WO2000058222A1

WO2000058222A1 - Water filter cartridge

Info

Publication number: WO2000058222A1
Application number: PCT/CA2000/000325
Authority: WO
Inventors: Pierre Jean Messier
Original assignee: Individual
Current assignee: Individual
Priority date: 1999-03-29
Filing date: 2000-03-24
Publication date: 2000-10-05
Anticipated expiration: 2001-09-29
Also published as: AU3412900A; CA2267511A1

Abstract

A system or means for removing microorganisms such as viruses from water which comprises associating a water/resin contact component (i.e. a residence time enhancer means or component) with a disinfectant resin component and a (particulate) filter component.

Description

WATER FILTER CARTRIDGE

The present invention relates to a water filter cartridge for use m a water filtration system and m particular a replaceable water filter cartridge. The water filter cartridge may for example be used to treat microorganism contaminated water so as to provide water suitable for drinking by a human being.

The applicant is not aware of any water purifier method or system that can kill viruses to a sufficient degree without having to rely on a chemical biocide.

A (replaceable) ceramic filter cartridge is described in U.S. patent no. 5,273,650 which comprises a ceramic pre-filter, having the general shape of a hollow cylinder, which defines a chamber that contains an (halogented (e.g. lodmated) ) purification resin. The purification resin is contained withm the chamber by an exit cap having a porous separator disc therein at a first end and an end cap at a second end The water to be treated flows from an inlet into a space between a wall of a housing and the (ceramic) pre-filter. The water then flows radially inward through the wall of the ceramic filter into the resm filled chamber. Thereafter water proceeds longitudinally through the resin and of then through the porous disc and out the exit cap through an opening or passageway in the exit cap. The pre-filter of such as system may be relatively effective in mechanically removing relatively large microorganisms such as protazoa and even relatively large bacteria. This system or cartridge, however, has a weakness in that water may enter the chamber adjacent to the porous disc such that any relatively small microorganisms (such as viruses as well as relatively small bacteria) in this water may effectively short circuit the resm in the chamber since such microorganisms may not be in contact with the resm for a time sufficient to render such microorganisms non-viable; i.e. the treated water may remain dangerously contaminated with viruses.

Accordingly, it would be advantageous to have a filter cartridge which could effectively treat water containing by avoiding or attenuating such short circuiting of the contact time with the resin so as to provide a sufficiently treated (potable) water.

STATEMENT OF INVENTION

In accordance with the present invention there is provided a system or means for removing microorganisms such as viruses from water which comprises associating a water/resin contact component (i.e. a residence time enhancer means or component) with a disinfectant resm component and a (particulate) filter component.

The present invention in general relates to a method for disinfecting liquid (e.g. water) containing liquid borne microorganisms such as viruses, said method comprising passing liquid containing liquid borne microorganisms through a suitably configured liquid path means having disposed therein a filter component as well as a disinfecting component such that liquid in said liquid path means is passed over a demand disinfectant resin such that liquid borne microorganisms contact said resm for a sufficient amount of time such that they are devitalized thereby. The present invention also generally relates to a system for disinfecting a liquid (e.g. water) containing liquid borne microbiological entities, said system comprising means for providing a liquid path for the movement of liquid therethrough, a filter element as well as demand disinfectant resm being disposed in said liquid path, said liquid path means being suitably configured such that liquid borne microorganisms (such a viruses) in the liquid passing through said liquid path are able to contact said resm for a sufficient amount of time and be devitalized thereby. The liquid path means may, for example, comprise suitably configured baffle means for increasing the relative length of the liquid path through the system.

