Filter element, method of producing a filter element, filtration device and liquid treatment system

Abstract

A filter element comprises a porous body. The porous body is made of bonded matter, including: at least one material for binding lead; and at least a binder having a Melt Flow Rate, MFR, of more than 1 g/10 min. The porous body has a Mean Flow Pore size, MFP, in a range of between 0.1 and 11 m.

Claims

1. A filter element, comprising: a porous body, wherein the porous body is made of bonded matter, including: at least one material for binding lead; and at least one binder having a Melt Flow Rate, MFR, of at least 2 g/10 min, wherein the porous body has a Mean Flow Pore size, MFP, in a range between 0.1 and 11 m.

2. The filter element according to claim 1, wherein the MFP is between 0.1 and 11 m.

3. The filter element according to claim 1, wherein the bonded matter includes a further material, wherein the further material comprises particles having a mean particle size D.sub.50 of between 60 m and 250 m.

4. The filter element according to claim 3, wherein the further material is present in the porous body in a proportion of between 25% and 94% by weight of the total of the bonded matter.

5. The filter element according to claim 3, wherein the further material comprises activated carbon.

6. The filter element according to claim 1, wherein the binder has a mean particle size D.sub.50 between 50 m and 120 m.

7. The filter element according to claim 1, wherein the binder is present in the porous body in a proportion of less than 20% by weight of the total bonded matter.

8. The filter element according to claim 1, wherein the binder has an average molecular weight of between 2*10.sup.5 g/mol and 5*10.sup.5 g/mol.

9. The filter element according to claim 1, wherein the binder has a Vicat softening point of at most 90 C.

10. The filter element according to claim 1, wherein the material for binding lead comprises at least one of an ion exchange material in the form of a zeolite and a metal oxide.

11. The filter element according to claim 1, wherein the material for binding lead comprises a granular material having a mean particle size of between 5 m and 50 m.

12. The filter element according to claim 1, wherein the material for binding lead is present in the porous body in a proportion of between 1% and 25% by weight of the total bonded matter.

13. A filtration device, including at least one filter element according to claim 1.

14. The filtration device according to claim 12, wherein the filtration device is a replaceable liquid treatment cartridge for a gravity-driven liquid treatment system.

15. The filtration device according to claim 12, wherein the filtration device further includes a cartridge housing made of liquid-impermeable material and having at least one inlet and at least one outlet, wherein a chamber is formed in the cartridge housing, wherein loose matter forming a liquid treatment medium is housed in the chamber, and wherein at least one of the at least one filter elements is comprised in one of a liquid inlet and a liquid outlet of the replaceable liquid treatment cartridge.

16. A liquid treatment system including a replaceable liquid treatment device comprising at least one filter element according to claim 1.

17. The liquid treatment system according to claim 16, wherein the liquid treatment device is replaceable.

18. The liquid treatment system according to claim 16, further comprising a container for holding liquid to be treated, wherein the liquid treatment device is held in a flow path from the container to an outlet for dispensing filtered liquid into a vessel.

19. The liquid treatment system according to claim 16, wherein the liquid treatment system comprises a drinking bottle having a mouthpiece, and wherein the filter element is arranged between an interior of the drinking bottle and the mouthpiece.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Various details of the embodiments will become apparent from the accompanying drawings, in which:

(2) FIG. 1 is a schematic perspective view of a filter element;

(3) FIG. 2 is a diagram of an apparatus for manufacturing filter elements;

(4) FIG. 3 is a detailed view of a section of the apparatus of FIG. 2;

(5) FIG. 4 is a perspective view of a liquid treatment system in the shape of a drinking bottle;

(6) FIG. 5 is a perspective view of a first part of a top of the drinking bottle, including a seat for receiving the filter element;

(7) FIG. 6 is a perspective view of a second part of the top of the drinking bottle, configured to co-operate with the first part to engage the filter element in a sealed manner;

(8) FIG. 7 is a perspective view of a gravity-driven liquid treatment system comprising a jug and a funnel;

(9) FIG. 8 is a schematic exploded cross-sectional view of a filtration device in the form of a replaceable cartridge including both a chamber for housing a liquid treatment medium and a filter element as shown in FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION

(10) A filter element 1 comprises a porous body 2 that is pervious to the liquid to be filtered, e.g. mains drinking water. The filter element 1 may include one or more sheets 3 of fabric, woven or non-woven, applied to a surface or surface section of the porous body 2. This fabric may be a mesh or fleece, for example non-woven fabric made of point-bonded polyester fibres. The porous body 2 is self-supporting.

