Macerator disinfection system and method

Abstract

Macerator comprising a hopper 2, an impeller within the hopper, a lid 3 for closing the hopper 2, and one or more light sources 8 for emitting ultra-violet light into the hopper. The light source is c

Description

The present invention relates to a system and method for disinfecting a macerator and, in particular the hopper, impeller and lid of a macerator, using ultraviolet light. In a conventional macerator, disinfection is commonly achieved by chemical dosing. A concentrated amount of chemical is dispersed into the hopper during or after a maceration cycle to disinfect the surfaces that have come into contact with the material being macerated. GB2533643 provides an example of such a system. The conventional chemical disinfection process has several drawbacks, notably: regular replacement of the chemical solution; when the container solution runs out, the disinfection doesn't take place; ongoing cost associated with the regular replacement of the chemicals; export / shipping restrictions of chemicals, and expiry date of chemicals. The present invention seeks to avoid these problems by using ultra-violet light to kill bacteria and viruses that may be in the macerator. The invention provides a non-chemical means for sanitisation of the macerator, including the air space contained within the hopper, which may contain airborne pathogens. The use of ultra-violet light to kill germs is known, particularly in the context of sterilising medical or dental tools. For example WO 2004 / 031706 describes methods and apparatus for ultraviolet sterilization and GB 427113 describes a UV virus deactivation chamber. However, these methods are generally directed to sterilizing clean objects placed within specially designed sterilising chambers rather than seeking to use ultra-violet light to sterilize a chamber used for another purpose. The inside of a macerator is often wet and dirty and is therefore an unforgiving environment for light sources which can easily become obscured by the waste in the hopper. A macerator hopper is generally not designed to accommodate powerful light sources and is not designed to ensure the appropriate distribution of intense light energy inside the macerator to kill germs. Accordingly, a number of adaptations and improvements, as described herein, are required for UV sterilization to be effectively used in a macerator. According to a first aspect, a macerator comprises a hopper containing a macerator impeller for macerating waste material contained in the hopper; a lid for closing the hopper; one or more light source for emitting ultra-violet (UV) light into the hopper; and a controller to control the light source(s), wherein light from the light source(s) reaches the lid of the macerator, and a water inlet into the hopper, wherein the water inlet is configured to distribute water for cleaning the light source by directing water towards the light source. The water inlet may be controlled by a controller which admits water to the hopper to facilitate maceration of waste material during a maceration cycle. The water inlet may be configured to distribute water into the hopper for cleaning internal surfaces of the macerator by directing water towards the hopper. The water inlet may be configured to distribute water into the hopper for cleaning substantially all internal surfaces of the macerator by directing water towards the internal surfaces. The water inlet may be controlled by one or more valves and / or one or more pumps. The valves and / or pumps may be controlled by the controller. The macerator may further comprise a drain in the bottom of the hopper through which the macerated waste leaves the hopper during a maceration cycle. The controller may be configured to control the light source to emit UV light into the hopper after the maceration cycle. The light source may be configured to emit short wavelength UV-C light. The UV-C light may act to disinfect air, surfaces and water within the hopper, i.e. to sterilise the inside of the macerator hopper. The hopper may have reflective walls. The light source(s) may be positioned in the lid. The back of the lid may be hinged to the back of the hopper and two UVC LEDs may be positioned at the back of the lid and two UVC LEDs may be positioned at the front of the lid. The light source(s) may be positioned in the base or side wall of the hopper. The base of the hopper may be tapered towards a drain outlet and the light source(s) may be positioned in the tapered region. The macerator impeller and internal surfaces of the hopper may be configured to reflect the UV light to the lid of the hopper. Each light source may be covered by a transparent cover which provides water-tight separation between the light source and the macerator chamber. The macerator may further comprise a water inlet into the hopper, wherein the water inlet directs water towards the light source(s), so that it flows over the transparent cover. The transparent cover may sit in a tapered recess in an internal surface of the macerator. Each light source may have an associated heat sink in contact with an inner surface of the hopper and a water inlet may direct water towards the heat sink. The internal surfaces of the hopper, lid and macerator impeller may be made of stainless steel. The light source(s) may be only operable when the lid is closed. The controller may switch on the light source for between 10 and 20 minutes after each maceration cycle. The