WO2006128187A2

WO2006128187A2 - Enhanced ceramic filter for drinking water treatment

Info

Publication number: WO2006128187A2
Application number: PCT/US2006/020983
Authority: WO
Inventors: Joseph Brown; Mark D. Sobsey
Original assignee: The University Of North Carolina At Chapel Hill
Priority date: 2005-05-27
Filing date: 2006-05-30
Publication date: 2006-11-30
Also published as: WO2006128187A3

Abstract

A method and device for the filtration of fluids containing microbiological contaminants and/or metal contaminants, wherein the fluid is passed through a purification material comprising a metal oxide, metal oxyhydroxide, or combinations thereof.

Description

DESCRIPTION ENHANCED CERAMIC FILTER FOR DRINKING WATER TREATMENT

CROSS REFERENCE TO RELATED APPLICATIONS This application is based on and claims priority to United States

Provisional Application Serial Number 60/685,599, filed May 27, 2005, herein incorporated by reference in its entirety.

GRANT STATEMENT These studies were supported by United States Environmental

Protection Agency P3 Grant No. 5-35403. As such, the U.S. Government has certain rights in the presently disclosed subject matter.

TECHNICAL FIELD The presently disclosed subject matter generally relates to a filtration system that removes contaminants from fluids. The presently disclosed subject matter also relates to a filtration medium comprising a metal oxide and/or a metal oxyhydroxide, as well as methods of making and using the filtration medium.

TABLE OF ABBREVIATIONS σ-FeO(OH) - goethite

K-FeO(OH) - lepidocrocite

AIO(OH) boehmite

As arsenic

BSF biosand filter

Cd cadmium cm centimeter

Co cobalt

Cr chromium

Cu copper

EPA Environmental Protection Agency

Fe₂O₃ hematite Fe₃O₄ magnetite g gravity h hour

HAV hepatitis A virus Hg mercury

IOSSF intermittently operated slow sand filtration kb kilobase log logarithm L liter LRV log reduction value mg milligram Mg magnesium min minute ml milliliter mM millimolar

Mn manganese mol mole

NaCI sodium chloride

ND not detected ng nanogram

Ni nickel nM nanomolar

NS not significant

NTU nephelometric turbidity units

Pb lead

PEG polyethylene glycol

POU point-of-use

SES socio-economic status t filtration time v velocity

V₀ initial velocity

Zn zinc microgram μ\ microliter μM micromolar

V vanadium

% percent degrees

> greater than or equal to

> greater than

< less than or equal to

< less than

BACKGROUND

Clean drinking water is often taken for granted in the developed world. However, in developing nations that lack the financial resources and/or infrastructure to build and maintain water treatment facilities and sewer systems, unsafe drinking water is still responsible for illnesses that kill more than two million people a year. Boiling water to make it safe to drink uses large amounts of fuel, which is unaffordable and poses a threat to the sustainability of natural resources. Thus, there is a need for inexpensive, easy-to-use systems to effectively decontaminate water. In addition to being essential tools to aid the population of the developing world, uses for such systems exist in the developed world as well, thanks in part to the popularity of outdoor recreational activities, such as camping and hiking. Events of September 11 , 2001 , and the consequent "war on terrorism", have further caused a shift in public thinking relative to the safety of water resources, both at home and abroad.

As a result of increased needs for pathogen detection due to bio- terrorism threats and other sources of water contamination, along with a general lack of funding for upgrading municipal water supplies, consumers are increasingly exploring safe drinking water options. Various point-of-use (POU) systems have been developed to allow people to treat drinking water themselves. The main goals of these systems have been ease of use, low maintenance requirements, low cost, the ability to produce sufficient quantities of water, and the effective removal of pathogenic microorganisms. POU systems include tablets or sachets of powders for coagulation- flocculation chlorination, intermittently operated slow sand filtration (IOSSF) (also known as the biosand filter (BSF)), and ceramic microfiltration. Of these, coagulation-flocculation chlorination, which relies on chemical coagulants such as aluminum sulfate or ferric chloride, tends to be the most expensive. Biosand filters rely on the development of microorganisms on the surface of sand or gravel filter media to help remove pathogens from water. While biosand filters are very inexpensive, they can be difficult to use and are not always as effective as the other methods in removing bacteria and viruses from water.

Ceramic microfiltration systems remove contaminants based on straining through ceramic membranes or other porous structures. Simple ceramic microfiltration systems, such as the Filtrόn, produced under the guidance of the international, non-government organization Potters for Peace (accessible via the World Wide Web, Bisbee, Arizona, United States of America), consist of a porous clay filter unit perched inside a lidded, spigoted receptacle of plastic or clay. The filter unit is saturated with colloidal silver as a germicide/disinfectant. The Filtrόn has been tested in over ten countries on four continents and is used by the International Red Cross and Doctors Without Borders. The unit has a flow rate of approximately 1- 3 liters of water per hour, although this depends on the manufacturing process used. Ceramic microfiltration units also are manufactured by commercial entities such as Katadyn (Wallisellen, Switzerland) and Stefani (Welshpool, Western Australia, Australia). Microfiltration is inexpensive and has been shown to remove bacteria and protozoa from water by greater than 99.9999% (6 log-m) due to size exclusion of the ceramic pores (which can be as small as 0.2 μm). The pores are not small enough, however, to filter out viruses, such as hepatitis A virus, the main cause of waterborne infectious hepatitis. In most cases, a combination of techniques is employed in order to completely purify fluids, such as water. Combinations of technologies can be implemented by combining functions in a single device or using several devices in series where each performs a distinct function. Many of these water purification techniques and practices are costly, energy inefficient and/or require significant technical knowledge and sophistication. Traditional approaches for reducing these complications require extensive processing or specially designed apparatus. Unfortunately, development of low-cost techniques do not adequately address the removal of harmful biological contaminants, including for example, viruses. Particularly, simple POU purification devices, such as filters attached to in-house water supply conduits or portable units for campers and hikers, cannot sufficiently remove bacteria and viruses. In addition to ceramic microfiltration, intermittently operated sand filters (IOSSF) and coagulation-flocculation-chlorination, interventions such as chlorine (used alone) and solar disinfection have been successful in the field. However, there are drawbacks to these forms of household water treatments as well. In particular, both chlorination and solar disinfection are less effective in waters with higher turbidity, creating a need for practical and affordable methods to remove turbidity from household drinking waters. In addition, chlorination, which has been widely advanced as a method of POU treatment, is not effective against some important waterborne pathogens, such as Cryptosporidium parvum. Thus, it is clear that while techniques currently available in the art are effective to a certain extent, they have limitations in terms of operations, resistance to pathogens, and creation of toxic by-products. It is therefore desirable to have a device that is effective against all kinds of microorganisms and will not generate toxic by-products.

