Discharge system and method for effluent

Abstract

Liquid discharge system 200 comprises a chamber 210 for receiving a liquid to be discharged, filter 240 and pump 220. The liquid to be discharged contains suspended solid waste material, such as micro

Description

Field The present application relates to a system and method for controlling the discharge of effluent, such as waste water from a washing machine. Background Microfibres are the most abundant form of microplastic pollution in rivers and oceans. Due to their microscopic scale, microfibers are eaten by organisms at all levels of the food chain, from plankton to top predators. The pervasiveness of microfibers in the food chain has naturally resulted in concern regarding transfer to humans, and contamination has been observed in animals such as crustaceans, molluscs and fish species destined for human consumption. Washing machines are a major source of such microfibres. The resulting effluent at the end of a wash cycle may be drained from the drum of the washing machine and subjected to various filtration processes in an attempt to remove the majority of the contaminants prior to drainage. However, while larger items of waste matter can be captured with relative ease by a filter for removal by a user, microfibers are more challenging to filter due to their small size. Furthermore, wastewater treatment plants cannot remove the millions of microfibres that pass through them every day. The microfibres that waste water treatment plants do capture are typically sprayed on fields as fertilising sludge, ultimately polluting the natural environment. Another difficulty concerning the use of a filter to reduce microfibres discharged from a washing machine is that through use, the filter will be fouled by waste materials such as microfibres. Some known filters have a capability for regeneration by removing waste materials from a filter to mitigate fouling. Nevertheless, there is continued interest in improving the removal of waste materials, especially microfibres. Summary The invention is defined in the appended claims. A discharge system for fluids is provided. The discharge system includes a chamber for receiving a liquid to be discharged, the liquid containing waste material including suspended solids. The discharge system further includes a filter configured to remove at least some of the waste material from the liquid prior to discharge of the liquid. The discharge system further includes a pump configured to transfer the liquid from the chamber to the filter for removal by the filter of at least some of the waste material from the liquid. The pump is configured to transfer the liquid to the filter at a controlled flow rate. A corresponding method for discharging fluids is also provided. Brief Description of the Drawings Examples of the invention are described below, by way of example only, with reference to the accompanying drawings in which: Figure 1 is a high-level schematic diagram of an example of a known washing machine. Figure 1A shows an example of a washing machine such as shown in Figure 1 coupled to a discharge system as disclosed herein. Figure 2 is a schematic diagram of an example of a discharge system as disclosed herein which may be used in conjunction with the washing machine of Figure 1. Figures 3A and 3B are schematic diagrams of examples of a discharge system as disclosed herein which may be used such as in conjunction with the washing machine of Figure 1 or Figure 1A. Figure 4 is schematic graph showing an example of the rate of water flow into and out of a buffer tank which is part of a discharge system as disclosed herein. Figure 5 is a flowchart illustrating in simplified form the operation of a discharge system such as depicted in Figure 2, 3A or 3B. Figure 6A is a schematic diagram of a discharge system as disclosed herein which feeds multiple sources into a shared buffer tank. Figure 6B is a schematic diagram of a discharge system as disclosed herein in which a shared buffer tank is linked to multiple pumps, each pump transferring liquid from the shared buffer tank to a respective filter. Detailed Description A typical front-loading domestic washing machine 100 is shown in Figure 1 in schematic form. A typical top-loading machine will have the axis of the drum vertical but will otherwise share many of the features of the front-loading machine 100. Other configurations of such washing machines exist, for example a top-loading washing machine having a drum which is positioned horizontally. In such a configuration, the user accesses the inside through a hatch in the drum. In a commercial washing setting, there may be further variations in the configuration of washing machines, including tunnel washers and front-loading appliances that are significantly larger than the domestic equivalent. The washing machine 100 includes a rotatable sealed drum unit 101 for receiving garments to be washed. The drum unit 101 has a perforated cylindrical rotatable drum mounted inside a static waterproof shroud. Clean water is fed into the drum 101 via a cold-water and / or hot water inlet 102. An electronic valve, under the control of a CPU 104, manages the water entering the drum 101. The inlet 102 is connected to a drawer 105 where a user can add detergent in any suitable form, such as liquid or powder. The drawer has an outlet that leads to the drum unit 101. The drum unit may include a heater under the control of the CPU 104 to heat the water to the desired wash temperature, for example up to 90 degrees Celsius. The drum is rotatable by an electric motor 106 under the control of the CPU 104 and operates at speeds typically from 5 to 1600 rpm. The drum unit can be emptied via a drain pump 108 controlled by the CPU. The drain pump is rated with a given power to produce a known pressure at its output. There is typically a pre-filter for the drain pump that may be designed to remove objects that might damage the mechanical operation of the pump. This is often referred to as a ‘penny-trap filter’. The drain pump 108 feeds into an outlet 109 which is connected to a household or industrial drain and eventually to the wastewater network. The washing machine 100 further includes a drain valve 107. This valve may be utilised, for example, to drain water from the washing machine 100 if the drain pump 108 is not operational. Figure 1A shows an example of a washing machine 100 such as shown in Figure 1 coupled to a discharge system 200 as disclosed herein. In Figure 1A the discharge system 200 is separate from the washing machine 100, but is installed and operated in conjunction with the washing machine. In other implementations, the discharge system 200 may be incorporated into the washing machine, whereby the washing machine 100 and the discharge system 200 may be integrated into a single appliance. Further information about the discharge system 200 is provided below. In some implementations the discharge system may be external to the washing machine appliance and contained in a plinth below the washing machine, which may be beneficial as an efficient use of floor space. In other implementations, such a location may not be desirable due to factors that include the weight of the washing machine, height restrictions and / or an inability to modify an existing facility. In such a circumstance, the discharge system may be located (for example) adjacent to the washing machine as shown in Figure 1A. In Figure 1A, effluent (waste water) from the washing machine 100 passes through the waste outlet 109 (see Figure 1) and then flows along pipe 109A (see Figure 1 A) into the discharge system 200. As described in more detail below, the discharge system 200 performs a filtering operation to remove waste materials from the effluent. The filtered (cleansed) water then exits the discharge system 200 and travels via pipe 199 to drain outlet 1009. The waste water from washing machine 100 may be fed along pipe 109A by a pump and / or by gravity into the discharge system 200. In the context of Figure 1A, there is expected to be at least some pumping to remove and raise the water from the level of the drum unit 101 (see Figure 1), which is approximately located in the middle of the washing machine 100, to the level of the outlet 109 (see Figure 1), which is approximately located at the top of the washing machine. Subsequent flow from the drain outlet 109 of the washing machine 100 down to the inlet pipe 109A to enter the discharge system 200 may be performed using a gravity feed or a pump feed. The waste water from the washing machine 100 flows through the discharge system 200 to filter the waste materials from the water. The cleansed effluent (water) is then fed out to pipe 199 which conveys the effluent to a drain pipe 1009. Typically, the drain pipe 1009 is part of the infrastructure of the building or room in which the washing machine and discharge system are located. In other words, the washing machine 100 and discharge system 200 may be provided with outlet pipe 199 for connection to the pipe 1009 at the time of installation. In Figure 1A, the connection between outlet pipe 199 and drain pipe 1009 generally occurs at a height corresponding approximately to the top of the washing machine 100. Typically, in such a configuration the discharge system 200 includes a pump to raise liquid from the level of the discharge system 200 to the level of the connection between the outlet pipe 199 and drain pipe 1009. In other implementations, the connection between the outlet pipe 199 and drain pipe 1009 may be at a level comparable to or below the level of the discharge system 200. In such implementations, the flow of effluent along outlet pipe 199 to drain pipe 1009 may be achieved by a gravity feed (or alternatively by a pump or by a combination of pump and gravity feed). Figures 2, 3A and 3B illustrate examples of a discharge system 200 such as shown in Figure 1A. In particular, Figure 2 depicts a discharge system 200A, Figure 3A depicts a discharge system 200B, and Figure 3B depicts a discharge system 200C. In all cases, the discharge systems 200A, 200B and 200C (also referred to generically as 200) are used to separate waste materials, such as suspended solids, from the liquid (such as water). In the particular context of washing machines 100, the fluid to be discharged from discharge system 200A-200C generally comprises water and the filter is configured to remove waste material such as microfibres or other suspended solids from the water before the water is then discharged from system 200A-200C. In Figure 2, the discharge system 200A receives waste water from a gravity or pump discharge 205. This discharge system 200A may, for example, be connected