POUR-THROUGH AND PITCHER MOUNTED WATER FILTER

Abstract: A gravity fed, pour-through water filtration device (10) includes a chamber housing (11), a spiral filter (30, 80) including a biocidal material and an annular holding chamber. Several porous separator disks, a volume of filtration media (64), and a cyst membrane (70) are positioned beneath the spiral filter and holding chamber. The device (10) is effective in significantly reducing the number of bacteria, viruses and cysts present in the filtrated water. The filtration device is a fully scaleable design for use in municipal flow-through and other systems. The configuration of the flow path may be a thin channel of minimal width lined with granular active material to improve the efficiency of the filtration and treatment process while keeping to a minimum the resistance to flow. The spiral or helical geometry lends itself to compact arrangement where space is limited. The fluid channel lined with granular material disrupts laminar flow and creates an environment inhospitable for the growth of bacterial contaminants such as biofilm typically found and described in dental water treatment lines.

Description: POUR-THROUGH AND PITCHER MOUNTED WATER FILTER Cross-References to Related Applications This application is a continuation-in-part of Application No. 08/641,762, filed May 2, 1996, still pending, and claims the benefit of U.S. Provisional Application No. 032,315, filed December 9, 1996 and U.S. Provisional Application No. 60/038,826, filed February 6, 1997. Technical Field This invention relates generally to water treatment devices, and more particularly, to a device and method for removing microbiological, pesticidal and cyst substances or metal substances from water. The device of the present invention has features making it optimal for use in a pour-through unit, in an in-line pressurized water system, or a municipal water treatment plant. Background Art Many types of contaminants are found in water, and often central water treatment plants fail to adequately remove all contaminants. For instance, herbicides, pesticides and PCB's, chemicals applied to land or used in industries, may enter drinking water as a result of misapplication, spills or industrial discharge. Inorganic compounds, occurring naturally in the environment, may enter water as they pass through rock or soil. Organic compounds may end up in the drinking water as a result of misapplication of agricultural chemicals, spills, or industrial discharge during manufacturing. Also of concern are bacteria, viruses and parasite cysts that survive the community water treatment. This is increasingly a problem due to the growth of the population of susceptible individuals as addressed by amendments of the Safe Drinking Water Act (August 6, 1996) . Another reference is entitled Sensitive Populations: Who is at the Greatest Risk? International Journal of Food Microbiology, Vol. 30, 1996, pages 113 through 123. The most common cysts are Giardia lamblia and Cryptosporidium which are excreted by animals. These two cyst types are sometimes found in drinking water systems which use surface water as the primary source. There are many proposed portable filtration devices in the prior art of which I am aware. Various point-of- use pour through none of which claim microbiological reduction. Other non-pour through units claim microbial reduction but are primarily intended to improve the aesthetic concerns in the water, i.e., taste, odor and/or color. U.S. Patent No. 5,076,922 to DeAre discloses a filtration apparatus for use with a water pitcher. The filter is filled with a combination of conventional resin and activated carbon which attracts lead and chlorine to improve the taste and quality of the water. However, this type of filter may not effectively reduce microbes, such as bacteria, viruses and cysts. Microbes are intended to encompass bacteria, viruses and cysts. A portable potable water purifier kit is disclosed in U.S. Patent No. 5,116,500 to Ceaton. The water traversing the filter encounters anthracite and an ion exchange material before entering a spiral structure containing activated carbon. U.S. Patent No. 5,308,482 to Mead discloses portable water purifying device intended to kill both bacteria and 2 viruses. The filter provides a microbicidal resin, specifically, iodine, in a flow path which increases contact time of the water with iodine, and a holding reservoir to expose water to iodine, and a post-filter volume of activated charcoal. The reference fails to disclose removal of cysts. Generally, pressurized water purification devices are more effective in reducing bacteria, viruses and cysts. For example, U.S. Patent No. 5,205,932 to Solomon et al . discloses an in-line, pressure driven water purification canister including five sequential stages of bacteriostatic purification, each employing a respective medium: polymer-bead, copper-zinc alloy, magnesium dioxide, anion ion-exchange resin, and activated carbon. The water treatment combination is hostile to bacterial growth and either removes or significantly reduces the amount of organic and inorganic contaminants in the water. Similarly, U.S. Patent No. 5,407,573 to Hughes discloses a water filter disposed in-line in a water delivery pipe. The filter includes a plurality of aligned chambers. The water passes through a first chamber containing a biocidal material such as iodine and into an extended contact time chamber to allow further contact time between the biocide and any microorganisms in the water. The water then passes through a biocide removal chamber, a chamber containing bacteriostatic media, and a cyst membrane screen. These devices are not portable and are not suited for pour-through use with, for example, a water pitcher. Within the water filtration industry, the 1980' s were characterized by water filtration devices adapted primarily to provide better tasting water {e.g., with the use of charcoal activated granular systems . With the advent of an aging population and increasing concerns for healthier living, the water filtration industry in the 1990's is becoming increasingly concerned with removal of bacteria and/or toxic and cyst materials, particularly on behalf of individuals suffering from various illnesses (e.g., AIDS) who might be at risk from consuming unfiltered or dirty water. To avoid these problems, the water filtration industry tends to rely upon systems, such as countertops, under the sink itemε, and in-line systems which are generally believed to be capable of removing bacteria, with the further belief that gravitational pitcher filters cannot satisfy these objectives. Accordingly, it is an object of the invention to provide an improved pour through water filter, such as a pitcher-mounted unit. Another object of the invention is to provide an improved portable water filter adapted for use with a pitcher. Yet another object of the invention is to provide an improved water filter for removal of microbes such as parasite cysts, bacteria and viruses. A further object of the invention is to provide an improved water filter permitting an extended path of contact with biocidal substances. Still another object is to provide a pour through unit for removal of bacteria from water. Yet another object is to provide a scaleable filter design that can be applied or used in municipal water systems, portable systems, in-line systems, by providing a narrow channel flow path lined with biocidal substances that disrupt laminar flow and ensure turbulent contact with the water stream entering the channel and the biocidal materials. Another object of the invention is to provide a unique cycling of reduction oxidation which may be substantially more effective in killing microbes. Yet another object of the invention is to provide an improved method of filtrating water resulting in significant removal of parasite cysts, bacteria and viruses. A further object of the invention is to provide an improved method of filtrating water providing a fluid path which disrupts laminar flow, making the method useful in preventing the accumulation of biofilm, both in the filter and generally in water lines, and in generally improving the efficacy of the biocidal material by increasing its contact with the water to be purified. Disclosure of the Invention These and other objects are achieved by the water filter and method of filtrating water of the present invention. The present invention provides a filter for purifying a liquid such as water. The filter comprises a member defining one or more channels each having an inlet and an outlet. In one embodiment, each channel is lined with at least one material reactive with the liquid flowing through the channel . Preferably, the material kills microbes, removes other toxins such as certain metals, particularly heavy- metals, from the liquid being filtered, or supplements the water with beneficial or otherwise desirable nutrients including food substances. To achieve microbiological reduction in the liquid, the bioactive material is preferably KDF material of any particular formulation (typically 55 or 85% copper) . Positioning of these materials provides a rapid fluctuation reduction-oxidation cycle to efficiently kill microbes present in the liquid. To achieve compactness, the channel may be arranged in a spiral or helical configuration. It is also within the scope of this invention to provide a multiplicity of spiral or helical flow paths in concentric like relationship to each other. The filter according to the above invention is preferred for use as a gravity fed, pitcher mounted, pour through filter unit. However, the scaleable geometry of the filter allows its use in municipal water systems, in¬ line filtration systems, or in other types of filtration systems known to persons of ordinary skill in this art. A highly preferred feature of the foregoing filters concerns the feature of lining the channel with the reactive material in combination with closely spaced channel walls so that the material disrupts laminar flow and forces the liquid to intimately interact with the material in a turbulent, low resistance, flow relationship. In one preferred embodiment, this type of laminar flow reduction is achieved by spacing the channel side walls a distance from each other equal to about one or two thickness of the mean granular size of the material. In accordance with another feature of this invention, there is provided a gravity fed, pitcher mounted, pour through filter