GB2606351A

GB2606351A - A separator with bypass protection

Info

Publication number: GB2606351A
Application number: GB2106280.7A
Authority: GB
Inventors: d'Orton Gibson Reuben; William Lawrance-Owen Michael; Thomas Daniel Lawrence Kettle Aiers Reuben; John Feeney Fergal; Root Adam
Original assignee: Inheriting Earth Ltd
Current assignee: Inheriting Earth Ltd
Priority date: 2021-04-30
Filing date: 2021-04-30
Publication date: 2022-11-09
Anticipated expiration: 2041-04-30
Also published as: GB202106280D0; GB2606351B

Abstract

A separator for separating microplastics from an effluent comprises a chamber 402 with an inlet 401 and an outlet 404, a sieve structure 403 forming a permeable barrier between the inlet, the sieve structure having an inlet side for unfiltered effluent and an outlet side for filtered effluent, and a bypass conduit 405 between the inlet and outlet to provide an alternative route for effluent in the event that the flow of fluid is impeded. The bypass conduit may include a pressure-activated valve 406 and may include a gravity bypass tube (figure 6) or a Pitot tube (figure 7). Alternatively, the bypass conduit may include a venturi (figure 8) and an electronically controlled valve. Preferably, the separator further comprises a filter pressure regeneration apparatus for dislodging filtered material from the sieve structure, the apparatus being activated in response to an output from a fluid level detector. A washing machine comprising the separator of the invention is also disclosed.

Description

A SEPARATOR WITH BYPASS PROTECTION BACKGROUND

Field of the Invention

The invention relates to preventing microplastics from entering the environment. In particular the invention is directed to regenerating the pressure consumption of filters for removing microplastics in effluent from any source but in particular removing microfibers from washing machine wastewater.

Description of Related Art

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. Once ingested, plastics reduce feeding efficiency (false satiation) they may damage the gut of the animal and transfer harmful additives like PCBs, pesticides, flame retardants to the animal that consumed it. Plastics consumed by animals low in the food chain also impact their predators, which consume numerous contaminated prey daily. The pervasiveness of microfibers in the food chain has naturally resulted in concern regarding their transfer to humans, and contamination has been observed in crustaceans, molluscs and fish species destined for human consumption.

Unlike microbeads, which are easily excluded from toiletries and cleaning products, microfibres are formed through damage to clothing. One third of all microplastics in the oceans come from washing of synthetic textiles. Synthetic fabrics derived from petrochemicals make up 65% of all textiles. Wear and tear caused by abrasive forces in washing machines result in the fragmentation of man-made textiles, forming hundreds of thousands of microfibres, less than 5 mm in length, which leak from homes and drainage networks into the ocean.

The vast impact of microplastics on marine ecosystems is starting to be understood. A 2019 study published in the 'Science of the Total Environment' journal found 49% of 150 fish samples from the North East Atlantic Ocean contained microplastics with evidence of this causing harm to brain, gills, and dorsal muscles. These microplastics are also passed onto people consuming fish at a rate of between 518-3078 microplastic items/year/capita.

The impact is not just being seen in fish stocks but also algae, the building blocks of life. A 2015 study published in the Aquatic Toxicology' journal demonstrated high concentrations of polystyrene particles reduced algal growth up to 45%. This should be of concern as microalgae are one of the world's largest producers of oxygen on this planet.

Wastewater treatment plants cannot remove the millions of fibres that pass through them every day. Currently, secondary level water treatment removes around 98% of the microplastics that pass through them. However, the small proportion that escapes still equates to tens of millions of fibres per treatment Furthermore, wastewater treatment plants produce a "sewage sludge" and plastic microfibers are found on discharge when released into the natural environment when the sludge is spread on agricultural land, thus microfibers make their way into the food chain, waste to energy (which can destroy fibres but release harmful gasses) or discharged into rivers or the ocean.

Current washing machine filters are designed to stop pennies and buttons breaking the washing machine pump. The filtration required to stop microfibres is less than 50 micrometers (um), which is about the width of a human hair.

It is known to provide mesh filters that stop the problem at source. However, mesh filters clog up quickly and when this happens their effectiveness drops off considerably. This causes the pressure to drop and the flow rate to reduce, which can lead to damage to pumps and other elements of the system and flooding.