by pipe 109A to outlet 109 (see Figure 1) of the washing machine 100. In Figure 3A and Figure 3B, the discharge system 200 receives waste water from a pump discharge 205. The use of such a pump discharge 205 to convey waste water into the discharge system 200B, 200C may be based, for example, on the location and / or height of the opening for the buffer tank for receiving effluent compared (for example) to the height of the discharge system. Figure 3A and Figure 3B further show that the drain 280 from the discharge system 200B, 200C, corresponding to outlet 199 (see Figure 1A), is generally higher than the main components of the discharge system 200B, 200C. In such circumstances a pump is typically utilised to help raise water from the level of the discharge system 200B, 200C to the height of the drain 280. In this way, water may be removed from the discharge system 200B down drain 280 (analogous to the flow of water through pipe 109A to the drain pipe 1009 in Figure 1A). In contrast, the drain 280 for the discharge system 200A is located beneath the filter unit 240 etc, and hence the discharge system 200A may be emptied by a gravity flow without further pumping (although the use of further pumping is not precluded). In the examples of Figure 2, Figure 3A and Figure 3B, the discharge system 200 may be used in conjunction with an automated washing machine 100 such as illustrated in Figure 1. The discharge system 200A-200C may be supplied as a component which is installed into a washing machine at manufacture. Another possibility is that the discharge system 200A-200C is supplied as a separate component which is connected to the washing machine 100 at installation. In this latter case, the provision of the discharge system 200A-200C for operation in conjunction with washing machine 100 may be intended to have minimal impact on the overall operation of the washing machine 100 (other than the removal of the waste material as described below). Note that the discharge systems 200A, 200B, 200C shown in Figure 2, Figure 3A and Figure 3B utilise two different pipe sizes - a smaller size and a larger size. The smaller size piping shown in Figures 2, 3A and 3B is depicted using a single line, while the larger size piping shown in Figures 2, 3A and 3B is depicted using two lines in parallel. In Figure 2, the pipe from an overflow outlet 225 down through pipe junction M1 and then to drain 280 has the larger size. The remainder of the piping in Figure 2, in effect the path from the buffer tank 210 through pump 220, evacuation unit 230, and filter unit 240 to the pipe junction M1, has the smaller size. In Figures 3A and 3B, the pipe from overflow outlet 225 to pipe junction N1 (via one-way valve 276) and then the piping to drain 280 has the larger size. The remainder of the piping in Figure 3A and Figure 3B, in effect the path from buffer tank 210 through pump 220, evacuation unit 230, and filter unit 240 to the pipe junction N1, has the smaller size. In general terms, the smaller pipe size is intended for normal operation of the discharge systems 200A, 200B, in particular the path for liquid provided from the pump 220. The larger pipe size is to accommodate the flow of liquid into the discharge system. The use of the buffer tank 210 and pump 220 may smooth the higher flows received into the discharge system 200 (as described in more detail below), so that the narrower piping may be used for conveying the effluent from pump 220 to the filter unit 240. This use of narrower piping may, for example, allow a more compact design for the discharge unit 200. In some cases, such as when the buffer tank 210 becomes (nearly) full, this flow received into the buffer tank 210 may be directed through the overflow outlet 225 of the buffer tank 210 to the drain 280. With particular focus now on the discharge system 205A shown in Figure 2, this shows a discharge pipe 205 which is connected from the washing machine 100 (not shown in Figure 2) into a buffer tank 210. The discharge pipe 205 may be gravity fed from the washing machine into the buffer tank 210 or the water may be pumped into the discharge pipe 205 (and hence into the buffer tank 210) from the washing machine 100. The nature of the discharge received via pipe 205, i.e. pumped or gravity fed, depends upon the design and configuration of the washing machine which is connected to the discharge system 200A of Figure 2, including the placement of the discharge system 200A relative to the washing machine 100. In any event, the buffer tank 210 accumulates water from the discharge pipe 205. There are two exit paths for water to leave the buffer tank 210. The first exit path is provided as an overflow 225, the second exit path is provided to a pump 220. In normal operation, the water leaving the buffer tank 210 follows the second exit path for most (or potentially all) of the time. The pump 220 may be provided with a pre-filter (not shown in Figure 2, but located in or close to the input to pump 220); this pre-filter is provided to remove objects that might damage the mechanical operation of the pump 220 (and so is sometimes known as a “penny-trap filter”). The second exit path is routed from the bottom of the buffer tank 210 downwards to the pump 220. Accordingly, the water from the buffer tank 210 may be gravity fed to the pump 220, although this flow from the buffer tank 210 to the pump 220 may also be achieved (or supplemented) by the pump action of the pump 220. The pump 220 drives water firstly through an evacuation unit 230 and then through a filter assembly 240 before returning the water to a pipe junction M1 to exit the discharge system 200A via drain 280. In particular, the pump 220 may be used to help impel liquid through the filter unit 240 at a controlled flow rate and / or pressure as described in more detail below. The overflow pipe 225 is provided in case of some issue with the operation of the pump 220 or other component of the discharge system 200A. For example, the overflow pipe 225 may empty automatically via pipe junction M1 to the drain 280 if the buffer tank 210 is being rapidly filled from the discharge pipe 205, compared with the rate that the pump 220 is emptying the buffer tank 210. Such a situation may occur, for example, if the pump 220 has some misfunction, so that it is not operating at full capacity (or potentially not operating at all). In this case, water will build up in the buffer tank 210 before eventually reaching, and then emptying through, the overflow facility 225. Another situation in which the overflow facility 225 may be relevant is if there is some partial or complete blockage along the path from the pump 220 to the evacuation unit 230, filter unit 240, and then back again to pipe junction M1. Such a blockage may again result in a buildup of water in the buffer tank 210, which then acts as above to discharge through the overflow facility 225. For example, with the buffer tank 210 located upstream of the filter 240, the overflow outflow 225 may be used to bypass the filter unit 240 to mitigate flow resistance experienced by equipment upstream of the discharge system 200. As mentioned above, the pipe connection from the overflow outlet 225 to the drain 280 (via pipe junction M1) may be larger, i.e. has a greater diameter and hence greater maximum flow rate, than the route of water from pump 220 to the evacuation assembly (unit) 230, then to the filter assembly (unit) 240, before returning to pipe junction M1. For such a case, the flow capacity of the overflow outlet 225 may be configured to match or exceed the flow capacity of the gravity or pump feed 205 into the discharge system 200A. Such matching of flow capacity would render the presence of a discharge system 200A largely transparent to the washing machine 100 or other upstream device to which the discharge system 200 is connected. Thus if the discharge system 200A were to be absent from the washing machine 100, the effluent from the washing machine would generally flow directly along a pipe from the gravity or pump outlet 205 to the drain 280. Substantially the same flow is experienced by any water which exits the buffer tank 210 via overflow outlet 225, such that the presence of discharge system 200A may be largely transparent to the washing machine 100 as mentioned above. Accordingly, the overflow path may allow fluid to bypass the filter 240 and flow directly to the drain 280 of the discharge system 200. This overflow operation may be facilitated by a pipe junction such as M1 which may include a valve. This valve may be electronically controlled, manually controlled and / or may operate as a passive valve that opens at a predetermined pressure threshold (or in any other desired configuration). The buffer tank 210 may be fitted with a pump (not shown in Figure 2) to support this overflow operation. A further possibility is for an additional output from pump 220 to be routed to pipe junction M1 (rather than to evacuation unit 230). In this case, the pump 220 may be configured to output water (or other effluent) directly to drain 280, i.e. bypassing the evacuation unit 230 and the filter unit 240. Such a bypass may be utilised in various situations, for example, if the buffer tank is about to overflow, or to allow the filter unit 240 to perform a regeneration operation. The buffer tank 210 is shown in Figure 2 with a rectangular shape and a flat bottom. However, in other discharge systems 200 the buffer tank may be provided with a different implementation. For example, the profile of the buffer tank may be adjusted to better support the flow of waste water from the buffer tank 210 to the pump 220. In some implementations, the buffer tank 210 may be provided with a slanted or conical base. The use of such a profile for the buffer tank may help to reduce sedimentation (in which suspended solids sink to the floor of the buffer tank 210) and / or generally improve the passage of waste water through the discharge system 200. As shown in Figure 2, in normal operation the water from pump 220 enters the evacuation facility (unit) 230 and passes through the one-way valve 236 and junction pipe M2 contained therein, with the water then exiting the evacuation unit 230 to the filter assembly 240. The evacuation unit 230 also includes an air vent 235 which is connected to the junction pipe M2. The air vent 235 acts as a one-way valve which only allows air to flow into the discharge system 200 through the air-vent 235 (rather than allowing any water or air to flow out of the discharge system 200 via air-vent 235). Accordingly, all the water entering the evacuation facility 230 is impelled by the pump 220 to travel through the evacuation facility 230 to arrive at the