unit, comprising a member defining a channel having an inlet and an outlet. The channel includes at least one material with which a fluid entering the channel through the inlet is reactive to achieve bacteriological reduction in the liquid exiting the outlet. In accordance with yet another feature of the invention, a filter adapted for placement in a pitcher for purifying water flowing through the filter under the influence of gravity only, comprises a housing including an inlet through which the water is received, and an outlet through which water exits the filter. A porous cyst membrane is disposed in the housing to remove cysts from the water. In accordance with other specific embodiments of this invention, the present invention provides a filter for purifying a liquid such as water. The filter includes a housing having an inlet through which the liquid is received and an outlet. A spiral filter structure includes a ribbon spirally or helically wound in a clockwise or counterclockwise direction to form a central hollow core and an exit at one spiral end thereof. The ribbon has adherent various biocidal granules. The housing inlet directs the liquid through the spiral or helical filter structure via the central core, and the liquid exits the spiral or helical structure at the end of the spirally wound ribbon. Alternately, the filter structure may be formed of layered concentric cylinders or horizontal layers. An annular holding chamber, adapted to receive liquid exiting the spiral structure, is disposed between the spiral filter structure and the housing. The annular holding chamber includes a plurality of outlet holes. A volume of filtration media is provided through which the liquid is passed, after exiting the holding chamber through the plurality of outlet holes. The liquid flows in contact with the filtration media and exits the housing via the outlet. Preferably, the biocidal substance includes a bioactive metal, such as copper-zinc alloy, or a halogenated resin, such as iodine, or both. If the biocidal substance is both a copper-zinc alloy and iodine, it is preferred that the copper-zinc alloy and iodine be repeatedly alternatingly secured to the ribbon, or that the copper-zinc alloy is secured to approximately 1/3 to 1/2 of the ribbon and the iodine is secured to a remainder of the ribbon, either order. If layered, alternating spaces may contain either a copper-zinc alloy or iodine. Also preferably, the ribbon is made of polyester (such as mylar) , or polyethylene or other inert, rigid material capable of supplying the active granules and being wound or molded into a spiral or helix, and the filtration media includes activated charcoal. According to one aspect of the invention, a lower portion of the exterior of the spiral filter structure forming the exit is sealed to the spiral filter structure such that the spiral filter structure forms a sediment trap and causes the level of fluid in the channel of the spiral filter to be higher and thereby minimize the volume of air contained in the fluid path. An upper porous separator disk, preferably formed of porous polyethylene, may be disposed between the annular holding chamber and the volume of filtration media. A diffuser screen may also be disposed between the separator disk and the annular holding chamber. The diffuser screen distributes the liquid entering the volume of filtration media through the plurality of outlet holes over the entire surface area of the screen. Preferably, the volume of filtration media is contained between upper and lower separator disks. It is preferred that a cyst membrane, formed of a porous polycarbonate or polyester material, be provided beneath the volume of filtration media. Preferably, the porous material includes a plurality of pores of a diameter of 3 microns or less. According to another preferred embodiment of the present invention, the spiral or helical filter structure may be replaced with a helical structure. Also preferably, the filter is of a pour-through type disposed in a pitcher. The present invention also provides a method for filtering a liquid such as water. The liquid is introduced into a filter such that the liquid traverses a lengthy path in intimate contact with at least one cycle of first and second biocidal materials. Upon leaving the filter, the liquid is routed through a volume of filtration media, and passed through a cyst membrane, in either sequence. Upon leaving filter, the liquid is routed through a volume filtration media and passed through a cyst membrane in either sequence or visa versa. According to a preferred embodiment, two or more biocidal materials are selected to provide a rapid fluctuation reduction-oxidation cycle, wherein the reduction-oxidation cycle kills microbes present in the liquid. Preferably, the two or more biocidal materials are a copper-zinc alloy and iodine, in either order, consecutively or in alternating succession. According to one preferred embodiment, the lengthy path is provided by utilizing a spiral filter structure including a ribbon spirally wound clockwise or counterclockwise to form a central hollow core and an exit at the exterior thereof, in which case the biocidal materials are held in place by the ribbon, and the liquid enters the filter at the central core and exits the spiral filter structure at the exit to enter the holding chamber. According to another preferred embodiment, the lengthy path is provided by utilizing a helical filter structure including a ribbon spirally wound and including an inlet and an exit at the exterior thereof. The biocidal materials are held in place by the ribbon, and the liquid enters the filter at the inlet and exits the spiral filter structure at the exit to enter the holding chamber. According to yet another preferred embodiment, the lengthy path is provided by utilizing a helical filter structure including a ribbon helically wound and including an inlet and an exit at the exterior thereof, in which case the liquid flows radially. The first and second biocidal materials are held in place by the ribbon, and the liquid enters the filter at the inlet and exits the spiral filter structure at the exit to enter the holding chamber. Alternatively, the lengthy path may be provided by concentric cylindrical layers or horizontal layers, in which case the liquid flows linearly. If it is not necessary to have a compact arrangement and a lengthy arrangement is either allowable or desirable the path may be straight, i.e. not spiral or helical. The present invention also provides a cycle of reduction-oxidation or an oxidation-reduction method for killing biological organisms. The biological organisms are exposed to a first biocidal material for a period of time, with the first biocidal material increasing or decreasing the number of electrons surrounding the biological organisms. The biological organisms are then exposed to a second biocidal material for a period of time, the second biocidal material decreasing or increasing the number of electrons in the biological organisms. The cyclical fluctuation in the concentration and electrical potential of the electrons in the immediate environment of the biological organisms renders inactive or kills the biological organisms. Preferably, the first biocidal material is iodine, and the second biocidal material is a copper zinc alloy such as KDF. The present invention is further directed to a method of manufacturing a filtrating element. A ribbon support substrate is provided, on which is disposed adhesive on selected areas of the substrate. At least one of a biocidal material and a pesticide is caused to contact the adhesive to adhere to the substrate. The adhesive may be disposed on only one side of the substrate, or on both sides of the substrate. The method of manufacture may further comprise the step of spirally or helically winding the substrate so as to form a spiral structure such that only the biocidal material or pesticide limits contact of one winding of the substrate to the next consecutive winding of the substrate. Yet another aspect of the invention is in providing a method of manufacturing a filtrating element, comprising the steps of providing a ribbon support substrate, spirally winding the substrate to form a spiral structure with gaps formed between each winding of the substrate and the next consecutive winding of the substrate, and spraying or otherwise filling at least one of a biocidal material or a pesticide into the gaps. Alternatively, the ribbon support structure may be wound helically to form a helical structure with gaps formed between each winding of the substrate and the next consecutive winding of the substrate, the gaps being filled with at least one of a biocidal material and a pesticide. Brief Description of Drawings Figure 1 is an exploded perspective view of the water filtration device according to the present invention; Figure 2 is a schematic cross-sectional view of the water filtration device inserted into a pitcher; Figure 3 is a cross-sectional view taken along lines 3-3 of Figure 1; Figure 4 is a cross-sectional plan view taken along lines 4-4 of Figure 1; Figure 4a is a cross-sectional plan view, similar to Figure 4, of an alternate embodiment of the water filtration device according to the present invention; Figure 5 is a schematic view of the ribbon of the filtration device; Figure 6 is a perspective view of an alternate embodiment of the filter of the present invention; Figure 7 is a perspective view of another alternate embodiment of a water filtration device according to the present invention; Figure 8 is a perspective view of the first of the two-part filter of Figure 7; Figure 9 is a perspective view of a spiral retainer cup utilized in the first filter part of Figure 8; Figure 10 is a top plan view of the cup of Figure 9; Figure 11 is a perspective view of the lower or second filter part of the Figure 7 embodiment; Figure 12 is an enlarged sectional view of the filtrating mechanisms of the second filter part of Figure 11; Figure 13 is a schematic view illustration of the pre-filter and track-etch or other cyst membrane used in the second filter part of Figure 12; Figure 14 is a schematic view illustration of equipment for attaching the pre-filter and track-etch membrane of Figure 13. Figure 15 is a schematic view illustration, partly in section, of a manufacturing step for forming a spiral ribbon used in the present invention; Figure 16 is a schematic view illustration, partly in section, of a manufacturing