controller may switch on the light source for a period of 5 hours or more at a prescheduled time. The controller may pause timing of the period if the macerator lid is opened and resume timing to complete the period when the lid is reclosed. The macerator may further comprise a water cooling block associated with each light source and a pump to circulate water through the cooling block. Another aspect comprises a method for sterilising the inside of a macerator, comprising switching on one or more UV light sources to direct light into the macerator hopper and reflecting the light from the macerator impeller and internal surface of the hopper back to the lid, and distributing water into the hopper to clean the light source by directing water towards the light source. The method may further comprise distributing water into the hopper to clean internal surfaces of the macerator by directing water towards the internal surfaces. The method may further comprise performing a maceration cycle to macerate waste material contained in the hopper and allowing the macerated waste to leave the hopper through a drain, and switching on the one or more light sources to emit ultra-violet (UV) light into the macerator hopper after the maceration cycle. The methods may be performed using the macerator of the first aspect. Various embodiments of the invention will now be described by way of examples and with reference to the accompanying drawings in which: Figure 1 shows a cross section of a macerator showing an area inside the hopper where proper sterilisation has been found to be particularly important; Figure 2 shows a perspective view of a macerator including an embodiment of the present invention; Figure 3 shows a top view of the macerator of Figure 2 with the lid closed and a top panel removed to show internal features of the lid, including the positioning of light sources in the lid; Figure 4 shows a cross section of the macerator of Figures 2 and 3, showing how light from the lid is reflected around the macerator hopper in one embodiment of the present invention; Figure 5 shows a close-up cross section through a light source fitting in the lid of an embodiment of the present invention; Figure 6 shows view from below of a horizontal cross section through an alternative embodiment of a macerator, with light sources in the base of the hopper; Figure 7 shows a cross section of the macerator of Figure 6, showing how the light from one light source is distributed around the hopper; Figure 8 shows the distribution of light from one of the light sources shown in Figure 7, as it contacts the lid; Figure 9 shows how the distribution of light from six light sources in the base covers the inner surface of the lid; Figure 10 shows how the distribution of light from three light sources in the base covers the inner surface of the lid of a differently shaped hopper; Figure 11 shows a close-up cross section through a light source fitting in the hopper wall of an embodiment of the present invention; and Figure 12 is a flow chart showing two modes of operation of an embodiment of the present invention. Figure 1 shows an area inside the hopper 2 that has been identified as the user interaction area 20. This is the area inside the macerator hopper 2 that a user is most likely to touch or come into contact with. In particular, it may include the inside surface of the hopper lid 3 which is easy for a user to accidentally touch when the lid is open. Importantly, the user interaction area 20 includes an air volume under the lid, which may be disrupted when the lid 3 is opened, allowing suspended water droplets and other particles, which may contain pathogens, to circulate near the open lid 3 and possibly settle on a user. It may also include the top region of the hopper wall which may be accidentally touched when loading the hopper 2. Although all areas inside the hopper 2 should be sterilised, one or more of these areas is the focus in terms of user health and in terms of the present invention. Figures 2 shows an example of a macerator unit 1 comprising a hopper 2 with a lid 3. The hopper 2 is essentially cylindrical and the lid 3 is essentially circular. The side walls of the hopper are substantially vertical. The lid 3 may have an internal and an external wall with space between to accommodate ancillary components of the macerator unit 1 such as locks, actuators, pumps, etc. The inner wall panel of the lid 3 may be curved and is preferably in the form or a spherical dome, which is preferably reflective of UV light. The lid 3 is connected to the top of the hopper 2, preferably by a hinge at the back of the unit. The lid 3 provides a water-tight seal to prevent waste leaking from the hopper 2 during maceration. The lid 3 may be opened by operation of a foot pedal 4 to avoid the need for an operator to use their hands to open the lid 3. The lid 3 may also be closed by operation of the foot pedal or by pressing the lid 3 itself down. The macerator unit 1 has a water inlet 5 controlled by a controller which admits water to the hopper 2 to facilitate pulping of solid material such as cardboard during a maceration cycle. The water inlet 5 may be positioned in the lid 3. The water inlet 5 may comprise a spray inlet in the centre of the lid 3 which provides a curtain of water around the whole internal surface of the hopper. One embodiment comprises a spray inlet at the highest point of the inner wall of the lid 3, distributing water in all directions around the lid 3, with water