Washing machines are found in domestic and commercial settings.

A typical domestic washing machine is shown in Figure 1 in schematic form. The machine 100 includes a rotatable sealed drum unit 101 for receiving garments to be washed. The sealed 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 inlet 102 connected to mains and under mains pressure of typically 1 bar. The water entering the drum 101 is managed by an electronic valve, under the control of a CPU 104. The inlet 102 is connected to a drawer 105 where liquid or powdered detergent can be added by a user. 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 to heat the water to the desired wash temperature, typically up to 90 degrees Celsius. The drum is rotatable by an electric motor 106 under the control of the CPU 104 at speeds of typically from 5 to 1600 rpm. The drum unit can be emptied via an outlet having an electronically operated drain valve 107 and a drain pump 108 both controlled by the CPU. The drain pump is rated with a given power to produce a known pressure at its output. The drain pump feeds into an outlet 109 which is connected to the household or industrial drain and eventually the wastewater network.

In use, dirty laundry is placed in the drum, and a wash cycle initiated by a user. The CPU allows cold water to flow via the drawer to mix with detergent and then on into the drum, where the water is heated. The combined water, detergent and laundry is agitated by rotating the drum. During this process, dirt and grease is released into the water and fibres from the clothing too. If the clothing is synthetic, microfibers are typically released as the clothes rub against each other. The resulting effluent at the end of the wash cycle is a mixture of debris, dirt, grease and microfibers and potentially large objects such as coins or nails left in the clothing. This effluent is then drained and pumped out of the drum at a typical rate of 2 gallons per minute. Second or third rinse cycles with clean water may be performed, resulting in effluent with less concentrated contaminants.

In a typical wash, the highest concentration of microfibers is in the range 5mm to 150 urn but shorter microfibers exist that are still harmful in the environment. If it were required to remove 99% of microfibers of all sizes down to 50um in length, a mesh with apertures of 50um would theoretically be able to achieve this. In practice however, such a mesh placed directly in the stream of effluent will clog almost immediately and the filter will become inoperable. This will create a rise in pressure consumption in the outlet and potentially damage the pump and cause flooding.

A conventional separator or filter arrangement is shown in Figure 2. An inlet 201 directs effluent into a filter housing 202, within which a sieve structure 203 is supported. The sieve structure could be a mesh or other perforated material where the mesh opening size is selected to trap particles of a required dimension. Filtered effluent passes through the sieve structure 203 to an outlet 204. The filtered waste accumulates on what is called the unfiltered side of the sieve structure, while the outlet side of the sieve structure is called the filtered side. Filter efficacy is its effectiveness at removing debris of a given size range while maintaining an acceptable flow rate and is closely related to the filter's pressure consumption. The sieve structure shown in Figure 2 will become blinded over by filtered debris rapidly, so that its pressure consumption will increase, and its efficacy decrease.

Curve 1 in Figure 3 is a measure of the effectiveness of the arrangement shown in Figure 2, given a constant flow of dirty water, with a consistent contamination level. The y-axis represents the fluid pressure, P, at the inlet 201 and it can be seen to rise gradually, then exponentially as the mesh becomes blinded over with filtrate.

In practice, the flow of effluent from a washing machine is not constant over time because a limited amount of water is used in each wash cycle. Curve 2 in Figure 3 shows how the inlet pressure varies over time where the flow of effluent stops, drains through the device and then starts again. Reductions in the pressure can be seen, as the flow stops and debris previously held against the mesh by the pressure of the flow falls away, revealing pores that allow fluid to flow through again, until they become re-blocked in the next cycle. Curve 2 demonstrates that the pressure consumption required by the conventional device increases through use, so the inlet pressure required to filter effluent eventually becomes greater than the pump is able to provide.

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If the pressure builds up too much in the filter then flooding can occur. It is an object of the invention to solve the problem of damage to property caused by a clogged filter.

SUMMARY OF THE INVENTION

In an embodiment, a separator is provided for separating microplastics from an effluent, the separator comprising: a chamber with an inlet and an outlet, a sieve structure forming a permeable barrier between the inlet and the outlet to filter the effluent, the sieve structure thus having an inlet side for unfiltered effluent and an outlet side for filtered effluent, wherein a bypass conduit is provided between the inlet and the outlet to provide an alternative route for effluent in the event that the flow of fluid is impeded.