step in which the ribbon material is extruded; Figure 17 is a schematic view illustration, partly in section, of a manufacturing step for applying KDF or other types of biocidal materials to one or both surfaces of the ribbon material manufactured according to the process of Figures 15 or 16; Figure 18 is a schematic view illustration, partly in section, of a manufacturing step for forming a triple spiral previously coated with KDF or other material for use as a spiral material of unitary construction; 12 Figures 19-21 are schematic view illustrations depicting other features of the triple-wound spiral for use in the filter embodiments of this invention; Figure 22 is an exploded view of an alternate embodiment of the present invention useable as a replaceable water filtration cartridge in a pitcher; Figure 23 is a schematic end view of a triple-wound spiral filter according to the present invention; and Figure 24 is a schematic end view of a double triple-wound spiral filter. Best Mode for Carrying out the Invention Figures 1-5 constitute an illustration of one embodiment of a water filtration device 10 according to the present invention which is effective in killing bacteria and viruses and removing cysts. As will be described in more detail below, the device 10 includes a unique spiral or helical filter 30, 80, preferably including a first portion containing a first biocidal material followed by a second portion containing a second biocidal material. By utilizing a copper-zinc alloy and iodine as the first and second biocidal materials, the spiral or helical filter advantageously provides a unique reduction-oxidation cycle in which it is difficult for biological organisms to survive. Water filtration device 10 also advantageously includes a volume of filtration media 64, such as activated charcoal and/or ion exchange resins to remove lead and other heavy metals, chlorine, pesticide or organics and act as an agent for water softening. Also provided in device 10 is a cyst membrane 70 for removing parasite cysts from the water. These unique features of device 10 of the present invention are compactly arranged to provide a gravity fed, pour-through filter, especially suited for use with a water pitcher, as depicted in Figure 2. Water entering 2Λ the device through an inlet 12, flowing through spiral or helical filter 30, 80 in intimate contact with the biocidal materials, and traversing the volume of filtration media and the cyst membrane, exits the outlet 20 of the device with significantly reduced levels of potentially toxic organisms commonly found in water. The unique configuration of spiral or helical filter 30, 80 also advantageously prevents the fluid traversing the filter from achieving laminar flow therethrough. The filter 30, 80 is generally made of a ribbon or other surface with biocidal materials disposed thereon wound into the spiral or helical filter shape. The resulting channel through which the fluid travels includes mechanical and physical properties that create turbulence, thereby impeding laminar flow which is hospitable to the growth of bacteria on the channel surface. The resulting filter is more toxic to bacteria, and thus the turbulence created by the filter maximize the bacteriocidal effect of the biocidal resin. It will be appreciated that this aspect of the invention may be adapted for use as an in-line filter, either by lining the surface of the conduit with a biocidal material or by providing a filter in, for instance, a distal end of the water line. More specifically, with particular reference to Figure 1, water filtration device 10 includes inlet 12, a housing 11 and an outlet 18. Housing 11 generally includes an outer circumferential wall Ila, an upper surface lib, and a lower surface lie. Outlet 18 may be a hole 20 secured to an outlet tube, as depicted in Figure 2, or alternately, outlet 18 may be a plurality of holes 24 in lower surface lie, as shown in Figure 1. Referring to Figure 2, the water filtration device 10 is depicted installed in a pitcher 25. Pitcher 25 may be any conventional pitcher, and generally includes a handle 26, spout 27 and lid 28. Device 10 is positioned such that water entering device 10 at inlet 12 must traverse the device before entering pitcher 25 via outlet 18. Thus, device 10 is commonly referred to in the industry as a pour-through unit. Device 10 may be maintained in position within pitcher 25 in any suitable and convention manner. One example is depicted in Figure 2, where housing 11 of device 10 includes a lip 13 which can rest in a circumferential cut-out 25a of upper edge 25b of pitcher 25. Alternative means of maintaining device 10 in position within pitcher 25 may include, for example, a filter holder formed in pitcher in which the device 10 is received, or a stand contacting the bottom of the pitcher for supporting device 10. Preferably, pitcher 25 includes a detachable reservoir 29 which rests on upper edge 25b pitcher 25 on which lid 28 rests. Water is received in reservoir 29, travels through inlet 12 to device 10. Reservoir 29 advantageously includes a lip 29a circumferentially disposed about the lower surface 29b of reservoir 29. Lip 29a prevents untreated water from entering pitcher 25. For convenience of description, the filter will be described as divided into an upper chamber 14 and a lower chamber 16, with upper chamber 14 housing the spiral filter 30 and lower chamber 16 containing, inter alia, the volume of filtration media 64 and the cyst membrane 70. As depicted in Figure 1, upper chamber 14 is contained by outer circumferential wall Ila, while lower chamber 16 is housed by a lower housing 60. However, it is to be understood that it is not required that the filter be physically divided into chambers 14, 16, and the present invention encompasses both a device physically divided into chambers for ease of manufacturing and a device including a housing within which the filter components are disposed. ii As will be described in greater detail below, spiral filter 30 is formed of a ribbon 32 on which is secured a biocidal material 34. Spirally winding ribbon 32, in either a clockwise or counterclockwise direction, results in the spiral structure 30, best seen in Figure 3. Alternatively, ribbon 32 may be helically wound and sealed at its edges, resulting in the helical structure 80 as depicted in Figure 6. When spirally winding ribbon 32, a space is left in the innermost portion thereof, forming a central hollow core 36. The gap between the innermost edge 32a of ribbon 32 and the next adjacent winding 32b of ribbon 32 forms a filter inlet 38. At the other end of ribbon 32, a lower portion of outermost edge 32c of ribbon 32 is sealed to the previous adjacent winding 32d to form an exit 40, as described below. Referring to Figure 4a, yet another embodiment of the spiral filter is depicted as filter 30' . As with filter 30, filter 30' is formed of a ribbon 32' on which is secured a biocidal material 34' . The upper surface 31' of filter 30' is conical in shape, and the upper surface lib' of housing 11' is likewise conical in shape. This configuration advantageously results in better fluid flow through the filter, as locking or trapping of air in the filter is less likely to occur because of the conical shape. Similarly, the bottom may be made to be conical, concave with the apex in the center. This would allow the liquid to flow under gravity toward the outside of the spiral . Spiral filter 30 is disposed inside housing 11 in contact with upper surface lib and a lower support plate 42. Upper and lower edges 30a, 30b of spiral filter 30 are covered with food grade epoxy or silicone, and the spiral filter 30 is compressed against both lower support plate 42 and upper surface lib. This effectively seals spiral filter 30 at its upper and lower surfaces to prevent seepage of water from the filter. II Water entering the filtration device 10 from outlet 18 is introduced into the central hollow core 36 of spiral filter 30. Because spiral filter 30 is sealed at its upper and lower edges 30a, 30b, water is forced to enter the spiral filter 30 at filter inlet 38 and traverse the entire length of the wound ribbon 32 before exiting the spiral filter 30 at exit 40. Preferably, as best seen in Figure 4, at least the lower half, and preferably the lower 4/5ths, of outermost edge 32c of ribbon 32 is sealed to the previous adjacent winding 32d, so that exit 40 is limited to the upper, unsealed portion of spiral filter 30. The sealing is accomplished, for instance, by providing a length of tape 41, covering both outermost edge 32c and the previous adjacent winding 32d. Alternately, an adhesive such as epoxy may be applied to the lower portion of outermost edge 32c. Because water is thus forced to exit the filter at the upper portion thereof, the filter permits trapping of sediment therein. As previously stated, the spiral filter is formed of a ribbon 32 on which is secured a biocidal material 34. Preferably, ribbon 32 is made of a very thin sheet of polyethylene, with a thickness in the range of approximately 0.030 inch. Ribbon 32 may be, for instance, a sheet of polyethylene having dimensions of approximately 8 ft by approximately 3 inches, such that when ribbon 32 is wound, the total diameter of the spiral filter 30 is approximately 4 1/2 inches. The biocidal material 34 may be a copper-zinc alloy sold by KDF Fluid Treatment, Inc. under the trade name "KDF-55." A list of U.S. patents directed to KDF material is as follows: 4,642,192 5,122,274 5,135,654 5,269,932 5,198,118 5 , 275 , 737 5 , 314 , 623 5 , 415 , 770 5 , 433 , 856 5 , 510 , 034 5,599,454 KDF-55 is a pesticidal device certified by the Environmental Protection Agency. KDF-55 has been found to be effective in removing heavy metals from water. It is believed that this is achieved by an exchange of ions resulting from an oxidation reduction process, such that heavy metals in the water attach to the zinc/copper complex of the KDF-55 media as the water passes therethrough. Such media, when used by itself, is also believed to be slightly bacteriocidal. Alternatively, biocidal material 34 may be iodine, a biocide known to function by destroying the outer cell wall of the microorganism when it comes in contact with the biocide for a sufficient length of time. Biocidal material 34 may also be any other resin such as an ion exchange resin. A preferred alternative is to alternate KDF with iodine, as depicted in Figure 5. Referring to Figure 5, ribbon 32 is depicted in