filter assembly (unit) 240. Further operation of the evacuation facility 230 is described below. The general design of the filter assembly is to receive water into an outer portion of the filter assembly 240. The filter assembly further includes a filter mesh 245 which typically has a circular (annular) shape but may also be made of another shape such as conical, or a planar surface that is either flat or slanted. The water is driven by pump 220 to pass through the filter mesh 245 in a radially inward direction to reach a central portion of the filter assembly. This central portion of the filter assembly is indicated in Figure 2 as regen 248 (short for regeneration facility 248). Note however that the regeneration facility 248 is generally not involved in the primary (normal) operation of the filter assembly 240, whereby water (or any other suitable liquid) is passed through the filter assembly 240 to remove waste materials which are filtered out of the water by the filter mesh 245. The water that passes through the mesh 245 falls into sump 265 before exiting the filter assembly under pressure from the pump 220. This water then travels along the pipe to the pipe junction M1, prior to being discharged from the discharge system 200A via drain 280. Depending on the level of water output from the washing machine 100, all the received water may have passed out of the bottom of the buffer tank 210. This water is then sent by pump 220 around the path including the evacuation assembly 230 and the filter assembly 240 to exit through the drain 280. In such circumstances, pump 220 generally then switches off (until further water is received into the buffer tank 210). In this situation with the buffer tank 210 empty, the discharge system 200A likewise empties of water. This draining of the discharge system is supported by the air vent 235, which allows external air to be drawn in through air vent 235 as a replacement for water exiting the discharge system 200A. Therefore the remaining water in the discharge system 200A flows through the filter unit 240 to the junction pipe M1, and then flows out of the discharge system 200A through drain 280. This movement is driven by gravity, since the air vent 235 for receiving air input is higher than the drain 280 as shown in Figure 2 through which the water departs. The air received through air vent 235 therefore acts to fill the space vacated by water exiting via drain 280. Note that the presence of one-way valve 235 prevents water from flowing in the reverse direction back to the pump 220 (rather than exiting via drain 280). Furthermore, a user may sometimes want to access the inside of the discharge system 200A such as to remove waste material that has accumulated on the filter mesh 245 - for example, because the filter unit 240 includes some accumulated waster material which has resisted removal by the normal filter regeneration procedure of regeneration facility 248. In such a situation, it may be easier for the user to remove a component such as the filter mesh which has been dried by air which entered through air vent 235 (rather than having to handle the filter mesh and captured material when still wet and possibly dripping). As mentioned above, the filter assembly 240 includes a regeneration facility 248 which cooperates with pump 260 and tube 268 to help maintain the cleanliness and operational status of the filter mesh 245. It will be appreciated that in the absence of such regeneration, the filter mesh 245 may clog up more quickly with waste materials filtered from the water, and this can reduce the overall efficacy of the filter assembly 240 and result in the filter becoming blocked or fouled more quickly (which will then reduce or prevent the flow of liquid through the filter unit 240). To reduce the risk (or delay the onset) of such blockage, the regeneration system 248 activates the pump 260, which is part of the filter assembly 240. This pump 260 obtains water from the sump 265 and passes this water through the central tube 268 to the regeneration system 248. The regeneration system 248 then sprays or pumps the water from the sump 248 through the filter mesh 245 in a radially outward direction (this is the opposite direction to the normal operation of the filter assembly in which water travels through the filter mesh 245 in an inward radial direction to remove waste materials). It will be appreciated that sending water in this reverse direction (compared to normal operation of the filter assembly 240) helps to remove any waste materials that may have accumulated on the outside of the filter mesh 245. The water used for the regeneration can then return to the sump 265 from where it can be accessed and retrieved by pump 260 for further regeneration, or else conveyed by pump 220 out of the discharge system 200A via pipe junction M1 and drain 280. In some implementations, the regeneration system 248 is activated when the pump 220 is not passing water through the discharge system 200A in the normal (forward) direction through the evacuation unit 230 and then through the filter unit 240 to the drain 280. However, other implementations may allow the regeneration system 248 to operate at the same time as the pump 220 is being used to feed water through the discharge system 200A in the normal (forward) direction, including through the evacuation unit 230 and then through the filter unit 240 to the drain 280. Figure 3A is a schematic diagram of another example of a discharge system 200B. Many operational features of discharge system 200B are the same as or very similar to counterpart features in the discharge system 200A shown in Figure 2. For the sake of conciseness, we do not repeat the full description of such shared features for the discharge system 200B, but rather make reference to the description already provided with respect to Figure 2 and discharge system 200A. For example, the filter unit 240 of discharge system 200B includes a regeneration facility 248 and is generally the same as the filter unit 240 of discharge system 200A. In addition, it will be appreciated that the examples provided in Figures 2 and 3 are intended to be illustrative rather than exhaustive, and the skilled person will be able to make modifications and adaptations according to the circumstances of any particular implementation. With this understanding, the discharge system 200B of Figure 3A includes a pump discharge unit 205 which directs waste water into buffer tank 210. The buffer tank 210 of Figure 3A is generally the same as the buffer tank 210 of Figure 2. In particular, the buffer tank 210 may be used to receive and hold (accumulate) effluent for subsequent processing to remove waste material from the effluent. The buffer tank 210 includes a connection to the pump 220 from the bottom of the buffer tank 210. Pump 220 in Figure 3A is likewise the same as pump 220 in Figure 2, and may again be at least partly fed by gravity from the buffer tank 210. The connections at the top of the buffer tank 210 are somewhat different from those shown in Figure 2. In particular, the input to the top of the buffer tank 210 receives water from a pump discharge 205 (rather than a gravity fed discharge). Furthermore, the overflow outlet 225 of buffer tank 210 of Figure 3A has different connectivity compared with the overflow outlet 225 of buffer tank 210 of Figure 2. These two changes relating to the pump discharge 205 and the overflow outlet 225 reflect the change in positioning of the drain 280 in Figure 3A (compared to the positioning of the drain 280 in Figure 2), as described in more detail below. In normal operation of the discharge system 200B, the incoming effluent for filtering is received as previously described into buffer tank 210 and then extracted from the buffer tank 210 by pump 220 and passed to the evacuation unit 230. The evacuation unit 230 of Figure 3A is similar to the evacuation unit 230 of Figure 2. In normal operation, the effluent then exits the evacuation unit 230 and passes to the filter unit 240. As already mentioned above, the filter unit 240 of discharge system 200B as shown in Figure 3A is generally the same as the filter unit 240 of discharge system 200A shown in Figure 2. The filtered water from the filter unit 240 of discharge system 200B then travels towards the drain 280 to exit the discharge system 200B. In contrast to the implementation of the discharge system 200A of Figure 2, the discharge system 200B has a raised drain 280. This raised position can be regarded as corresponding to the location of the connection between the outlet pipe 199 and the drain pipe 1009 as shown in Figure 1A. The cleansed water from filter unit 240 passes through a pump 270 and a valve 271 on route to the drain 280 in Figure 3. The pump 270 is used to raise waste water to the level of drain 280 for subsequent discharge. An example of such a pump 270 can be found in WO 2022 / 229390 (albeit for a somewhat different overall configuration). The valve 271 prevents water travelling in an opposite direction, namely from the drain 280 back towards the filter unit 240 and instead maintains a column of water from the valve 271 up towards the drain 280, even if there is a loss of power from pump 270. In a somewhat similar vein, a further valve 276 may be fitted to the overflow outlet 225 of the buffer tank 210. This valve 276 may be used to prevent return flow from drain 280 travelling back into the buffer tank 210 via overflow outlet 225. Also, in the case of normal overflow operation, namely from overflow outlet 225 to drain 280, the pump discharge 205 is able to convey water from the buffer tank 210 via overflow outlet 225 and through valve 276 and pipe junction N1 which are set as appropriate to allow the water to travel upwards to the drain 280 (impelled by the pump discharge 205). The valve 276 also acts to prevent reverse flow from the filter unit 240 passing through valve 276 to re-enter the buffer tank 210 via the overflow outlet 225 (rather than exiting the discharge system 200B via drain 280). Figure 3B is another schematic diagram of an example of a discharge system 200C as disclosed herein. Many operational features of discharge system 200C are the same as or similar to counterpart features in the discharge system 200B shown in Figure 3A. For the sake of conciseness, we do not repeat the full description of such shared features for the discharge system 200C, but rather make reference to the description already provided with respect to Figure 3A and discharge system 200B. For example, the filter unit 240 of discharge system 200C includes a regeneration facility 248 and is generally the same as the filter unit 240 of discharge system 200B. In addition, it will