SUMMARY

Disclosed herein are methods of preparing a filtration medium, the methods comprising: (a) contacting a component selected from the group consisting of a metal oxide, a metal oxyhydroxide, and combinations thereof with a starting filtration medium; and (b) curing the contacted starting filtration medium to form a filtration medium.

Also disclosed herein are filtration mediums comprising a component selected from the group consisting of a metal oxide, a metal oxyhydroxide, and combinations thereof.

Additionally disclosed herein are methods of decontaminating fluid, the methods comprising: (a) providing a filtration medium comprising a metal oxide, a metal oxyhydroxide, or combinations thereof; and (b) passing a volume of fluid to be decontaminated through the filtration medium.

Further disclosed herein are kits for use in filtering fluid, the kits comprising: (a) a filtration medium comprising a metal oxide, a metal oxyhydroxide, or combinations thereof; and (b) a container in which to collect the filtered fluid. In some embodiments the starting filtration medium is selected from the group consisting of clay, sand, gravel, crushed ceramics, fiber, fabric, polymers, and membranes.

In some embodiments, the metal oxide or metal oxyhydroxide is selected from the group consisting of goethite (α-FeO(OH)), hematite (Fe₂O₃), lepidocrocite (κ-FeO(OH)), magnetite (Fe₃O₄), boehmite (AIO(OH)), and diaspore (AIO(OH)).

In some embodiments, the contacting a component selected from the group consisting of a metal oxide, a metal oxyhydroxide, and combinations thereof with a starting filtration medium imparts a positive charge to the filtration medium.

In some embodiments, the metal oxide, a metal oxyhydroxide, and combinations thereof impart a positive charge to the filtration medium.

In some embodiments, the curing comprises firing in a kiln.

In some embodiments, the starting filtration medium and the metal oxide, metal oxyhydroxide, or combinations thereof are combined in about a 6:1 , 1 :10, 1 :20, 1 :30, 1 :50, or 1 :100 filtration medium-to-metal or metal oxyhydroxide weight/weight ratio.

In some embodiments, the improved filtration property is selected from the group consisting of improved microorganism filtration, improved metal filtration, and combinations thereof.

In some embodiments, a filtration medium prepared by the taught methods is disclosed. In some methods a filtration device comprising the filtration medium is disclosed.

In some embodiments, the filtration medium has a design characteristic selected from the group consisting of a Filtrόn design, a candle-shaped design, a filter disk design, and combinations thereof.

In some embodiments, the fluid to be decontaminated comprises a contaminant selected from the group consisting of a microorganism, a toxic metal, and combinations thereof.

In some embodiments, the microorganism is selected from the group consisting of a virus, a bacterium, a protozoan, and combinations thereof.

In some embodiments, the toxic metal is selected from the group consisting of arsenic, mercury, lead, manganese, magnesium, cadmium, zinc, nickel, chromium, cobalt, and vanadium.

In some embodiments, the decontaminated fluid is collected. , In some embodiments, the filtration medium is regenerated.

In some embodiments, the regeneration of the filtration medium comprises an abrasive scrubbing step.

In some embodiments, the passing of the water to be decontaminated through the filtration medium is achieved through gravitational force.

BRIEF DESCRIPTION OF THE DRAWINGS

Figures 1A-1 D are photographs depicting several embodiments of structures comprising the presently disclosed filter medium.

Figure 1 E is an unmodified Stefani candle filter. Figure 2 is a schematic diagram depicting a method by which the presently disclosed filtration medium is used.

Figure 3 is a bar graph of the log-io reduction in microbes of several available methods of water treatment. The right diagonal bars represent protozoa reduction, the left diagonal bars represent virus reduction, and the solid bars represent bacteria reduction.

Figure 4 is a bar graph showing initial batch sorption tests of ceramic filter materials comprising crushed ceramic particles with groundwater and groundwater supplemented with wastewater effluent. The diagonal bars represent groundwater, the solid bars represent groundwater plus primary effluent.

Figure 5 is a line graph representing the results of a longitudinal test of the improved filtration medium disclosed herein, showing reduced effectiveness against test microbes MS2 and PhiX-174 over time, and the recharge capacity at time = 500 hours through abrasive scrubbing. "0" represents reagent-grade water, "■" represents reagent grade water plus primary effluent.

Figure 6A is a bar graph indicating phages PRD-1 and ΦX174 reduction in groundwater by commercially available and modified ceramic filters. Solid bars represent pH 6, right diagonal bars represent pH 8, and left diagonal bars represent pH 9.

Figure 6B is a bar graph indicating male-specific coliphage MS2 reduction in groundwater by commercially available and modified ceramic filters. Solid bars represent pH 6, right diagonal bars represent pH 8, and left diagonal bars represent pH 9.

DETAILED DESCRIPTION

The presently disclosed subject matter is directed in some embodiments to filter media having improved filtration capability, filtration systems containing such filter media, and methods of making and using the same.

L Definitions It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood to one of ordinary skill in the art to which the presently disclosed subject matter belongs.

Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the presently disclosed subject matter, representative methods and materials are herein described. Following long-standing patent law convention, the terms "a", "an", and "the" refer to "one or more" when used in this application, including the claims. Thus, for example, reference to "a carrier" includes mixtures of one or more carriers, two or more carriers, and the like. Unless otherwise indicated, all numbers expressing quantities of ingredients, reaction conditions, and so forth used in the specification and claims are to be understood as being modified in all instances by the term "about". Accordingly, unless indicated to the contrary, the numerical parameters set forth in the present specification and attached claims are approximations that can vary depending upon the desired properties sought to be obtained by the presently disclosed subject matter.

The term "about", as used herein when referring to a measurable value such as an amount of weight, time, dose, etc. is meant to encompass in one example variations of ±20% or ±10%, in another example ±5%, in another example ±1 %, and in yet another example ±0.1 % from the specified amount, as such variations are appropriate to perform the disclosed method.

Several terms herein can be used interchangeably. Thus, "virion",

"virus", "viral particle", "viral vector", "viral construct, and "vector particle" can refer to virus and virus-like particles that are capable of introducing a nucleic acid into a cell through a viral-like entry mechanism.

With respect to the methods of the presently disclosed subject matter, a preferred subject is a vertebrate subject. A preferred vertebrate is warmblooded; a preferred warm-blooded vertebrate is a mammal. The subject that consumes water treated by the presently disclosed methods is desirably a human, although it is to be understood that the principles of the presently disclosed subject matter indicate effectiveness with respect to all vertebrate species which are included in the term "subject." As used herein "subject" includes both human and animal subjects. Thus, animal husbandry uses are provided in accordance with the presently disclosed subject matter. As used herein, "filter medium" includes any material that performs fluid filtration.