its unwound configuration. An adhesive 74 is applied to ribbon 32, either continuously along ribbon 32 or in strips. Adhesive 74 is preferably a quick setting epoxy and/or an FDA certified epoxy, such as that made by Masterbond, Inc., of Hackensack, New Jersey, and sold as EP21LV, EP30, or EP75. KDF and iodine are then secured to ribbon 32 by adhesive 74 in alternating strips 76, 78. One possible configuration is to provide one of each strip 76, 78, in which case each strip 76, 78 might cover approximately one-half of the length of ribbon 32, to provide a single reduction- oxidation cycle as discussed below. Another possible configuration is to provide multiple strips 76, 78, repeatedly alternating, as depicted in Figure 5. While providing strips 76, 78 covering approximately one-half of the length of ribbon 32 has proven successful by exposing microbes to a single reduction-oxidation cycle, the configuration depicted in Figure 5 is advantageous when making smaller filters, since it increases the number of reduction-oxidation cycles to which the microbes are exposed. To provide a greater concentration of biocidal material 34, it may be advantageous to apply the adhesive and resin to both sides of ribbon 32. It is preferred that ribbon 32 be wound tightly enough to allow ready flow and adequate purification, either spirally to form spiral filter 30 or helically to form helical filter 80, such that the coils of the ribbon are separated by as little as the thickness of the biocidal material disposed thereon. In other words, only the biocidal material 34 limits contact of one coil of the ribbon with the adjacent coils. This is advantageous for several reasons. First, it permits utilization of a lengthy ribbon, thus ensuring that the water travels a prolonged path of contact with the biocidal material. Additionally, the tightness of the coils permits only a small amount of water to traverse the space between the coils, thus guaranteeing that the water and its contaminants are exposed closely to the biocidal material as the water flows through the spiral filter. If it is desired to improve the flow rate of water through the filter, spacer beads may be inserted between adjacent coils of the ribbon. Spiral filter 30 may optionally be manufactured by winding ribbon 32 into a spiral structure, and spraying or otherwise inserting the resin into the structure. Yet another alternative for manufacturing ribbon 32 is to utilize a flexible, thin polyethylene tube, sprayed with adhesive on the inner surface. The tube may be filled with biocidal material 34 so that the resin IP. adheres to the adhesive. After the excess resin is released from the tube, the tube may be collapsed and then wound to form the spiral or helical shape. An annular holding chamber 50 is formed between spiral filter 30 and the inside surface 52 of housing 11. A plurality of outlet holes 54 are provided, preferably spaced about the outside circumferential edge of lower surface 42. Alternatively, lower surface 42 may be a porous membrane. Water flowing out of spiral filter 30 is held in holding chamber 50 to provide an additional contact time with any biocide that may have dissolved, until the water exits to lower chamber 16 via outlet holes 54. Referring to Figure 4, lower chamber 16 includes a plurality of cylindrical or disk-shaped filter elements contained within housing 11. Specifically, a diffuser screen 62 is positioned directly beneath lower surface 31 of upper chamber 14. Diffuser screen 62 is made of porous polyethylene and distributes the water which entered lower chamber 16 via the circumferential outlet holes 54 along the entire surface area of diffuser screen 62 to provide a more even distribution of the water flowing through lower chamber 16. A volume of filtration media 64, bounded on both sides by upper and lower porous separator disks 66, 68, is disposed underneath diffuser screen 62. Filtration media 64 is preferably activated charcoal with ion exchange beads or other materials, and thus is effective in removing lead and other heavy metals as well as iodine that may have been used in the spiral filter, chlorine, pesticide, and organics. Ion exchange material may also act as an agent for water softening. A cyst membrane 70, made of polycarbonate and being extremely thin, is positioned beneath lower separator disk 68 and protected by a porous disk 72. Cyst membrane 70 is held in place against disk 72 by a retention ring 71, positioned on top of and cemented to cyst membrane 70. The membrane is manufactured by a process of radiation followed by acid etching which creates pore sizes of a specified diameter. Preferably, the pore sizes are of a diameter of 3 microns or less. These pore sizes permit fluid to flow at a rate unaffected by the cyst membrane. One example of a suitable cyst membrane is manufactured by Poretics. Cyst membrane 70 removes cysts such as Giardia lamblia from the water by filtration. Depending on design factors, such as the type of outlet 18 desired, porous disk 72 may be a component separated from the lower surface lie of housing 11, as depicted in Figure 4. This configuration provides enough space for outlet 18 to be in the form of a hole secured to an outlet tube, as previously described with reference to Figure 1. Alternatively, porous disk 72 may form the lower surface lie of housing 11. In this configuration, the plurality of outlet holes 24 may be formed in porous disk 72. This configuration is advantageous in conserving space in the filtration device. Water entering lower chamber 16 via outlet holes 54 enters diffuser screen 62 and is distributed along the entire surface area of diffuser screen 62. The water flows through upper separator disk 66, filtration media 64, lower separator disk 68, cyst membrane 70, and finally porous disk 72 before exiting filtration device 10 at outlet 18. The housing, including outer circumferential wall Ila and upper and lower surfaces lib, lie, may be formed of any suitable material approved by the EPA or FDA for contact with potable water, such as polyethylene. The spiral or helical filter 30, 80, described above, provides a unique and advantageous reduction- oxidation cycle. Utilized alone, the KDF-55 biocidal resin removes lead and other heavy metals, chlorine, pesticides, and organics, and reduces the quantity of bacteria. Iodine is typically used to destroy viruses. However, when used in sequence, the KDF-55 coupled with the iodine produces a unique reduction/oxidation cycle which has been found to significantly reduce the concentration of bacteria and viruses. During the reduction/oxidation process, water flowing in intimate contact with the KDF-55 particles is reduced, i.e., the electrons in the biological organisms are increased. Because iodine tends to have an affinity for electrons, the fluid contacting the iodine is oxidized, i.e., the biological organisms lose electrons. Biological organisms are sensitive, and their reduction/oxidation states are maintained by delicate balances. Excessive reduction or oxidation destroys a significant portion of proteins found in the organisms. It is theorized that while bacteria and viruses can tolerate gradual changes in their reduction/oxidation environment, the cycling of reduction and oxidation provided by the spiral filter is more difficult for the organism to contend with. Thus, exposing the bacteria to KDF-55 and sequentially to an oxidation process stimulated by the iodine enhances the killing of bacteria. It further is theorized that the spiral flow pattern of water in the spiral filter creates an electrical field, enhancing the killing of bacteria and exerting an electrostatic separation affect to pull contaminant particles, including cysts, out of suspension in the water. More specifically, as stated previously, the spiral or helical coil filter element may be wound spirally or helically in either a clockwise or counterclockwise direction. Since an electrical potential develops over the length of the fluid flow path as the fluid is flowing, a second axially oriented electrical field develops when the flow path is spiral or helical. Using the right hand rule of electrical field forces, electron movement in a spiral direction imposes a force oriented in the axial direction on any charged particle, be it a bacterium, virus, cyst or other charged particulate impurity suspended in the liquid to be purified. Depending on the direction of fluid flow through the spiral or helical filter, i.e., clockwise or counterclockwise, the force on any charged particle in suspension may be in the direction of the fluid inlet or the fluid outlet. This secondary electrical field acts to push any charged particulate to one edge or the other of the fluid channel, the actual direction of movement of the particle depending on the field orientation and the charge of the particle. Thus, by varying the direction of fluid flow, through either a clockwise or counter¬ clockwise spiral or helix, the desired effect can be realized. It is further within the scope of this invention to place clockwise and counterclockwise spiral or helical filters in series to take advantage of the respective purification effect of each filter on positively and negatively charged particles in suspension. Thus, the filter of the present invention embodies a physical principle of electrostatic separation that makes it uniquely capable of removing from suspension any charged particulate, such as bacteria, viruses or parasite cysts. Further, this separation effect increases as the flow rate of fluid through the filter increases, because the electrical field is magnified in direct proportion to the flow rate, making this filter design extremely suitable for in-line, high- flow applications. Similarly, it will be appreciated by one skilled in the art that a smaller filter will provide a shortened flow path, thereby reducing the electrostatic separation effect of the filter. Thus, in a smaller filter, it is preferred that multiple reduction-oxidation cycles be provided by utilizing the multiple alternating strips 76, 78 of KDF and iodine as depicted in Figure 5 to offset the loss of the electrostatic separation effect in a smaller filter. The feature of providing a band of iodine and KDF in successively immediately adjacent stages within a thin channel magnifies the anti-bacterial effect sufficiently such that the iodine which is used can be a zero or low residue iodine releasing little or no iodine into the fluid being treated. This may be particularly