FILTER UNIT, TEXTILE TREATMENT APPARATUS AND METHOD

Abstract

The present invention relates to a filter unit suitable for filtering microfibres within a feed, especially a feed originating from a textile treatment apparatus. The present invention also relates to a textile treatment apparatus comprising said filter unit and a method of filtering utilising said filter unit.

Claims

1. A filter unit suitable for filtering microfibres within a feed, the filter unit comprising: a) a housing; b) an inlet configured to allow the feed to enter the housing; c) an outlet configured to allow a filtered feed to exit the housing; d) a filter cage supporting one or more filter media, the filter cage being rotatably mounted and rotating about an axis of rotation within the housing, the filter media having pores with a mean pore size of no more than 100 microns; e) one or more baffle surfaces being located adjacent to at least a portion of the interior and/or exterior surfaces of the one or more filter media; the baffle surfaces and filter cage being configured such that during rotation of the filter cage, the one or more filter media move relative to the one or more baffle surfaces and turbulent flow of liquid when present in the filter unit is encouraged near the interior and/or exterior surface of the one or more filter media; f) a drive means for rotating the filter cage; g) the filter unit being configured such that feed from the inlet is directed towards the interior of the filter cage, the feed then passes through the one or more filter media and exits as a filtered liquid via the outlet.

2. A filter unit according to claim 1 wherein the one or more baffle surfaces are located either radially outward from or radially inward from the one or more filter media.

3. A filter unit according to claim 1 wherein the one or more baffle surfaces is adjacent to at least a portion of the exterior surface of the one or more filter media.

4. A filter unit according to claim 1 wherein the one or more baffle surfaces is connected to the housing and remains static during rotation of the filter cage.

5. A filter unit according to claim 1 wherein the one or more baffle surfaces have one or more waves.

6. A filter unit according to claim 5 wherein the wave is or comprises a square wave, arc wave, sine wave, triangular wave or a combination thereof.

7. A filter unit according to claim 5 wherein: the one or more waves on the one or more baffles provide a variation in the distance from any point on the baffle surface to the filter media, when measured along any radial direction towards the axis of rotation of the filter cage; the one or more waves on the one or more baffles provide a furthest distance from the any point on the baffle surface to the filter media, when measured along any radial direction towards the axis of rotation of the filter cage; and the variation in the distance is at least 5% of the furthest distance.

8. A filter unit according to claim 5 wherein: the one or more waves on the one or more baffles provide a variation in the distance from any point on the baffle surface to the filter media, when measured along any radial direction towards the axis of rotation of the filter cage; and the variation in the distance is at least 2 mm.

9. A filter unit according to claim 1 wherein the at least one baffle surface is parallel to the filter media.

10. A filter unit according to claim 1 wherein the at least one baffle surface is adjacent to the second surface of the one or more filter media, wherein the second surface is the surface of the filter media which filtered feed passes from when in use.

11. A filter unit according to claim 1 wherein the baffle surface(s) cover no more than 90% of the axial length of the one or more filter media.

12. A filter unit according to claim 1 wherein the filter cage supports the one or more filter media so that it is retained in the shape of a frustrum of a cone, a cone, a pyramid, a prism, or a hemisphere.

13. A filter unit according to claim 1 wherein the pores in the one or more filter media have a mean pore size of from 1 to 100 microns.

14. A filter unit according to claim 1 wherein the filter unit comprises a pipe configured such that feed from the inlet passes through the interior of the filter cage through the pipe.

15. A filter unit according to claim 14 wherein the filter unit is configured so that feed exits from the pipe and passes through the exterior surface of the one or more filter media and exits the interior surface of the one or more filter media as a filtered liquid.

16. A filter unit according to claim 1 wherein the one or more filter media are in the form of a non-woven mesh, a woven mesh, a knitted mesh or a perforated sheet.

17. A filter unit according to claim 1 wherein the filter unit comprises one or more impeller(s) in the housing, and wherein the one or more impeller is upstream and/or downstream of the filter media.

18. A filter unit according to claim 1 wherein the housing comprises an opening and a moveable lid that is movable between a first configuration and a second configuration; in the first configuration the moveable lid cooperates with the housing to seal the opening so entry of the effluent into the housing is through the inlet only, and exit of the filtered effluent from the housing is through the outlet only; and in the second configuration the moveable lid has moved to expose the opening in the housing so that filtride accumulated on the filter media can be removed from the housing through the opening; and wherein the filter cage is rotatable to throw filtride from the filter media through the opening when the moveable lid is in the second configuration.

19. A filter unit according to claim 18, wherein the filter unit is configured to rotate the filter media via the drive means to throw filtride from the filter media.