The bypass conduit may include a pressure-activated valve.

The bypass conduit may include a gravity bypass tube.

The bypass conduit may include a series of gravity bypass tubes.

The bypass conduit may include a Pitot tube.

The bypass conduit may include a venturi.

The bypass system may include an electronically controlled valve.

The separator may further comprise a filter pressure regeneration apparatus for dislodging filtered material from the sieve structure, wherein a fluid level detector may be provided, and wherein the filter pressure regeneration apparatus may be arranged to be activated in accordance with the output from the fluid level detector.

A reservoir may be provided below the chamber and the fluid level detector may be located in the reservoir.

The fluid level detector may be a float switch.

The filter pressure regeneration apparatus may comprise a conduit and a nozzle assembly having at least one cleaning nozzle directed towards the outlet side of the sieve structure.

The chamber may be cylindrical and the sieve structure may be a coaxial cylinder within the chamber and wherein a wall may be provided to one side of the inlet such that the effluent may be guided around the sieve structure through a channel such that filtered microplastics dislodged by the wash water from the cleaning nozzle accumulates on the side of the wall away from the inlet.

A trap may be provided comprising an opening in the base of the channel to a sub-chamber, where the accumulating filtered microplastics can be collected.

The nozzle assembly may comprise a plurality of cleaning nozzles that are rotatable around the central axis of the sieve structure.

A pump may be provided in fluid communication with the outlet of the chamber.

The pump may be a water pump arranged to drain the separator.

The pump may be arranged to recirculate the filtered effluent to the conduit of the filter pressure regeneration apparatus.

A restriction may be provided in a conduit downstream from the pump, wherein the aperture of the restriction may be set to ensure that a preset amount of filtered effluent is recirculated into the filter pressure regeneration apparatus and an amount of the filtered effluent is drained.

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An air vent may be provided in a conduit between the pump and the filter pressure regeneration apparatus to introduce air into the conduit.

A second pump may be arranged to recirculate the filtered effluent to the conduit of the filter pressure regeneration apparatus.

The separator may further comprise an air pump located between the pump and the filter pressure regeneration apparatus to introduce air into the conduit and to drain the separator.

In an embodiment, a washing machine with a separator is provided.

In an embodiment, a method of operating a separator of the type described above is provided, comprising the steps of, filtering effluent through a sieve structure, allowing the effluent to bypass the sieve structure when the pressure at an inlet of the sieve structure exceeds a predetermined threshold.

The method may further comprise the step of allowing the effluent to bypass the sieve structure through a passive bypass system.

The method may further comprise the step of detecting the pressure at the inlet using a sensor and controlling an electronic valve in a bypass conduit when the pressure differential reaches the predetermined threshold.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 shows a typical domestic washing machine. Figure 2 shows a conventional separator.

s Figure 3 is a graph showing the efficacy of different types of filter assembly.

Figure 4 shows a bypass system comprising a pressure-activated valve. Figure 5 shows a bypass system comprising an upstanding tube.

Figure 6 shows a bypass system comprising a pair of upstanding tubes joined by an anti-syphon chamber.

lo Figure 7 shows a bypass system comprising a Pitot tube.

Figure 8 shows a bypass system comprising a Venturi.

Figure 9 shows an embodiment with a drain system and bypass.

Figure 10 shows a cross section of an embodiment having a pressure consumption regeneration apparatus and a bypass.

Figure 11 shows an embodiment having a cylindrical sieve structure and an array of rotating cleaning nozzles and a bypass system.

Figure 12 shows the embodiment of Figure 11 with a recirculation system. Figure 13a shows an embodiment of a separator with combined recirculation and drain pumps with a bypass system.

Figure 13b shows an alternative arrangement of the embodiment shown in Figure 13a.

Figure 14 shows an embodiment of a separator with separate recirculation and drain pumps with a bypass system.

Figure 15 shows an embodiment of a separator with a liquid recirculation 25 pump and an air drain pump, with a bypass system.

Figure 16 shows an embodiment having a bypass system operated by a float switch.

