceration chamber 10, preventing any large particles from escaping the cutting process and ensuring that all material is adequately macerated.

[0092] Referring to Figure 9, the rotor disc 30 may have cutouts 32 around its periphery. This may enhance the cutting action between the rotor disc 30 and the cutting apertures 50. The cutouts 32 may be scalloped cutouts 34. This may provide a greater surface area for cutting and reducing the likelihood of clogging. The rotor disc 30 may have a conical form, The conical form of the rotor disc 30 may facilitate effective conveyance of the slurry towards the drain 70, enhancing the overall flow dynamics within the maceration chamber 10.

[0093] The cutting apertures 50 are static with respect to the base 12, consistent and uniform maceration. In this manner, the cutting apertures 50 may work harmoniously with the collector, promoting efficient maceration by preventing any unnecessary relative movement between the cutting apertures 50 and the collector 60 that could disrupt the slurry retention or discharge depending on the desired operation mode. Alternatively, the cutting apertures 50 may be moveable with respect to the base 12.

[0094] The impeller 20 may have blades 38 extending from the rotor disc 30. The impeller 20 may have blades 38 extending into the maceration chamber 10. The blades 38 may enhance cutting action within the maceration chamber 10. The blades 38 may be strategically positioned to interact with the material within the maceration chamber 10, ensuring that the material is subjected to additional cutting surfaces as the rotor disc 30 rotates.

[0095] The blades 38 may contribute to creating turbulent flows within the maceration chamber 10. As the rotor disc 30 rotates, the blades 38 generate turbulence, which may help to mix and circulate the material. In this manner, the material may be continuouslyexposed to the cutting action of the blades 38 and the cutting apertures 50, resulting in a finer and more uniform maceration.

[0096] Additionally, the blades 38 extending from the rotor disc 30 may help to prevent blockages within the maceration chamber 10. The continuous cutting and mixing action facilitated by the blades 38 ensures that the material does not settle or accumulate in one area, reducing the likelihood of blockages and maintaining a steady flow of macerated material towards the collector 60 and the drain 70.

[0097] As shown in Figure 6, the macerator 1 may have a plurality of drains 70 with respective collectors 60, ensuring even distribution and effective channelling of macerated material. Each drain 70 may be associated with a respective collector 60. Each collector 60 may be configured to convey the macerated material from the cutting apertures 50 to the drain 70. Each collector 60 may be further configured to convey the macerated material from the cutting apertures 50 to their associated drain 70. The collectors 60 are positioned radially outwardly from the impeller axis of rotation 22 and beyond the cutting apertures 50, as illustrated in Figure 6.

[0098] The collector volume 62 of each collector 60 may be designed to decrease in a circumferential direction about the impeller axis of rotation 22 away from the respective drain 70. This configuration ensures that the macerated material is evenly distributed and effectively channelled towards the drains 70, reducing the potential for blockages and maintaining a steady flow of slurry.

[0099] The multiple drains 70 with their respective collectors 60 allow for a more balanced load distribution across the maceration system. This balanced load distribution minimizes wear and tear on individual components, thereby extending the operational lifespan of the macerator 1. The reduced strain on each drain 70 and collector 60 also means that the system can handle larger volumes of material without compromising performance.

[0100] Additionally, the multiple drains 70 and collectors 60 facilitate a smoother flow of macerated material through the maceration chamber 10. The design ensures that the material is efficiently processed and directed towards the drains 70, enhancing the overall efficiency and reliability of the macerator 1.

[0101] The macerator 1 may have multiple impellers 20 with cutting apertures 50 arranged back-to-back as shown in Figure 11. This may enhance the cutting capabilities for thorough maceration. Each impeller 20 may be mounted in the base 12 of the maceration chamber 10 and may include a rotor disc 30. The back-to-back arrangement of the cutting apertures 50 may allow for a reduction in the size of each impeller 20 and 28, which in turn reduces the required motor torque for rotating the impellers 20 and 28. By attaching multiple impellers to a single motor via a sprocket, the mechanical efficiency of the system may be enhanced, allowing for smoother operation and reduced energy consumption.