20. A filter unit according to claim 18 wherein the filter unit comprises a container for receiving filtride that is external to the housing.

21. A filter unit according to claim 20, wherein the container is adjacent to and radially outwards of the opening from the axis of rotation when the moveable lid is in the second configuration.

22. A filter unit according to claim 18, wherein the moveable lid is shaped as a frustrum, a cone, a cylinder, or a pyramid.

23. A filter unit according to claim 18, wherein the moveable lid moves linearly between the first and second configurations; and optionally wherein the moveable lid moves linearly in the horizontal direction.

24. A textile treatment apparatus comprising a filter unit according to claim 1 where the filter unit is connected to the textile treatment apparatus to receive feed therefrom.

25. A textile treatment apparatus according to claim 24 which is a washing machine.

26. A method of filtering a feed comprising microfibres using a filter unit according to claim 1.

27. A method of filtering a feed comprising microparticles comprising: i. providing a filter unit according to claim 18; ii. placing the filter unit in the first configuration; iii. supplying effluent from a textile treatment apparatus to the inlet of the filter unit; iv. filtering the effluent through the filter medium and passing the filtered effluent to the outlet; v. stopping the supply of effluent; vi. placing the filter unit in the second configuration; vii. rotating the filter cage to throw filter residue from the filter medium through the opening.

28. A method according to claim 27, further comprising the subsequent steps of: vii. returning the filter unit to the first configuration; ix. resuming supply and filtering of feed.

29. A method according to claim 26, wherein the feed is from a single treatment cycle of the textile treatment apparatus.

30. A method according to claim 26 wherein the feed comprising microfibres originates from a textile treatment apparatus.

31. A method according to claim 26 wherein during filtration the filter cage is rotated at a speed such that the internal surface of the one or more filter media experiences a G force of at least 20 G.

32. A method according to claim 26 wherein during filtration the turbulence at the outermost surface of the filter media corresponds to a Reynolds number of at least 3000.

33. A method according to claim 26 wherein the feed is passed through the filter unit only once.

34. A method according to claim 26 wherein the feed is passed through the filter unit multiple times.

35. A method according to claim 26 wherein the filter unit filters feed from at least 5 textile treatment cycles before requiring any cleaning.

36. A method according to claim 26 wherein the microfibres are or comprise a cellulosic material.

37. A method according to claim 26 wherein the microfibres have a longest linear dimension of less than 1 mm.

38. A method according to claim 26 wherein the efficiency of the filter unit at removing microfibres is at least 70% by mass relative to all the microfibres originally present in the feed.

39. A method according to claim 26 wherein the flow rate of the feed through the filter unit is at least 1 litre/minute.

Description

FIGURES IN SUMMARY

[0269] FIG. 1a shows a first baffle surface as can be used in the filter unit of the first aspect of the present invention, the baffle surface is shown in plan view.

[0270] FIG. 1b shows a first baffle surface as can be used in the filter unit of the first aspect of the present invention, the baffle surface is shown in isometric perspective.

[0271] FIG. 2a shows a second baffle surface as can be used in the filter unit of the first aspect of the present invention, the baffle surface is shown in plan view.

[0272] FIG. 2b shows a second baffle surface as can be used in the filter unit of the first aspect of the present invention, the baffle surface is shown in isometric perspective.

[0273] FIG. 3a shows a filter unit according to the first aspect of the present invention in cross-sectional view.

[0274] FIG. 3b shows a filter unit according to the first aspect of the present invention as an exploded view.

[0275] FIG. 4 shows a schematic of a first textile treatment apparatus according to the second aspect of the present invention.

[0276] FIG. 5 shows a schematic of a second textile treatment apparatus according to the second aspect of the present invention.

[0277] FIG. 6 shows a schematic of a third textile treatment apparatus according to the second aspect of the present invention.

[0278] FIG. 7a shows an isometric view of an alternate filter unit according to the present disclosure, with the filter in a first configuration.

[0279] FIG. 7b shows an isometric view of an alternate filter unit according to the present disclosure, with the filter unit in a second configuration.

[0280] FIG. 7c shows a cross-section through the alternate filter unit, with the filter unit in a first configuration.

[0281] FIG. 7d shows an isometric cross section of a housing of the alternate filter unit, with the filter unit in a first configuration.

[0282] FIG. 7e shows an isometric cross section of a housing of the alternate filter unit, with the filter unit in a second configuration.

[0283] FIG. 7f shows a side view of a housing of the alternate filter unit, with the filter unit in a second configuration.