Figure 17a shows a washing machine equipped internally with an embodiment of the separator Figure 17b shows a washing machine retro-fitted externally with an embodiment of the separator.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

While the description that follows focuses on washing machines for clothes, it is to be understood that the teachings herein are not limited to use in washing machines as they are equally suited to other processing appliances, such as but not limited to driers, such as tumble driers, dyeing machines, cutting machines, recycling machines, dry cleaning machines and so on. The teachings herein could also be used in other industries in which microparticles may be generated as a result of processing of items. References to washing machines herein are therefore to be understood as comprising any similar appliance of the types contemplated herein.

The separator described herein may be installed within the appliance itself during manufacture as shown in Figure 17a, or retro-fitted externally to a 15 washing machine or other appliance, as shown in Figure 17b.

The separator system 1700 described above may be installed within a washing machine, as shown in Figure 17a. The waste from the washing machine drum connects to the inlet 1707 of the separator 1700 and the outlet of the separator connects to the waste outlet 1709. A supply of fresh water 1706 for the regeneration apparatus is shown but if the recirculation system is used then this supply is unnecessary. A separator system 1708 may be located outside a washing machine, connected to the waste water outlet of the washing machine, as shown in Figure 17b. The inlet 1709 supplies effluent into the separator 1708 and the outlet 1710 feeds into the soil pipe 1705. The embodiment shown is fitted with a drain pump to enable installation below the dotted water line in the figure, i.e. the top of the soil pipe. The embodiment shown also has a recirculation system therefore a separate supply of fresh water is not needed. The device may be connected to an electrical power supply (not shown) to operate the pump or pumps.

It will further be appreciated that the teachings herein are suited to any application which requires the removal of microplastics, including microfibers, from any effluent, including wastewater, within which such materials may be entrained.

Effluent is understood to include wastewater from the sources mentioned 5 above. It can also include the wastewater from Wastewater Treatment Plants. Effluent includes entrained dirt, detergent and micropollutants including microplastics, which include microfibers.

Figure 4 shows an embodiment of a separator unit having a bypass feature for allowing effluent to go around the filter if it becomes clogged. The separator unit has an effluent inlet 401, a housing 402 supporting a sieve structure and an outlet 404. A bypass conduit 405 links the inlet 401 to the outlet 403. A pressure-activated valve 406 is located in the conduit 405. An example valve is an X-Fragm valve. The pressure-activated valve opens when the pressure at the inlet exceeds a certain pre-set value. Therefore, if effluent backs up at the inlet because the filter is clogged, the valve will open and let effluent through to the outlet where it can safely discharge to a waste pipe.

Alternatively, the valve 406 may be of a type that can be electronically controlled. A pressure sensor that detects a pressure differential between the two sides of the sieve structure can control the valve, so that if the pressure differential reaches a predetermined level, the valve is operated and the bypass activated.

Figure 5 shows another embodiment with an alternative bypass system, where an upstanding tube 504 links the inlet 501 to the outlet 502 of a separator unit 503. The height "H" of the tube determines the pressure at which the bypass operates. A disadvantage of this system is that a significant height is required above the separator unit to fit the tube 504, which can be a problem when a washing machine is located in a confined space.

Figure 6 shows another embodiment with a further alternative bypass system, with a lower profile for fitting in confined spaces. The system comprises a pair of upstanding tubes 601a, 601b that link the inlet 602 to the outlet 603 of a separator unit 604. The tubes are connected by chamber 605. The first upstanding tube 601a empties effluent into the top of the chamber 605 at height "H". When effluent reaches the height "H" of the second tube 601b it will pass through to the outlet 603. This arrangement creates an anti-syphon and means that filtered effluent must have sufficient pressure to reach 2 x H. The above embodiments work by creating an obstruction to the flow of the effluent. This may be undesirable from the point of view of washing machine manufacturers who often stipulate that anything connected to the outlet of their machines must not cause an obstruction. Figures 7 and 8 shows a bypass system that uses the pressure of the flow of the incoming effluent to maintain an obstruction until the lowering flow rate associated with a blockage decreases. Figure 7 is a bypass system that comprises a Pitot tube in the outlet 702 from a separator 703. The Pitot tube is connected to the inlet 704 of the separator 703. While the filtered effluent is flowing out of the outlet into the Pitot tube the pressure is enough to prevent the fluid from bypassing the separator from the inlet to the outlet. When filtered effluent stops flowing out of the outlet because of a blockage in the separator, there will be no reverse pressure in the Pitot tube and the effluent will be free to flow directly from the outlet to the inlet.