The present invention in particular provides in a water filter cartridge, having at least a water filtration component and a water disinfection component, for use in a water filtration system, the filtration component comprising a wall member defining a first cavity, said wall member comprising a water permeable filtration wall element; and the disinfection component comprising disinfection resm, the improvement wherein the cartridge includes a res /water contact (e.g enhancement) component, said resin contact component comprising a water impervious wall element, an inlet means and an outlet means, said water impervious wall element defining a second cavity, said inlet means communicating with said first cavity, said outlet means comprising a water permeable plug element (e.g. porous disc - se blow) for retaining resin in said second cavity, said disinfection resm being disposed at least withm said second cavity such that water passing through the water filter cartridge passes between said inlet means and said water permeable plug element through the disinfection resm disposed in said second cavity. In accordance with the present invention the wall member defining the first cavity may consist more or less entirely of a water permeable materialisation If desired or necessary the water disinfection component may be disposed outside of the water filtration component, alternatively, as shall be discussed hereinafter (by way of example only), the water disinfection component may be disposed withm the water filtration component in order to conserve space

In accordance with the present invention disinfection resm may additionally be contained withm said first cavity

In accordance with the present invention there is further provided in a water filter cartridge having at least a water pre-filtration component and a water disinfection component, for use in a water filtration system, the water pre-filtration component having a water permeable, cylindncally shaped, filtration wall and having a bore extending along the longitudinal axis of the cylindncally shaped filtration wall to a first end opening of the water filter component, the water disinfection component comprising disinfection resm, the filter cartridge including containment means comprising a water permeable plug element for retaining the resm in said bore and cover means attached to said filtration wall covering the first end opening, said cover means comprising a water passageway the improvement wherein the cartridge includes a water/resin contact enhancement member disposed in said bore for enhancing contact time between water and resin, said resin contact member having a water impervious, cylindncally shaped, wall element, an inlet end and an outlet end, said water impervious wall element defining a cavity and being spaced apart from said filtration wall so as to define an annular space therebetween, said mlet end being m liquid communication with said annular space, wherein disinfectant resin is disposed in said second cavity, and wherein said outlet end is attached to said cover means and is disposed about said passageway such that water passing through the water filter cartridge passes, between said inlet end and the passageway, through the disinfection resin in said second cavity.

In accordance with the present invention the annular space may also be filled with disinfection resin. On the other hand if resin is to be confined to the cavity of the resin/water component, the inlet may also be provided with a water permeable plug element for retaining the resin in said cavity (i.e. within the cavity disposed in said bore).

In accordance with the present invention a system for disinfecting water may be associated with means for urging the liquid through the filter cartridge (e.g. it may for example be associated with a suitable or appropriate pumping system).

The disinfection resin may, for example, be a demand disinfectant resin comprising an iodinated strong base anion exchange resin; such iodinated resins are mentioned or taught for example in U.S. patent no. 5,639,452 (the entire contents of which are incorporated herein by reference).

The filtration component may comprise a particulate or microorganism filter element; the filter element may, for example, be a high efficiency particulate liquid filter ( i.e., an HEPL filter); e.g. a filter able to remove particles of 0.2 microns or larger. The filter may be of ceramic material or be of an aggregate base material comprising polyethylene, nylon, polystyrene, stainless steel, etc.. In accordance with the present invention due to the presence of the water/resin contact component it may be possible to use a less efficient filter element (i.e. a filter element only able to stop larger particles such as, for example, only particles greater in size than 0.2 microns e.g. only particles of more than 0.2 to 3 microns in size e.g. 3 microns or larger); in this case there may be an attendant benefit m that the pressure drop across such a lower efficiency filter element may be relatively significantly lower than if a 0.2 micron stopping filter is used for example.

The filter cartridge of the present invention may in particular be used for canteens so as to provide potable water therefrom.

In the drawings which illustrate an example embodiment of the present invention:

Figure 1 is a schematic side view of a known water filter cartridge;

Figure 2 is a schematic longitudinal cross-sectional view of the known water filter cartridge shown m figure 1 ; Figure 3 is an exploded schematic longitudinal cross-sectional view of an example water filter cartridge in accordance with the present invention; Figure 4 is a schematic longitudinal cross-sectional view of the example water filter cartridge in accordance with the present invention shown in figure 3; Figure 5 is a schematic longitudinal cross-sectional view of the example water filter cartridge in accordance with the present invention shown in figure 4 disposed in a water filtration system housing; and Figure 6 is a schematic longitudinal cross-sectional view of another example water filter cartridge m accordance with the present invention.