[0284] FIG. 7g shows a side view of a filter cage of the alternate filter unit.

FIGURES IN DETAIL

[0285] FIG. 1a shows first baffle surface (101) in the form of five saw-teeth which conform to the curvature of a cylinder. The teeth are continuous for approximately 90 degrees of radial angle when considering the rotation of the cage and when viewed down the axis of rotation. Thus, the angle α in FIG. 1a is approximately 90 degrees. The arrows show the direction of the rotation of the filter cage relative to the baffle surface.

[0286] FIG. 1b shows the same baffle surface (101) as that of FIG. 1b but in isometric perspective. It can be seen that the label (b) which is the axial length of the baffle surface covers approximately 50% of the axial length of the filter media shown by label (c).

[0287] The baffle surface (101) in FIGS. 1a and 1b is the same as that as mentioned below in the examples as BS1.

[0288] FIG. 2a shows a second baffle surface (201). The baffle surface has one tooth which conforms to the curvature of a cylinder. The tooth is continuous for approximately 30 degrees of radial angle when considering the rotation of the cage and when viewed down the axis of rotation. Thus, the angle α in FIG. 2a is approximately 30 degrees. The arrows show the direction of the rotation of the filter cage relative to the baffle surface.

[0289] FIG. 2b shows the second baffle surface (201) this time in isometric perspective.

[0290] The baffle surface (201) in FIGS. 2a and 2b is the same as that mentioned below in the examples as BS2.

[0291] It can be seen that the label (b) which is the axial length of the baffle surface covers approximately 50% of the axial length of the filter media shown by label (c).

[0292] FIGS. 3a and 3b shows a filter unit (300) comprising a baffle surface (301), a housing (302) in the form of a cylinder, an inlet (303) and outlet (304), a filter cage (305), filter media (306), a drive means in the form of an electric motor (307). The filter also comprises an impeller (308) located within the filter cage. The filter cage is fitted with a mating surface (309) which engages a spline (310) located at the end of a drive shaft (311) extending from the electric motor.

[0293] When in use feed comprising microfibres enters the inlet of the filter unit (303). The electric motor (307) is actuated so as to rotate the filter cage which supports the filter media. The feed is directed towards the interior of the filter cage, the feed then passes through the filter media and exits as a filtered liquid via the outlet (304). The impeller (308) assists in driving the feed through the filter media and thereby improves the flow rate. The baffle surface (301) is located adjacent to the exterior surface of the filter media (306). During rotation of the filter cage (305), the filter media (306) move relative to the baffle surface (301) and turbulent flow of liquid is encouraged near the exterior surface of the filter media. The turbulent flow is believed to advantageously help to prevent microfibres from blocking the filter media.

[0294] FIG. 4 shows a textile treatment apparatus (400) which comprises: [0295] a frame (401); [0296] a drum (402) which is rotatably mounted in the frame (401); [0297] a tub (403) which surrounds the drum; [0298] a storage compartment (404) for storing solid particles. [0299] a dispensing means (405) in the form of a pump for transporting the solid particles from the storage compartment to the drum; [0300] a collecting means for transporting the solid particles from the drum to the storage compartment which takes the form of holes in drum (not shown) and a storage compartment (404) in the form of a sump which is located directly underneath the drum.

[0301] FIG. 4 also comprises a filter unit (407) according to the first aspect of the present invention. Filtered feed exiting the filter unit (407) may go to the outlet as effluent or can be recycled back to the drum depending on the valve (406). Solid particles (408) are shown in the storage compartment (404).

[0302] FIG. 5 shows a textile treatment apparatus (500) which comprises: [0303] a frame (501); [0304] a drum (502) which is rotatably mounted in the frame (501); [0305] a tub (503) which surrounds the drum; [0306] a storage compartment (504) for storing solid particles which is located in the rear of the drum. [0307] a dispensing means (505) which is in the form of angled surfaces which during rotation move the solid particles towards a poppet valve (506); [0308] a collecting means for transporting the solid particles from the drum to the storage compartment which takes the form of lifters having holes to permit entry of the solid particles, the lifters (507) having internal flow paths leading from the treatment area of the drum to the rear of the drum and which comprise a paternoster arrangement. During rotation of the drum the paternoster arrangement urges solid particles entering the lifter towards the storage compartment at the rear of the drum. By opening the poppet valve the solid particle can be dispensed into the treatment area of the drum or by closing the poppet valve the solid particles can be collected automatically back in to the rear storage area of the drum. The textile treatment apparatus of FIG. 5 also comprises a sump (508) fluidly connected to a filter unit (509) according the first aspect of the present invention. Filtered feed exits the filter unit (509) and as controlled by a valve (510) may go to the outlet as effluent or may be recycled to the drum either directly or via a path which permits the filtered feed to pass through a detergent compartment (not shown). Solid particles (511) are shown in the storage compartment (504) at the rear of the drum.