advantageous since EPA and other governmental regulations concerning water filters require that for water treatment systems used on a regular basis for preparation of water for ingestion that iodine not be present at significant levels, on a long term basis so as to prevent long term toxicity. A prototype device, as described above, has been extensively tested to determine the potential of the device to serve as a microbiological water purifier. The results of this testing have been exceptional. The testing system used was modeled as close as possible to the specifications contained in the EPA document, "Guide Standard and Protocol for Testing Microbiological Water Purifiers, " the contents of which are incorporated herein by reference. The test water used was deionized Detroit city water that was reconstructed by the addition of AOAC Synthetic hard water to achieve the defined chemical properties of "general test water, " as described in the above-identified document. Specifically, the chemical properties of the water included: pH of 7.5 ± 0.5; TOC ≤ 5 ppm; turbidity ≤ 1 NTU; temperature of 21 ± 1 °C; and TDS of 320 ppm. The device was challenged with 5 gallons of test water per day for 30 test days, or a total challenge of 100 gallons. The test water was pumped through the inlet of the device at a rate of 100 ml per minute. The unit 2.5 was tested for 16 hours per test day, with an 8 minute "on" and 32 minute "off" cycle. Although the testing protocol for pour-through type units is not clearly defined in the EPA document, the testing protocol for this device, described below, is believed to be a rigorous challenge of the unit at its estimated capacity of 100 gallons. The test water included the bacteria Klebsiella terrigena (ATCC # 33257) at a concentration greater than 1 x 10 7 cfu/100 ml, with the total challenge over the course of the test approaching 1 x 10 12 . The required log reduction for the EPA Protocol is 6 logs (1 x 10 s per ml to less than 1 per 10 ml) . The influent and effluent concentration was measured once each test day. The bacterial virus Q-Beta was used as a model of animal viruses such as Poliovirus. The capsid of the bacteriophage Q-Beta is 25 nanometers in diameter and is ideal for testing filtration of Poliovirus. Poliovirus is a member of the virus family Piconaviridae and the size range of the over 200 animal viruses in this family is 24 to 30 nanometers. Simian Rotavirus (the other virus required in the EPA Protocol) is 80 nanometers in diameter and thus should easily be removed by a device that removes Q-Beta. The testing of Q-Beta was similar to the periodic challenge used in the EPA Protocol. The device was challenged 10 times during the 20 day test period at a concentration of greater than the 1 x 10 5 virus/ml (10 times that required in the EPA Protocol for Poliovirus and Rotavirus) . The required virus reduction in the EPA protocol is 4 logs (1 x 10* per ml to less than 1 per ml) . The virus concentration (pfu/ml or plaque forming units) in the influent and effluent water was measured using the Q-Beta host Escherichia coli . The ability of the unit to remove protozoan cysts was tested using oocysts of the humanpathogen 2jό Cryptosporidium parvum . The unit was challenged 5 times during the 20 day test with a concentration of from 4.7 x 10 5 to 7.3 x 10 s oocysts per liter. The limit of detection using a fluorescent staining procedure was 300 oocysts per liter in the effluent water. The required reduction of protozoan cysts by the EPA Protocol is three logs, yet, the filter yields no detectable oocysts in the effluent. This makes the filter's reduction efficacy 3-5 logs. The results of the testing are set forth in Appendix A. Referring to Table 1, there were no detectable survivors of the bacterium Klebsiella terrigena during each of the 20 test runs for an average log reduction of greater than 8 logs. This reduction is at least two logs greater than is required by the EPA Protocol and clearly indicates that this device can be safely used to remove potentially pathogenic bacteria from drinking water. The reduction of the bacterial virus A-Beta and the pathogenic protozoan Cryptosporidium parvum were also equally impressive. As seen in Table 2 of Appendix A, the bacterial virus used as a model of Poliovirus was reduced greater than 6 logs, and the Cryptosporidium parvum oocysts were reduced at least by 3 logs (Table 3) and the limits of the test system were exceeded by approximately 2 logs, indicating a 3-5 log reduction of parasite cysts. These test results meet or exceed the results required by the EPA, as set forth in the Protocol document. Accordingly, the device of the present invention has been proven to safely purify water of unknown quality. In summary, the water filtering device described herein provides significant advantages over the filters of the prior art. The reduction-oxidation cycle provided by the spiral filter is uniquely effective in bacterial reduction, as evidenced by the disclosed test results. The combination of the spiral filter with biocidal material, the bed of filtration media, and the cyst membrane significantly reduces or eliminates the potentially toxic organisms commonly found in water. It will become apparent to one of ordinary skill in the art that the water filtering device described above may be modified, for instance, by providing a conventional layered filter, either concentrically or horizontally layered, rather than the spiral or helical filter described herein. As with the spiral filter, such a layered filter would provide a lengthy path of water flow to significantly increase contact time with the biocidal material disposed within. Such a layered filter may also provide a reduction-oxidation cycle, as described herein. Such modifications are intended to be within the scope of the present invention. The foregoing embodiment of filter 10 depicted in Fig. 1 utilizes a single spiral defining one flow path lined with, for example, KDF and/or iodine in the manner described above. In accordance with another feature of this invention, multiple spirals may be provided as depicted in Figs. 20, 23 and 24 to improve the overall flow rate through the filter by a factor proportional to the number of spirals. In one presently preferred embodiment depicted in Figure 20, three spirals 100 are provided to define three spiral channels 100' dimensioned, by way of example only, to have a spiral channel length of 24 inches, a channel height (i.e. in the vertical direction) of about 3 inches, and a channel width (i.e. spacing between the channel opposing side walls 101) of a distance equal to one to two times the mean granular size of the KDF particles lining the side walls. The KDF material lining the channel side walls 101 is preferably of granular form and, as a percentage of weight of crude KDF, represents the smallest 31st percentile of particle size, by weight. As described above, the particles may be epoxy bonded to the spiral. A non-solvent glue, such as a hot melt glue (preferably non-toxic) may also be used. One example of a suitable hot melt glue is FPC 725 All-Temp which is comprised of a hydrocarbon resin and ethylene vinyl acetate. Based upon experimentation, this glue has been found useful to accelerate the process of binding the KDF to the backing material forming the spiral elements. In an alternate preferred embodiment, each backing element 101 is made of a three inch by twenty-four inch piece of polyethylene or mylar. When using glue to bind the KDF to the backing 101, mylar is preferred since it has a much higher melting point than polyethylene and is less subject to distortion when using hot melt glue. The small granule size KDF material is preferably applied with hot melt glue to a mylar backing sheet 101 having a thickness of about between .005-.0075 inch. In yet another alternative preferred embodiment, not requiring the use of hot melt glue or other adhesive, or a mylar backing sheet, a polyethylene or polypropylene sheet is extruded in a known manner. While hot, KDF material which has also been raised to an appropriate temperature close to the melting point of the extruded material is poured on and then rolled onto the semi- molten polyethylene or polypropylene backing and adhered to the material in this manner. Alternatively, hot KDF granular material can be pressed into already cooled piece polyethylene or polypropylene backing material. Figs. 7-13 are illustrations of an alternate preferred embodiment of a filter 110 comprising a first part 112 containing a KDF triple spiral 114 mounted atop a second part 116 containing a charcoal bed 118 (see Fig. 12) , a pre-filter 120 and a track etch membrane 122. The two parts 112,116 are preferably detachably mounted to each other (e.g. via threaded or bayonet mounted engagement) to enable more frequent replacement of the second part, since the first part, or spiral holder, containing the KDF spiral 114 will tend to have greater longevity. The KDF spiral 114 is preferably mounted within a cylindrical cup 124 (Figure 9) having a closed bottom (e.g. by means of a circular disk 126 heat sealed or otherwise secured to the cylinder bottom edge) in preferably snug or slightly loose fitting engagement with the inner cylindrical sidewall 128 thereof. The cup-like holder 124 is inserted (open top end first) into the bottom of the larger diameter cylindrical spiral holder 112 to locate the fluid inlet 130 formed in the top wall 132 of the first part in coaxial alignment with the center 134 of the spiral 114, assuring that fluid to be filtered initially enters into the spiral center and then flows through one of the three spiral channel flow paths 100 to the fluid outlet 136 (Figure 20) located at the trailing end of the radially outermost trailer edge of the spiral coils. Fluid exits the spiral 114 by flowing upwards and outwards over the upper edge 138 of the cup 124 into an annular region defined between the outer cylindrical surface 140 of the cup and the inner cylindrical surface 142 of the spiral holder 112. The circular disk 126 closing off the bottom end of the cup 124, as best depicted in Fig. 10, is formed with a plurality of circumferentially equi-spaced tabs 144 preferably formed in diametrically opposed pairs so that each pair defines an outer diameter equal to the inner diameter of the spiral holder 112. The tabs 144 may be adhesively secured to the first part inner wall 142 to locate the cup 124 therewithin. It will be understood that the spaces 