As used herein, "Filtrόn" is a ceramic filter shaped like a flowerpot. In some commercially available forms, these filters can be saturated with an industrial concentration of colloidal silver. The filters can be press-molded, formed by hand, or turned on a potter's wheel before being fired in a brick kiln. Made from a mix of clay and sawdust, the filters block the larger water- borne particles while the colloidal silver inactivates bacteria small enough to get through the filter's tiny holes.

As used herein, "absorbent" means any material that is capable of absorbing a substance by drawing the substance into its inner structure.

As used herein, "fluid" means a continuous, amorphous substance whose molecules move freely past one another and that has the tendency to assume the shape of its container.

As used herein, "adsorbent" means any material that is capable of adsorbing a substance by physical and/or chemical adsorption to the surface.

As used herein, "membrane" means a porous medium wherein the structure is a single continuous solid phase with a continuous or otherwise organized pore structure.

As used herein, "microorganism" includes any living organism that can be suspended in a fluid, including but not limited to bacteria, viruses, fungi, protozoa, and reproductive forms thereof including cysts and spores. As used herein, "ceramic" materials refer to solid materials produced from essentially inorganic, non-metallic substances, and which are formed simultaneously or subsequently matured by the action of heat.

\l Filter Medium In some embodiments, the presently disclosed subject matter comprises a filter medium for use in the filtration and purification of a fluid, in particular an aqueous solution or water. The filter medium can be used to remove microbiological contaminants, including bacteria and viruses and components thereof, as well as metals, from water destined for consumption and use by humans and other animals. The filter medium is particularly useful in reducing the concentration of microbiological and certain metal contaminants to exceed the EPA standards for microbiological water purification devices, and to exceed the effectiveness of known filtration and purification devices.

The filter medium of the presently disclosed subject matter can comprise a component including but not limited to, sand, ceramics, crushed ceramics, other granular filter media, fiber, fabric, polymers, membranes, and combinations of any of the foregoing. These component(s) can be referred to as a starting filter medium and can comprise particles for use in preparing a fluid filter medium.

In some embodiments, the ceramic material used is brick. Basic brick is a refractory brick that can comprise basic materials such as lime, magnesia, chrome ore, or dead burned magnesite, which reacts chemically with acid refractories, acid slags, or acid fluxes at high temperatures.

In other embodiments, the ceramic material is a refractory. A refractory material is an inorganic, nonmetallic material that will withstand high temperatures, and is frequently resistant to abrasion, corrosion, pressure, and rapid changes in temperature. By way of non-limiting example, suitable refractories include, but are not limited to, alumina, sillimanite, silicon carbide, zirconium silicate, and the like.

In some embodiments, the ceramic material can comprise a structural ceramic, such as, e.g., silicon nitride, sialon, boron nitride, titanium bromide, and the like. In some embodiments, the ceramic material can comprise or consist essentially of clay or shale.

In some embodiments., the ceramic material can be glass. As used herein, glass refers to an inorganic product of fusion that has cooled to a rigid configuration without crystallizing. By way of non-limiting example, some suitable glasses include sodium silicate glass, borosilicate glass, aluminosilicate glass, and the like. Many other suitable glasses will be apparent to those skilled in the art upon a review of the present disclosure.

The filter medium can comprise a component that gives the filter medium a positive charge. Such components include mineral additives, such as but not limited to metal oxides and metal oxyhydroxides. The metal oxide or metal oxyhydroxide can be selected from the group including but not limited to goethite (α-FeO(OH)), hematite (Fe₂O₃), lepidocrocite (y-

FeO(OH)), magnetite (Fe₃O₄), boehmite (AIO(OH)), and diaspore (AIO(OH)).

While it is not desired to be bound to any particular theory, it is suggested that since most viruses and other microorganisms are negatively charged at neutral pH, viruses in contaminated water that come into contact with the filter medium surfaces become attached to the surfaces via electrostatic attraction. The viruses and microorganisms are not only merely attracted to the surface, but can be inactivated and killed by the surface charge differential and the resulting physical and chemical forces between the microorganisms and the surface. Thus, in some embodiments, the presently disclosed filter medium is capable of removing microorganisms from water, including pathogenic microorganisms, such as, but not limited to, viruses, bacteria, and protozoa.

The filter medium is also capable of removing metal contaminants from the water, including arsenic (As) and other metals such as, but not limited to, mercury (Hg), lead (Pb), manganese (Mn), magnesium (Mg), cadmium (Cd), copper (Cu), zinc (Zn), nickel (Ni), chromium (Cr), cobalt (Co), and vanadium (V).

The filter medium of the presently disclosed subject matter is such that it can be formed into any desired shape, and thus provides ease of handling and use. For example, the filter medium can be used to form filtration devices of a wide variety of designs, such as candle-shaped devices, Filtrόn designs (flowerpot shape), or ceramic filter disks. The filter medium can be provided as particles, which can be provided in the shape of a sphere, polyhendron, and/or cylinder, as well as other symmetrical, assymetrical and irregular shapes. Additionally, the filter medium can be formed into a monolith or block that fits into conventional housings for filtration media, or can be shaped to provide purification as part of a portable or personal filtration system. Alternatively, the filter medium can be formed into several different pieces, through which water flows in series or in parallel. Sheets or membranes of the filter medium can also be formed. The rigidity of the filter medium, whether in block form or in sheet/membrane form, can be altered through inclusion of flexible polymers in the starting filter medium.

Like shape, the size of the filter medium can vary, and the size need not be uniform among filter particles used in any single filter implementation. The physical dimensions of the filter medium are such so as to provide a sufficiently thick filter bed for sufficient contact with a fluid and filtration thereof. The filter medium can contain fillers and/or components for obtaining structural integrity of the filter medium, so long as the filtration function of the filter medium is not significantly compromised. Thus, upon a review of the present disclosure, one of ordinary skill in the art will appreciate that the pore size and physical dimensions of the filter medium can be manipulated for different applications and that variations in these variables can alter flow rates, back-pressure, and the level of contaminant removal. In addition to providing direct mechanical interception of microbiological contaminants, the filter medium can comprise a germicide and/or disinfectant. Germicides are well known in the art. See, for example, the section on "Quaternary Ammonium and Related Compounds" in the article on Antiseptics and Disinfectants" in Kirk-Othmer Encyclopedia of Chemical Technology 2nd Edition (vol. 2, pp.632-635). In some embodiments, the germicide is a cationic germicide having a broad spectrum of antimicrobial and antifungal activity. Disinfectants suitable for use with the disclosed materials can include, but are not limited to, inorganics such as silver salts, colloidal silver, nanosilver, ozone, chlorine dioxide, chlorine, sodium hypochlorite, chloramine, or combinations thereof. The disinfecting agent can also be organic, such as, for example, a quaternary ammonium compound.