[0309] FIG. 6 shows a textile treatment apparatus in the form of a conventional washing machine which comprises which comprises: [0310] a frame (601); [0311] a drum (602) which is rotatably mounted in the frame (601); [0312] a tub (603) which surrounds the drum; [0313] a sump (604) fluidly connected to a filter unit (605) according to the first aspect of the present invention. The filtered feed exits the filter unit to a valve (606) which can be operated to recycle the filtered feed to the drum (either directly or via a path which permits the filtered feed to pass through the a detergent compartment—not shown) or to the waste outlet as effluent.

[0314] FIGS. 7a to 7c show an alternative embodiment of a filter unit 2000. FIGS. 7d, 7e and 7f show a housing 2001 of the filter unit 2000 and FIG. 7g shows a filter cage 2038 of the filter unit 2000. The filter unit 2000 comprises a housing 2001. The housing 2001 comprises a moveable lid 2005. The moveable lid 2005 is in the form of a hollow cylinder closed at one end and comprising a cylindrical sidewall 2005a and a circular end wall 2005b. The housing 2001 also comprises an end wall 2002a and a sidewall 2002b. The sidewall 2002b is in a volute shape with a tangential port which extends to form an outlet 2004 from the housing 2001. The outlet comprises a valve 2004a to control the flow of filtered feed out of the housing 2001. The sidewall 2002b also comprises a secondary drain 2056 at bottom of the sidewall. The end wall 2002a comprises an opening therein which is the inlet 2003 to the housing 2001. A pipe 2070 passes through the opening of the inlet 2003. The pipe 2070 supplies feed into the housing 2001 through the inlet 2003. The pipe 2070 is configured to rotate about central axis S which is aligned in the horizontal direction. The pipe 2070 is mounted to the housing 2001 via bearings 2067 and 2066, which connect via mount 2054. A seal 2076 is present between the end wall 2002a and the pipe 2070 to prevent leakage of feed. The pipe 2070 is also connected to a supply pipe 2052 to receive feed from a textile treatment apparatus. A seal 2075 prevents leakage of feed from between the supply pipe 2052 and the pipe 2070. The supply pipe 2056 comprises a valve 2053 to control supply of feed into the filter unit 2000.

[0315] Inside the housing 2001 is a frusto-conical filter medium 2006. The housing is shown in detail in FIGS. 7d to 7f. The external, outward facing surface of the filter medium 2006 is the first surface of the filter medium 2006 which receives unfiltered feed from pipe 2070. The internal inward facing surface of the filter medium 2006 is the second surface of the filter medium 2006 from which filtered feed passes. The filter medium 2006 is supported by the filter cage 2038. The filter cage 2038 is configured to rotate about the central axis S. The filter cage 2038 is shown in greater detail in FIG. 7g. The filter cage 2038 comprises two annular supports 2093, 2094 angled to support the filter medium 2006 in the frusto-conical shape. The filter cage 2038 also comprises a plurality of blades 2091 proximal to and upstream of the first surface of the filter medium 2006. These blades, when rotated act to enhance rotation of the unfiltered feed in the housing 2001, which assists in pumping feed though the filter unit 2000, thus the blades function as an impeller. The blades connect to a disc 2092 which contacts the circular endwall 2005b of the movable lid 2005 when the moveable lid 2005 is in the first configuration. The filter cage 2038 also comprises an annular X-seal 2072 around the outer circumference. The X-seal 2072 contacts the inner circumference of the sidewall 2005a of the moveable lid 2005 when in the first configuration to prevent leakage of feed liquid. The filter cage 2038 also comprises a smooth surface 2095 on the outer circumference for rotation against a seal 2039 connected to housing 2001. Also contained within the housing 2001 is an impeller 2085 which extends from proximal to the second surface of the filter medium to adjacent to the end wall 2002a. The impeller 2085 comprises a plurality of blades with a profile that occupies most of the volume of the housing 2001 downstream of the filter medium 2006. The impeller 2085 comprises a hollow bore with the pipe 2070 located therein. The impeller 2085 is configured to rotate around the central axis S and rotates with the pipe 2070, filter cage 2038 and filter medium 2006. Rotation of the impeller 2085 helps to drive filtered feed from the volute part of the housing 2001 and draws unfiltered feed into the housing 2001 via inlet 2003 and the pipe 2070.