(11) The porous body 2 may be planar, having an essentially uniform thickness. In the illustrated embodiment, the porous body 2 is disc-shaped. In other embodiments, it may be square or rectangular. The thickness of the porous body 2 may be in the range of 1-10 mm, e.g. 5-10 mm. Its diameter may be at least twice, e.g. at least ten times its thickness. The opposing major surfaces may be essentially parallel. The fabric sheet 3 may be applied to one or both of the major surfaces only.

(12) The porous body 2 is made of one or more layers of thermally bonded granular matter, which includes at least one material for binding lead present in ionic form in the liquid to be filtered. This material specifically sorbs lead and optionally other metal contaminants, as opposed to a specific sorbent such as activated carbon. The material for binding lead may comprise at least one of an ion exchange material, e.g. a zeolite, and a metal oxide. In one particular example, it is a granular ceramic ion exchange material having a mean particle size D.sub.50 in the range of 5-200 m, e.g. 5-50 m. In particular, the nominal particle size D.sub.50 may be within the range of 20-35 m.

(13) The thermally bonded matter further includes a binder having a melt flow rate (MFR) of more than 1 g/10 min, e.g. at least 2 g/10 min (measured in accordance with ISO 1183 using an MFR temperature of 190 C. and a load of 21.6 kg). The binder may be a thermoplastic binder. In the particular example of the porous body 2 referred to above, it is polyethylene with a molecular weight in the range of 2*10.sup.5-5*10.sup.5 g/mol, e.g. about 4*10.sup.5 g/mol, and an MFR of about 3.6 g/10 min. It has a Vicat softening temperature (in accordance with ISO 306) below 100 C., e.g. in the range of 50100 C., for example in the range of 7090 C. The mean particle size D.sub.50 may be in the range of 20-200 m, e.g. in the range of 100-120 m.

(14) The thermally bonded matter forming the porous body 2 further comprises activated carbon, e.g. granular activated carbon. The activated carbon may be coconut-based, for example. The activated carbon has a mean particle size D.sub.50 in the range of 60-250 m.

(15) The activated carbon, binder and material for binding lead may together make up at least 99% by weight of the thermally bonded matter forming the porous body 2. In the example referred to above, the proportion of activated carbon lies in the range of 25-94%, the proportion of binder lies in the range of 5-50% and the proportion of the material for binding lead lies in the range of 1-80% by weight, e.g. 1-25% by weight. The porous body has a mean flow pore size MFP in a range of 0.1-11 m.

(16) As mentioned, the porous body 2 may be a layered structure, each layer being made of thermally bonded matter. One or more properties, e.g. porosity or mean flow pore size may vary between layers. In other embodiments, one or more parameters such as porosity or mean flow pore size may exhibit a gradient in the direction of flow.

(17) An apparatus (FIGS. 2 and 3) for manufacturing a filter element 1 provided with a covering fabric sheet 3 on both major surfaces includes a main endless belt 4 on support drums 5,6, of which at least one is driven by a motor (not shown). A lower web 7 of fabric is unwound from a first reel 8 onto the main belt 4.

(18) A device 9 for depositing a layer of loose matter to be thermally bonded onto the moving lower web 7 may comprise a hopper, for example. A doctor blade 10 is provided to set an initial height of the layer. Thereafter, the layer and the lower web 7 pass through a double-belt press 11, where heat is applied and the height of the layer is reduced from an initial value h.sub.1 to a final value h.sub.2 corresponding to the thickness of the filter element 1. The degree of compression, h.sub.1/h.sub.2/h.sub.1, has a value in the range of 5-60%, specifically in the range of 30-50%.