HL The Mineral Additives The microorganism and metal-attracting mineral additive components of the presently disclosed filter medium can be positively charged when provided in a fluid having a pH commonly associated with the pH of drinking water. In general, the pH range of drinking water is between about 5 and about 9. As disclosed herein, exemplary components that have been found to be particularly effective in attracting microorganisms and metals include metal oxides and metal oxyhydroxides.

In some embodiments, mineral additives that are used for the preparation of the presently disclosed filter medium are selected from the group of mineral additives including but not limited to metal oxides, metal oxyhydroxides, and combinations thereof. The metal oxide and oxyhydroxide additives of the presently disclosed subject matter include, but are not limited to, goethite (α-FeO(OH)), hematite (Fe₂Os), magnetite (Fe₃O₄), lepidocrocite (κ-FeO(OH)), boehmite (AIO(OH)), and diaspore (AIO(OH)). Synonyms for goethite, magnetite, and hematite include iron yellow, iron black and iron red, respectively. The additives of the presently disclosed subject matter can be naturally occurring or synthetic.

A starting filtration medium can be mixed with a metal oxide or metal oxyhydroxide capable of creating a positive charge within the filtration medium. The metal oxides or metal hydroxides can be provided as particles, such as in a powder; as a dispersion; or as a solution. The metal oxides and metal hydroxides can be incorporated into the filter medium using methods known in the art. The presence of the metal oxide, metal oxyhydroxide, or combinations thereof can produce a strong positive charge within the filter medium, thus forming a cationic metal complex on or in at least a portion of the filter medium.

As surprisingly discovered herein, the metal oxides, metal oxyhydroxides, and combinations thereof provide for removal of a wide range of contaminants from fluids, such as water using the presently disclosed subject matter. The metal oxides, metal oxyhydroxides, and combinations thereof can remove at least about 99.9999% of the contaminants from water. Thus, the presence of the metal oxides, metal oxyhydroxides and combinations thereof can be useful in attracting, collecting, sequestering, retaining or removing negatively charged microorganisms, and metal contaminants.

Microorganisms that can be removed by the improved filtration media of the presently disclosed subject matter include bacteria and viruses. Particular species of bacteria which are sometimes found in drinking water and which can be removed by the filter of the present invention include, but are not limited to, E. coli, Salmonella typhi, other salmonellae, Shigella spp., Vibrio cholerae, Yersinia enterocolitica, Legionella, Pseudomonas aeruginosa, Aeromonas spp., Mycobacterium spp., and mixtures thereof. Viruses typically have a size of between about 20 nm and about 200 nm. Viruses found in drinking water and which are of particular concern for removal therefrom by the presently disclosed filter medium include, but are not limited to, adenoviruses, enteroviruses, Hepatitis A virus, Hepatitis E virus, noroviruses, reoviruses, rotavirus, astroviruses, and mixtures thereof.

Most viruses have outer coats (capsids) comprising protein polypeptides that contain amino acids such as glutamic acid, aspartic acid, histidine, and tyrosine. In general, these amino acids contain weakly acidic and basic groups {i.e., carboxyl and amino groups) that ionize to provide the viral capsid with an electrical charge. In addition, each amino acid ionizing group in the polypeptide has a characteristic disassociation constant. The variation of disassociation constants among the various polypeptides ensures that most viruses have net charges that vary continuously with pH, and can be measured by iso-electric focusing or electrophoretic mobility and are expressed as iso-electric point (pH of zero net charge on the virus particle or virion) or zeta potential (electrical potential at a specified pH level). Viruses are typically negatively charged at neutral pH ranges. So, viruses coming into contact with the presently disclosed filter medium can become attached through electrostatic attraction. The strength of the attraction has been shown to be associated with virus inactivation on contact, killing viruses as they come into contact with the presently disclosed filter medium.

The presently disclosed filter medium has also been shown to remove arsenic (As) and other metals (Hg, Pb, Mn, Mg, Cd, Cu, Zn, Ni, Cr, Co, V) from neutral pH (about pH 7) and nearby pH ranges of drinking water (pH 5 to 10).

The amounts of the mineral additives incorporated into the filter medium can be chosen to provide sufficient contact time to remove microorganisms and metals from a fluid, taking into account, for example, the flow rate, the particle size, and the configuration of the filter medium. Also, the operating life of the filter medium should be considered, as the filter is gradually consumed by use. The amount of mineral additives is chosen to provide sufficient contact time to provide a desired reduction in microorganism and metal concentration.

Thus, using the filter medium disclosed herein, biological and mineral contaminants can be removed from a fluid. While any percentage of removal is possible, such possibilities can include about 70% reduction, about 80% reduction, about 90% reduction, and about 100% reduction.

The filter medium is sufficiently porous to allow fluid to flow through at desirable flow rates under the conditions of operation. Representative pore sizes can range between about 0.05 and 3.0 microns, but can be outside this range. The presence of the mineral additive will not significantly decrease the porosity of the filter medium or flow rate of liquid through the filter medium. That is, the filter medium that includes the mineral additive provides a desirable degree of flow and maintains a desired pore range under the intended conditions of operation.

JV. Method Of Making Filter Medium

The filter disclosed herein incorporates mineral additives into the filter medium that make the filter electropositive, or possessing a permanent positive charge. There are several naturally occurring minerals that can give the ceramic filter this property. As disclosed herein above, they include a class of minerals known as metal oxides and oxyhydroxides, naturally occurring around the world and also producible synthetically. The addition of metal oxides and oxyhydroxides to a starting filter medium, such as ceramic clay, before firing has been shown to greatly improve the virus removal properties of the filters, from around 90% to greater than 99.99%, representing a significant advancement in filter technology for fluid purification.

The filter medium can remove microorganisms and metals, such as arsenic, through electrostatic attraction to the filter medium modified with metal oxides, metal oxyhydroxides, and combinations thereof. Additives shown to give the filter medium these properties include (but are not limited to) goethite (FeOOH)₁ hematite (Fe₂O₃), lepidocrite (FeOOH), boehmite (AIOOH), and diaspore (AIOOH). In some embodiments, the mineral additives are added to ordinary ceramic clay in a low-fire process. The properties of the modified filter are independent of base filter medium used, or the firing process used. Unlike other materials, virus sorption to the modified filter medium inactivates viruses, rendering them non-infectious on contact. In some embodiments, the mineral additive is added to the filter medium in a ratio of 1 :6 weight/weight (1 part mineral additive, 6 parts filter medium) and fired to cone 012 (i.e., to a temperature of about 1600⁰F) using a standard process for constructing porous water filter devices. In some embodiments, the mineral additive can be added to the filter medium in ratios of 1 :10 weight/weight (1 part mineral additive, 10 parts filter medium), 1 :20, 1 :30, 1 :50, and 1 :100. The modified filter medium can subsequently be fired to a temperature within the range of 1600⁰F ± 800⁰F using a standard process for constructing porous filtration medium.