Figures 1 and 2 schematically illustrate the water filter cartridge 1 taught m U.S. no. 5, 273, 650. The water filter cartridge 1 comprises a ceramic prefilter wall 2 element having the general shape of a hollow cylinder open at both first 3 and second 4 ends; the cylinder has a circular cross section . The prefilter wall element 2 forms the outer wall of a cylmdncal chamber 5 (also of circular cross section) which contains the halogenated purification resm 6; as may be seen the resin 6 occupies the entire length of the chamber 5. The first end 3 is provided with an exit cap 9 having a passageway 10 covered by a porous disc 12. The porous disc 12 maintains the resin 6 within the chamber 5. The exit cap 9 has attachment means 14 for removably attaching the cartridge to a water filtration system housing; the attachment means may take any suitable known form for this purpose (e.g. rubber O-πng(s)). An end cap 16 is attached to the second 4 end of the wall element 2 to block off the opening associated therewith , i.e. again so as to maintain the resm withm the chamber 5.

Turning to figure 2 this figure includes arrow pairs 18, 19 and 20 which show the radial flow of water through the ceramic wall element 2 towards the chamber 5. As may be seen the water flow represented by the arrow pair 20a have a relatively short path to the passageway 10 of the exit cap 9; i.e. the viruses etc, in this portion of the water flowing into the chamber 5 can effectively short circuit the resm 6 in the chamber 5 such that viable viruses are able to escape treatment; in this case the water risks to remain undπnkable to an unsuspecting user. Figures 3, 4 and 5 illustrate an example water filter cartridge in accordance with the present invention.

As in the case of the above prior art cartridge 1 the cartridge 25 shown in figures 3, 4 and 5 has a ceramic prefilter wall element 27 having the general shape of a hollow cylinder open at both first 28 and second 29 ends; the cylinder has a circular cross section (it may of course have a non circular cross section as desired or necessary) . The prefilter wall element 27 forms the outer wall of a cylindrical chamber 30 (also of circular cross section for this example embodiment). The cartridge 25 also has an exit cap 32 provided with a passageway 34 and an end cap 36; the cartridge 25 also has a porous disc member 38 held in place in any suitable (known) fashion such as by an adhesive etc,. The exit cap 32, end cap 36 and the porous disc member 38 serve to maintain the resin (not shown) within the chamber 38 defined by the ceramic wall element 27.

The cartridge illustrated m figures 3, 4 and 5 also has a baffle member 40. The baffle member 40 likewise has the general shape of a hollow cylinder ; the cylinder has a circular cross section (it may of course have a non circular cross section as desired or necessary ) The baffle member 40 at its outlet end 42 is sealingly attached in any known or suitable manner (e.g. glue or adhesive) to the exit cap 32 such that the walls of the baffle 40 are disposed around the passageway 34. The baffle member 40 extends along the longitudinal axis of the chamber 30 to a point where the mlet end 46 is spaced from the end cap 36.

The outer surface 48 of the baffle member 40 is spaced apart from the inner surface 50 of the ceramic prefilter wall element 27 such that an elongated annular space 54 is defined therebetween. The baffle member 40, however, is made of a suitable water impervious material. Although not shown disinfection resin may be disposed if so desired not only in the cavity 58 defined by the baffle member 40 but also in the annular space 54. For the example embodiment shown about 32 grams of resin may, for example, be maintained within the chamber 30 defined by the ceramic wall element 27 i.e. in the baffle cavity 58 and the annular space 54.

For the example cartridge 25 shown in figure 3, 4 and 5, the baffle member may have a length designated by the arrow 62 of 7.5 cm from the porous disc 38 to the inlet end 46; the distance designated by the arrow 64 from the porous disc 38 to the outlet end 42is about 1cm. The ceramic wall element 27 on the other hand may have a length designated by the arrow 66 of about 10 cm. The inner diameter 68 of the ceramic wall element 27 may be 2.2 cm whereas the outer diameter 70 of the baffle member 40 may be 1.96 cm.