be appreciated that the examples provided in Figures 2, 3A and 3B are intended to be illustrative rather than exhaustive, and the skilled person will be able to make modifications and adaptations according to the circumstances of any particular implementation. A primary difference between the discharge system 200C of Figure 3B and the discharge system 200B of Figure 3A relates to the discharge through the drain 280 which is located above the discharge system 200B, 200C. As discussed above in relation to Figure 3A, for discharge system 200B, pump 270 is provided to raise the waste water from filter unit 240 up to the drain 280. In contrast, as shown in Figure 3B, discharge system 200C omits pump 270. Instead, the functionality of pump 270 of discharge system 200B is in effect incorporated into a modified evacuation system 232 for discharge system 200C which includes an air drainage tank 238. For normal operation, with waste water passing through the evacuation unit 232, the operation is generally the same as for the evacuation unit shown in Figures 2 and 3A (discharge systems 200A, 200B). However, at the end of operation of the buffer tank 210 and 220, i.e. when the flow of water from pump discharge 205 terminates, then discharge system 200C uses the air drainage tank 238 (rather than a pump 270) to drive the remaining water out of the discharge system 200C through drain 280 by pulsing the pump 220 at a controlled frequency. Note that while the pump 270 pulls through water such as from the filter unit 240 which is located above the pump 270, the evacuation unit 232 in effect uses air from above the filter unit 240 to push the remaining water out of the discharge system 200C via drain 280. An example of the implementation of such an evacuation facility with an air drainage tank can be found in PCT application PCT / IB2024 / 052303 (albeit for a somewhat different overall configuration). Existing discharge systems, whether standalone or incorporated into a washing machine 100 or the like, are generally not provided with a buffer tank 210 and pump 220 such as shown in Figures 2, 3A and 3B. In these existing systems, the gravity or pump discharge 205 may be connected directly to the filter assembly 240. However, it has been found that including a buffer tank 210 and pump 220 in a discharge system such as 200A-200C provides various benefits, such as the buffer tank 210 may provide increased flexibility in controlling the water flow through the discharge system 200. For example, if the water rate provided from the gravity or pump discharge 205 is very high, such as when a washing machine drum full of water is being emptied, the filter mesh 245 may struggle to cope fully with this high flow rate. Conversely, if the water rate provided from the gravity or pump discharge 205 is very low, this may also be detrimental for the operation of the filter assembly. The provision of the buffer tank 210 between the gravity or pump discharge 205 and the filter assembly 240 can help to avoid or at least ameliorate such issues. Accordingly, for conventional pump-drained machines, the flow rate provided by the drainage pump 205 may not be suitable for optimum performance of the filter unit 240. The combination of the buffer tank 210 and the pump 220 for the discharge system 200 disclosed herein may therefore be used, for example, to help control the flow rate to and through the filter unit 240 for good or optimum filtration. One example of such control is illustrated in Figure 4, which is a schematic graph showing an example of the rate of water flow into and out of a buffer tank 210 provided in a discharge system 200. The x-axis represents Time, while the y-axis represents Flow rate. Two curves are plotted. The first curve (dashed line) is indicated as Input, and represents the flow rate into the buffer tank 210 such as from discharge 205. This input may for example reflect periods when a washing machine 100 is pumping out effluent which is then received by the discharge system 200 (such as via pipe 109A as shown in Figure 1A). The second curve (solid line) is indicated as Output, and represents the flow rate out of the buffer tank, whereby the water or other effluent then passes through filter unit 240 to the drain 280. It will be appreciated that in a discharge system that does not include a buffer tank 210, the input flow as indicated by the Input line in Figure 4 is passed directly to the filter unit 240 (so there would be no Output flow different from the Input flow). For the sake of illustration, in Figure 4 it is assumed that the washing machine 100 produces an input which is fed to the buffer tank 210; this is depicted by the Input line of Figure 4, which starts off at zero and increases rapidly to provide a high flow level. However, the resulting peak is of relatively short duration, and the flow rate soon begins to drop quickly to a much lower input rate. The input rate as depicted by the Input line of Figure 4 then starts to increase again, albeit more slowly, to produce a second, smaller and gentler peak. Finally, the input to the buffer tank falls back from this smaller, second peak, and reduces to zero, as shown by the Input line of Figure 4. In contrast, the output flow rate out of the buffer tank 210 is depicted by the solid line marked Output. The output rate of Figure 4 is smoothed compared to the input rate discussed above. There may be a slight time-lag between variations in the input of liquid into the buffer tank and variations in the output of liquid from the buffer tank 210. In addition, the output from the buffer tank 210 may be configured to smooth at least some of the variation in flow rate level from the input as supplied to buffer tank 210 (and as illustrated by the Input and Output lines shown in Figure 4). In some respects, the buffer tank 210 may therefore be regarded as a form of low pass filter (LPF), in which some of the higher frequency variation present in the input to the buffer tank 210 is reduced or removed in order to form the output from the buffer tank 210 (again as illustrated by the Input and Output lines shown in Figure 4). The buffer tank 210 can also be regarded as a form of buffering, in that the buffer tank 210 stabilises the flow-rate (compared to the situation without the buffer tank being present). There can be one or more considerations for determining the form of the output for a given input to the buffer tank 210. For example, the filter unit 240 may perform better if the flow rate into the filter mesh 245 is above a particular threshold, shown as line B in Figure 4. If the flow rate is below this threshold, the performance of the filter unit 240 may be reduced, for example due to a relatively low pressure drop across the filter mesh 245. Conversely, Figure 4 depicts a higher threshold shown as Line A. If the flow rate is above this threshold, the performance of the filter unit 240 may again be reduced due to a relatively high pressure across the filter mesh 245. It can be seen from Figure 4 that the flow-rate of the Output line from the buffer tray 210 is generally maintained in a band between the upper and lower thresholds corresponding to Lines A and B respectively, so that the operation of the filter unit 240 remains in a satisfactory or optimal condition. As another example of the use of buffer tank 210, the filter unit may monitor the flow-rate to try and determine whether the water is still flowing efficiently through the filter mesh 245, or whether the operation of the filter mesh 245 is starting to be impacted by a buildup of waste material. In the latter case, it may be appropriate to clean the filter mesh 245 using the regeneration facility 248 to restore the desired behaviour. However, if the input flow rate has a relatively high degree of variability, such as exhibited by Input line in Figure 4, then it may become more difficult to detect when the filter mesh 245 is starting to suffer from reduced performance. In particular, it may be unclear whether a change in flow rate through the filter unit 240 is due to a variation in flow received from a washing machine 100, or whether such a change in flow rate is due to reduced performance of the filter mesh 245 caused by an accumulation of waste material in the filter mesh 245. The provision of buffer tank 210 helps to address this issue because as shown in Figure 4, the flow represented by the Output line is significantly smoothed compared to the raw input flow (corresponding to the Input line in Figure 4). In particular, the extra variation of the input flow-rate can be regarded as a form of noise in the Input line of Figure 4. Smoothing to produce the Output line of Figure 4 in effect reduces this noise, so that flow variations which are observed in the Output line of Figure 4 are more likely to represent a reduced performance in the operation of the mesh filter 245 (compared with representing a variation in the input flow rate from discharge 205). This in turn helps the discharge system 200 to determine whether a regeneration process should be performed. Figure 5 is a flowchart illustrating in simplified form the operation of a discharge system 200 such as depicted in Figures 2, 3A and 3B. In operation 510, liquid is received into a chamber (such as the buffer tank 210). The liquid is effluent and includes waste material in the form of suspended solids. These suspended solids represent a form of contaminant and are entrained in the flow of the liquid. Microfibres that have separated from clothing during a washing machine cycle form a significant component of this waste material. The discharge system 200 may incorporate one or more sensors (not shown in Figures 2, 3A and 3B) to obtain information about the liquid received into the chamber. For example, a sensor provided in the buffer tank 210 or associated with the gravity / pump discharge 205 may be used to measure the flow rate of liquid into the buffer tank 210, the presence of waste water and / or the amount of waste water currently held in the buffer tank 210. It will be appreciated that the measured flow rate of liquid into the buffer tank corresponds to the Input line (dashed) as depicted in Figure 4. As discussed above, the discharge system 200 may be integrated into a washing machine 100 or may be a separate component as shown in Figure 1A. In the former case, the discharge system 200 may already be provided with information about the received liquid, such as the input flow rate at different stages (timings) of a washing machine cycle. This information may help to optimise the operation of the discharge system for working with the washing machine 100 that incorporates the discharge system 200. In the latter case, the discharge