[0102] The multiple impellers 20 and 28 may work in tandem to enhance the maceration process by providing additional cutting and shredding capabilities. This configuration ensures that the material undergoes a more thorough and efficient breakdown, resulting in finer and more consistent maceration. The repeated exposure to the cutting actions of the impellers 20 and the cutting apertures 50 ensures that even the toughest materials are adequately processed and broken down.

[0103] Referring to Figures 3 and 5, the base 12 may be inclined relative to the horizontal. This may help with the efficient discharge of macerated material during outflow mode. In this manner, the lowermost region of the base 12 where liquid slurry in the maceration chamber 10 will fall to under the effect of gravity. This may improve ease of draining liquid, optionally macerated waste, out of the maceration chamber, for example via a drain inlet 72.

[0104] Referring to Figures 3 and 10, the maceration chamber 10 may have a maceration chamber side wall 18 defining a cylindrical or conical volume with an axis of rotational symmetry 16. The impeller axis of rotation 22 may be offset from the axis of rotational symmetry 16, as illustrated in Figure 8.

[0105] The macerator 1 may be a free-standing macerator, comprising a lid 2 movable between a closed position (as shown in Figure 1) and an open position (as shown in Figure 2) to provide a user access to an interior of the macerator 1. The lid 2 may be coupled to a body 4 of the macerator 1 via a pivotal connection 6. The pivotal connection 6 may comprise a simple hinge joint, and movement of the lid 2 may be manual or electrically actuated. The lid 2 may be openable to provide user access toinsert maceratable materials into the maceration chamber. The openable lid 2 may have a pivotal connection to a body of the macerator

[0106] The maceration chamber 10 may define a maceration zone 14 in the lower part of the chamber volume, where the impeller 20 causes maceration of maceratable materials 250.

[0107] The macerator 1 can be operated between an outflow mode and a retain mode. During the outflow mode, the slurry may be conveyed to the drain 70 passively with the force of gravity and / or actively, by preserving the momentum of slurry passing through the cutting apertures 50, which is generated by the rotation of the impeller 20 impacting on the slurry inside the maceration chamber 10.

[0108] In the retain mode, the slurry may enter the collector 60 at an angle such that the flow path of slurry misses the drain 70 and impacts a sloped portion of the collector 60, for example the collector surface 64 or the interior wall 68. The impact causes turbulence within the stream of slurry which creates a back pressure in the collector 60 thus filling up the collector volume 62 with slurry and promoting backflow to retain the slurry within the maceration chamber 10.

[0109] The collector inlet 66 is positioned adjacent to the cutting apertures 50 to facilitate that, once macerated, the slurry can be directed into the collector 60. This proximity minimizes the distance the slurry has to travel, reducing the risk of blockages and ensuring a continuous flow of material.

[0110] The collector surface 64 forms different angles with adjacent cutting apertures 50 at various angular positions. This design optimizes the flow of slurry towards the drain 70, reducing the likelihood of blockages. The angled surfaces help guide the slurry efficiently during the outflow mode and promote turbulence during the retain mode.

[0111] The macerator 1 is configured to process various maceratable materials 250, making it suitable for diverse applications. The method 300 of operating the macerator 1 involves driving the impeller in a first direction of rotation of the impeller 306, and in a second direction of rotation of the impeller 308. This creates a dual-directional operation of the impeller, thus facilitating a first orbit of flow 260 and a second orbit of flow 270 respectively.

[0112] The method 300 may further involve introducing maceratable materials into the maceration chamber when the lid is open 302. The method 300 may involve closing the lid of the maceration chamber 304. The method 300 may involve opening the lid 310. The method 300 may be operable in its entirety, whilst at least one drain 70 having a drain inlet 72 is always open.

[0113] Although the invention has been described above with reference to one or more preferred embodiments, it will be appreciated that various changes or modifications may be made without departing from the scope of the invention as defined in the appended claims.