Turning to figure 5 this figure shows the cartridge 25 disposed in a water filtration system housing 74 ; the rest of the system is not shown but it may take for example the form of the system shown in U.S. patent no. 5,273,650. The housing 74 shown in figure 5 may be of screw on cap type as illustrated in Figure 2 of U.S. patent no. 5,273,650 so as to facilitate replacement of the water cartridge therein. As may be appreciated from figure 5 water enters the housing 74 in the direction of the arrow 76 ; this may be due to the action of a pump means (not shown). Thereafter the water flows radially through the ceramic prefilter wall element in the direction of the arrows 78 . However as may be seen the baffle member 40 prevents water flow from having a short direct access to the passageway by forcing the water to flow upwards in the annular space 54 to the inlet end 46 of the baffle member (see arrows 80). The water then flows down through the baffle cavity filled with disinfection resm (resm not shown) through the porous disc to finally exit the housing m the direction of the arrow 82.

As may be appreciated from figure 5, the presence of the water impermeable baffle member increases the relative contact time (i.e. residence time) between the water and the resin so as to enhance devitahsation of bacteria, viruses and the like.

Figure 6 illustrates another example embodiment of a water filter cartridge 85 of the present invention; the same reference numerals will be used to designate elements common with the embodiment shown in figure 3, 4 and 5. The major differences between the embodiment shown m figure 6 and that of figures 3, 4 and 5 is that the baffle member 40a is not within the chamber defined by the ceramic wall element and the periphery 32a of the exit cap is disposed at the inlet end of the baffle member; for this embodiment both the chamber 30a and cavity 58a may contain the disinfectant resm designated by reference numeral 90.

In order to perform adequately as a water purifier, a device must be able to stop and/or eradicate protozoa (Giardta or Cryptosporidium) , bacteria (Klebstella terrigena) and viruses (pohovirus and rotavirus). The most recognized protocol for such a claim is the US Environmental Protection Agency's Guide Standard and Protocol for Testing Water Purifiers (ref. no. 1). The requirements for this protocol are very stringent.

In the following test examples the filtration capacity of a high quality ceramic filter (washable) cartridge associated with about 32 grams of a Tnosyn resm was tested; the Tnosyn resin is a well documented demand-release iodinated biocidal resm (i.e. an iodinated strong base anion exchange resin) which may be made in accordance with the teachings of U.S. patent

no. 5,639,452 (the entire contents of which are incorporated herein by reference). A unique feature of Tnosyn is its ability to devitalize microbiological entities (i.e. microorganisms) such as bacteria and viruses in many environments such as air, water and dermatology; see U.S. Patent no. 5,639,452 above.

Table 1: U.S. EPA 's Guide Standard and Protocol for Testing

Microbiological Water Purifiers

11

SUBSTIIUTE SHEET (RULE 26) Table 2: Microbiological Reduction Requirements:

Material and Methods

Tested materials

• Three ceramic filter cartridges (each of the same structure as described herein with respect to figures 3, 4 and 5) were tested against various microbiological entities; the ceramic filters were able to filter particulates of 0.2 microns or larger. The cartridges were each loaded with about 32 grams of the same demand disinfectant resin comprising an iodinated strong base anion exchange resm (i.e. Tnosyn T50 resm obtainable from Hydro biotech Mirabelle, Quebec Canada) The testing procedures were carried out using the herein described U.S. Environmental Protection Agency (EPA) procedures (e.g. see ref. no. 1, no. 2 and no. 3). In each case the three cartridges A, B and C were tested along with a positive control C+. The contaminated water was passed through the filter cartridges at the rates indicated below.

Methods

Viral challenge

The propagating host of coliphage MS2 is Escherichia coli (ATCC 15597) which was rehydrated m 10 ml of TSB and overnight incubation at 35 °C. 250 ml of the following specialized media was spiked with this fresh strain and overnight incubation occurred at 35 °C.

