GB2606348A

GB2606348A - A pressure consumption regenerating filter

Info

Publication number: GB2606348A
Application number: GB2106260.9A
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: GB202106260D0; GB2606348B

Abstract

A separator for separating microplastics from an effluent comprises a sieve structure 704 forming a permeable barrier between an inlet 703 and an outlet of a chamber and a filter pressure regeneration apparatus for dislodging filtered material from the sieve structure, the filter pressure regeneration apparatus comprising a conduit 702 and a nozzle assembly having at least one cleaning nozzle 701a, 701b directed towards an outlet side of the sieve structure to dislodge filtered material from an inlet side. The nozzle assembly preferably comprises a plurality of cleaning nozzles rotatable about a central axis of the sieve structure. The nozzle assembly may be rotated by a rotor or may be rotated by propulsion nozzles (801a, 801b, figure 8a) arranged to direct a stream of water in a direction tangential to a circumference of the sieve structure. A fluid level detector may be located in a reservoir below the chamber and the filter pressure regeneration apparatus may be activated in response to an output of the detector. A washing machine comprising the separator is also disclosed.

Description

A PRESSURE CONSUMPTION REGENERATING FILTER 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 works per day.

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.

Solutions are being developed to capture microfibers produced in domestic washing machines by filtering the effluent from these machines.

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.

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.

In a typical wash, the highest concentration of microfibers is in the range 5mm to 150 um 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.

A conventional separator or filter arrangement is shown in Figure 2a. 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 2a will become blinded over by filtered debris rapidly, so that its pressure consumption will increase, and its efficacy decrease.

In use, as the effluent fills the chamber, particles are filtered out and remain stuck to the outside of the mesh, increasing the power consumption and lowering the efficacy of the filter as the mesh starts to clog.

Curve 1 in Figure 2b is a measure of the effectiveness of the arrangement shown in Figure 2a, 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 2b 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.

It is necessary to open this device and clean the mesh by hand to return its pressure consumption back to a level for it to operate effectively, i.e. to regenerate its pressure consumption. This is a tedious and messy process. For some filter types, regeneration is not possible, for example if the filter is a cartridge type filter. These filters require the user to remove and replace them regularly which provides a worse user experience and results in wastage from consumable parts. The present invention therefore seeks to overcome the problem of effectively regenerating the pressure consumption of mesh filters used for separating microplastics from a flow of effluent.

Figure 3 shows an alternative arrangement where the effluent inlet 301 is located at one end of a channel 302, where the sieve structure 303 forms a wall of the channel 302. In this way the incoming effluent will urge the filtered waste towards the other end of the channel. The sieve structure will not blind over as quickly as that shown in Figure 2a, but the pressure consumption will increase until the filtering action ceases. It is therefore an object of the invention to regenerate the pressure consumption of a microplastic separator unit.

SUMMARY OF THE INVENTION

In an embodiment, a separator for separating microplastics from an effluent is provided, 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, the separator further comprising a filter pressure regeneration apparatus for dislodging filtered material from the sieve structure, 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 to dislodge filtered material from the inlet side of the sieve structure.

The chamber may include a channel formed of the chamber wall and the sieve structure and wherein the inlet may be located at an end of the channel such that in use the effluent flows through the channel and the microplastic material dislodged by wash fluid from the cleaning nozzle may be swept towards the other end of the channel away from the inlet by the movement of the effluent.

The chamber may be cylindrical and the sieve structure may be a coaxial cylinder within the chamber and wherein a wall is provided 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 may accumulate 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.

The cleaning nozzles may be arranged opposite to each other and mounted on a central feed tube.

The nozzle assembly may be rotated by a motor.

S

The nozzle assembly may be rotated by propulsion nozzles arranged to direct a stream of water having a vector that is tangential to the circumference of the sieve structure The cleaning nozzles may be arranged to direct wash fluid perpendicularly against the sieve structure.

The cleaning nozzles may be arranged in a helix around the central feed tube.

is The chamber may have a closed top and bottom.

The sieve structure may have an opening at the top to relieve pressure.

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

The separator further may 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.