146 between adjacent tabs 144 define drainage openings through which fluid exiting the spiral 114 flows downward into the second part 116 of the filter 110. IP. The foregoing arrangement advantageously assures that the spiral channels 100' remain entirely immersed in fluid to prevent the KDF or other active material from becoming dry between periods of use. It has been discovered that KDF material, for example, may lose its activity in the event that drying occurs. The exterior lower portion of the spiral holder 114 may be formed with threads 148 adapted to engage with corresponding internal threads 150 formed in the top edge of the inner cylindrical wall 152 of the second part 116 (see Figs. 7, 8 and 11) . Together, the first and second filter parts 112,116 make up the filter cartridge 110 that may be disposed atop a pitcher or used in other manners that will now occur to persons of ordinary skill in this art from reviewing this specification. It is not critical that the first and second parts 112,116 be threaded together or that the interior and exterior threads 148,150 be formed in the manner described above. Other types of locking mechanisms are contemplated (e.g. a bayonet mount) . Indeed, in some applications in which both parts of the filter 110 may be replaced simultaneously, the first and second parts 112,116 may be fixedly mounted to each other. In the alternate preferred embodiment discussed above, it is also preferred to seal the bottom edge 154 of the spiral 114 to the disk 126 forming the cup bottom, thereby preventing fluid from bypassing the spiral flow channels 100' by flowing radially beneath the lower spiral edges. In alternate preferred embodiment filter 110, the first part 112 is disclosed for use in a gravity fed, pitcher mounted configuration, and may have nominal dimensions of 3.75 inch outer diameter, 3 3/8 inch height, with the cylinder and disk elements preferably made of acrylic stock of 1/8 inch thickness. Of course, other materials and dimensions are possible. The lower or second filter part 116 is also of cylindrical configuration having nominal outer diameter dimensions of 4 1/2 inch and a height of 1 1/8 inch. With reference to Figs. 11-14, the second filter part 116 may be formed with a series of multiple layers therewithin. The first or uppermost layer 160 may be a nylon weave or other type of liquid permeable coarse material defining the uppermost extent of a cavity 162 containing, for example, the granular charcoal and ionic exchange resin 118 loosely contained therewithin. The bottom of this cavity 162, as best depicted in Fig. 12, is defined by a membrane 'sandwich' 120, 122 and 124. The bed 118 preferably is 1/2-3/4 inch in thickness. The membrane sandwich preferably has a track etch membrane (i.e. cyst membrane) 122 for removal of cysts as small as 3 micrometers, and an ACNS pre-filter 120 positioned atop the track etch membrane for removal of certain types of sediment material that might otherwise bind and clog the track etch membrane. It is to be understood that the presence of one or more pre-filters is optional. An important preferred feature of the present invention is the discovery that the track etch membrane 122 has both an excellent and operable flow rate when used in a gravity fed environment, for example, under a gravity fed force of several inches of water. As best understood by the present inventor, conventional industry practice is to utilize track edge membranes in pressurized in-line systems wherein high pressure flow is considered critical to achieve adequate flow rates through the membrane. The discovery by the present inventor that track edge membranes may be used under low gravity flow conditions as described above is believed to be novel since the flow rate through the gravity fed membrane 122 has been discovered to be approximately 20 times greater than predicted. It is within the scope of this invention to construct a filter consisting solely of one or more track etch membranes 122 of the type described above in the event that the sole filtrating concern relates only to cyst removal in a gravity fed environment . The outer periphery of the pre-filter 120 and track etch membrane 122 may be sealed to the inner cylindrical wall of the second part 116, or may be disposed and supported by a porous nylon weave backing disk 164 as depicted in Fig. 12. The pre-filter 120 and track etch membrane 122 generally have two different coefficients of expansion when wet. The pre-filter 120 expands and the track etch membrane 122 actually contracts and both therefore move disproportionately in opposite directions when wet. In accordance with another feature of the invention, it is desirable to assemble the pre-filter 120 and track etch membrane 122 in tight pressing contact with each other when both are wet and have already experienced respective expansion and shrinkage. Since assembly of wet materials is often difficult, a preferred alternative manufacturing method in accordance with another aspect of the present invention is to stretch both the pre-filter 120 and track etch membrane 122 prior to bonding peripheral edges thereof to a cylindrical ring support. Once stretched, the pre-filter and track etch membrane may then be wetted and brought together. When bringing the flat surfaces of these materials together, it is important that air be removed from between these flat surfaces. Otherwise, trapped air will block the fluid path between the pre-filter and track etch membrane. To prevent entrapped air between the surfaces, it is possible to immerse these materials in a fluid. However, a preferred manufacturing method is to utilize a convex shaped dome 165 formed of a compressible material that is adapted to initially contact the centers 21 of both materials to gradually express air in a radially outward direction as the dome(s) progressively contact radially outward portions of the materials. This type of manufacturing method is depicted schematically in Fig. 14. Therein, the dome 165 can be formed from a stretchable membrane press-like material 167 that inflates in the direction of arrow A under the force of pressurized air. Figs. 15-21 are schematic process diagram illustrations depicting various novel techniques for manufacturing the KDF coated ribbon material . Although in the alternate preferred embodiment there is disclosed the sole use of KDF granular material as the active material within the spiral 114, it is to be understood that other materials for treatment of water or other fluids may be used in substitution for KDF, or in combination with KDF, to achieve desired effects. For example, KDF and iodine may be alternately disposed at successively adjacent intervals on the ribbon as discussed above in connection with filter 10. It is even possible to use preferably granular materials other than KDF for the purpose of removing metal contaminants from industrial, residential, or municipal water or other types of processed streams. Fig. 15 is an illustration utilizing a preformed roll 172 of polyethylene or polypropylene ribbon material (e.g. 20-30 mil thickness) that is gradually unrolled from a spool having a horizontal axis of rotation. Hot melt glue 174 is then sprayed onto top and/or bottom surfaces of the unrolled material 172 and uniformly distributed along the surfaces by means of upper and lower squeegees 176 (e.g. made of aluminum) . Alternatively, molten polyethylene or polypropylene can be extruded into ribbon sheet form as depicted in Fig. 16. Following either forming method depicted in Fig. 15 or 16, hot KDF granular material 176 is preferably poured onto the top surface of the ribbon 172 and then rolled into bonded or adhesively secured lining contact with the ribbon surface utilizing a pair of pressing rollers 178. An appropriate turning mechanism (not shown in detail) can then be utilized to flip the ribbon 172 (after separating the pressing rollers 178 from each other into retracted positions) so that excess KDF granules can drop off from the ribbon surface and be preferably recycled. Additional KDF material 176 is then applied onto the newly exposed opposite ribbon surface for pressing contact beneath the now extended pressing rollers 178. Under certain circumstances, it may be desirable to apply KDF material 176 to only one side of the ribbon 172, the opposite ribbon surface being free of material. Under other circumstances, it may be desirable to apply KDF material 176 to one side of the material and another material (e.g. iodine) to the opposite side. It is also within the scope of this invention to provide more than one material on one ribbon side in successive intervals along the length of the ribbon. Persons of ordinary skill in the art will easily understand, based upon the foregoing description, how the manufacturing process disclosed herein may be modified to accomplish these alternate design options. It is to be understood that hot KDF material 176 is preferably used on preformed ribbon surfaces to ensure bonded engagement with the surface. When used with polyethylene or polypropylene materials, the KDF granules 176 are preferably preheated to about 350°F. Even if used with freshly extruded polyethylene or polypropylene material, it is desirable to preheat the KDF material to ensure proper bonding with the ribbon surface. Fig. 18 is a schematic process illustration disclosing one manner for rolling three or more of the 15 ribbons manufactured according to process Figs. 15-17 into a triple spiral form 114. Three of the material coated ribbons enter a guide arrangement 180 which serves to align the side edges of the ribbons with each other. The staggered leader ends 182 of these ribbons are respectively forced into three circumferentially spaced retaining slots 184 formed in the length of a drum surface having a rotational axis L extending perpendicular to the longitudinal axis of the juxtaposed ribbons. Glue nozzles (not shown in detail) are strategically positioned to apply beads of hot melt or other type of glue beads 186 at both laterally spaced locations along the ribbon width and longitudinally spaced locations along the ribbon length to adhesively connect the plural ribbons together and thereby form a wound roll of multiple ribbons that may be used to form multiple spirals 114 of the type described herein (as also depicted in Fig. 19) . In the embodiments described above, mylar having a thickness between .005-.075 inch is preferred as the sheet ribbon backing material . It has been