[0316] The moveable lid 2005 is moved between the first and second configurations by the linear actuator 2031 which is directly connected to the moveable lid by linkage 2032 and the bearing 2083, which each permit rotation in different directions. The moveable lid 2005 is moved between the first and second configuration in the horizontal direction. When the movable lid is in the second configuration, an annular opening 2011 is present between the cylindrical sidewall 2005a of the moveable member 2005 and the sidewall 2002b of the housing 2001. FIG. 7f illustrates the opening 2011. FIGS. 7a and 7d show the movable lid 2005 in the first configuration and FIGS. 7b, 7c, 7e and 7f show the moveable lid 2005 in the second configuration.

[0317] Radially outwards of the opening 2011 is a container 2007 for receiving filtride from the first surface of the filter medium. The container 2007 is shown in FIG. 7b only and in part in FIGS. 7a and 7c. The container 2007 is generally cylindrical and extends 360 degrees around the central axis. A bottom quadrant of the container 2007 comprises a detachable portion in the form of a tray 2074. The tray 2074 can slide out from the filter unit 2000 for emptying by a user. The container 2007 also comprises a tertiary drain 2077 for draining any residual liquid in the bottom of the container 2007.

[0318] The filter unit 2000 comprises a drive means (not shown) e.g., an electric motor. The filter medium 2006 is rotatable around the central axis by the drive means. Filter residue can be removed from the first surface of the filter medium 2006 by rotating the filter medium 2006 to induce a centrifugal force to throw the filter residue radially outwards off the filter medium 2006. The drive means is connected to the filter medium 2006 via a belt (not shown) and pulley 2009 connected to the pipe 2070. Rotation of the drive means rotates the pulley 2009 which in turn rotates the impeller 2085, the filter cage 2038 and the filter medium 2006.

[0319] Proximal to the second surface of the filter medium 2006 is a baffle surface 2080. The baffle surface 2080 is shown in detail in FIG. 7g along with the filter cage 2038. The baffle surface 2080 is connected to the sidewall 2002b of the housing 2001 by the baffle support 2081. The baffle surface 2080 is static and does not rotate with the filter medium 2006. The baffle surface 2080 affects fluid flow close to the filter medium 2006 which reduces the tendency of the filter medium 2006 to become blocked with filter residue.

[0320] In use the filter unit is placed in the first configuration, where the moveable lid 2005 is in contact with the seal 2072. In this configuration the housing 2001 is sealed so that the feed may enter only via the inlet 2003 and leave via the outlet 2004 and optionally via the secondary drain 2056. Feed is supplied to the housing 2001 from a textile treatment apparatus through the supply pipe 2052. If the valve 2053 is open, feed passes into the pipe 2070, where it is carried through the inlet 2003 into the housing 2001 and along the interior of the impeller 2085, through the middle of the filter cage 2038, the feed leaves the interior of the impeller 2085 and thus exits from the filter cage 2038, and then passes through the first surface of the filter medium 2006. The filter cage 2038, filter medium 2006, impeller 2085 and pipe 2070 are all rotated together by rotation of pulley 2009 by a belt (not shown) and drive means (not shown). Rotation of the impeller 2085 and blades 2091 may function as a centrifugal pump to draw feed into the housing 2001 through the inlet 2003 and expel feed from the housing 2001 via the outlet 2004. After the feed from the textile treatment apparatus has been filtered, the flow of feed is stopped, which may optionally be by valve 2053.

[0321] Residual feed liquid is then allowed to drain from the housing 2001 through the secondary drain 2056. The filter unit 2000 is then placed in the second configuration by moving the moveable lid 2005 to the second configuration with the linear actuator 2031. The filter medium 2006, pipe 2070, impeller 2085 and filter cage 2038 are then rotated at a sufficiently high speed to throw the filter residue from the first surface of the filter medium 2006, through the opening 2011, where it is collected in the container 2007 and falls to the bottom under gravity. Any residual liquid in the filter residue in the container 2007 can be drained via the tertiary drain 2077. After one or more of the above cycles, the residue accumulated in the container 2007 can be removed by sliding the tray 2074 out the filter container 2007 and transferring the residue out of the tray 2074 for disposal.

EXAMPLES

[0322] The present invention will now be illustrated using the following non-limiting examples.

[0323] Textile Treatment Apparatus

[0324] The Textile Treatment Apparatus used to prepare the feeds for filtration was a commercially available Beko washing machine (herein BK1) model number WM5102W having a load capacity of 5 Kg.