The modified filter medium reduced bacteriophages (human enteric virus surrogates) by 99.9999% in initial tests. The efficacy of the filter medium was reduced over time as a constant volume of virus-spiked water was added to the filter. Thus, the filter loses capacity for virus sorption/inactivation over time. However, the filter has the potential for recharge through abrasive scrubbing of the inside of the filter (Figure 5), or other suitable recharging technique.

In some embodiments, the starting filter medium can be coated with the mineral additives, in accordance with known methods in the art. Methods for coating the filter medium can include chemical precipitation, electrolytic coating, heat, or other physical and chemical processes. By way of example, the filter mediums illustrated in Figures 1A-1 D are examples produced by the methods disclosed herein. Figure 1A represents an enhanced Filtrόn filter with yellow iron oxyhydroxides. Figure 1 B is a Katadyn filter coated with Al/Fe oxyhydroxides. Figure 1 C is a Katadyn filter coated with magnetite, naturally occurring black iron oxide. Figure 1 D is a Katadyn filter coated with hematite, naturally occurring red iron oxide. Figure 1 E is a photograph of an unmodified Stefani candle filter of the prior art. Further, Figure 4 recites a plurality of filter medium formulations for use in the presently disclosed subject matter. Particularly, clays, ceramics, minerals, sands, activated carbon, synthetic fibers, and other porous media can be used as starting filter medium. Ag (unfired), Ag (fired), Al hydrate, goethite, magnetite, and hematite can be used as the mineral additives. Figure 4 shows several test media that are natural clays and low-fire ceramics that are coated with the mineral additives.

V. Filtration Systems Utilizing the Improved Filter Medium

The improved filter can be implemented for various uses, including, but not limited to: (a) removal of contaminants from water; (b) point of use applications; (c) point of entry applications; and (d) industrial applications.

The presently disclosed subject matter discloses materials and methods for the purification and filtration of aqueous fluids, in particular water (such as drinking, swimming, or bathing water), or other aqueous solutions (such as fermentation broths and solutions) used in cell culture. The use of the materials and methods of the presently disclosed subject matter results in the removal of a high percentage of microbiological contaminants, including bacteria and viruses and components thereof, as well as metals.

In some embodiments, the filter medium of the presently disclosed subject matter can be easily incorporated into prior art filtration systems that utilize particulate filtration medium immobilized as solid composite blocks; flat; spiral or pleated sheets; monoliths; or candles.

In some embodiments, a prefilter stage can be utilized to remove larger particles from the water to prolong the effectiveness of the filter between cleanings. The prefilter can be of paper or other fibrous material positioned above the ceramic filter to prevent larger particles from reaching the ceramic filter.

Referring now to Figure 2, an exemplary filtration system 100 is shown in a schematic diagram. Filter system 100 includes a pair of vertically stacked vessels, namely a lower receiving vessel 104 and an upper filtering vessel 108. Vessels 104 and 108 are stacked in a nested relationship. A lid can optionally be provided for use with upper vessel 108 in order to prevent ambient particles such as dust, pollen leaves, etc. from dropping into the raw water 120 while it is in upper filtering vessel 108. In some embodiments, system 100 is provided in a kit.

Receiving vessel 104 can be of cylindrical shape, conical shape, or other suitable or desirable shape open at its top and can optionally include a handle. Receiving vessel 104 also can optionally include a spout 116, by which filtered water 124 can be dispensed. Receiving vessel 104 can be made of any of a variety of suitable materials, including, but not limited to, plastics and ceramics. To preserve the potability of the filtered water, the surfaces of receiving vessel 104 can be made from or treated with a disinfectant or with the microbiological interception-enhancing agent. Preferably, the disinfectant used does not alter or affect the taste of filtered water 124.

Continuing with reference to Figure 2, upper filtering vessel 108 is closed at its lower end 118. A lip 112 can also be provided. At lower end 118, the circumference of the periphery can be reduced to form a shoulder or flange for supporting upper filtering container 108 in nested position on receiving vessel 104 in conjunction with Kp 112. Upper filtering vessel 108 comprises a filtering medium in accordance with the presently disclosed subject matter, and serves to filter microorganisms and other pollutants from unfiltered water 120.

Continuing with Figure 2, filtration system 100 can be used as follows. A user takes a reservoir 121 to a water source. Reservoir 121 is filled with a quantity of raw water 120 and the user carries reservoir 121 back to a preferred location. It is possible that raw water 120 is contaminated with microorganisms and chemical contaminants and is not potable.

To facilitate filtration, reservoir 121 can be suspended or hung from a support (not shown in Figure 2). Depending upon any significant sediment present as evidenced by turbidity, raw water 120 can remain suspended or held without mixing for a period of time sufficient for the sediment to settle. Raw water 120 to be filtered is poured from reservoir 121 into upper filtering vessel 108. If a lid is supplied with filtering system 100, it is placed in a position to prevent further contamination of raw water 120. Gravity filtration through upper filtering vessel 108 allows raw water 120 to be filtered to flow through upper filtering vessel 108. As raw water 120 passes through filtering vessel 108 with sufficient contact time, filtering vessel 108 renders raw water 120 potable by providing a desired reduction of microorganisms and metals. Filtered water 124 is collected in lower vessel 104 and can be dispensed for use through spout 116. In some embodiments the flow rate into the lower vessel is about 1 L/hour, but can range from about 0.5 L/hour to 3 L/hour, depending on the manufacturing site and process. In some embodiments, the flow rate is not constant throughout the filter medium, but varies according to the falling head in upper filtering vessel 108. To accelerate the collection of filtered water 124, upper filtering vessel 108 can be refilled periodically in order to maintain a tall head of water and to increase the pressure on upper filtering vessel 108.

Continuing with Figure 2, after a length of time, filtering vessel 108 can become saturated with filtered particles. Accordingly, surfaces of the upper filter vessel 108 can be cleaned and recleaned from time to time with a suitable tool, such as, for example, a stiff brush. The intervals between cleanings can depend largely upon the quantity and quality of water treated and the amount of contaminants in the water.

In some embodiments, a circulation element can be used for mechanical movement, or to drive or force water movement, such as, but not limited to, an air blower, air conditioner, water pump, or any device for producing a current flow of water. Physically moving a fluid includes any type of movement made by a user or occurring naturally, such as but not limited to stirring, breathing, blowing of the wind, pouring, flowing of a river, and the like.