then running down the hopper walls. This helps to ensure that the internal surfaces of the macerator are self-cleaning. The water inlet 5 is controlled by one or more valves and / or one or more pumps which are in turn controlled by the controller, preferably according to a predetermined maceration cycle. The macerator unit 1 also has a drain in the bottom of the hopper 2 through which the macerated waste leaves the hopper 2 during the maceration cycle. The base of the hopper 2 may be tapered (for example, conical) to direct the contents of the hopper 2 towards the drain. A drain valve may be operated by the controller, preferably according to a predetermined maceration cycle. The macerator unit 1 also has a macerator impeller 6 inside the hopper 3, which has blades 7 on its top surface for pulping the contents of the hopper 2. The impeller 6 may also have blades or other profiling around its circumference to assist in the maceration process. The top surface of the impeller 6 may be reflective to UV light. It may be made from metal, such as steel, or another reflective material. The top of the impeller 6 may be shaped and / or contoured to reflect the light in a predetermined direction and, in particular, towards the lid 3 of the maceration unit 1. For example, the impeller 6, and particularly the hub portion of the impeller 6, may be dome shaped to direct incident light. The impeller may be frustoconical or in the form of a spherical dome or spherical cap. The impeller 6 spins as directed by the controller, preferably according to a predetermined maceration cycle. The macerator unit 1 has one or more light sources 8 which illuminate the interior of the hopper 2. In one embodiment, the light sources 8 are positioned in the lid 3 of the macerator unit 1. The light sources 8 may be positioned towards the edge of the lid. They may be on the circumference of an imaginary circle which may be concentric with the lid and would have a smaller diameter than the lid. In one embodiment, four light sources 8 are used and are positioned as shown in Figure 3, with two at the back, near the hinge of the lid 3 and two at the front, near the opening side of the lid 3. The positioning of the light sources 8 contributes to ensuring that the light reaches all areas inside the hopper and particularly that it is reflected back to the user interaction area 20 with the desired intensity. The light sources in the lid 3 are generally directed down from the lid into the hopper 2. They are preferably oriented to direct light diagonally down and across the hopper chamber to endure that reflections reach all areas inside the chamber. The angle is preferably towards the central axis of the hopper. The light may be directed perpendicular to the curved internal surface of the lid 3. The light sources 8 are preferably light emitting diodes (LEDs) and preferably emit ultraviolet light. They are preferably germicidal LEDs each with sufficient power to kill germs. In the embodiment shown, four lOOmW LEDS with a 1.5mm chip diameter are used. The LEDs may emit short wavelength UV-C light, which is a known disinfectant for air, surfaces and water. The wavelength of the LEDs is preferably between 100 and 380nm and, in one embodiment is specified as 265nm-275nm. The LEDs may have a wide beam angle, such as 120 degrees. Each LED 8 is set on a circuit board and forms part of a LED unit comprising a holder 9 including a heat sink 10, and a transparent cover or lens 11 to focus and protect the LED. Each LED unit may also include a water-cooling block 12 and clamping plates 13. The holder 9 is bonded to the top side of the inner wall panel of the lid 3. The lens 11 may be flat and is preferably slightly recessed into the inner wall of the lid 3. This allows water to flow over the lens 11 and improves the water flow used in the macerator for self-cleaning. The recess also helps keep the lens securely in the holder 9. The inner wall panel of the lid 3 may be curved and a sealing compound such as silicone may be used to ensure a watertight seal between the lens 11 and the inner wall panel of the lid 3. Contouring of the inner wall of the lid 3 may also improve the lens seal. Using LEDs for the light source(s) is advantageous as they have a long lifetime and so do not need frequent replacement. They require less energy than alternative UV light sources providing the same light intensity. The internal surfaces of the hopper 2, lid 3 and impeller 6 reflect light from the light source 8. The whole of each internal surface may be reflective or only certain parts may be reflective. For example, the impeller blades 7 may not be reflective, or part of the hopper wall may not be reflective. Non-reflective areas may be heated by the incident light, which may itself assist in disinfecting certain parts of the macerator. The reflective parts are preferably made a shiny material such as a metal, such as steel or aluminium. A matt / glossy 2B cold roll finish on stainless steel has been found to be sufficiently reflective of UV light to provide effective sterilisation within a reasonable time. Aluminium provides significantly greater UV reflectivity and may be used for some or all internal surfaces. For example, the impeller 6 may be made of or coated with aluminium. The positioning of the light sources and the shape of the reflective inner walls of the hopper 2, and lid 3 are important for ensuring that UV light is spread to all areas inside the macerator unit 1 but particularly to the user