Figure 8 shows a further embodiment that uses the Venturi effect to operate a bypass system. A tube 801 connects to the inlet 802 of a separator 803. A restriction 804 is provided in the tube 801. A conduit 805 is provided between the restriction and the outlet 805 of the separator 803. When the separator is operating normally, the unfiltered effluent flowing through the restriction 804 to the inlet will have a lower pressure than the filtered effluent flowing out of the outlet, so the bypass will not operate. If the separator blocks and filtered effluent stops flowing out of the outlet then the pressure against the inlet will drop and the bypass will operate.

The bypass may be used to both provide passage for effluent directly to the outlet of the device when the filter membrane becomes blocked and also when the device is opened by the user during disassembly for maintenance or emptying. The bypass is advantageous as it can be used to stop the flow of water from exiting the device through the disassembled product, which would otherwise result in a leak or flood.

Figure 9 shows an embodiment of a separator that can be fitted to a washing machine below the waterline and includes a bypass system that could be any one of the type described above. The separator includes a reservoir 903 with a sensor for detecting when there is fluid in the reservoir. A pump is provided lo that is arranged to operate when fluid is detected in the reservoir and thus the separator will always be emptied of fluid ready for emptying of filtered microplastics. The bypass system ensures that if the pump and sensor arrangement fails, the entire wash load of effluent will not back up and cause a flood. The sensor could be a float switch in the reservoir or a pressure sensor.

Figure 10 shows an embodiment of a separator having a filter pressure regeneration system and that includes a bypass system that could be any one of the type described above. It comprises an effluent inlet 1001 feeding a channel bounded by a filter housing 1002 and a sieve structure 1003. The filtered effluent exits from the separator via an outlet 1004. A cleaning nozzle 1005 is provided that is arranged to direct a cleaning jet of wash fluid towards the filtered side of the sieve structure 1003. The cleaning nozzle 1005 is connected by conduit 1006 to a supply of wash fluid. The cleaning nozzle is periodically supplied with cleaning fluid to dislodge filtered material from the unfiltered side of the sieve structure, which allows more effluent to be filtered out and thus regenerate the pressure consumption. As the waste material is dislodged, the flow of effluent carries it further away from the inlet towards the far end of the channel. The bypass system 1007 connects the inlet to the outlet. It ensures that if the regeneration system fails for some reason, the entire wash load of effluent will not back up and cause a flood.

Figure 11 shows an embodiment of a separator unit that includes a filter pressure regeneration system and a bypass system. The separator unit 1100 comprises an outer cylindrical wall 1101. In this embodiment the outer wall is transparent so that a user can see when the separator is operational and can also see the accumulated filtered waste. The separator unit 1100 has a circular cap 1102 and base 1103. An inlet 1104 is provided in the wall 1101.

An outlet 1105 is provided in the base 1103.

A cylindrical sieve structure is provided coaxially with the outer wall 1101. The sieve structure extends between the cap 1102 and the base 1103 and provides a seal beyond which unfiltered effluent cannot pass. The sieve structure comprises an open support scaffold to which is fixed a mesh of aperture 25 micrometers. Mesh sizes in the range 5 -75 micrometers are also suitable. The mesh separates the solid material from the liquid component of the effluent. An interior dividing wall 1107 creates a channel for the effluent to flow around the sieve structure, starting at the inlet 1104. The chamber is divided horizontally into two parts by a partition 1108. The partition 1108 has an opening on the other side of the interior dividing wall 1107. The combination of the opening and the lower part of the chamber beneath the partition 1108 provide a trap 1109 within which waste material can accumulate. The outlet 1105 is connected to a scoop 1110 that collects filtered effluent that passes through the mesh. A central vertical conduit 1111 provides wash fluid to the nozzle assembly. The nozzle assembly includes propulsion nozzles 1112 mounted on a rotatable hub 1113. The nozzle assembly includes cleaning nozzles (not shown) mounted on the rotatable hub 1113. The cleaning nozzles extend radially out from the hub to be proximal to the filtered side of the sieve structure.