[0325] Textile Substrate

[0326] The textile substrate used along with the textile treatment apparatus (BK1) which provided the microfibres in the feed was in the form of polycotton jumpers (herein PJ1) as supplied by Primark. These polycotton jumpers were all prewashed (PW) 4 times in a cotton 40 degrees cycle in a Beko washing machine model number WMB91233LW.

[0327] Textile Treatment Cycle

[0328] The Beko washing machine (BK1) was loaded with 1.5 Kg of polycotton jumpers.

[0329] The textile treatment cycle used in the Beko washing machine (BK1) loaded with the polycotton jumpers (PJ1) was a 40 degrees cotton cycle, using approximately 47 Kg of water and taking a time of 90 minutes. No detergent or additives were present in the treatment cycle. The cycle included a spin dry.

[0330] Tumble Drying

[0331] After each textile treatment cycle the polycotton jumpers (PJ1) were unloaded from the washing machine (BK1) and tumble dried. The tumble drying took 30 minutes at a temperature of 60 degrees Celsius in an Electrolux T4250 tumble dryer. The polycotton jumpers can then be re-used to prepare further microfibre containing feeds when loaded into BK1 and treated using the abovementioned textile treatment cycle. Once the polycotton jumpers have been through 30 cycles of textile treatment they are no longer used and instead they are replaced with a fresh set of polycotton jumpers. Each fresh set of polycotton jumpers were prewashed (PW) exactly as indicated above prior to any textile treatment cycles.

[0332] Poly Cotton Feed

[0333] Following each textile treatment cycle the feed (effluent from BK1) was stored in a first tank.

[0334] Filter Unit

[0335] Three different filter units were used to filter the effluent from BK1 stored in the first tank.

[0336] In every case the filter unit had the same cylindrical housing and the drive means was in the form of the same electrical motor. In all cases the filter media was in the form of a cylindrical shaped Nylon mesh having pores and which was glued to the filter cage.

Comparative Example 1

[0337] In Comparative Example 1 the filter unit—Comparative filter Unit 1 (CFU1) was fitted with a woven Nylon mesh filter media having a pore size of 36 microns. CFU1 had no baffle surfaces present and was accordingly not within the scope of the present invention.

Comparative Example 2

[0338] In Comparative Example 2 the filter unit—Comparative filter Unit 2 (CFU2) was fitted with a woven Nylon mesh filter media having a pore size of 140 microns. CFU2 had no baffle surfaces present and was accordingly not within the scope of the present invention.

Example 1

[0339] In Example 1 the filter unit—Example filter unit 1 (EFU1) was exactly as per CFU1 but it additionally comprised a baffle surface (BS1) formed by 3D printing and which was constructed from ABS. As mentioned above BS1 is as shown in FIGS. 1a and 1b. BS1 was located within the filter unit such that the baffle surface occupied the lowermost (furthest from the inlet) portion of the internal space within the housing. Thus, there existed a portion axially above this where no baffle surface was adjacent to the filter media.

[0340] The baffle surface (BS1) was in the form of a saw-tooth wave. The baffle surface covered 90 degrees of the axis of rotation of the filter cage. The baffle surface covered 50% of the axial length of the filter media surface. The saw-tooth wave had an amplitude of 8 mm. The saw-tooth wave was 5 mm from the filter media, i.e. it had a nearest distance from the any point on the baffle surface to the filter media of 5 mm. The baffle surface was located adjacent to the exterior surfaces of the filter media. The baffle surface was located within the housing and conformed to the cylindrical shape of the housing. The baffle surface was static. The baffle surface had several teeth.

[0341] Filter Unit Operation and Method

[0342] In each case the first tank and the feed were located above the filter units. The filter units were primed with the feed and the feed was then allowed to pass through the filter unit via gravity and assisted by a second pump. The flow rate was simply that which the gravity and the second pump determines. This was approximately 7 litres per minute. The feed was passed through the filter unit just once. Whilst the feed was passed through each filter unit the electric motor was activated and the filter cage and filter media were rotated at a speed of 1400 rpm. This resulted in a G force at the internal surface of the filter media of 88 G. The rotation of the filter cage and filter media in concert with the baffle surface also encouraged and provided turbulent flow near the exterior of the filter media.

[0343] Second Tank

[0344] A second tank was used to capture and store the feed after it has passed through the filter unit on every occasion.

[0345] The contents of the second tank are then passed through a filter bag of known initial dry weight (W.sub.i) having a pore size of 1 micron.

[0346] Efficiency

[0347] Each filter bag, after collecting the microfibres from the second tank was dried in an oven at 50 degrees Celsius for a minimum of 12 hours.

[0348] The final dry filter bags along with dry microfibres not collected by the filter unit were weighed (W.sub.f).