interaction area 20. In particular, light from each light source 8 is directed down towards the base of the hopper 2. There it is reflected from the base of the hopper, or the impeller 6 back towards the lid 3, either directly or via the hopper wall. The shape of the impeller 6 causes light reflecting from near the outer edge of the impeller to travel back to the wall of the hopper 2 and on to the central area of the lid 3, as shown in Figure 4. Light hitting the impeller 6 towards the centre of the hub is reflected back to the opposite side of the lid 3, possibly via the hopper wall. Thus, although the LEDs are positioned within the lid 3 and directed into the hopper 2 the user interaction area 20 receives sufficient UV radiation to effectively disinfect it. A source of user contamination in macerators is the airborne water droplets generated during the macerator cycle that may remain in the air inside the macerator for some time after the cycle has completed and may be released to the atmosphere when the lid 3 is opened. A user is likely to carefully ensure that they do not touch the internal surface of the macerator 1 when loading it but some exposure to these water droplets is almost inevitable. UV light has the advantage of directly targeting germs or pathogens that may be in the airborne water droplets and ensuring that they are not harmful to the user. A close up of one LED and its mounting in the lid 3 is shown in Figure 4. One issue with LEDs or other types of ultra-violet light source is that they can get hot, particularly when delivering light of sufficient power to kill germs or operating for long periods of time. One solution is to use heat sinks 10, usually made of metal or another good conductor of heat. In one embodiment, these may be in thermal contact with the internal panel of the lid 3 as well as the LED board, which helps conduct the heat away. Another or an additional solution is to have the LEDs 8 water cooled. A water cooling block 12 is placed in thermal contact with each LED. The water cooling block may be clamped in position by clamping plates 13. The water cooling block contains a number of internal channels or chambers which can be connected to a source of water. Hoses can be used to connect the block 12 to a water source. In one embodiment, there is an internal cistern and pump to circulate the water. Yet another solution is to specifically direct the flow of water from the water inlet 5 across the lens 11 as part of the maceration cycle to cool or assist in cooling the light source 8. Another issue in a macerator environment is that the lens 11 of each light source unit may become covered in opaque waste material that splashes around the macerator hopper 2 during the maceration cycle. This can reduce the amount of light from the light source 8 entering the hopper 2 for disinfection purposes. It can also cause additional heating of the LEDs 8 or the cover or lens 11. In one embodiment of the present invention, the flow of water described above as part of the maceration cycle may rinse the lens 11 and help keep it clear for the passage of light. It has also been found to be advantageous to recess the lens 11 in the inner panel of the lid to reduce the build-up of waste on the lens 11 and generally improve the self-cleaning process. A chamfer, of for example 45 degree, on the recess can improve the water flow across the lens 11 and facilitate the washing off of any remining waste or dirt. It is also possible to mount one or more light sources 8 in the base or side wall of the hopper 2. This may be in substitution for or in combination with light sources mounted in the lid 3. If this positioning is used, the sterilization process relies less on reflections from hub 6 and the inner walls of the hopper 2 as the lights sources 8 can be more easily directed at the user interaction area 20. Particularly for light sources positioned in the base of the hopper, the self-cleaning and cooling aspects become more important because macerated or partially macerated material tends to fall to the bottom of the hopper and is more likely to obscure a light source positioned in the base or lower side wall. In an embodiment shown in Figure 7, six light sources are evenly spaced around the base of the hopper but a different number of light sources could be used. There is a trade-off between the number of light sources 8 and the power that each light source need to provide and the cost of each light source 8 and light source mounting is also a consideration. As shown in Figure 7, each light source 8 is positioned in the base of the hopper 2. The base is tapered to join the side walls of the hopper 3 and the light sources 8 are preferably placed in this taper. The light sources are preferably close to the part of the hopper with the widest diameter as, during maceration, this tends to be the region where the water and macerated waste moves fastest around the hopper 2. The positioning thus helps to reduce the waste that may remain on the cover or lens 11 of the light sources 8. Water flow from the water inlet 5 can be directed to flow down the hopper walls when the blades 7 are not spinning and further assists in cleaning by rinsing the cover or lens 11. As well as assisting with cleaning, positioning in the tapered region of the base also helps to direct the light source 8 directly towards the user interaction area 20. The light source 8 is preferably directed so that an area of maximum light intensity falls on the inner surface