Water suitable for use with the presently disclosed subject matter can be derived from a natural or man-made body of water, including but not limited to a stream, any type of plumbing system, faucet, or any water source. Water can include raw water, or even primarily treated water. Raw water is understood to be any water that is in a natural, uncultivated, or even unrefined state. It may be untreated water, or water from a river, ocean, stream, rain, and the like. Primary treated water can include water which has been previously filtered, for example, water as received in a home or office, which has gone through a municipal filtration system, such as water found in a residential or commercial building or the like.

The presently disclosed subject matter is also suitable for application in conjunction with a tap or faucet outlet as the culinary water outlet. This can be accomplished by providing a system that can be attached to a culinary water outlet in the form of a canister or canisters, or indeed any suitable container(s) that can attach to the faucet outlet by any suitable approach. Water can also be passed through the filter medium by gravity percolation or by pumping and is purified thereby. In some embodiments, a water treatment apparatus comprising the presently disclosed filter medium can be attached to a wide variety of plumbing systems, and can even be attached to a water outlet attachment. After attachment, the presently disclosed subject matter can include running water through the water treatment apparatus to remove any impurities or contaminants that are in the water. A water attachment can include any type of attachment configured to attach to a conduit, a sink faucet, outdoor conduit, and the like. The water treatment apparatus can be used to treat different quantities of water.

The water can contain impurities that are desirably removed before a human, animal, or the like consumes, or is exposed to the contaminants. When the filter loses its effectiveness, it can be easily accessed and cleaned by scrubbing it with a brush to remove the debris and sediment from its pores. This arrangement eliminates the waste that accompanies replacing the entire water filter system. Although the flow rate is diminished, the filter can maintain its microbiological and metal interception capabilities for an extended period of time.

Thus, in general, the presently disclosed subject matter comprises a medium and a method for the filtration and purification of a fluid, in particular an aqueous solution or water, to remove organic and inorganic elements and compounds present in the water as particulate material. In particular, the medium and method can be used to remove microbiological and metal contaminants, including bacteria and viruses and components thereof, from water destined for consumption and use by humans and other animals.

EXAMPLES

The following Examples have been included to provide illustrations of the presently disclosed subject matter. In light of the present disclosure and the general level of skill in the art, those of skill will appreciate that the following Examples are intended to be exemplary only and that numerous changes, modifications and alterations can be employed without departing from the spirit and scope of the presently disclosed subject matter.

EXAMPLE 1

Ceramic Filter Medium

The filter disclosed herein incorporates mineral additives into the ceramic material that make the surface of the filter electropositive, or possessing a permanent positive charge. Viruses are negatively charged at near neutral pH ranges (about pH 7). So, viruses coming into contact with the filter surface become attached through electrostatic attraction. The strength of this attraction has been shown to be associated with virus inactivation on contact, killing viruses as they come into contact with the surface. The filter removes viruses and metals, such as arsenic, through electrostatic attraction to ceramic surfaces modified with metal oxyhydroxides. Additives shown to give the filter surface these properties include (but are not limited to) goethite (FeOOH), hematite (Fe₂Os), lepidocrite (FeOOH), boehmite (AIOOH), and diaspore (AIOOH). The additives were added to ordinary ceramic clay in a low-fire process. The properties of the modified filter appear to be independent of base clay used, or the firing process used. Initial tests indicate that metal oxyhydroxides are the best candidate materials to use in modified ceramic filters for the reduction of viruses in water (Figure 4). Figure 4 illustrates virus inactivation following sorption. From Figure 4, goethite appears to be the best ceramic additive for the sorption of viruses, although other metal oxides would also exhibit this property. Unlike other materials, virus sorption to oxyhydroxide-modified ceramic surfaces appeared to inactivate viruses, rendering them non-infectious on contact.

The model oxyhydroxide used in the manufacture of prototypes was goethite, a naturally occurring oxyhydroxide of iron. Geothite was added to a naturally occurring dry kaolinite clay in a ratio of 1 :6 wt/wt (1 part goethite, 6 parts dry clay) and fired to cone 012 using a standard process for constructing porous water filter devices. Alternate ratios of goethite:dry clay were tested in the test filters, from 1 :3 to 1 :50. Alternate firing temperatures were also tested, ranging from 016 to 05. The modified filters of varying ratios and temperatures reduced bacteriophages (human enteric virus surrogates) by 99.9999% in initial tests. The efficacy of the filter was reduced over time as a constant volume of virus-spiked water was added to the filter. Thus, the filter appeared to be losing capacity for virus sorption/inactivation over time. The filter did show the potential for "recharge" or regeneration of virus adsorption capacity, however, through abrasive scrubbing of the inside of the filter (Figure 5). Figure 5 indicates longitudinal test of the filters, showing reduced effectiveness against test microbes MS2 and PhiX-174 (bacteriophages) over time and the recharge or regeneration capacity of the filter at time = 500 hours though abrasive scrubbing. The test waters were reagent grade water and the same spiked with 20% primary sewage effluent from the OWASA (Orange Water and Sewer Authority) wastewater treatment plant in Chapel Hill, North Carolina, United States of America (soluble portion, sterilized).

EXAMPLE 2 Analysis of the Effectiveness of Three Distinct POU Technologies

The effectiveness in improving water quality of a ceramic microfiltration device employing an embodiment of the presently disclosed subject matter was analyzed. The effectiveness of the technology for improving water quality by removing bacteria and viruses, which are major causes of waterbome disease, was tested. Effectiveness was measured by the ability of the ceramic microfiltration device to remove enteric bacteria, enteric viruses, and coliphage MS-2 (a surrogate for a wide range of pathogenic human viruses) from in bench-scale testing. The system was challenged with natural waters spiked with test microorganisms. The log-io reduction of each microorganism was measured, and was evaluated for the ability to achieve 4 logs (99.99%) of inactivation or removal of the microorganisms, in accordance with the U.S. Environmental Protection Agency (EPA) standards for POU drinking water treatment systems.

The F2 ceramic filter is a conventional filter that has been modified by the inclusion of iron oxides in its structure. The standard predecessors of the modified F2 ceramic filters have been proven to remove bacteria and protozoa by greater than 99.9999% (6 log-m) due to size exclusion (Sobsev, M.D. (2002) Managing Water in the Home: Accelerated Health Gains from Improved Water Supply WHO/SDE/WSH/02.02, World Health Organization, Geneva; Lantagne, D. (2002) Investigation of the Potters for Peace Colloidal Silver Impregnated Ceramic Filter - Report 1: Intrinsic Effectiveness. Alethia Environmental. Allston, MA). But for this Example, the F2 filter was modified with an iron coating in accordance with the presently disclosed subject matter. Particularly, the F2 filter was combined using a ratio of 1 :6 goethite:low-fire white (kaolinite) clay, mixed with ground rice husks for porosity, formed into wet clay, hydraulically pressed into a mold, fired to cone 012, and dipped in colloidal silver solution (around 20 ppm). For this Example, commercially available Katadyn and Stefani filters were modified by coating mineral oxides onto their surfaces. Particularly, Katadyn red and black were coated using heat.