The separator may further comprise a filter pressure regeneration apparatus for dislodging filtered material from the sieve structure, 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.

io The fluid level detector may be a float switch or a pressure sensor.

A bypass conduit may be provided between the inlet and the outlet to provide an alternative route for effluent in the event that the flow of fluid is impeded.

is The bypass conduit may include a pressure-activated valve.

In an embodiment, a washing machine has a separator of the type described above.

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, washing the filtered side of the sieve structure with a jet or jets of fluid from a nozzle or nozzles to clean accumulated debris from the unfiltered side of the sieve structure and regenerate the pressure consumption of the separator.

The method may include the further step of sweeping the nozzle or nozzles across the filtered side of the sieve structure.

BRIEF DESCRIPTION OF THE DRAWINGS

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

s Figure 2b is a graph showing the efficacy of different types of filter assembly.

Figure 3 shows a cross section of a conventional filter assembly.

Figure 4 shows a cross section of an embodiment having a single nozzle for regenerating the pressure consumption of the filter.

Figure 5 shows a cross section of an embodiment having an array of nozzles lo for regenerating the pressure consumption of the filter.

Figure 6a shows a embodiment having a cylindrical sieve structure and an array of fixed cleaning nozzles Figure 6b shows another view of the embodiment of 6a.

Figure 7a shows an embodiment having rotating cleaning nozzles.

is Figure 7b shows a detailed view of waste material being ejected from the unfiltered side of the sieve structure by spraying with a jet of fluid from the filtered side of the sieve structure.

Figure 8a shows an alternative arrangement of cleaning nozzles.

Figure 8b shows an alternative arrangement of cleaning nozzles.

Figure 9a shows an alternative arrangement of cleaning nozzles.

Figure 9b shows an alternative arrangement of cleaning nozzles. Figure 10a shows a propulsion nozzle assembly.

Figure 10b shows a propulsion nozzle assembly in action.

Figure lla shows a perspective view of an embodiment of a separator.

Figure llb shows a cross sectional view of an embodiment of a separator.

Figure 11c shows a cross sectional view of an embodiment of a separator. Figure 11d shows a cross sectional view of an embodiment of a separator. Figure 12 shows a cross sectional view of an embodiment of a separator having a recirculation pump for recirculating filtered effluent as wash fluid.

Figure 13a shows a cross sectional view of an embodiment of a separator having a combined recirculation and drain pump for recirculating filtered effluent as wash fluid and for draining the separator.

Figure 13b shows an alternative arrangement of pump and conduits.

Figure 14 shows a cross sectional view of an embodiment of a separator having separate recirculation and drain pumps for recirculating filtered effluent as wash fluid and for draining the separator.

Figure 15 shows a cross sectional view of an embodiment of a separator having a water pump for recirculation and an air pump for draining the separator.

Figure 16a shows an embodiment having a float switch for detecting when there is water in a reservoir.

Figure 16b shows an embodiment having a pressure sensor for detecting lo when there is water in a reservoir.

Figure 17 shows an embodiment having a bypass system.

Figure 18 shows a bypass system comprising a pressure-activated valve.

Figure 19 shows a bypass system comprising an upstanding tube.

Figure 20 shows a bypass system comprising a pair of upstanding tubes is joined by an anti-syphon chamber.

Figure 21 shows a bypass system comprising a Pitot tube.

Figure 22 shows a bypass system comprising a Venturi.

Figure 23 shows a washing machine equipped internally with an embodiment of the separator Figure 24 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 23a, or retro-fitted externally to a washing machine or other appliance, as shown in Figure 23b.

The separator system 2800 described above may be installed within a washing machine, as shown in Figure 28a. The waste from the washing machine drum connects to the inlet 2807 of the separator 2800 and the outlet of the separator connects to the waste outlet 2809. A supply of fresh water 2806 for the regeneration apparatus is shown but if the recirculation system is used then this supply is unnecessary. A separator system 2808 may be located outside a washing machine, connected to the waste water outlet of the washing machine, as shown in Figure 28b. The inlet 2809 supplies effluent into the separator 2808 and the outlet 2810 feeds into the soil pipe 2805. 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. For example, for capturing the solid components entrained in the runoff from roadside gullies, as discussed in more detail below.

