Biodegradable filter media, methods of manufacture thereof and articles comprising the same

Abstract

Disclosed herein is a biodegradable filter media comprising a mixture of biodegradable fibers and a positively charged binder; where the positively charged binder is present in an amount of less than 5 wt%, where the biodegradable fibers are present in an amount of greater than 90 wt%, and where the filter media comprises a total non-biodegradable content in an amount of less than 10 wt%, based on a total weight of the filter media.

Description

AMJ0051PCT(P4471)BIODEGRADABLE FILTER MEDIA, METHODS OF MANUFACTURE THEREOF AND ARTICLES COMPRISING THE SAME BACKGROUND

[0001] This disclosure relates to a biodegradable filter media, methods of manufacture thereof and articles comprising the same. In particular, this disclosure relates to biodegradable high-strength water filter media, methods of manufacture thereof and articles comprising the same.

[0002] Conventional filter media used for the purification of water typically includes large amounts of adsorbents and antimicrobial components such as, for example, activated carbon, metal salt or alumina in order to facilitate the removal of greater than 99 weight percent (wt%) of bacterial components. The adsorbents and the antimicrobial components are typically in particulate form and are present in the filter media in addition to fibers and may be present in large quantities of greater than 40 wt% or greater than 50 wt%, based on the total weight of the filter. Metal oxides, metal salts, alumina and some of the fibers present (e.g. microglass or synthetic fibers) in the media are non-biodegradable, with the filter media typically containing well over 50% of non-biodegradable materials.

[0003] The presence of such a large amount of particles relative to the total amount of fibers reduces certain desirable properties in the filter media (for example, toughness, flexibility, burst strength and fold resistance). There therefore remains a need to develop filter media that can purify water while at the same time being tough, flexible and having a high wet burst strength and high fold resistance.SUMMARY

[0004] Disclosed herein is a biodegradable filter media comprising a mixture of biodegradable fibers and a positively charged binder; where the positively charged binder is present in an amount of less than 5 wt%, where the biodegradable fibers are present in an amount of greater than 90 wt%, and where the filter media comprises a total non-biodegradable content in an amount of less than 10 wt%, based on a total weight of the filter media.

[0005] Disclosed herein is a method of manufacturing a biodegradable filter media, the method comprising blending together water, biodegradable fibers and a1AMJ0051PCT(P4471)positively charged binder to form a slurry; where the positively charged binder is present in an amount of less than 5 wt%, where the biodegradable fibers are present in an amount of greater than 90 wt%, and where the filter media comprises a total non-biodegradable content in an amount of less than 10 wt%, based on a total weight of the filter media; transporting the slurry to a headbox of a paper-making machine;applying the slurry onto a wire conveyor in the papermaking machine to form a fibrous web; applying a continuous vacuum during the applying of the slurry onto the wire conveyor; and drying the fibrous web to manufacture the filter media.DETAILED DESCRIPTIONDefinitions

[0006] The folding resistance of filter media is defined as the ability of the filter material to withstand repeated folding or creasing without experiencing significant degradation in its structural integrity or filtration performance. Folding resistance is expressed as the number of times the media is folded before breaking or tearing.

[0007] Biodegradable refers to the ability of a substance or material to be broken down naturally by microorganisms, such as bacteria, fungi, or other biological processes, into simpler, non-toxic substances, like water, carbon dioxide, and biomass. This breakdown occurs over time and leaves no harmful residues, allowing the material to be reintegrated into the natural environment.

[0008] Stiffness in filter media indicates how much force is used to bend or deform the material. Stiffness is often measured in milligrams (mg), which indicates the mass that can be supported or resisted by the material without significant deformation.

[0009] The EN 13432:2000 standard is a European industrial compostability certification for packaging materials. It specifies the requirements for packaging recoverable through composting and biodegradation, ensuring that the material can be processed in industrial composting facilities without negatively impacting theenvironment. The material must biodegrade into carbon dioxide, water, and biomass through microbial action. This is assessed by measuring the amount of carbon dioxide produced when the material is composted. At least 90% of the organic carbon in the material must convert to CO₂ within 180 days. The material must break down into2AMJ0051PCT(P4471)fragments that are indistinguishable in the compost. After 12 weeks, less than 10% of the original material's dry weight should remain on a 2 mm sieve.

[0010] The OK Compost Home certification standard is a certification provided by TÜV Austria (formerly Vincotte) that ensures a product or material is compostable in a home composting environment. This certification indicates that the product can break down in a home compost pile under typical home composting conditions, without harming the environment or leaving toxic residues. Generally, this period is around 6 months, but it may vary based on specific requirements and conditions.

[0011] A modified version of the OK Compost test standard is carried out as follows: the disintegration of samples placed in a compost bin at room temperature and pressure is measured over a period of 6 months. The samples all have the same grammage and test area. Samples are placed in a compost bin and covered in soil. The disintegration of the samples is measured over a period of 6 months, by visual inspection, and samples which have been completely digested are no longer visible. Samples are considered fully biodegradable if they disintegrate completely by 6 months (180 days).

[0012] The pore size is measured according to the American Society of Testing and Materials (ASTM) Standard 316-03 (2011). The pore size is measured using a technique known as capillary flow porosimetry. The sample is first wetted with a wetting fluid such that all the pores in the sample are filled. A nonreacting gas of increasing pressure is applied to one side of the wet sample to displace the liquid from the pores. The gas pressure and gas flowrate downstream of the sample are measured and plotted for the wet sample. After the sample is dry, the test is repeated to plot a gas flow vs. the applied pressure curve for the dry sample. Using such capillary porosimetry technique, the “maximum pore size”, “minimum pore size” and “mean flow pore size” can be determined.