discovered that mylar of about .075 inch thickness is preferential within this range since it does not distort as much when heated, has very good tensile properties, and does not stretch very easily. The KDF granules 176 are approximately 0.1-0.8 mm, and preferably 0.5 mm. Fig. 20 is a perspective view illustration of an assembled triple spiral KDF cylinder 100 or 114. As mentioned above, the top and bottom ends of the spiral cylinder 114 are respectively sealed to a polyethylene disk 126 that has been heated to a temperature in which the melted polyethylene bonds to the spiral edges to define a sealed flow path between the spiral channels 100' . The resulting structure of Fig. 21 can then simply 2£ be dropped into the retainer cup 124 depicted in Fig. 9 of the filter 110 embodiment. The outermost surface of the triple spiral winding 114 depicted in Fig. 20 is preferably also coated with KDF or other material in accordance with the unique manufacturing methods described hereinabove. In this manner, as the water exits the spiral into contact with the inner cylindrical surface of the cup wall, the outer coated spiral wall creates a separation between the spiral and the cup inner wall to prevent flow restriction. In the preferred embodiment, the mylar or polyethylene ribbon sheets when coated with the FPC hot melt glue require about 3-6 grams of glue per linear foot. Depending on the granular size of the KDF material 176, approximately 0.5-2.5 grams of KDF material may be utilized to cover each square inch of ribbon surface. This range is not intended to be a limiting factor for this invention and other types of coverage densities may be possible without departing from the scope of this invention. Another embodiment is depicted in Fig. 22 which is particularly useful in pour through pitchers such as those sold by Brita™. This embodiment is directed to a small replaceable cartridge that are placed into a reservoir in a pour through pitcher. These cartridges advantageously are more effective than presently available cartridges and removal of bacteria, of cysts and virus removal. As depicted in Fig. 22, a replaceable cartridge 200 includes a plastic top 202 and a plastic bottom 204 that are snapped together. Alternatively, the top 202 and base 204 can be fused together. Additionally, base 204 may also include a pod 206 filled with charcoal and/or other material including an ion exchange resin. A spiral filter element 208 is located within base 204. Spiral filter 208 is sealed at the 11 bottom by a sealed disk 210 which can also have a membrane built into the disk 210. The purpose of base 204 is to maintain the water level at a maximum height so that the filter element 208 can be kept wet throughout. A radial gap exists between the outer diameter of spiral element 208 and the inner diameter of base 204. Sealed disk 210 can be made of any typical injection molded plastic such as polyethylene or polypropylene. Sealed disk 210 is the same material as base 204. A radial spacer or membrane support 212 is located at approximately the longitudinal midpoint of base 204. Radial spacer 212 can also be called a membrane support. Membrane support 212 is a plastic molded part. As depicted in Fig. 22, membrane support 212 extends from approximately the midpoint of base 204 to the bottom thereof. Membrane support 212 has approximately a cylindrical shape with certain irregularities, such as pleats, that would provide gaps for the proper flow of water therethrough. Spiral element 208 is approximately 3 inches tall whereas base 204 is approximately 2 1/2 inches tall. As depicted in Fig. 22, membrane 208 extends outwardly beyond base 204. The direction of flow of water is down through the center of the spiral 214 and through a channel 216 formed by the spiral in a clockwise or counter clockwise direction. The top 202 has an inner surface thereof in sealed relationship with membrane filter 208. Water is directed through top 202 into the center of filter spiral member 208 and travels counter clockwise or clockwise through the spiral into an area between the outer diameter of spiral member 208 and the inner diameter of base 204. The area may be filled with a filter media such as charcoal. The water then flows downwardly into pod 206. Top 204 has a vent opening that 18 allows equilibration of air pressure between the outside air and the space between the spiral and the membrane. Spiral member 208 is formed of a ribbon sheet material which is preferably 3 inches in width and 6 inches - 12 inches or more in length. The ribbon is an impermeable material whether it is coated with mylar or a velcro-like substance that would hold granular material. Therefore, the ribbon will direct flow spirally along its length and not allow any flow therethrough. As depicted in Fig. 23, there is shown a filter element 208 made which is called a triple spiral configuration. It should be understood that the number of spirals can be any number above 1. Preferably, the number would be between 1 and 10, because above 10 the filter becomes too large. As depicted in Fig. 23, three layers of ribbon sheet material 250, 252, 254 are wound one about the other forming three spiral paths therebetween. The goal of the spiral configuration is that it provides a compact configuration for a fluid flow path. Path length can be varied depending upon the number of spiral layers. Additionally, the ratio of the path length to the diameter or circumference of the unit provides different ratios. Three representative sizes of a spiral member will demonstrate the ratio as being discussed. A triple winding of a three strips of mylar each being two feet in length will have an 8 inch circumference and a 2 1/2 inch diameter. A one foot path length for each of the spirals would have a 5 1/2 inch circumference and a 1 1/2 inch diameter. A 6 inch path length would have a 4 1/4 inch circumference and a 1 3/8 inch diameter. The above ratios contemplate using a specific granular size attached to the mylar ribbon. Using a courser material on the spiral will make the spiral smaller or larger as the spiral is wound between each layer of the spiral. A courser material will have a more open path and lower resistance. This will result in a higher flow rate at a given pressure. A less course material will result in a lower flow rate at a given pressure. The flow rate can be improved by making a taller spiral resulting in lower resistance, other dimensions remaining unchanged. This is because the height is in direct proportion to the cross-sectional area of each of the fluid flow paths. Depending on the efficacy and homogeneity of actual fluid flow through the spiral, the base 204 around the spiral can be removed, for example, the base 204 may be removed if it is found that the flow rate is greater through the top part of the spiral than through the bottom. The purpose of the base 204 is to help keep the filter element 208 wet, however, it may be necessary to place holes in it at appropriate points to direct the flow in a generally optimum (homogeneous) manner through the spiral . An additional consideration is that the spiral element 208 can be turned upside down thereby reversing the flow. For example, if the flow was counter clockwise and the filter element was flipped upside down, the flow would then become counter clockwise. On a theoretical level, one configuration may work better than the other, with some consideration being given to the fact that spiral flow in the northern hemisphere is counter clockwise and is clockwise in the southern hemisphere. Thus far, the flow path of the water has been directed through the center of spiral element 208 and flows radially outwardly therefrom. Alternatively, water could be directed from the outside diameter of filter element 208 and flow radially inwardly therefrom. It is 4J) anticipated that the two arrangements are comparable, and should have equal efficacy with regard to flow characteristics. As stated previously, it is possible to implement a process of redox potential cycling within spiral 208. This is achieved by having a fluid flow path have materials with different redox potential (lining its wall) . The fabrication of a spiral filter element 208 is accomplished by placing one or more strips with their ends staggered and are then rolled about a mandrel. The spiral filter element can be formed with one or more strips so with each additional strip one additional channel is formed. The multiplication of strips and channels allows the resistance to flow to be improved and improve proportionally the flow through the spiral. In estimating the ratio of total path length to the diameter and circumference of the cylinder formed by the spiral, the total path length should be considered as the sum total path length of all the individual flow paths since the diameter of a single 6 foot path length spirally wound is the same as three 2 foot path length spirally wound. The strips after being wound should have their ends sealed. This can be accomplished by the use of hot melt glue that is coated on the ends and pressed such that it seals the ends of the spiral filter element and is pressed somewhat into each of the channels. This end seal is very important because the fluid may otherwise pass from one part of the spiral and jump across the channel which is immediately adjacent thereto. With a leak, the efficacy of the unit can be diminished dramatically. Each mylar strip is coated with KDF. The granularity of each of the KDF strips can be varied. For example, KDF 55 comes as a course material. KDF 55 is then passed through a series of sieves and all granular sizes less than size 30 are collected. That is according to U.S. Series No. 30 which is the Tyler equivalent 28 mash, the opening of the sieve if 595 microns or 0.0234 inches . The ribbon containing KDF is made by placing the mylar that is coated with hot melt glue on a bed of granular KDF 55 of less than sieve size 30, then heating the KDF to approximately 425-450°F. Pressure is then applied by a roller to the KDF so that it is pressed and embedded into the hot melt glue on the surface. Alternatively, instead of mylar and the hot melt glue coating, polyethylene could be used but the KDF would have to be pressed more firmly and care would have to be taken to ensure that the polyethylene is not overheated and distorted. It should be understood that the granularity (particle size) distribution in the coating may be modified to achieve various flow rates and efficacies as