Tryptone 10.0 g

Yeast extract 1.0 g

NaCl 8.0 g

Glucose 1.0 g

CaCl₂ 1M 4 ml

Thiamme 10 mg

Purified water 1.0 L pH 7.2 ± 0.2

Coliphage MS2 was added to this log phase culture broth and placed m the 35 °C incubator for 24 hours with constant agitation. This suspension was centnfuged for 60 minutes at low RPM. 10 drops of chloroform were added to the collected surnatant. The stock suspension gave a titer of 7.1 X 10⁹ plaque forming units per ml (PFU/ml) and was stored at 4 °C.

This stock suspension was diluted in purified water (reverse osmosis) in order to achieve a minimal recommended EPA (see ref. No. 1 ) concentration of 1 X 10⁷ viral units/litre.

Sampling was performed at the end of the volume tested. A positive control was performed at each sampling point. Phage assay was done with the single layer technique with incorporation in 10 ml 10% MS2 agar of 1 ml host bactena (E coh, ATCC No. 15597, Rockville, MD) in log growth phase and 1 ml of sample. Each sample was assayed in duplicate. Readings were taken after overnight incubation at 35°C General laboratory methods were performed according to Standard Methods for the Evaluation of Water and Wastewater (see ref. No. 2). Sodium thiosulfate was added immediately after the sampling occurred (0.1 mL @ 5% per mL of sample). The detection level with this method is 1 PFU / mL.

The results of the tests are shown in table 3 below: Table 3: MS2 challenge of Filter Cartridge @ 400 mL /min

BACTERIAL CHALLENGE

Klebsiella terrigena was grown overnight in Trypticase Soya Broth (TSB, Becton Dickinson, Cockseysville, MD). Bacteria was in the stationary growth phase with a titer of 10⁹ colony forming units per ml (CFU/ml). This suspension was diluted in purified water (reverse osmosis, deiomzation, sterilization) m order to achieve a minimal recommended EPA (1) concentration of 10⁷ CFU / 100 ml. Sampling was performed at the end of the volume tested with plate count technique on TSA and the membrane filter technique on m-Endo according to Standard Methods or the Examination of Water and Wastewater (2). 100 ml samples were assayed for each filter. Sodium thiosulfate was added immediately after the sampling occurred (0.1 mL @ 5% per mL of sample) The detection level with these methods is 1 CFU / 100 mL.

The results of the tests are shown in table 4 below:

Table 4: Klebsiella terrigena challenge of Filter Cartridge

400 mL /min

PROTOZOAN CHALLENGE

Live Cryptosporidium parvum oocysts in water were used for this study at a minimum concentration of 10⁶ oocysts / litre. One litre was pumped through the actual prototype that was in our possession. A positive control was performed as well as 0%, 50% and

100% sampling points. Sodium thiosulfate was added immediately after the sampling occurred (0.1 mL @ 5% per mL of sample). The samples were centrifuged at 2000

RPM for 15 minutes at 7 degrees Celsius. The residue was put on slides with the Ziehl-

Neelsen stain and microscopic observation performed under phase-contrast microscopy by an expert in this particular field.

The test results are shown in table 5 below:

Table 5: Cryptosporidium parvum oocysts challenge of Filter

Cartridge @ 400 mL /min

IODINE QUANTIFICATION

The procedure for the evaluation of free iodine (I₂) and iodide (I^") was conducted according to Standard Methods for the Examination of Water and Wastewater (ref No. 2).

IODINE METHOD Mercuric chloride (Fisher Scientific, Fair Lawn, New Jersey) added to aqueous elemental iodine solutions cause complete hydrolysis of iodine and the stoichiometnc production of hypoiodous acid. The compound 4,4,4 methylidynetns (Leuco crystal violet, Aldrich Chemical Company Milwaukee, WI) reacts with the hypoiodous acid to form crystal violet dye. The maximum absorbance the crystal violet dye solution is produced in the pH range of 3.5-4.0 and measured at a wavelength of 592 nm. The absorbance follows Beer's law over a wide range of iodine concentration. Iodme can be measured in the presence of max 50 PPM iodide ions without interference.