system 200 may be designed separately from the washing machine 100, such that the discharge system is not aware of the operating parameters of the washing machine 100. In this latter case, the discharge system 200 may adopt a more generic manner of operation in conjunction with the washing machine 100. Operation 520 includes transferring the liquid from the chamber (buffer tank) 210 to the filter unit 240 using a pump 220. The rate of liquid supplied from the buffer tank 210, corresponding to the Output line of Figure 4, may be determined from a suitable control facility which regulates the operation of the pump 220 (and hence also regulates the flow rate through the discharge system 200). The control facility may include some form of processing device and may use information from one or more sensors as described above to determine a desired output rate of liquid to be supplied by the pump 220. This output rate corresponds to the Output line in Figure 4, and the processing device may control the pump to produce an output having desired properties, for example, maintaining the Output line generally within the region between lines A and B as shown in Figure 4. Operation 530 acts to remove waste material from the liquid using the filter unit 240. In other words, operation 520 transfers liquid to the filter unit 240, and operation 530 passes the liquid through the filter unit 240 to remove waste material from the liquid. The filter unit 240 in the discharge system 200 may support a regeneration function which uses a jet or stream of liquid to remove waste material from a mesh surface 245 of the filter unit 240. As described herein, the use of the buffer tank 210 and pump 220 can be configured to support and enhance the operation of the filter unit 240. For example, the control facility of the pump 220 may provide an output flow-rate, corresponding to the Output (solid) line in Figure 4, by adapting the flow-rate of the Input line of Figure 4, thereby controlling the flow-rate of liquid transferred from the pump 220 to the filter unit 240 so as to support reliable and efficient operation of the filter unit 240. In operation 540, the (filtered) liquid from the filter 240 is transferred to the drain 280 for discharge. Such a transfer is typically performed using the pump 820, but may be implemented by other means, such as another pump, or gravity. This discharge continues until the buffer tank 210 is emptied of the water that is received in operation 510, whereupon the discharge system 200 can deactivate to wait (for example) to detect the next time liquid from the washing machine 100 is received into the buffer filter 210, in which case the discharge system can then be reactivated. In some existing systems, a variation in the flow rate out from the filter unit 240 might potentially be regarded as indicative of a reduction or loss of performance by the filter unit, and so might prompt a regeneration of the filter unit 240. However, such a variation in the flow rate might instead reflect one or more changes in the level of the received input flow rate (such as the changes illustrated by the Input line of Figure 4). Accordingly, even if the discharge system 200 detects a fall in the flow rate through a filter unit 240, this may potentially be indicative of variation in the input flow-rate, rather than being indicative of a reduction or loss of performance for the filter unit 240. However, using a discharge system 200 such as shown in Figures 2, 3A and 3B helps to address the above problem. In particular, the flow rate from the pump 220 is generally known and leads to a smoothed (consistent) performance, as per the Output line of Figure 4. Since the output from the pump 220 to the filter unit has such a known and relatively consistent flow level, then a subsequent decline in the flowrate through the filter unit 240 is more likely to be due to a clogging or some other issue with the filter unit 240 (and so this may indicate that a regeneration should be performed). Accordingly, the discharge systems 200 disclosed herein generally provide an improve ability to detect filter degradation and hence provide a clearer indication of whether / when a filter regeneration 248 should be performed. In some cases, the discharge system 200 may be developed and provided separately from some apparatus which is the source of the effluent (water with waste materials) received into the buffer tank 210. In such a situation, the operating parameters of the apparatus for coupling to the buffer tank 210 may not be known (or may only be partly known) to the operator of the discharge system 200. If the level of inflow from the apparatus is not known to the operator, there may be a risk that this inflow exceeds (or possibly falls short of) the normal operating parameters of the filter unit 240 and this may potentially lead, for example, to reduced performance of the filter unit 240. In such a situation, the smoothing of the output flow-rate transferred by the pump 220 from the buffer tank 210 to the filter unit 240 (such as shown in Figure 4) decreases the risk that the filter unit is operated outside the normal operating parameters (and hence reduces the risk that the performance of the filter unit may be reduced by such operation). This smoothing effect may also be exploited in situations in which the discharge system may receive inputs from two or more sources. These inputs can be smoothed not only on an individual basis (for each input separately) but also by smoothing (averaging) across multiple inputs. Again, the result of such smoothing can be used to help retain the output flow provided to the filter unit 240 within the normal operating parameters of the filter unit 240; this should again lead to more consistent and flexible operation of the discharge system 200 (compared with discharge systems that do not have a buffer tank 210 and associated pump 220). The capacity chosen for the buffer tank 210 may vary according to the circumstances and context of any given system. For example, a buffer tank 210 intended for use with a conventional domestic washing machine 100 might be provided with a buffer tank having a volume in the range 5 to 30 litres. Typically, the capacity of a buffer tank may be in the range of 10-100% of the drum capacity of a domestic washing machine which incorporates or is configured for use with such a discharge system. (It will be understood that a larger volume provides better buffering or smoothing, but occupies more space in a house). A buffer tank 210 intended for use with a commercial washing machine might be provided with a buffer tank having a volume in the range from 8 to 120 litres. Typically, the capacity of the buffer tank may again be in the range of 10-100% of the drum capacity of a commercial washing machine which incorporates or is configured for use with such a discharge system. In some cases, the volume may be larger still, such as up to 650 litres, especially if a commercial machine is provided with more than one drain outlet and / or more than one water inlet, such as including soft and hard water inlets. Still larger discharge systems may be utilised in some large-scale industrial operations, such as water treatment and textile processing (as discussed below). Figures 6A and 6B are schematic diagrams of discharge systems 200 as disclosed herein. For ease of understanding and conciseness, these diagrams omit certain features such as one-way valves that have been described above. It will be appreciated by the skilled person that such features from the examples of Figures 2, 3A and 3B may be used as appropriate in the discharge systems 200 of Figures 6A and 6B. The implementation of Figure 6A includes source inputs 205A, 205B, 205C (205 collectively) having pump and / or gravity discharge, buffer tank 210, pump 220, filter 240 and drain 280. It can be seen that the implementation of Figure 6A therefore has multiple source inputs 205 that all share the same buffer tank 210 and in general two or more of the different source inputs may simultaneously provide input to the buffer tank 210. This sharing of one buffer tank 210 across multiple sources 205 can be regarded as a form of spatial averaging or smoothing. This spatial averaging may be used to obtain similar benefits compared to the (temporal) averaging shown in Figures 2, 3A and 3B and discussed above. For example, assuming that sources 205A, 205B, 205C are generally independent from one another, it is unlikely that all three sources are simultaneously at their peak outcome at the same time. Figure 6B is a schematic diagram of a discharge system 200 as disclosed herein in which a shared buffer tank 210 is linked to multiple downstream pumps 220A, 220B, 220C. Each pump 220A-220C is connected to a corresponding (respective) filter unit 240A, 240B, 240C and is used to transfer water or other material from the buffer tank 210 to the corresponding filter unit 240A-240C. The configuration shown in Figure 6B may be used, for example, when each of the individual filter units 240 is too small to handle the input from the source discharge 205 on an individual basis. However, by including multiple filter units in the discharge system 200 which are connected in parallel to the buffer tank 210, the liquid flow from the source input 205 can be shared over multiple individual filter units, thereby increasing the effective filtering capacity of the overall discharge system 200. Moreover, the buffer tank 210 (chamber) and pumps 220 may be equipped with suitable control devices (not shown in Figure 6B) to provide a convenient and effective mechanism for splitting the input to the buffer tank 210 across outputs to multiple respective filter units 240. For example, compared with a simple flow splitting device, the buffer tank may allow the flow from the buffer tank 210 to each of the filters 240A-240C to be individually configured (and changed with time if so desired). It will be appreciated that Figures 6A and 6B are provided by way of illustration only and other implementations may be adopted. For example, Figure 6A shows three sources of input 205A-205C but other implementations may have fewer or more sources of input. Similarly, Figure 6B shows three filter units 240A-240C but other implementations may have fewer or more filter units. A further possibility is to combine the configurations of Figures 6A and 6B to provide a discharge system which has multiple sources as per Figure 6A and multiple filter units as per Figure 6B. Another possible modification to the discharge systems described above is to provide a non-return valve at the inlet to the buffer tank 210 to prevent or reduce foam returning as a form of backflow to a washing