The separator unit is around 15cm in diameter. However, it will be appreciated that larger or smaller diameters could be selected depending on the application. The size of the unit is selected on the flow rate of effluent to be filtered. A separator diameter of 15 cm is sufficient to process the effluent from a domestic washing machine flowing at a rate of 10 litres per minute.

The open area of the mesh that enables the passage of water at a given flowrate can be adjusted by changing either the surface area of the mesh or the mesh aperture. The mesh aperture effects the efficiency, so a smaller mesh aperture is generally preferable to provide greater efficiency. The mesh surface area is a function of the height and diameter, therefore a given area can be matched by increasing the height if the diameter is reduced, and visa versa. All variables can be adjusted to meet product packaging and efficiency

specification requirements.

The bypass system 1115 connects the inlet to the outlet. It ensures that if the regeneration system fails for some reason, the entire wash load of effluent will not back up and cause a flood.

In another embodiment, the filtered effluent is used to wash the sieve structure. Figure 12 shows a separator unit with an inlet 1201, a cylindrical housing 1202 and a sieve structure 1203. An outlet 1205 collects filtered effluent. A portion of the filtered effluent is diverted into conduit 1206, where it is pressurised by pump 1207 and directed into the central vertical conduit 1208 that provides wash fluid to the nozzle assembly 1209. The bypass system 1210 connects the inlet to the outlet. It ensures that if the regeneration system fails for some reason, the entire wash load of effluent will not back up and cause a flood. This embodiment is not suitable for location below the waterline because the outlet is not pumped, it must drain by gravity.

Figure 13a shows an embodiment that is suitable for location below the waterline and that also recirculates some of the filtered wastewater to regenerate the filter pressure. The separator unit 1300 has an inlet 1301, housing 1302, sieve structure 1303 and outlet 1304. All of the filtered effluent from the outlet 1304 is pumped out via pump 1305. The pump 1305 is arranged to divert a portion of the filtered effluent back via conduit 1306 to the central vertical conduit 1307 that provides wash fluid to the nozzle assembly 1308. A restriction 1309 is provided in the pump outlet pipe 1310 to ensure that an adequate volume of fluid is re-circulated to the pressure regeneration system. Alternatively, the pump 1305 may have a single outlet as shown in Figure 13b and a junction 1312 that diverts some filtered effluent to conduit 1313 to be re-circulated into the pressure regeneration system and the rest to the soil pipe. A restriction 1314 is provided to determine the proportion of filtered effluent that is re-circulated. An air inlet 1315 in the conduit 1306 may be provided that allows air into the pressure regeneration system to enhance the cleaning effect of the jet of cleaning fluid against the filtered side of the sieve structure. A bypass system 1310 of the type described above connects the inlet to the outlet. It ensures that if the regeneration system fails for some reason, the entire wash load of effluent will not back up and cause a flood.

It may be advantageous to be able to control the drainage of a separator unit and the pressure regeneration separately. Figure 14 shows an embodiment that allows this by the provision of two pumps; a drainage pump 1405 and a recirculation pump 1408. The separator unit has an inlet 1401 into a housing 1402 that supports a sieve structure 1403 that separates the inlet 1401 from the outlet 1404. The outlet 1404 has a conduit that leads to the drainage pump 1405. Also on the filtered side of the sieve structure is a wash fluid conduit 1407 that leads to a wash fluid pump 1408 and on to a further wash fluid conduit 1409 that feeds the cleaning nozzle assembly 1410. The drainage pump 1405 may be a positive displacement pump or a centrifugal pump that operates at around 0.1 Bar 10 litres per minute, but could be in the range up to 1 bar and 15 litres per minute. The recirculation pump 1408 operates at around 0.3 Bar and 5 litres per minute, but could be in the range up to 5 bar and 10 litres per minute. A bypass system 1411 of the type described above connects the inlet to the outlet. It ensures that if the regeneration system fails for some reason, the entire wash load of effluent will not back up and cause a flood.