Claims

27CLAIMS1. A macerator comprising:a maceration chamber; andan impeller mounted in a base of the maceration chamber, the impeller having a rotor disc and a rotary axis,wherein the maceration chamber has a side wall, the side wall having a plurality of cutting apertures extending around at least a portion of the periphery of the rotor disc, andwherein the side wall having the plurality of cutting apertures extends in the direction of the rotary axis of the impeller, anda collector having a collector volume, at least part of which is radially outwardly from an axis of rotation of the impeller and beyond a plurality of the cutting apertures,wherein the collector volume is in fluid communication with at least one drain, and the collector is arranged to convey slurry passing through the cutting apertures to the at least one drain,wherein i) the collector volume radially outwardly from the axis of rotation of the impeller beyond the cutting apertures defines a collector area which decreases in a circumferential direction about the axis of rotation of the impeller away from the at least one drain, and / orii) the collector has a surface whose distance from the axis of rotation of the impeller decreases in a circumferential direction about the axis of rotation of the impeller away from the at least one drain, and / oriii) the collector volume radially outwardly beyond the cutting apertures extends over an arc of less than 360 degrees around the periphery of the rotor disc, and wherein the drain is located closer to one end of the arc than the other end of the arc and / or wherein the cutting apertures are unevenly arranged either side of the drain between the ends of the arc.

2. A macerator according to claim 1, wherein the collector area decreases in the circumferential direction about the axis of rotation of the impeller away from the at least one drain, and wherein the impeller is rotatable in two directions, and wherein the decreasing collector area is biased towards a first direction of rotation of the impeller as compared with an opposite, second direction of rotation of the impeller, preferably wherein the decreasing collector area is in a direction substantially aligned with the impeller first direction of rotation.

3. A macerator according to claim 1 or claim 2, wherein the collector has the collector surface, and wherein the collector has a collector inlet adjacent the cutting apertures and the collector surface is a surface of an interior wall of the collector opposite the collector inlet.

4. A macerator according to claim 1 or claim 2, wherein the collector has the collector surface, and wherein the collector surface is located between a collector inlet adjacent the cutting apertures and an interior wall of the collector opposite the collector inlet.

5. A macerator according to any preceding claim, the collector has the collector surface, and wherein a first portion of the collector surface forms a first angle with an adjacent cutting aperture at a first angular position with respect to the axis of the impeller, and wherein a second portion of the collector surface forms a second angle with an adjacent cutting aperture at a second angular position with respect to the axis of the impeller closer to the drain than is the first angular location, and wherein the second angle is smaller than the first angle.

6. A macerator according to any preceding claim, wherein the uneven arrangement of the cutting apertures comprises an uneven spacing of the cutting apertures.

7. A macerator according to claim 6, wherein the uneven spacing of the cutting apertures comprises progressively increasing or decreasing the spacing between the neighbouring cutting apertures over at least a portion of the arc.

8. A macerator according to any preceding claim, wherein the uneven arrangement of the cutting apertures comprises an uneven sizing of the cutting apertures.

9. A macerator according to claim 8, wherein the uneven sizing of the cutting apertures comprises progressively increasing or decreasing the size of neighbouring cutting apertures over at least a portion of the arc.

10. A macerator according to any preceding claim, wherein the uneven arrangement of the cutting apertures comprises a different number of the cutting apertures on opposite sides of the drain.

11. A macerator according to any preceding claim, wherein the at least one drain has a drain inlet, wherein the drain inlet is located below a lowermost region of the base, and preferably wherein the drain inlet is always open.

12. A macerator according to claim 11, wherein the drain inlet is gravity fed, and preferably is solely gravity fed.

13. A macerator according to any preceding claim, wherein the collector has an inlet diameter adjacent the cutting apertures that is at least twice the drain inlet diameter.

14. A macerator according to any preceding claim, wherein the cutting apertures extend over an arc of less than 270 degrees around the periphery of the rotor disc, and the remainder of the circumference around the periphery of the rotor disc is without any cutting apertures, and wherein the collector volume is arranged around only the portion of the periphery of the rotor disc having the cutting apertures in the side wall.

15. A macerator according to claim 14, wherein the plurality of apertures extend over an arc of less than 180 degrees, preferably less than 90 degrees, preferably approximately 60 degrees, around the periphery of the rotor disc.

16. A macerator according to any preceding claim, wherein the base has a recess and the rotor disc is seated in the recess.

17. A macerator according to claim 16, wherein the rotor disc is fully within the recess.

18. A macerator according to claim 16 or claim 17, wherein the recess has a recess side wall and a recess floor, and wherein the recess side wall is the side wall having the plurality of cutting apertures.