indicated for various applications. The triple spiral configuration of Figure 23 may also be formed with three to four inches of iodine as the leader material followed by six to nine inches of KDF material to provide for one redox cycle. Figure 24 is an illustration of a triple spiral within a triple spiral . The innermost spiral may be coated with iodine in the various manners described above and the outermost spiral may be coated with KDF material, likewise in the manner described above. These separate spiral configurations allow for manufacturing of each individual triple spiral with one type of material only, unlike the modification to the single Figure 23 spiral described in the immediately preceding paragraph. The foregoing designs described hereinabove can be used to treat water and other process streams in different types of markets and industries. For example, the unique filters according to this invention can be used in water bottling plants. In formed bottling plants, filters constructed according to principles of the invention may also be used in portable water units commonly used in certain foreign countries, and on commercial aviation aircraft to replenish on-board fresh water supplies utilizing water obtained in different foreign ports of call. Other applications include water delivered to use locations by trucks. In certain countries, domestic water is often available only during pre-determined times during the day. For example, in certain third world countries, it is not uncommon for domestic water piping systems to be pressurized by municipalities for only two hours per day. This phenomenon disadvantageously results in a vacuum generated in the domestic supply lines which can suck in sewage and other contaminants. Thus, water filtration units in accordance with the present invention find optimal use in these types of systems. Although the water filters described hereinabove are disclosed for preferred use in gravity fed pitcher mounted units, it will now occur to persons of ordinary skill in the art that the filters of the invention can also be used in other types of pour through and in-line systems as known in the art and as described briefly hereinabove. The filters constructed in accordance with the principles of the invention also find use in other fields. For example, spiral KDF line filters may be used in industry sewage treatment to remove lead. Other types of material, in substitution for KDF, may be used to remove other types of metal. It is to be understood that the spiral configuration is best suited for uses requiring compactness. It is within the scope of this invention to treat water and other effluent streams with non-spiral configurations of the invention wherein the channel walls are lined with KDF and other types of material with extremely close spacing between the opposing channel side walls limited 11 by one or two times the thickness of the granular materials lining the walls. This unique arrangement prevents laminar flow between the channel side walls, ensuring turbulent flow and proper diffusion of liquid to obtain complete activating contact with the materials lining the channel walls. It is also within the scope of this invention to provide a pour through or pitcher mounted filter provided only with a KDF and/or iodine sequenced material to achieve bacteriological reduction only. It will be readily seen by one of ordinary skill in the art that the present invention fulfills all of the objects set forth above. After reading the foregoing specification, one of ordinary skill will be able to effect various changes, substitutions of equivalents and various other aspects of the invention as broadly disclosed herein. It is therefore intended that the protection granted hereon be limited only by the definition contained in the appended claims and equivalents thereof.

Claims: CLAIMS 1. A filter for purifying water, the filter comprising: a housing including an inlet through which the water is received and an outlet; a spiral filter structure including a ribbon spirally wound to form a central hollow core and an exit at the exterior thereof, the ribbon including a first biocidal material and a second biocidal material contained therein, the inlet directing the liquid through the spiral structure via the central core, the water exiting the spiral structure at the exit; an annular holding chamber disposed between the spiral filter structure and the housing and adapted to receive water exiting the spiral structure, the annular holding chamber including a plurality of outlet holes; a volume of filtration media through which the water is passed upon exiting the holding chamber through the plurality of outlet holes, the water flowing in contact with the filtration media and exiting the housing via the outlet. 2. A filter for purifying a liquid, the filter comprising: a housing including an inlet through which the liquid is received and an outlet; a filter structure including a coiled structure having a first biocidal material and a second biocidal material secured thereto, the filter structure being adapted to receive liquid from the inlet and to permit substantially all the liquid to travel along substantially the entire length of the coiled structure in extended intimate contact with the first and second 15 biocidal materials, the filter structure including an exit for directing liquid from the filter structure; a holding chamber adapted to receive liquid from the exit, the holding chamber including a plurality of outlet holes; a volume of filtration media through which the liquid is passed, the liquid entering the volume of filtration media through the plurality of outlet holes. 3. The filter of claim 2, wherein the coiled structure is in a spiral configuration. 4. The filter of claim 2, wherein the coiled structure is in a helical configuration. 5. A method for filtering water comprising: introducing the water into a filter such that the liquid traverses a spiral or helically arranged channel in intimate contact with at least one cycle of first and second biocidal materials; and routing the liquid from the filter. 6. A reduction-oxidation method for killing biological organisms, comprising the steps of: (a) putting first and second biocidal materials into a spirally or helically arranged channel; (b) exposing the biological organisms to the first biocidal material for a period of time, the first biocidal material increasing the number of electrons in the biological organisms; (c) exposing the biological organisms to the second biocidal material for a period of time, the second biocidal material decreasing the number of electrons in the biological organisms; 16 wherein the cyclical increase and decrease in the number of electrons in the biological organisms kills the biological organisms. 7. A filter for purifying a liquid, comprising: (a) a filter container having an inlet and an outlet and a longitudinal axis extending therebetween; (b) a filter disposed in said filter container, said filter having an elongate channel arranged in a predetermined geometric configuration; and (c) a active granular material disposed in said channel, at least some of said active granular material being adhered to interior walls of said channel. 8. The filter of claim 7, wherein said active granular material includes a first biocidal material and a second biocidal material arranged in alternating sequence to each other within said channel . 9. The filter of claim 8, wherein said channel is arranged in a spiral configuration. 10. The filter of claim 8, wherein said channel is arranged in a helical configuration. 11. The filter of claim 1, wherein internal walls of said ribbon are lined with said first and second biocidal materials. 12. The filter of claim 2, wherein internal walls of said coiled structure are lined with said first and second biocidal materials. 13. The method of claim 5, wherein said liquid traverses through the channel in intimate contact with at least said one cycle of first and second biocidal materials lining the channel walls. 14. The method of claim 5, wherein said liquid contacts, in said channel, with a plurality of alternating regions of said first and second biocidal materials disposed along the length of said channel. 15. The method of claim 6, wherein said liquid traverses through the channel in intimate contact with at least said one cycle of first and second biocidal materials lining the channel walls. 16. The filter of claim 7, wherein said active granular material is adhesively secured to the interior walls of said channel. 17. The filter of claim 7, wherein opposing side walls of the channel are closely spaced from each other by a distance equal to the thickness of the two layers, one on each surface, particles of the granules of active material. 18. A filter adapted for placement in a pitcher for purifying water flowing through the filter under the influence of gravity only, comprising a housing including an inlet through which the water is received and an outlet; and a porous cyst membrane disposed in said housing to remove cysts from said water. 19. A filter, comprising: a member defining a channel having an inlet and an outlet, said channel lined with at least one material reactive with a liquid flowing through the channel. 20. The filter of claim 19, wherein said material is an ion exchange resin. 21. The filter of claim 20, wherein said resin is KDF material. 22. The filter of claim 20, wherein said resin is iodine. 23. The filter of claim 20, wherein said resin includes KDF and iodine in adjacent sequence. 24. The filter of claim 19, wherein said channel is arranged in a spiral or helical configuration. 25. The filter of claim 19, further comprising plural ones of said channels. 26. The filter of claim 25, wherein said channel is arranged in a spiral or helical configuration. 27. A gravity fed, pitcher mounted, pour through filter unit, comprising a member defining a channel having an inlet and an outlet, said channel including at least one material with which a fluid entering the channel through the inlet is reactive to achieve microbiological reduction in the liquid exiting the outlet. 28. The filter of claim 27, wherein said channel is spiral or helical. 29. The filter of claim 28, further comprising plural ones of said spirals or helices.

Inventors: MOZAYENI ROBERT B, MOZAYENI, B., ROBERT
Applicants: MOZAYENI ROBERT B, MOZAYENI, B., ROBERT
Application year: 1997
Main classification: B01D24
IPC codes: B01D39, B01D71, C02F1