machine 100. (Such a non-retum valve may be utilised with any of the discharge systems disclosed herein and variations thereof, for example, the discharge systems of Figures 200A-200C, as well discharge systems 200 such as shown in Figures 6A and 6B). The discharge system 200 disclosed herein is generally intended to remove suspended solids, for example, solid particulates that are entrained in a flow of liquid through a discharge system 200. Examples of such suspended solids include microfibres, microplastics, organic, sand, hair, grit and so on. The microfibres for removal may have a size in the range 5 to 250 pm, typically in the range 10 to 100 pm, and the filter mesh 245 may be provided with a suitable mesh sizing to perform the desired filtration for this size of contaminant particles. The discharge system 200 may be used in conjunction with (or possibly incorporate) one or more other types of filter system, such as a membrane bioreactor, ultrafiltration, reverse osmosis, purification, sedimentation and so on. These other forms of filter system may be intended to remove different types of contamination, such as chemical, biochemical and / or biological contamination. Note that the discharge system 200 is generally not intended to provide sedimentation (in which the solid particulates fall out of suspension from the liquid), however, discharge system 200 may be utilised in conjunction with appropriate other forms of filter, such as a sedimentation filter, if so desired. It will be appreciated that the skilled person is aware of further filtration systems, and can determine the type of filtration system(s) to provide according to the circumstances of any given implementation. Although the above description has focussed on providing a discharge system for a device such as a washing machine, the discharge system described herein may be used in other contexts. For example, a typical textile manufacturing factory may include fabric knitting, dyeing and finishing processes which are distributed across several buildings. Processes are often grouped by type, for example with all dyeing processes contained in one facility. One factory may contain several instances of each process, often arranged in banks or rows of several machines. Effluent including suspended solids, such as microfibres, salt and processing chemicals, may become entrained in water during 'wet' processes such as dyeing and finishing. This effluent is typically discharged from the process machines into a centralised effluent sewer or waste water system which combines all of the effluent from machines within the facility or building. The effluent may be discharged from the processes into the effluent sewer system by gravity, while other processes may pump effluent into the sewer (waste-water) system. In either case, the effluent then flows through the sewer system by gravity. Effluent from separate buildings at a given facility may be further combined into a single flow which passes to an Effluent Treatment Plant (ETP) for treatment The ETP may be on the factory site, or it may be a Centralised ETP (CETP) which treats effluent from several factories. The ETP generally comprises: a) Primary screening - this separates large particles from the effluent. b) Equalisation - the effluent is collected in a large tank and homogenised, enabling a constant effluent composition and flow rate through the downstream treatment stages. c) Secondary treatment - such treatment uses biological agents and chemicals to treat the chemical components of the effluent. d) Tertiary treatment (if used) - this treatment utilises advanced membrane technology to produce clean water from the effluent. Tertiary treatment is not always implemented. A discharge system which includes a filtration solution as described herein may be implemented in several locations in the process described above. Such a discharge system may be positioned locally to a machine or a bank of machines, for example, locally to a dyeing machine. Effluent from one or more processing machines may feed into a chamber (such as buffer tank 210 located in a discharge system 200). This feed may use a separate drainage connection for each machine or bank of machines (analogous to the example shown in Figure 6A), or there may be a shared (combined) connection that serves multiple machines or banks of machines The effluent from the various processing machines (such as textile processing machines) may pass into the chamber at different times and at different rates according to the usage and capacity of the machine. Accordingly, input of effluent into the chamber can vary quite considerably depending on the current discharge rate from different processing machines. As illustrated in Figure 4, the discharge system described herein having the chamber or buffer tank is able to control and smooth such variability, and this can facilitate operation of the discharge system. The effluent in such textile processing is then pumped from the chamber, for example by a pump 220, through a filtration device, such as one or more filter units 240. The output from such a filtration device is generally connected to a combined effluent sewer, and effluent then flows from the discharge system to the ETP for further treatment. In some implementations, discharge device 200 including a filtration device (such as filtration device 240) may be positioned in or close to a facility containing a number of similar processes. The combined effluent from these processes may be captured, for example at the outlet of a dye house facility. Multiple (e.g. textile or fabric) processing machines may feed into a chamber such as buffer tank 210. As mentioned above, such a feed may involve separate drainage connections or a combined drainage connection (or possibility a mix of both configurations). The processing machines then drain the effluent into the chamber at different times and at different rates (according to the usage of the different processing machines), and effluent is pumped from the chamber through a number of filtration devices having regard to the required flow rate. The outlets of the filtration devices of the discharge systems may be combined and subsequently connect to the combined effluent sewer which flows to the ETP for further treatment. As above, the use of a chamber or buffer tank 210 can help to smooth the flow rate of effluent through the discharge system 200, which in turn can facilitate overall operation of the discharge system 200 and the components therein. At the factory level, a discharge system 200 including a filter device 240 may be positioned at the outlet of the whole factory, either before the ETP, or before the ETP secondary treatment. Multiple facilities may then feed effluent into the chamber of the discharge system, either with separate drainage connections or with a combined connection (as above). Machines and facilities are configured to drain their effluent into the chamber (or potentially into a plurality of chambers) at different times and at different rates. This effluent may then be pumped (such as by pump 220) from the chamber 210 through a number of filtration devices 240 according to the required flow rate. As described above, the chamber 210 helps to smooth the flow of effluent through the discharge system 200. The outlets of the filtration devices are then combined and subsequently connect to the ETP for further treatment. The filtration devices 240 described herein may be used to remove suspended solids from effluent. Such filtration devices may be used in conjunction with other types of filtering or processing according to the particular context. For example, UV light might be utilised to nullify biological contaminants from the effluent, while chemical processing may be used to remove chemical contamination. Multiple facilities may feed into the chamber, either with separate drainage connections or with a combined connection. Machines and facilities drain effluent into the chamber at different times and at different rates, and effluent may be pumped from the chamber through a number of filtration devices according to the required flow rate. The outlets of the filtration devices may be combined and may subsequently connect to the ETP for further treatment. It will be appreciated that the flow rate through a discharge system 200 as described herein will vary according to the context of the discharge system, such as a domestic washing machine, a commercial washing machine, textile manufacturing, a waste water treatment plant, and so on. In the case of textile manufacturing (processing), a small dye machine might be around 500 litres - e.g. in the range 100 to 3000 litres. The size of a chamber might be selected to have a capacity adapted for use with the dye machine. For example, the capacity of a chamber for use with a dye machine might be in the range of 10-100% of the capacity of a dye machine. A typical flow rate from such a system for textile processing may be in the range 200 -3000 litres per minute. Accordingly, the approach described here can be utilised in a wide range of contexts, especially where there is an interest in removing microfibres from waste water and similar effluent. Examples of such contexts include machines for laundry, whether in a domestic or commercial environment; textile manufacturing facilities, and waste water treatment plants, e.g. such as for municipal sewage systems. The municipal sewage systems may in some cases be similar in layout and operation to the above-mentioned ETP from textile manufacturing facilities, and thus the provision of such a discharge system would provide similar benefits. In many cases, the supply of effluent to a discharge system may be smoothed by having multiple machines / devices which are draining at different times and different rates. Further smoothing may be achieved by a discharge system having a chamber and pump as described above (see also the smoothing of Figure 4). *** Unless the context clearly indicates to the contrary, it is specifically disclosed that the features of any independent claim and / or its associated dependent claims may be combined with the features of any other independent claim and / or any other dependent claims irrespective of whether such a combination is explicitly recited in the claims. In conclusion, while various implementations and examples have been described herein, they are provided by way of illustration and example, and many potential modifications will be apparent to the skilled person having regard to the specific circumstances of any given implementation. Accordingly, the scope of the present case should be determined from the appended claims and their equivalents.