(19) The temperature at the point of contact between the double-belt press 11 and the layered structure is between 130 and 230 C., that is to say between 50 and 150 C. above the Vicat softening temperature of the binder, but the contact time is relatively short, e.g. in the range of 5-20 min. The pressure applied is relatively low, e.g. below 5000 Pa. An upper web 12 of fabric is unwound from a second reel 13 and applied to the layer.

(20) A first cutting device 14 cuts plates 15 from the layered structure. Each plate 15 is then transferred to a second cutting device 16, where the individual filter elements 1 are cut from the plate. The remainder can be shredded and recycled, e.g. processed into activated carbon or milled and admixed to the loose matter deposited by the depositing device 9. The first cutting device 14 and the step of cutting plates 15 may be dispensed with in an alternative embodiment. In that alternative case, the filter elements 1 would be cut from the layered structure directly in a continuous process. The second cutting device 16 may be a laser cutting device or a water jet cutting device, for example.

(21) The filter element 1 forms or is comprised in a replaceable component of a liquid treatment system.

(22) A first example of a liquid treatment system (FIGS. 4-6) comprises a drinking bottle 17 with a top 18 comprising a first part 19 and a second part 20 that co-operate to hold the filter element 1 in a sealed relationship to the bottle top 18 between the interior of the bottle and a mouthpiece 21. The first part 19 is releasably connected to the drinking bottle 17 at a mouth of the latter. The second part 20 is releasably attached to the first part 19, in this case by means of a threaded connection, after the filter element 1 has been placed in a recess formed in the first part 19. In use, water is sucked through the filter element 1. To re-fill the drinking bottle 17, the entire top 18, with the filter element 1 held in it, is removed.

(23) A second example of a liquid treatment system (FIG. 7) is a gravity-driven liquid treatment system comprising a jug 22 in which a funnel 23 is suspended above a bottom of an interior of the jug 22. An arrangement for holding the filter element 1 in a sealed relation to the funnel 23 at an outlet thereof comprises a removable mounting ring 24 allowing for replacement of the filter element 1. Such an arrangement is described in more detail in WO 2017/097494 A1, the contents of which are incorporated by reference.

(24) Alternatively, the funnel 23 can be provided with a seat for sealingly engaging a liquid treatment cartridge 25 (FIG. 8) of the type disclosed in more detail in WO 2013/139821 A1, the contents of which are incorporated by reference. This cartridge 25 includes a cartridge housing made of liquid-impermeable material and having at least one inlet 26a-e and at least one outlet. In this example, the cartridge housing includes a first, beaker-shaped, housing component 27 having a side wall for forming a boundary of a chamber in radial direction with respect to a main axis 28. The first housing component 27 is closed at an axial end forming an axial end of the cartridge 25 by a filter element 1 framed by a rim of liquid-impermeable material bonded to the first housing component 27, so that the filter element 1 forms an outlet of the cartridge 25 and a bottom wall of the chamber formed therein. The first housing component 27 is closed at an opposite axial end by a second, cap-shaped, housing component 29, in which openings forming the inlets 26a-e are formed. The chamber formed in the liquid treatment cartridge 25 may house at least one of ion exchange resin and loose activated carbon. Thus, the liquid treatment system in which the liquid treatment cartridge 25 is deployed can remove other substances, e.g. those contributing to carbonate hardness, in addition to meeting standards for lead removal such as NSF 53.

(25) Filter elements for a liquid treatment system according to the second example (FIG. 7) have been produced and tested. The filter elements were manufactured without the fabric sheets 3. Each had a thickness of about 6.3 mm and a diameter of about 90 mm. Three specifications A-C were used and two filter elements of each specification were tested. All were manufactured on an apparatus of the type described above.

(26) The specifications were as shown in Table 1.

(27) TABLE-US-00001 TABLE 1 Com- Activated pression MFP carbon Components [%] [m] A D.sub.50,3 = 78 m. 65 wt.-% activated carbon; 33 10 25 wt.-% binder; 10 wt.-% lead adsorbent B D.sub.50,3 = 78 m. 65 wt.-% activated carbon; 45 7 25 wt. -% binder; 10 wt.-% lead adsorbent C D.sub.50,3 = 60 m. 65 wt.-% activated carbon; 33 7 25 wt.-% binder; 10 wt.-% lead adsorbent

(28) The binder was High-Molecular Weight Polyethylene (HMW-PE) having an MFR (in accordance with ISO 1183) of 3.6 g/10 min. (MFR temperature: 190 C.; MFR load 21.6 kg) and an average particle size D.sub.50 of 110 m. The lead adsorbent was a ceramic ion exchange material having nominal particle sizes between 20 and 35 m, marketed as ATS by BASF Corp.