Figure 15 shows an alternative embodiment of a separator unit where an air pump is used to assist with regeneration and drainage. An inlet 1501 is provided into a housing 1502 that supports a sieve structure 1503 that separates the inlet 1501 from an outlet 1504. A conduit leads to a pump 1506 that pumps filtered effluent into a further conduit 1507 that feeds wash fluid to a cleaning nozzle assembly 1508. An air pump 1509 is connected into the further conduit 1507 to pump air into the wash fluid system. Air enhances the cleaning effect of the wash fluid jet emanating from the cleaning nozzle 1508. The air pump can also be operated to push any remaining fluid in the pipe connected to the outlet 1504 up to the waterline, which enables this embodiment to be mounted below the waterline. A one-way valve would need to be provided at the inlet (not shown) to prevent fluid from being pushed back into the washing machine. The bypass system 1515 connects the inlet to the outlet. It ensures that if the regeneration system or the drainage system fails for some reason, the entire wash load of effluent will not back up and cause a flood.

A reservoir 1516 with a float switch 1517 may be provided beneath a separator unit, as shown in Figure 16. The float switch detects when fluid is present in the reservoir. The float switch is arranged to control the pump 805 to wash the sieve structure to regenerate the filter pressure. Alternatively a sensor can be provided at the inlet to detect when effluent is backing up and this can be used to activate the pump to regenerate the filter pressure. A bypass system may be provided, where an electronically controlled valve 1618 is operated by the float switch 1617, so if the level in the reservoir exceeds a predetermined value, then the bypass system operates. A pressure sensor may be provided to operate the valve 1617, where the pressure sensor is arranged to detect the difference in pressure between the unfiltered side of the sieve structure and the filtered side. If the pressure exceeds a predetermined value then the valve is operated and the separator is bypassed.

A separator may be provided where the inlet feeds the interior of the sieve structure and the outlet collects filtered effluent from the outside of the sieve structure.

The separator housing may be opened to empty the trap when the effluent has been drained. An opening at the top of the sieve structure may be provided to avoid air locks.

An air inlet may be provided at the inlet of the separator to avoid syphoning all of the waste water out of a washing machine.

As an alternative to regenerating the pressure of the separator unit, a disposable cartridge may be provided. The part of the separator that contains the filtering element, i.e. the sieve structure, could be provided as a cartridge, that is removed and disposed of and replaced with a new one. Alternatively, the cartridge could be sent for cleaning and then re-used.

Wastewater expelled from textile factories is contaminated with microfibres and it is not guaranteed it will be filtered at municipal facilities. When these facilities exist, they may remove up to 98% of microplastics, however what escapes still equates to millions of microfibres every day. Microfibres removed from water may then be passed to the environment as "sewage sludge", spread on agricultural land as fertiliser. Ultimately microfibres are passed as pollutants into the natural environment -they need to be stopped at source.

Wet-processing factories currently operate in a linear system, whereby microfibre resources are expelled as pollutants from the technical process into the biological environment. Use of the separator system described herein closes the loop into a continued cycle to retain the value of the microfibres within the technical process and stop damage to the biological environment.

An embodiment of the separator system can be retrofitted onto the existing wastewater outlet of wet-processing textile factories to enable microfibre capture at source before pollution of the natural environment can occur.

The separator system can be used to filter microplastics and other micropollutants from environmental drainage systems, such as roadside 3o gullies. A lot of microplastics in the environment break down from larger items of plastic such as car tyres, road surfaces and road markings. After synthetic textiles, tyres are the largest source of microplastics and contain harmful materials such as mineral oils.

Catalytic converters are fitted on most cars and contain highly valuable materials such as platinum, palladium, copper and zinc. During use, small amounts of these metals are lost from cars and fragments are deposited on the road surface. While metal concentrations vary geographically, collection and recycling of these materials not only reduces environmental pollution but can also be a revenue stream in a circular economy.

A larger-scale embodiment of the invention can be applied to the treatment of effluent in Wastewater Treatment Plants. For example, the chamber of the separator could be 1 meter in diameter or 2 meters or greater.

Typical sewage networks are built along one of two designs: i) Combined sewers. These collect surface water and sewage together, meaning all waste water passes through a Wastewater Treatment Plant (VVVVTP). During heavy rainfall, it is common for sewers to overflow, releasing untreated sewage and pollution into waterbodies.

ii) Separate sewers. These discharge surface water directly into waterbodies.

In both systems, roadside runoff, i.e. surface water from the roads, is released into the environment. Most roadside gullies have drains located at regular points and these drains have a sediment "pot", which lets heavy materials like gravel and sand settle to prevent blockage. These hold some micropollutants, but the majority of microplastics and valuable metals are too small and are not retained.