Filter testing was performed using bacteriophages and viruses as models for human pathogenic viruses. Ceramic filters coated with iron compounds achieved 4-7 log-io reduction of bacteriophages in groundwater. Results are given in the last four entries of Table 1.

Metal oxide coatings have been observed to capture and inactivate viruses under certain conditions. Testing of several of these new filters was performed, as indicated in Table 1 and Figures 6A and 6B. Table 1 indicates log™ reduction values of bacteriophage by several modified and unmodified filters. Figures 6A and 6B indicate the bacteriophage reduction (6A: PRD-1 and ΦX174; 6B: MS2) in groundwater by commercially available and modified ceramic filters.

Log₁₀ reduction values (LRV) of bacteriophages by several modified and unmodified filters. Values are averages of n assays. Phages enumerated by Method 1602 (US EPA 2001). Stefani filters (Stefani, Welshpool, WA, Australia), Katadyn filters (Katadyn, Minneapolis, Minnesota, United States of America), and Filtrόn (Potters for Peace/Nicaragua, Managua, Nicaragua). The F2 ceramic filter, which is a conventional filter modified with an iron coating as disclosed herein, showed promising results for viral capture. Figure 3 shows a comparison of the effectiveness in removing microbes for three technologies (porous ceramic filtration, slow sand filtration, and disinfection/coagulation) to other methods of water treatment. Maximum E. coli reductions were achieved at the end of the filter run.

Data for Figure 3 for the other methods of water treatment were compiled from Souter. P.F., et al. (2003) Water Sci Tech 31 (5-6): 81-84; Lantagne, D. (2001 ) Investigation of the Potters for Peach Colloidal Silver Impregnated Ceramic Filter - Report 1: Intrinsic Effectiveness Alethia Environmental, Allston, MA; Sobsey, M.D. (2002) Managing water in the Home: Accelerated Health Gains from Improved Water Supply, WHO/SDE/WSH/02.07 (Limited Distribution), Geneva; Hiinen. WAM.. et al. (2004) Water Sci and Tech 50(1 ): 147-154; Timms, S., et al. Water Sci Tech 31(5-6): 81-84; Hug, A., et al. (1996) App and Environ Microbiology 62(7):2508-2502; Loqsdon, G. S. (1990). Microbiology and Drinking Water Filtration. In: Drinking Water Microbiology: Progress and Recent Developments. G. A. McFeters (ed.). New York, Springer-Verlag: pp. 120- 146; Schuler, P.F., et al. (1988) Comparing the Removal of Giardia and Cryptosporidium using Slow Sand and Diatomaceous Earth Filtration, pp 789-802, Proceedings 1988 AWWA Annual Conference, Denver: American Water Works Association; Sobsev, M.D. (1989) Water Sci and Tech 21(3):179-195; Blatchlev, I.E.R.. et al. (2001 ) Disinfection by Ultraviolet Irradiation, Disinfection, Sterilization and Preservation, Lippincott, Williams and Wilkins (ed.) New York; Weqelin, M. et al. (1994) SRT 43(3): 154-169; and Mendez-Hermida, F., et al. (2005 Mar) Appl Environ Microbiol 71 (3):1653-1654.

EXAMPLE 3 Field Assessment of the Ceramic Filter

The capability of a novel ceramic filter in accordance with the presently disclosed subject matter to remove microbes in a field intervention setting is assessed. A community intervention trial is conducted in a rural Third World village setting. All households in the study are visited bi-weekly by a field sampling team to collect water for microbiological analysis. Untreated and filter-treated drinking water samples are taken for analysis of turbidity, pH, F+ RNA coliphages (a viral indicator), total coliforms, and E. coli. Data from the baseline and study period are produced from 26 biweekly sampling periods. Every 2 weeks, 2 samples are taken from each intervention and placebo group (filter influent and effluent) and 1 sample from each control household. Eight weeks of wet/dry season baseline sampling is completed to determine baseline concentrations of indicator microbes in drinking water.

EXAMPLE 4

Assessment of Health Impacts of Ceramic Filters The health impacts of ceramic filters in the field intervention in a rural Third World village setting are assessed. A blinded, randomized controlled trial is conducted. Households are randomly assigned to one of three groups: those receiving the new and improved filter, those receiving no filter at all, and those receiving a placebo filter. The health impacts of the filter are based on bi-weekly interviews of all participating households, usually conducted at the time of water quality sampling. These are conducted by a local health worker with experience in survey data collection.

EXAMPLE 5

Analysis of Sustainabilitv of a Ceramic Filter The sustainability of a ceramic filter in a field intervention setting is analyzed. Continued effectiveness of the filter as measured by microbiological and health data over the period of one year is the focus of the sustainability. Data on the durability (number of breakages, number of filters no longer in use for any reason, etc.) and economic feasibility are collected. A cost-benefit analysis is conducted to evaluate the economic feasibility of the intervention. REFERENCES

The references listed below as well as all references cited in the specification are incorporated herein by reference to the extent that they supplement, explain, provide a background for or teach methodology, techniques and/or compounds employed herein.

Blatchley, I. E. R., et al. (2001 ) Disinfection by Ultraviolet Irradiation, Disinfection, Sterilization and Preservation, Lippincott, Williams and Wilkins (ed.) New York.

Brown, J. (2003) Ceramic Microfiltration for Drinking Water Treatment in Rural Boliva, MPhil Dissertation, University of Cambridge,

Department of Geography. Fewster, E., et al. (2004) Long term Sustainability of Household Bio-Sand

Filtration 30^th WEDC International Conference, Vientiane, Lao PDR. Gerba, CP. and G. Bitton. (1984) Microbial Pollutants: Their Survival and Transport Pattern to Groundwater. Groundwater Pollution

Microbiology. John Wiley & Sons. New York, NY. Hijnen, W.A.M., et al. (2004) Water Sci and Tech 50(1 ): 147-154. Huq, A., et al. (1996) App and Environ Microbiology 62(7):2508-2502. Kirk-Othmer Encyclopedia of Chemical Technology 2nd Edition "Quaternary Ammonium and Related Compounds" in the article on Antiseptics and

Disinfectants" (vol. 2, pp.632-635).