[0349] The mass of microfibres not collected W.sub.nc by the filter unit was given by W.sub.f−W.sub.i.

[0350] The total mass of microfibres which were released from the textile substrate were established by passing the feed from BK1 directly through a 1 micron bag. An average was then taken from 3 measurements. This provided the average total mass of microfibres W.sub.totav.

[0351] The efficiency in each case is then given by (W.sub.totav−W.sub.nc)/W.sub.totav×100.

[0352] Higher efficiencies represent a more successful filtration by the filter unit.

[0353] The efficiency was averaged. The average efficiency was that taken from efficiencies for the first three and last three filtration cycles, however for comparative example 2 the average was taken from all successful washes.

[0354] Successful Number of Filtration Cycles

[0355] Successive full feeds from each treatment cycle were passed through each filter unit.

[0356] The number of feeds successfully filtered (successful filtration cycles) was recorded for each of the filter units. The point of blockage where the filtration cycles fail was determined by an abrupt reduction in the feed flow rate through the filter unit.

[0357] The number of successful filtration cycles does not include the cycle in which the filter unit blocks. Thus, as an example a filter unit which blocks on the 12.sup.th treatment cycle is recorded as having 11 successful filtration cycles.

[0358] Results

[0359] The results were as summarised in Table 1.

TABLE-US-00001 TABLE 1 Showing the average efficiency and number of successful filtration cycles for different feeds and for different filter media pore sizes. PolyCotton Successful Polycotton number of Efficiency (%) filtration cycles Comparative n/a (could not be 0 (blocks on the Example 1 measured as it 1.sup.st filtration 36 Micron filter blocked prior to cycle) media, with no completion of a baffle surface single filtration present cycle) Comparative 64 11 Example 2 140 Micron Filter media, with no baffle surface present Example 1 73 >15 36 micron filter media, with baffle surface present

Examples 2 and 3

[0360] Examples 2 and 3 were performed in exactly the same way as Example 1 with the exceptions that: [0361] i. the flow rate of the feed through the filter unit was 30 litres per minute, this resulted from connecting the filter unit to pipes with somewhat a wider diameter; [0362] ii. The efficiency was calculated as an average of only the first 3 filtration cycles; [0363] iii. The two different baffle surfaces were compared in two separate filter units.

[0364] For Example 2 the filter Unit was CFU1 fitted with baffle surface BS1 again with the baffle surface located in the lowermost (furthest from the inlet) portion of the filter unit.

[0365] For Example 3 the filter unit was CFU1 fitted a different Baffle Surface (BS2). BS was as shown in FIGS. 2a and 2b. BS2 was a single wave in the form of a single saw-tooth, the baffle surface covered 30 degrees of the axis of rotation of the cage, the baffle surface was located in the upper portion of the filter unit towards the inlet, the saw-tooth had an amplitude of 8 mm and was separated from the filter media surface by a nearest distance of 5 mm. The filter unit was such that there remained a portion of the filter media below the baffle surface axially where there was no baffle surface adjacent to it. The baffle surface was made from polylactic acid (PLA).

[0366] Results

TABLE-US-00002 Number of successful Efficiency (%) filtration cycles Example 2 73 >15 Example 3 83 >15

[0367] Table 2: shows the average efficiency of filtration along with the number of successful filtration cycles for examples 2 and 3.

CONCLUSION

[0368] The results in Table 2 show that the baffle surface in Example 2 using a single saw-tooth is even more effective than that of Example 1 using several saw-teeth

[0369] General

[0370] In the present invention, any items expressed in the singular are also intended to encompass the plural unless stated to the contrary. Thus, words such as “a” and “an” mean one or more.

[0371] The words one or more also mean one or more than one.