Effluent is understood to include wastewater from the sources mentioned 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 the invention for separating microplastics from an effluent that regenerates the pressure consumption of a filter, comprising an effluent inlet 401 feeding a channel bounded by a filter housing 402 and a sieve structure 403. The filtered effluent exits from the separator via an outlet 404. A cleaning nozzle 405 is provided that is arranged to direct a cleaning jet of wash fluid towards the filtered side of the sieve structure 403. The cleaning nozzle 405 is connected by conduit 406 to a supply of wash fluid. The cleaning nozzle is periodically activated 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 pressure regenerating effect can be enhanced by a filter pressure regeneration system. This system comprises a nozzle assembly having an array of cleaning nozzles. Figure 5 shows an embodiment for separating microplastics from an effluent, comprising an effluent inlet 501 feeding a channel bounded by a filter housing 502 and a sieve structure 503. The filtered effluent exits from the separator via an outlet 504. The nozzle assembly 505 comprises a plurality of cleaning jets 506a, b, c, d, e fed with wash fluid by conduit 507. The cleaning jets are periodically activated 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.

Figures 6a and 6b show an embodiment of the invention for separating microplastics from an effluent that regenerates the pressure consumption of a filter back to the level, or close to the level, of when it was new. A cylindrical chamber 601 is provided having an inlet 602 and a central cylindrical sieve structure 603. A wall 604 is provided to one side of the inlet that serves as a baffle to allow effluent to only flow one way when it enters the chamber and to allow filtered debris to collect in a specified location in the chamber. The inner wall of the chamber 601, the outer wall of the sieve structure 603 and wall 604, define a channel through which unfiltered effluent flows around to the other side of the wall 604 where it can accumulate. An aperture 605 is provided through which the filtered material can pass and be trapped. A filter pressure regeneration system is provided comprising a wash fluid conduit 606 that supplies wash fluid to an array of cleaning nozzles 607 that project radially outwards from the conduit 606 and are arranged to direct wash fluid perpendicularly at the filtered side of the sieve structure 603 to dislodge material that accumulates against the unfiltered side of the sieve structure. As material is dislodged it is swept by the flow of effluent towards the end of the channel, through the aperture 605 and into the trap. A trap is desirable but the embodiment will work without it. The jets of wash fluid can be operated continuously or periodically. The wash fluid is pressurised and forced through the cleaning nozzles so that the jets of wash fluid emanating from the cleaning nozzles have enough power to dislodge material, against the flow of the fluid component of the effluent passing through the sieve structure. The wash fluid could be clean mains water and the pressure provided by mains water pressure. A pump could also be used to pump clean water or another fluid from another source. If the wash fluid is pressurised by a pump, then the power consumption of the pump is a design consideration; minimising this power consumption is preferred to reduce the costs of the pump itself and its operating cost.

Figure 7a shows an embodiment having a filter pressure regeneration system comprising a nozzle assembly that has two rotatable opposing cleaning nozzles 701a, b extending radially from a central conduit 702. The central conduit 702 feeds the cleaning nozzles with pressurised wash fluid. Effluent enters the separator via inlet 703 and passes around the channel formed by the outer wall of the chamber and the sieve structure 704 around to the wall 705 where filtered material M accumulates in the trap 706. The cleaning nozzles 701a, b are aligned perpendicularly to the sieve structure 704. The cleaning nozzles can be rotated by a motor (not shown) or other means. Other means include harnessing the upstream flow of unfiltered effluent to provide energy for mechanical operation of the propelling nozzles.

In Figure 7a, the cleaning nozzles are rotated in the direction of flow of the effluent. Figure 7b shows a detailed view of the waste material M being ejected from the unfiltered side of the sieve structure 704 by a jet of wash fluid 707 emanating from the cleaning nozzle 701a. By having a reduced number of rotating cleaning nozzles, the same coverage of the jet of wash fluid against the sieve structure can be achieved as with the array of fixed cleaning nozzles shown in Figure 6a, but with less power required of the wash fluid pump. The cleaning nozzles could also be directed downwards to urge the ejected material down towards the trap.