Claims

1. A discharge system comprising:a chamber for receiving a liquid to be discharged, wherein the liquid contains waste material including suspended solids;a filter configured to remove at least some of the waste material from the liquid prior to discharge of the liquid; anda pump configured to transfer the liquid from the chamber to the filter for removal by the filter of at least some of the waste material from the liquid;wherein the pump is configured to transfer the liquid to the filter at a controlled flow rate.

2. The discharge system of claim 1, wherein the discharge system is configured to modify the flow-rate of liquid transferred to the filter based on the flow-rate of liquid received into the chamber.

3. The discharge system of claim 2, wherein the discharge system is further configured to modify the flow-rate of liquid transferred to the filter by smoothing peaks and / or dips in the flow rate of the liquid received into the chamber.

4. The discharge system of any preceding claim, wherein the chamber acts as a buffer and / or low pass filter to control the rate of fluid transfer by the pump to the filter.

5. The discharge system of any preceding claim wherein the controlled flow rate is set to provide a desired flow rate through the filter, optionally wherein the desired flow rate is specified as a range or band of desirable flow rates.

6. The discharge system of any preceding claim, wherein the controlled flow rate is set to provide a desired flow rate downstream of the filter.

7. The discharge system of any preceding claim, wherein the filter is cleaned by a backwashing system.

8. The discharge system of claim 7, wherein the controlled flow rate facilitates detection of a reduction in filter performance, whereby the backwashing system should be operated to clean the filter.

9. The discharge system of any preceding claim, wherein the controlled flow rate is configured to facilitate detection of a reduction in filter performance and to reduce or stop the transfer of liquid from the pump to the filter in response to such a detection.

10. The discharge system of any preceding claim, wherein the filter is configuredto remove microfibres from the liquid.

11. The discharge system of claim 10, wherein the filter incorporates a mesh having a size in the range 5 to 250 pm, typically in the range 10 to 100 pm; and / or wherein the mesh size may be in the range 5 to 25 pm, 25-50 pm, 50-100 pm, or 100-250 pm, or in any contiguous combination of these ranges.

12. The discharge system of any preceding claim, wherein the liquid is partly or fully fed by gravity into the chamber.

13. The discharge system of any preceding claim, wherein the discharge systemis configured to empty into a drain which is above the height of the chamber.

14. The discharge system of any preceding claim, further comprising a path from the chamber which allows liquid to be discharged into a drain without passing through the filter.

15. The discharge system of claim 14, wherein the path from the chamber provides an overflow route from the chamber to the drain, optionally wherein the discharge system is configured to use the overflow route if the filter is blocked or has reduced performance.