TOTAL IODINE METHOD. Iodide is selectively oxidized to iodme by the addition of potassium peroxymonosulfate (Oxone, Aldrich Chemical Company Milwaukee, WI). The iodine produced reacts instantaneously with the indicator reagent Leuco crystal violet over the same conditions described previously for iodine methods. Total iodine plus iodide results from this procedure and iodide is calculated from subtraction of iodine concentration. Readings of absorbance are to be performed on a spectrophotometer with a hghtpath of 1.0 cm and selected at 592 nm.

The results of the tests are shown in tables 6, 7 and 8 below: Table 6: Total iodine quantification for MS2 challenge

Table 7: Free iodine quantification for MS2 challenge

Table 8: Total iodine quantification for Klebsiella terrigena challenge

Table 9: Free iodine quantification for Klebsiella terrigena challenge

CONCLUSION

The water filter cartridge performed perfectly according to the test parameters involved in this study. No virus, bacteria and protozoan ocyst was detected in the filtered water.

REFERENCES: REFERRRED TO ABOVE

1. US Environmental Protection Agency 1986. Guide Standard and Protocol for Testing Water Purifiers. Washington, DC (ref. No. 1).

2. APHN AWWA, WPCF. 1989. Standard Methods for the Evaluation of Water and Wastewater, 17^th edition. Clesceri, L.S. et al. (ed.), Washington, DC (ref. No. 2).

3. Hurst, C.J. et al. 1997. Manual of Environmental Microbiology. ASM Press, Washington, DC (ref. No. 3).

Claims

I CLAIM:

1. In a water filter cartridge, having at least a water filtration component and a water disinfection component, for use in a water filtration system, the filtration component comprising a wall member defining a first cavity, said wall member comprising a water permeable filtration wall element; and the disinfection component comprising disinfection resm, the improvement wherein the cartridge includes a resm/water contact component, said resm contact component comprising a water impervious wall element, an inlet means and an outlet means, said water impervious wall element defining a second cavity, said inlet means communicating with said first cavity, said outlet means comprising a water permeable plug element for retaining resin in said second cavity, said disinfection resm being disposed at least within said second cavity such that water passing through the water filter cartridge passes between said inlet means and said water permeable plug element through the disinfection resm disposed in said second cavity.

2. A water filter cartridge as defined in claim 1 wherein disinfection resm is additionally contained within said first cavity.

3. A water filter cartridge as defined in claim 1 wherein the water permeable filtration wall element is a ceramic water permeable filtration wall element.

4. In a water filter cartridge having at least a water pre-filtration component and a water disinfection component, for use m a water filtration system, the water pre-filtration component having a water permeable, cylindncally shaped, filtration wall and having a bore extending along the longitudinal axis of the cylindncally shaped filtration wall to a first end opening of the water filter component, the water disinfection component comprising disinfection resin, the filter cartridge including containment means comprising a water permeable plug element for retaining the resm in said bore and cover means attached to said filtration wall covering the first end opening, said cover means comprising a water passageway the improvement wherein the cartridge includes a water/resin contact enhancement member disposed in said bore for enhancing contact time between water and resm, said resin contact member having a water impervious, cylindncally shaped, wall element, an mlet end and an outlet end, said water impervious wall element defining a cavity and being spaced apart from said filtration wall so as to define an annular space therebetween, said inlet end being in liquid communication with said annular space, wherein disinfectant resm is disposed m said second cavity, wherein said water permeable plug element is disposed in said second cavity and wherein said outlet end is attached to said cover means and is disposed about said passageway such that water passing through the water filter cartridge passes, between said mlet end and the passageway, through the disinfection resm m said second cavity

A water filter cartridge as defined m claim 4 wherein said annular space is filled with disinfection resin

A water filter cartridge as defined in claim 4 wherein the water permeable filtration wall element is a ceramic water permeable filtration wall element.