The wash fluid could be water or it could be a mixture of air and water. Figure 7c shows a jet of cleaning fluid that includes water and air, where a pellet of 10 water 708 is seen being ejected from the cleaning nozzle 701a. This increases the speed and ejection effect of the wash fluid.

The cleaning nozzles of the filter pressure regeneration system can be constructed so that a component of the pressurised wash fluid is tangential to the filtered side of the sieve structure. Figure 8a shows a filter pressure regeneration system having such an arrangement. The end of the cleaning nozzles 801a, b are angled in the direction of flow of the effluent. This has the effect of ejecting the filtered material further out into the flow of effluent where it can be swept further along towards the trap 802 before it re-attaches to the sieve structure under the action of the flow of effluent through the sieve structure. Figure 8a shows the nozzle assembly being rotated in the direction of flow of the effluent. Figure 8b shows the nozzle assembly being rotated against the flow of effluent.

Figure 9a shows an alternative arrangement of a nozzle assembly for the filter pressure regeneration system. A central hub 901 supports an array of cleaning nozzles 902a, b etc that extend radially from the hub 901. The hub includes a conduit to feed pressurised wash fluid to the cleaning nozzles. The cleaning nozzles are arranged as a stack of four directly above each other and a matching stack directly opposite on the hub. This arrangement ensures that the entire width of the sieve structure is cleaned in each sweep of the nozzle assembly.

Figure 9b shows a nozzle assembly where the array of cleaning nozzles are arranged in a helix configuration around a central hub. This encourages the ejected filtered material downwards in the flow of effluent and to reach the trap more quickly.

Figure 10a shows a nozzle assembly rotation unit 1000 for propelling the nozzle assembly of the filter pressure regeneration system. The nozzle assembly rotation unit 1000 is fixed to the cleaning nozzles. The rotation unit comprises a central hub 1001 that acts as a conduit for propulsion fluid. The propulsion fluid and the wash fluid could be the same fluid, where the wash fluid conduit and rotation unit hub are connected. The rotation unit 1000 has radially extending arms 1002a, b that terminate in propulsion nozzles 1003a, b that are directed perpendicularly to the arms. Fluid exiting the propulsion nozzles is directed tangentially to the axis of the hub, causing the rotation unit 1000 to rotate and thus rotate the nozzle assembly that is fixed to it.

Figure 10b shows a nozzle assembly rotation unit 1000 in action.

Figure 11 a shows an embodiment of a separator unit that includes a filter pressure regeneration 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.

Figure 11 b shows a side view of the separator unit 1100. 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 pads 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.

Figure 11c is a cross section of the separator unit 1000 taken along line A-A' in Figure 11a, where components of the filter pressure regeneration system are shown. 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.

Figure 11d is a cross section of the separator unit 1000 taken along line B-B' in Figure 11a, where components of the filter pressure regeneration system are shown. The nozzle assembly includes cleaning nozzles 1114a to d 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.

In an embodiment, the filtered effluent itself is re-circulated to clean the sieve structure. Figure 12 shows a separator unit 1270 has an inlet, a cylindrical housing 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. 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.

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.

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.

A reservoir 1616 with a float switch 1617 may be provided beneath a separator 1601, as shown in Figure 16a. The float switch detects when fluid is present in the reservoir. The float switch is arranged to control a pump 1605 that recirculates filtered effluent to wash the sieve structure to regenerate the filter pressure. A pressure sensor 1618 may also be provided as shown in Figure 16b. 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 1700 may be provided to connect the inlet 1701 to the outlet 1702, as shown in Figure 17. It ensures that if the separator gets blocked or the regeneration system fails for some reason, the entire wash load of effluent will not back up and cause a flood but be diverted to the waste outlet.

Figure 18 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 1801, a housing 1802 supporting a sieve structure 1803 and an outlet 1804. A bypass conduit 1805 links the inlet 1801 to the outlet 1803. A pressure-activated valve 1806 is located in the conduit 1805. 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 1106 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 19 shows another embodiment with an alternative bypass system, where an upstanding tube 1904 links the inlet 1901 to the outlet 1902 of a separator unit 1903. 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 1904, which can be a problem when a washing machine is located in a confined space.