16. The discharge system of claim 15, wherein the overflow route uses a pipe having a larger diameter than a pipe used for pumping the effluent to the filter.

17. The discharge system of any preceding claim, wherein the discharge system further includes an air vent configured to allow the discharge system to be emptied into a drain when no further liquid is received into the chamber.

18. The discharge system of any preceding claim, further comprising: a first one-way valve to prevent flow back from the filter unit towards the pump; and / ora second one-way valve to prevent flow back from the drain to the filter unit.

19. The discharge system of any preceding claim, wherein the discharge system is intended for use with a domestic washing machine, and the chamber has a volume in the range 5 to 30 litres, or where the discharge system is intended for use with a commercial washing machine, and the chamber has a volume in the range 8 to 650 litres, optionally in the range 8 to 120 litres.

20. The discharge system of any preceding claim, wherein the discharge system is configured for use in or with a domestic or commercial washing machine, wherein the buffer tank has a capacity in the range of 10-100% of the capacity of a drum included in the domestic or commercial washing machine.

21. The discharge system of any preceding claim, wherein the discharge system is configured to receive two or more separate inputs of liquid into the chamber, optionally where the separate inputs of liquid into the chamber are simultaneous with one another.

22. The discharge system of any preceding claim, wherein the discharge system comprises multiple filters which are configured to receive liquid in parallel from the discharge system.

23. The discharge system of any preceding claim, further comprising one or more sensors, optionally wherein the one or more sensors may be used to determine the flow rate of liquid into the chamber, the presence of liquid in the chamber and / or the amount of liquid currently held in the chamber.

24. A washing machine incorporating or in combination with a discharge system of any preceding claim.

25. A textile processing facility or a sewage treatment facility incorporating or in combination with a discharge system of any preceding claim.

26. A method of operating a discharge system comprising:receiving into a chamber a liquid to be discharged, wherein the liquid contains waste material including suspended solids;removing with a filter at least some of the waste material from the liquid prior to discharge of the liquid; andtransferring with a pump the liquid from the chamber to the filter for removal by the filter of at least some of the waste material from the liquid;wherein the pump is configured to transfer the liquid to the filter at a controlled flow rate.

27. The method of operating a discharge system according to claim 26, wherein said method utilises a discharge system as defined in any of claims 1 to 23.

28. The method of claim 26 or 27, wherein the discharge system is incorporated into or used with a washing machine, a textile processing facility or a sewage treatment facility.AMENDMENTS TO THE CLAIMS HAVE BEEN FILED AS FOLLOWS:22 05 25Claims1. A discharge system comprising:5 a chamber for receiving a liquid to be discharged, wherein the liquid containswaste material including suspended solids;a filter configured to remove at least some of the waste material from theliquid prior to discharge of the liquid; anda pump configured to transfer the liquid from the chamber to the filter forio removal by the filter of at least some of the waste material from the liquid;wherein the pump is configured to transfer the liquid to the filter at a controlled flow rate, andwherein the discharge system is configured to modify the flow-rate of liquid transferred to the filter based on the flow-rate of liquid received into the chamber.

152. The discharge system of claim 1, wherein the discharge system is further configured to modify the flow-rate of liquid transferred to the filter by smoothing peaks and / or dips in the flow rate of the liquid received into the chamber.20 3. The discharge system of any preceding claim, wherein the chamber acts as abuffer and / or low pass filter to control the rate of fluid transfer by the pump to the filter.

4. The discharge system of any preceding claim wherein the controlled flow rate25 is set to provide a desired flow rate through the filter, optionally wherein the desired flow rate is specified as a range or band of desirable flow rates.

5. The discharge system of any preceding claim, wherein the controlled flow rate is set to provide a desired flow rate downstream of the filter.

306. The discharge system of any preceding claim, wherein the filter is cleaned by a backwashing system.

7. The discharge system of claim 6, wherein the controlled flow rate facilitates35 detection of a reduction in filter performance, whereby the backwashing system should be operated to clean the filter.22 05 258. The discharge system of any preceding claim, wherein the controlled flow rate is configured to facilitate detection of a reduction in filter performance and to reduce or stop the transfer of liquid from the pump to the filter in response to such a detection.

59. The discharge system of any preceding claim, wherein the filter is configured to remove microfibres from the liquid.

10. The discharge system of claim 9, wherein the filter incorporates a mesh io having a size in the range 5 to 250 pm, typically in the range 10 to 100 pm; and / or wherein the mesh size may be in the range 5 to 25 pm, 25-50 pm, 50-100 pm, or 100-250 pm, or in any contiguous combination of these ranges.

11. The discharge system of any preceding claim, wherein the liquid is partly or is fully fed by gravity into the chamber.

12. The discharge system of any preceding claim, wherein the discharge system is configured to empty into a drain which is above the height of the chamber.20 13. The discharge system of any preceding claim, further comprising a path fromthe chamber which allows liquid to be discharged into a drain without passing through the filter.

14. The discharge system of claim 13, wherein the path from the chamber25 provides an overflow route from the chamber to the drain, optionally wherein the discharge system is configured to use the overflow route if the filter is blocked or has reduced performance.

15. The discharge system of claim 14, wherein the overflow route uses a pipe so having a larger diameter than a pipe used for pumping the effluent to the filter.

16. The discharge system of any preceding claim, wherein the discharge system further includes an air vent configured to allow the discharge system to be emptied into a drain when no further liquid is received into the chamber.3517. The discharge system of any preceding claim, further comprising:22 05 25a first one-way valve to prevent flow back from the filter unit towards the pump; and / ora second one-way valve to prevent flow back from the drain to the filter unit.5 18. The discharge system of any preceding claim, wherein the discharge systemis intended for use with a domestic washing machine, and the chamber has a volume in the range 5 to 30 litres, or where the discharge system is intended for use with a commercial washing machine, and the chamber has a volume in the range 8 to 650 litres, optionally in the range 8 to 120 litres.1019. The discharge system of any preceding claim, wherein the discharge system is configured for use in or with a domestic or commercial washing machine, wherein the buffer tank has a capacity in the range of 10-100% of the capacity of a drum included in the domestic or commercial washing machine.1520. The discharge system of any preceding claim, wherein the discharge system is configured to receive two or more separate inputs of liquid into the chamber, optionally where the separate inputs of liquid into the chamber are simultaneous with one another.2021. The discharge system of any preceding claim, wherein the discharge system comprises multiple filters which are configured to receive liquid in parallel from the discharge system.25 22. The discharge system of any preceding claim, further comprising one or moresensors, optionally wherein the one or more sensors may be used to determine the flow rate of liquid into the chamber, the presence of liquid in the chamber and / or the amount of liquid currently held in the chamber.so 23. A washing machine incorporating or in combination with a discharge system of any preceding claim.

24. A textile processing facility or a sewage treatment facility incorporating or in combination with a discharge system of any preceding claim.3525. A method of operating a discharge system comprising:receiving into a chamber a liquid to be discharged, wherein the liquid contains waste material including suspended solids;removing with a filter at least some of the waste material from the liquid prior to discharge of the liquid; and5 transferring with a pump the liquid from the chamber to the filter for removalby the filter of at least some of the waste material from the liquid;wherein the pump is configured to transfer the liquid to the filter at a controlled flow rate.io 26. The method of operating a discharge system according to claim 25, wherein said method utilises a discharge system as defined in any of claims 1 to 22.

27. The method of claim 25 or 26, wherein the discharge system is incorporated into or used with a washing machine, a textile processing facility or a sewageis treatment facility.22 05 25

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