19. A macerator according to claim 18, wherein the recess floor is inclined with respect to the base of the maceration chamber such that the recess side wall height varies around the rotor disc, preferably wherein the recess side wall height is substantially zero at one edge.

20. A macerator according to claim 19, wherein the rotor disc is inclined at substantially the same angle as the recess floor with respect to the base of the maceration chamber.

21. A macerator according to any of claims 16 to 20, wherein the recess has a recess geometric centre, and the base has a base geometric centre, and wherein the recess geometric centre is offset with respect to the base geometric centre.

22. A macerator according to claim 21, wherein the recess is located with respect to the base such that a portion of an edge of the recess is substantially coincident with a portion of an edge of the base.

23. A macerator according to any of claims 16 to 22, wherein a portion of the base adjacent the recess defines a ridge above the plurality of cutting apertures.

24. A macerator according to claim 23, wherein the ridge has a tapering width which tapers to substantially zero at one end of a row of the plurality of apertures.

25. A macerator according to any of claims 16 to 24, wherein the base is substantially elliptical and the recess in the base is substantially circular.

26. A macerator according to any preceding claim, wherein the rotor disc forms a gap with the plurality of cutting apertures, wherein the gap is less than 5mm, preferably approximately 2mm.

27. A macerator according to any preceding claim, wherein the rotor disc has one or more cut outs around its periphery for providing a cutting action by cooperating with the plurality of cutting apertures as the rotor disc rotates.

28. A macerator according to claim 27, wherein the rotor disc cut outs are formed as scallops in a peripheral edge of the rotor disc.

29. A macerator according to any preceding claim, wherein the rotor disc has a substantially conical form.3130. A macerator according to any preceding claim, wherein the plurality of apertures are static with respect to the base of the maceration chamber.

31. A macerator according to any preceding claim, wherein the impeller further comprises one or more blades extending from the rotor disc into the maceration chamber, preferably wherein the blades are fixed with respect to the rotor disc.

32. A macerator according to any preceding claim, wherein the collector area decreases in the circumferential direction about the axis of rotation of the impeller away from the at least one drain, and the macerator further comprising a plurality of drains associated with the same impeller, each drain having a respective collector having a collector area which decreases in the direction away from the respective drain.

33. A macerator according to any preceding claim, further comprising a plurality of the impellers, preferably wherein the plurality of impellers is two impellers each with respective sets of the cutting apertures, preferably wherein the sets of cutting apertures are arranged back-to-back.

34. A macerator according to any preceding claim, wherein the base is inclined relative to the horizontal.

35. A macerator according to any preceding claim, wherein the maceration chamber has a sidewall upstanding from the base, the maceration chamber sidewall defines a conical volume comprising an axis of rotational symmetry, and wherein the impeller has an axis of rotation offset from the axis of rotational symmetry the maceration chamber, preferably wherein the maceration chamber is inclined relative the vertical.

36. A macerator according to any preceding claim, further comprising an openable lid which together with the maceration chamber defines a maceration volume when the lid is in a closed position.

37. A macerator according to any preceding claim, wherein the maceration chamber defines a maceration zone in a lower part of chamber volume, and in which the impeller causes maceration of maceratable materials.

38. A macerator according to any preceding claim, wherein the macerator is configured to process maceratable materials including incontinence briefs, pads, pans, wipes, food waste or dog waste.

39. A method of operating a macerator according to any preceding claim, comprising driving the impeller in a first direction of rotation to cause material within the maceration chamber to flow in a first orbit, and driving the impeller in a second direction of rotation opposite the first direction to cause material within the maceration chamber to flow in a second orbit, whereby preferably, wherein the collector is shaped to resist the flow of slurry from passing through the cutting apertures to the at least one drain when the impeller rotates in the second direction as compared with when the impeller rotates in the first direction.

40. A method according to claim 39, wherein the maceration chamber has an openable lid, the method further comprising introducing maceratable materials into the maceration chamber when the lid is open, then closing the lid of the maceration chamber, then driving the impeller in a first direction of rotation, then driving the impeller in the second direction of rotation, then opening the lid; preferably wherein the at least one drain has a drain inlet which is always open.

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