(29) In the test, filter elements in accordance with specifications A-C were compared with a filter element according to a further specification D. A sample with specification D had an MFP of 11.4 m and activated carbon with a mean particle size D.sub.50,3 of 110 m. The proportions by weight of the activated carbon, binder and lead adsorbent were the same as for specifications A-C and the binder and lead adsorbent used were also the same

(30) Challenge water in accordance with NSF 53/ANSI Standard 53, 7.4.3.5.2.3 was prepared and the influent and effluent lead concentrations were measured. The detection limit was 5 ppb.

(31) The results for specification A were as set out in Table 2.

(32) TABLE-US-00002 TABLE 2 Influent Particulate Particulate Effluent lead concentration Total total <1.2 m Sample 1 Sample 2 Liter [ppb] [ppb] [%] [ppb] [%] [ppb] [ppb] 1 133 92 69 62 67 7 6 4 133 92 69 62 67 <5 7 5 145 74 51 37 50 <5 <5 8 145 74 51 37 50 <5 <5

(33) The results for specification B were as set out in Table 3.

(34) TABLE-US-00003 TABLE 3 Influent Particulate Particulate Effluent lead concentration Total total <1.2 m Sample 1 Sample 2 Liter [ppb] [ppb] [%] [ppb] [%] [ppb] [ppb] 1 164 95 58 44 46 <5 6 3 164 95 58 44 46 <5 6 5 164 95 58 44 46 <5 <5 10 153 88 58 31 35 <5 <5

(35) The results for specification C were as set out in Table 4

(36) TABLE-US-00004 Influent Particulate Particulate Effluent lead concentration Total total <1.2 m Sample 1 Sample 2 Liter [ppb] [ppb] [%] [ppb] [%] [ppb] [ppb] 1 157 106 68 63 59 <5 6 3 157 106 68 63 59 <5 6 5 159 126 79 85 67 <5 <5 10 159 103 65 55 53 <5 <5 12 159 103 65 55 53 <5 <5

(37) The results for specification D were as set out in Table 5

(38) TABLE-US-00005 TABLE 5 Influent Particulate Particulate Effluent lead concentration Total total <1.2 m Sample 1 Sample 2 Liter [ppb] [ppb] [%] [ppb] [%] [ppb] [ppb] 1, 5 147 115 78 26 23 17 16 3 147 115 78 26 23 12 16 6 147 115 78 26 23 11 11 7, 5 154 130 84 67 52 15 14 9 154 130 84 67 52 11 13 12 154 130 84 67 52 9 10

(39) It will be apparent that the sample filter elements in accordance with specifications A-C were easily able to meet current requirements for lead reduction. Moreover, the filtration rate was determined to be below 10 min./l for the gravity-driven system used for testing.

(40) The invention is not limited to the embodiments described above, which may be varied without departing from the scope of the accompanying claims. For example, different materials for binding lead may be incorporated into the porous body 2 and together have the properties (particle size, proportion of thermally bonded matter) of the material for binding lead disclosed above. The same is true for the binder.

(41) In cases in which the mean particle size of the material for binding lead is relatively high, more of that material may be present. Indeed, activated carbon may be omitted in such embodiments.

LIST OF REFERENCE NUMERALS

(42) 1 filter element 2 porous body 3 sheet 4 main belt 5 first support drum 6 second support drum 7 lower web 8 first reel 9 depositing device 10 doctor blade 11 double-belt press 12 upper web 13 second reel 14 first cutting device 15 plate 16 second cutting device 17 drinking bottle 18 bottle top 19 first bottle top part 20 second bottle top part 21 mouthpiece 22 jug 23 funnel 24 mounting ring 25 cartridge 26a-e inlets 27 first housing component 28 main axis 29 second housing component