Figure 20 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 2001a, 2001b that link the inlet 2002 to the outlet 2003 of a separator unit 2004. The tubes are connected by chamber 2005. The first upstanding tube 2001a empties effluent into the top of the chamber 2005 at height "H". When effluent reaches the height "H" of the second tube 2001b it will pass through to the outlet 2003. 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 21 and 22 show 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 21 is a bypass system that comprises a Pitot tube 2104 in the outlet 2102 from a separator 2103. The Pitot tube is connected to the inlet 2101 of the separator 2103. 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 22 shows a further embodiment that uses the Venturi effect to operate a bypass system. A tube 2201 connects to the inlet 2202 of a separator 2203. A restriction 2204 is provided in the tube 2201. A conduit 2205 is provided between the restriction and the outlet 2205 of the separator 2206. When the separator is operating normally, the unfiltered effluent flowing through the restriction 2204 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 separator system 2300 described above may be installed within a 30 washing machine, as shown in Figure 23. Figure 24 shows a separator system 2400 located outside a washing machine, connected to the waste water outlet of the washing machine.

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 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 lo 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, the separator further comprising a filter pressure regeneration apparatus for dislodging filtered material from the sieve structure, 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 to dislodge filtered material from the inlet side of the sieve structure.
2. The separator of claim 1, wherein the chamber includes a channel formed of the chamber wall and the sieve structure and wherein the inlet is located at an end of the channel such that in use the effluent flows through the channel and the microplastic material dislodged by wash fluid from the cleaning nozzle is swept towards the other end of the channel away from the inlet by the movement of the effluent.
3. The separator of claim 2, wherein the chamber is cylindrical and the sieve structure is a coaxial cylinder within the chamber and wherein a wall is provided 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.
4. The separator of any preceding claim, 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.
5. The separator of any preceding claims, wherein the nozzle assembly comprises a plurality of cleaning nozzles that are rotatable around the central axis of the sieve structure.
6. The separator of any preceding claims, wherein the cleaning nozzles are arranged opposite to each other and mounted on a central feed tube.
7. The separator of any preceding claim when dependent on claim 5, wherein the nozzle assembly is rotated by a motor.
8. The separator of any preceding claim when dependent on claim 5, wherein the nozzle assembly is rotated by propulsion nozzles arranged to direct a stream of water having a vector that is tangential to the circumference of the sieve structure.
9. The separator of any preceding claim, wherein the cleaning nozzles are arranged to direct wash fluid perpendicularly against the sieve structure.
10. The separator of any preceding claim when dependent on claim 6, 20 wherein the cleaning nozzles are arranged in a helix around the central feed tube.
11. The separator of any preceding claim, wherein the chamber has a closed top and bottom.
12. The separator of any preceding claim, wherein the sieve structure has an opening at the top to relieve pressure.
13. The separator of any preceding claim, having a pump in fluid communication with the outlet of the chamber.
14. The separator of any preceding claim, wherein the pump is a water pump arranged to drain the separator.
15. The separator of any preceding claim, wherein the pump is arranged to recirculate the filtered effluent to the conduit of the filter pressure regeneration apparatus.
16. The separator of claims 9 to 11, wherein a second pump is arranged to recirculate the filtered effluent to the conduit of the filter pressure regeneration apparatus.
17. The separator of claims 9 to 12, wherein the separator further 10 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.
18. 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.
19. The separator of claim 17, wherein a reservoir is provided below the chamber and the fluid level detector is located in the reservoir.
20. The separator of claims 18, wherein the fluid level detector is a float 25 switch.
21. The separator of any preceding claim, 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.
22. The separator of claim 20, wherein the bypass conduit includes a pressure-activated valve.
23. A washing machine with a separator as claimed in claims 1 to 22.
24. A method of operating a separator of the type claimed in claims 1 to 22, comprising the steps of; filtering effluent through a sieve structure, washing the filtered side of the sieve structure with a jet or jets of fluid from a nozzle or nozzles to clean accumulated debris from the unfiltered side of the sieve structure and regenerate the pressure consumption of the separator.
25. The method of claim 23 including the further step of sweeping the nozzle or nozzles across the filtered side of the sieve structure.