of the lid 3 diametrically opposite the position of the LED, as shown in Figures 8 and 9. Some light may still be reflected from the hopper 2 wall to reach the lid. The arrangement shown, with six LEDs covers the entire user interaction area 20 with the high intensity light. The combined irradiation pattern is shown in Figure 10. An alternative arrangement with a non-circular hopper 3 and three light sources 8 is shown in Figure 11. As with other embodiments, the light sources 8 are preferably LEDs. The mounting for the LEDs in the base of the hopper is shown in Figure 11. It is substantially similar to the mountings for the LEDs in the lid 3 with substantially similar fixing (holder 9, clamping plate 13) and optional cooling features (heat sink 10, water cooling block 12). To ensure that each LED is directed correctly, it may not be mounted parallel to the base of the hopper or other internal surface in which it is positioned, as shown in Figure 11. The angle of taper in the hopper base or hopper wall is determined to ensure the best maceration. This does not necessarily allow for the LEDs to be directed towards the lid 3 of the hopper to provide direct illumination of the user interaction area 20. While reflections from the hopper wall or the impeller 6 may be used as they are when the light sources are positioned in the lid 3, an alternative is to orientate the LEDs independently to facilitate direct illumination of the hopper lid. For example, in Figure 11 the LED is directed at a more vertical angle than the tapering wall of the hopper base. This results in the space between the LED 8 and the lens 11 being an oblique conical frustrum. The side wall of this space is coated with a material that is particularly reflective of UV light, such as aluminium, to form a short light pipe and ensure that as much light as possible is transmitted through the lens 11. If the light source 8 is positioned in a near horizontal base of the macerator then, although it may be possible to illuminate the user interaction area 20 with fewer lights, the lenses will not be adequately cleaned by the water flow in the macerator 1. If the light source 8 is positioned in a wall less than 35 degrees to the vertical (such as the side wall of the hopper 3), then it is difficult to efficiently direct the light directly towards the lid 3, even using a light pipe as described above. Accordingly, for direct illumination of the user interaction area 20, placing the light sources 8 in a tapered region of the base of the hopper 2 is preferred. A controller controls the macerator unit 1 and, in particular, the UV disinfection system. One example of a control flow-chart is shown in Figure 12. In one embodiment, there are two disinfection modes. Mode 1 turns the UV-C LEDs on after each maceration cycle for 10 to 20 minutes. This is a light disinfection and, for example, a 15 minute exposure with four lOOmW LEDs arranged as shown in Figure 2 has been found to provide over 90% average disinfection. Mode 2 turns the UV-C LEDs on for a longer period, such as 4 to 6 hours. A 5 hour exposure with the same arrangement of LEDs has been found to achieve a full disinfection in accordance with BS 8628 standards. This has been found to achieve over 99.9999% average disinfection. As a safety feature, to prevent an operator being exposed to UV-C radiation, the light sources 8 may only operate when the lid 3 of the macerator 1 is closed, sealing the hopper 2. If the lid 3 is opened during a Mode 1 disinfection cycle it is abandoned and starts again after the next maceration cycle. Mode 2 is preferably arranged to begin the disinfection cycle at a time when the macerator 1 is unlikely to be used: for example, starting after 11pm, after midnight, after lam, after 2am or after 3am. If the lid 3 is opened during the full disinfection cycle, the disinfection cycle may pause and resume when the lid 3 is closed or after completion of maceration cycle. Importantly, the UV cycle does not inhibit use of the macerator 1. A disadvantage of the light source 8 always being switched off when the lid 3 is open is that it is not possible to check that it is operating by simply looking at it. This would be dangerous with a UV-C LED in any event. Accordingly, the controller may monitor the current draw of each individual light source 8 and a warning indicator signals that the light source 8 should be replaced if the current falls outside a defined range. More powerful light sources could shorten the time for disinfection cycles but would increase the risk to users of UV exposure and may increase overall power consumption. More or fewer LEDs than described above might also be used in other embodiments and some LEDs may only be turned on in certain modes. Multiple small LEDs (e.g. 4 or 6) are preferred to fewer large LEDs (e.g. 1 or 2) as the different light sources assist in evenly distributing light throughout the macerator. The two modes and LED arrangement described above are preferred as they provide a good compromise between speed, safety and power consumption. It is to be understood that any feature described in relation to one embodiment may be used alone or in combination with other features described and may also be used in combination with one or more features of one or more other embodiments, so long as technically feasible. Furthermore, equivalents and modifications not described may also be employed without departing from the scope of the invention, which is defined by the following claims.