Lantagne, D. (2002) Investigation of the Potters for Peace Colloidal Silver Impregnated Ceramic Filter - Report 1: Intrinsic Effectiveness Alethia Environmental. Allston, MA). Logsdon, G. S. (1990). Microbiology and Drinking Water Filtration. In: Drinking Water Microbiology: Progress and Recent Developments. G. A. McFeters (ed.). New York, Springer-Verlag: pp. 120-146. Mendez-Hermida, F., et al. (2005 Mar) Appl Environ Microbiol 71(3):1653-

1654 Schuler, P. F., et al. (1988) Comparing the Removal of Giardia and Cryptosporidium using Slow Sand and Diatomaceous Earth Filtration, pp 789-802, Proceedings 1988 AWWA Annual Conference, Denver: American Water Works Association. Sobsey, M.D. (1989) Water Sci and Tech 21(3):179-195.

Sobsey, M.D. (2002) Managing Water in the Home: Accelerated Health

Gains from Improved Water Supply WHO/SDE/WSH/02.02, World

Health Organization, Geneva. Souter, P. F., et al. (2003) Water Sci Tech 31(5-6): 81-84. Timms, S., et al. Water Sci Tech 31(5-6): 81-84. Wegelin, M. et al. (1994) SRr43(3): 154-169.

It will be understood that various details of the presently disclosed subject matter can be changed without departing from the scope of the presently disclosed subject matter. Furthermore, the foregoing description is for the purpose of illustration only, and not for the purpose of limitation.

Claims

CLAIMS What is claimed is:

1. A method for preparing a filtration medium, the method comprising:

(a) contacting a component selected from the group consisting of a metal oxide, a metal oxyhydroxide, and combinations thereof with a starting filtration medium; and (b) curing the contacted starting filtration medium to form a filtration medium.

2. The method of claim 1 , wherein the starting filtration medium comprises a component selected from the group consisting of clay, sand, gravel, crushed ceramics, fiber, fabric, polymers, membranes, and combinations thereof.

3. The method of claim 1 , wherein the metal oxide or metal oxyhydroxide is selected from the group consisting of goethite (σ-FeO(OH)), hematite (Fe2θ₃), lepidocrocite (κ-FeO(OH)), magnetite (Fe₃θ₄), boehmite (AIO(OH)), and diaspore (AIO(OH)).

4. The method of claim 1 , wherein the contacting a component selected from the group consisting of a metal oxide, a metal oxyhydroxide, and combinations thereof with a starting filtration medium imparts a positive charge to the filtration medium.

5. The method of claim 1 , wherein the curing comprises firing in a kiln.

6. The method of claim 1 , wherein the starting filtration medium and the metal oxide, metal oxyhydroxide, or combinations thereof are combined in about a 6:1 , 1 :10, 1 :20, 1 :30, 1 :50, or 1 :100 filtration medium- to-metal oxide, metal oxyhydroxide, or combinations thereof weight/weight ratio.

7. A filtration medium prepared by the method of claim 1.

8. A filtration device comprising the filtration medium of claim 7.

9. The filtration device of claim 8, wherein the filtration device has a design characteristic selected from the group consisting of a Filtrόn design, a candle-shaped design, a filter disk design, and combinations thereof.

10. A filtration medium comprising a component selected from the group consisting of a metal oxide, a metal oxyhydroxide, and combinations thereof.

11. The filtration medium of claim 10, comprising a component selected from the group consisting of clay, sand, gravel, crushed ceramics, fiber, fabric, polymers, membranes, and combinations thereof.

12. The filtration medium of claim 10, wherein the metal oxide or metal oxyhydroxide is selected from the group consisting of goethite (α- FeO(OH)), hematite (Fe₂O₃), lepidocrocite (κ-FeO(OH)), magnetite (Fe₃O₄), boehmite (AIO(OH)), and diaspore (AIO(OH)).

13. The filtration medium of claim 10, having a positive charge.

14. The filtration medium of claim 10, wherein the filtration medium is fired in a kiln.

15. The filtration medium of claim 11 , wherein the component and the metal oxide, metal oxyhydroxide, or combinations thereof are combined in about a 6:1 , 1 :10, 1 :20, 1 :30, 1 :50, or 1 :100 component-to-metal oxide, metal oxyhydroxide, or combinations thereof weight/weight ratio.

16. A method of decontaminating fluid, the method comprising:

(a) providing a filtration medium comprising a metal oxide, a metal oxyhydroxide, or combinations thereof; and

(b) passing a volume of fluid to be decontaminated through the filtration medium.

17. The method of claim 16, wherein the filtration medium comprises a component selected from the group consisting of clay, sand, gravel, crushed ceramics, fiber, fabric, polymers, membranes, and combinations thereof.

18. The method of claim 16, wherein the metal oxide or metal oxyhydroxide is selected from the group consisting of goethite (α-FeO(OH)), hematite (Fe₂O₃), lepidocrocite (κ-FeO(OH)), magnetite (Fe₃O₄), boehmite (AIO(OH)), and diaspore (AIO(OH)).

19. The method of claim 16, wherein the filtration medium has a positive charge.

20. The method of claim 17, wherein the filtration medium comprises a weight/weight component-to-metal oxide, metal oxyhydroxide, or combinations thereof ratio of 1 :6, 1 :10, 1 :20, 1 :30, 1 :50 or 1 : 100.

21. The method of claim 16, wherein the fluid to be decontaminated comprises a contaminant selected from the group consisting of a microorganism, a toxic metal, and combinations thereof.

22. The method of claim 21 , wherein the microorganism is selected from the group consisting of a virus, a bacterium, a protozoan, and combinations thereof.

23. The method of claim 21 , wherein the toxic metal is selected from the group consisting of arsenic, mercury, lead, manganese, magnesium, cadmium, zinc, nickel, chromium, cobalt, and vanadium.

24. The method of claim 16, comprising collecting the decontaminated fluid.

25. The method of claim 16, comprising regenerating the filtration medium.

26. The method of claim 25, wherein the regenerating of the filtration medium comprises an abrasive scrubbing step.

27. The method of claim 16, wherein the passing of the fluid to be decontaminated through the filtration medium is achieved through gravitational force.

28. A kit for use in filtering fluid, the kit comprising: (a) a filtration medium comprising a metal oxide, a metal oxyhydroxide, or combinations thereof; and (b) a container in which to collect filtered fluid.

29. The kit of claim 28, wherein the filtration medium comprises a component selected from the group consisting of clay, sand, gravel, crushed ceramics, fiber, fabric, polymers, membranes, and combinations thereof.

30. The kit of claim 28, wherein the metal oxide or metal oxyhydroxide is selected from the group consisting of goethite (α-FeO(OH)), hematite (Fe₂Os), lepidocrocite (κ-FeO(OH)), magnetite (Fθ₃θ₄), boehmite (AIO(OH)), and diaspore (AIO(OH)).

31. The kit of claim 29, wherein the filtration medium comprises a weight/weight component-to-metal oxide, metal oxyhydroxide, or combinations thereof ratio of 1 :6, 1 :10, 1 :20, 1 :30, 1 :50 or 1 :100.