[0372] The following numbered clauses are not the claims. The claims are defined in the following section titled “Claims”. [0373] 1. A filter unit suitable for filtering microfibres within a feed, the filter unit comprising: [0374] a) a housing; [0375] b) an inlet configured to allow the feed to enter the housing; [0376] c) an outlet configured to allow a filtered feed to exit the housing; [0377] d) a filter cage supporting one or more filter media, the filter cage being rotatably mounted and rotating about an axis of rotation within the housing, the filter media having pores with a mean pore size of no more than 100 microns; [0378] e) one or more baffle surfaces being located adjacent to at least a portion of the interior and/or exterior surfaces of the one or more filter media; [0379] the baffle surfaces and filter cage being configured such that during rotation of the filter cage, the one or more filter media move relative to the one or more baffle surfaces and turbulent flow of liquid when present in the filter unit is encouraged near the interior and/or exterior surface of the one or more filter media; [0380] f) a drive means for rotating the filter cage; [0381] g) the filter unit being configured such that feed from the inlet is directed towards the interior of the filter cage, the feed then passes through the one or more filter media and exits as a filtered liquid via the outlet. [0382] 2. A filter unit according to clause 1 wherein the one or more baffle surfaces have one or more waves. [0383] 3. A filter unit according to clause 2 wherein the one or more baffle surfaces have a wave with a shape which repeats. [0384] 4. A filter unit according to clause 2 or clause 3 wherein the wave is or comprises a square wave, arc wave, sine wave, triangular wave or a combination thereof. [0385] 5. A filter unit according to clause 4 wherein the shape of the baffle surface is an arc wave or a saw tooth wave. [0386] 6. A filter unit according to any one of clauses 2 to 5 wherein: [0387] the one or more waves on the one or more baffles provide a variation in the distance from any point on the baffle surface to the filter media, when measured along any radial direction towards the axis of rotation of the filter cage; [0388] the one or more waves on the one or more baffles provide a furthest distance from the any point on the baffle surface to the filter media, when measured along any radial direction towards the axis of rotation of the filter cage; and the variation in the distance is at least 5% of the furthest distance. [0389] 7. A filter unit according to any one of clauses 2 to 6 wherein: [0390] the one or more waves on the one or more baffles provide a variation in the distance from any point on the baffle surface to the filter media, when measured along any radial direction towards the axis of rotation of the filter cage; and [0391] the variation in the distance is at least 2 mm. [0392] 8. A filter unit according to any one of the preceding clauses wherein at least one baffle surface is continuous through an angle of at least 10 degrees around the axis of rotation of the filter cage and measured in a plane perpendicular to the axis of rotation of the filter cage. [0393] 9. A filter unit according to clause 8 wherein at least one baffle surface is continuous through an angle of at least 20 degrees. [0394] 10. A filter unit according to any one of the preceding clauses wherein the baffle surface(s) cover no more than 90% of the axial length of the one or more filter media. [0395] 11. A filter unit according to any one of the preceding clauses wherein the baffle surface(s) cover no more than 70% of the axial length of the one or more filter media. [0396] 12. A filter unit according to any one of clauses 10 or 11 wherein the baffle surface(s) do not cover at least 5 mm in length along the axial direction of the one or more filter media. [0397] 13. A filter unit according to any one of the preceding clauses wherein the pores in the one or more filter media have a mean pore size of from 1 to 100 microns. [0398] 14. A filter unit according to any one of the preceding clauses wherein the one or more baffle surface are static. [0399] 15. A filter unit according to any one of the preceding clauses wherein the one or more baffle surfaces are located adjacent to the exterior surfaces of the one or more filter media. [0400] 16. A filter unit according to any one of the preceding clauses wherein the one or more filter media are in the form of a non-woven mesh, a woven mesh, a knitted mesh or a perforated sheet. [0401] 17. A textile treatment apparatus comprising a filter unit according to any one of the preceding clauses. [0402] 18. A textile treatment apparatus according to clause 17 which is a washing machine. [0403] 19. A method of filtering a feed comprising microfibres using a filter unit according to any one of clauses 1 to 16 or a textile treatment apparatus according to clause 17 or 18. [0404] 20. A method according to clause 19 wherein the feed comprising microfibres originates from a textile treatment apparatus. [0405] 21. A method according to clause 19 or 20 wherein during filtration the filter cage is rotated at a speed such that the internal surface of the one or more filter media experiences a G force of at least 20 G. [0406] 22. A method according to any one of clauses 19 to 21 wherein during filtration the turbulence at the outermost surface of the filter media corresponds to a Reynolds number of is at least 3000. [0407] 23. A method according to any one of clauses 19 to 22 wherein the feed is passed through the filter unit only once. [0408] 24. A method according to any one of clauses 19 to 22 wherein the feed is passed through the filter unit multiple times. [0409] 25. A method according to any one of clauses 19 to 24 wherein the filter unit filters feed from at least 5 textile treatment cycles before requiring any cleaning. [0410] 26. A method according to any one of clauses 19 to 25 wherein the microfibres are or comprise a cellulosic material. [0411] 27. A method according to any one of clauses 19 to 26 wherein the microfibres have a longest linear dimension of less than 1 mm. [0412] 28. A method according to any one of claims 19 to 27 wherein the efficiency of the filter unit at removing microfibres is at least 70% by mass relative to all the microfibres originally present in the feed. [0413] 29. A method according to any one of clauses 19 to 28 wherein the flow rate of the feed through the filter unit is at least 1 litre/minute.