An embodiment of the separation system of the present invention can be retrofitted as an insert into the sediment pot of a drain to filter micropollutants at source. It is designed to fit existing gullies and to be emptied using a mobile vacuum pump.

The disclosure in the abstract is incorporated herein by reference.

Claims

CLAIMS1. A separator for separating microplastics from an effluent, the separator comprising: a chamber with an inlet and an outlet, a sieve structure forming a permeable barrier between the inlet and the outlet to filter the effluent, the sieve structure thus having an inlet side for unfiltered effluent and an outlet side for filtered effluent, wherein a bypass conduit is provided between the inlet and the outlet to provide an alternative route for effluent in the event that the flow of fluid is impeded.
2. The separator of claim 1, wherein the bypass conduit includes a pressure-activated valve.
3. The separator of claim 1, wherein the bypass conduit includes a gravity bypass tube.
4. The separator of claim 1, wherein the bypass conduit includes a series of gravity bypass tubes.
5. The separator of claim 1, wherein the bypass conduit includes a Pitot tube.
6. The separator of claim 1, wherein the bypass conduit includes a venturi.
7. The separator of claim 6, wherein the bypass system includes an electronically controlled valve.
8. The separator of any preceding claim, the separator further comprising a filter pressure regeneration apparatus for dislodging filtered material from the sieve structure, wherein a fluid level detector is provided, and wherein the filter pressure regeneration apparatus is arranged to be activated in accordance with the output from the fluid level detector.S
9. The separator of claim 7 to 8, wherein a reservoir is provided below the chamber and the fluid level detector is located in the reservoir.
10. The separator of claims 7 to 9, wherein the fluid level detector is a float switch.
11. The separator of claims 7 to 10, wherein the filter pressure regeneration apparatus comprises a conduit and a nozzle assembly having at least one cleaning nozzle directed towards the outlet side of the sieve structure.
12. The separator of claims 7 to 11, wherein the chamber is cylindrical and the sieve structure is a coaxial cylinder within the chamber and wherein a wall is provide to one side of the inlet such that the effluent is guided around the sieve structure through a channel such that filtered microplastics dislodged by the wash water from the cleaning nozzle accumulates on the side of the wall away from the inlet.
13. The separator of claims 7 to 12, wherein a trap is provided comprising an opening in the base of the channel to a sub-chamber, where the accumulating filtered microplastics can be collected.
14. The separator of claims 7 to 13, wherein the nozzle assembly comprises a plurality of cleaning nozzles that are rotatable around the central axis of the sieve structure.
15. The separator of any preceding claim, having a pump in fluid communication with the outlet of the chamber.
16. The separator of claim 15, wherein the pump is a water pump arranged to drain the separator.
17. The separator of claim 16, wherein the pump is arranged to recirculate the filtered effluent to the conduit of the filter pressure regeneration apparatus.
18. The separator of claims 13 to 17, wherein a restriction is provided in a conduit downstream from the pump, wherein the aperture of the restriction is set to ensure that a preset amount of filtered effluent is recirculated into the filter pressure regeneration apparatus and an amount of the filtered effluent is drained.
19. The separator of claims 13 to 18, wherein an air vent is provided in a conduit between the pump and the filter pressure regeneration apparatus to introduce air into the conduit.
20. The separator of claims 13 to 19, wherein a second pump is arranged to recirculate the filtered effluent to the conduit of the filter pressure regeneration apparatus.
21. The separator of claims 13 to 20, wherein the separator further comprises an air pump located between the pump and the filter pressure regeneration apparatus to introduce air into the conduit and to drain the separator.
22. A washing machine with a separator as claimed in claims 1 to 21.
23. A method of operating a separator of the type claimed in claims 1 to 21, comprising the steps of; filtering effluent through a sieve structure, allowing the effluent to bypass the sieve structure when the pressure at an inlet of the sieve structure exceeds a predetermined threshold.
24. The method of claim 23, further comprising the step of allowing the effluent to bypass the sieve structure through a passive bypass system.
25. The method of claim 23, further comprising the step of detecting the pressure at the inlet using a sensor and controlling an electronic valve in a bypass conduit when the pressure differential reaches the predetermined threshold.