Claims

1. A macerator comprising:a hopper containing a macerator impeller for macerating waste material contained in the hopper;a lid for closing the hopper;one or more light sources for emitting ultra-violet (UV) light into the hopper;a controller to control the light source, whereinlight from the light source reaches the lid of the macerator, anda water inlet into the hopper, whereinthe water inlet is configured to distribute water for cleaning the light source by directing water towards the light source.

2. The macerator of claim 1, wherein the water inlet is configured to distribute water into the hopper for cleaning internal surfaces of the macerator by directing water towards the hopper.

3. The macerator of claim 2, wherein the water inlet is configured to distribute water into the hopper for cleaning substantially all internal surfaces of the macerator by directing water towards the internal surfaces.

4. The macerator of any previous claim, wherein the water inlet is controlled by one or more valves and / or one or more pumps, preferably wherein the valves and / or pumps are controlled by the controller.

5. The macerator of any previous claim, further comprising a drain in the bottom of the hopper through which the macerated waste leaves the hopper during a maceration cycle, and wherein the controller is configured to control the light source to emit UV light into the hopper after the maceration cycle.

6. The macerator of any previous claim, wherein the light source is configured to emit short wavelength UV-C light.7.The macerator of any previous claim, wherein the hopper has reflective walls.

8. The macerator of any previous claim, wherein the one or more light sources are positioned in the lid.

9. The macerator of claim 8, wherein the back of the lid is hinged to the back of the hopper and two UV light emitting diode (LED) light sources are positioned at the back of the lid and two UV LED light sources are positioned at the front of the lid.

10. The macerator of any previous claim, wherein the one or more light sources are positioned in the base or side wall of the hopper.

11. The macerator of claim 10, wherein the one or more light sources are positioned in the base of the hopper, and wherein the base of the hopper is tapered towards a drain outlet and the one or more light sources are positioned in the tapered region.

12. The macerator of any previous claim, wherein the macerator impeller and internal surfaces of the hopper are configured to reflect the UV light to the lid of the hopper.

13. The macerator of any previous claim, wherein the one or more light sources are covered by a transparent cover which provides water-tight separation between the light source and the macerator chamber.

14. The macerator of claim 13, wherein the water inlet directs water towards the one or more light sources, so that it flows over the transparent cover.

15. The macerator of either claim 13 or claim 14, wherein the transparent cover sits in a tapered recess in an internal surface of the macerator.

16. The macerator of any previous claim, wherein each of the one or more light sources has an associated heat sink in contact with an inner surface of the hopper and wherein a water inlet directs water towards the heat sink.

17. The macerator of any previous claim, wherein the internal surfaces of the hopper, lid and macerator impeller are made of stainless steel.

18. The macerator of any previous claim wherein the one or more light sources are only operable when the lid is closed.

19. The macerator of any previous claim, wherein controller switches on the light source for between 10 and 20 minutes after each maceration cycle.

20. The macerator of any previous claim wherein the controller switches on the light source for a period of 5 hours or more at a prescheduled time.

21. The macerator of claim 20 wherein controller pauses timing of the period if the macerator lid is opened and resumes timing to complete the period when the lid is reclosed.

22. The macerator of any previous claim further comprising:a water cooling block associated with each of the one or more light sources; and a pump to circulate water through the cooling block.

23. A method for sterilising the inside of a macerator, comprising:switching on one or more ultra-violet (UV) light sources to direct light into the macerator hopper;reflecting the light from the macerator impeller and internal surface of the hopper back to the lid; anddistributing water into the hopper to clean the light source by directing water towards the light source.

24. A method of claim 23, further comprising: distributing water into the hopper to clean internal surfaces of the macerator by directing water towards the internal surfaces.

25. A method of claim 23 or claim 24, further comprising:performing a maceration cycle to macerate waste material contained in the hopper and allowing the macerated waste to leave the hopper through a drain; andswitching on the one or more light sources to emit UV light into the macerator hopper after the maceration cycle.

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