[0013] Maximum Pore Size: The gas pressure using the capillary flow porosimetry technique described hereinabove at which air flow through the media is firstdetected (i.e. the pressure at which the bubbles first begin to flow) is used to calculate the maximum pore size.

[0014] Minimum Pore Size is determined from the pressure at which the wet flow rate curve merges with dry curve using the capillary flow porosimetry technique described hereinabove.3AMJ0051PCT(P4471)

[0015] Mean Flow Pore Size is the pore diameter at which the flow through a wetted medium is 50% of the flow through the dry medium at the same pressure drop using the capillary flow porosimetry technique described hereinabove.

[0016] In the context of filtration, the terms “6-log bacterial removal” and “3-log or 4-log virus removal” refer to the effectiveness of the filter media in reducing the concentration of bacteria and viruses, respectively. These terms use logarithmic scales to quantify the reduction in microbial load. A 1-log reduction corresponds to a 10-fold (or 90%) reduction in the number of microorganisms. A 2-log reduction corresponds to a 100-fold (or 99%) reduction. A 3-log reduction corresponds to a 1,000-fold (or 99.9%) reduction. A 6-log reduction corresponds to a 1,000,000-fold (or 99.9999%) reduction.

[0017] “Fibers” refers to material with aspect ratio above 3:1 and average lengths above 0.2mm.

[0018] “Fibrillation” refers to a process where the fibers are mechanically or chemically treated to create fine, hair-like strands or fibrils on their surface.

[0019] “Fibrillated fibers” means fibers that have been further acted upon to create numerous fibrils. Fibrillated Fibers, are preferably characterized by a Canadian Standard Freeness , measured according to TAPPI T227 om-94, of about 300 mL or less, preferably about 200 mL or less, typically between about 1 to about 200 mL

[0020] “Fibrils” are tiny, minute irregular threadlike elements of a fiber that has been fibrillated by a fibrillation process.

[0021] “Non-fibrillated” means unprocessed fibers having essentially no fibrils and which exhibit a Canadian Standard Freeness of greater than about 500 mL.

[0022] The term homogeneous refers to a blend of two or more ingredients that is preferably uniform in composition or character throughout. In different contexts, it can describe mixtures, groups, or systems that are consistent and similar in nature. It can include small local variations in the composition such as local fluctuations, gradients, and the like.

[0023] Disclosed herein is a filter media that is environmentally friendly (e.g., biodegradable and compostable) and is efficient at removing biological contaminants from a liquid stream. The liquid stream preferably contains water. The filter media is advantageous in that it has sufficient stiffness, burst strength and folding resistance to form a self-supporting and pleatable structure without the use of a backing (e.g., a wire4AMJ0051PCT(P4471)mesh support, a spunbond scrim, and the like) and / or without the use of additional binder and binder fibers that reduce filtration surface area. In an embodiment, the filter media is substantially devoid of inorganic particles or fibers such as for example, alumina particles or fibers or glass particles or fibers.

[0024] In conventional filter media, the presence of such a large amount of particles relative to the amount of fibers makes the media display reduced toughness and folding resistance and have a low wet burst strength and low tensile strength. These filter media cannot be pleated for inclusion in a filter housing without additional mechanical support. In this case, a wire mesh support or, more typically, a spunbond scrim are laminated with the conventional filter media in order to form a rigid, composite filter with sufficient folding resistance and wet burst strength.

[0025] The additional layers are usually non-biodegradable (e.g., a polyester spunbond) and the lamination using these additional layers is facilitated by the use of a non-biodegradable adhesive. The adhesive seals some of the pores in the filter media and results in a smaller surface area available for filtering the water.

[0026] In addition, the lamination necessitates additional process steps that involve greater energy consumption with the accompanying emission of undesirable volatile organic compounds, all of which result in increased energy costs.

[0027] Some of these aforementioned deficiencies in conventional filter media (such as the lack of toughness and flexibility) can be rectified by the addition of binder fibers or binders. These binders and binder fibers are usually non-biodegradable chemicals and have to be added in large amounts of greater than 10 wt%, greater than 20 wt%, greater than 30 wt%. This results in a filter media that is non-biodegradable and cannot be disposed of in a composting stream. The binder can also close some of the pores of the filter media, which results in a filter media that has a lower surface area for filtration with a consequent reduction in filtration efficiency.

[0028] The filter media comprises biodegradable fibers and a positively chargedbinder (which preferably comprises or is a cationic polymer). The biodegradable fibers preferably have an average aspect ratio (ratio of average length to average diameter) of greater than or equal to 3:1, preferably greater than or equal to 5:1, more preferably greater than or equal to 10:1 and most preferably greater than or equal to over 20:1. In an especially preferred embodiment, the filter media is devoid of particulate matter having5AMJ0051PCT(P4471)an aspect ratio of less than 3:1, preferably less than 2:1 and preferably less than 1.5:1. In an especially preferred embodiment, the filter media is substantially devoid of particulate matter having an aspect ratio of less than 3:1, preferably less than 2:1 and preferably less than 1.5:1.

[0029] The lack of such particulate matter is advantageous in that it permits the filter media to display sufficient stiffness, burst strength and folding resistance to form a self-supporting and pleatable structure without the use of any backing.

[0030] In particular, the filter media is biodegradable as per the EN13432:2000 industrial compostability standard and also preferably meets the OK Compost Home certification standard. In an embodiment, the filter media has a fibrous content that is greater than 90 wt%, preferably greater than 95 wt%, based on a total weight of the filter media. The filter media comprises less than 5 wt%, preferably less than 2.5 wt% non-biodegradable components while having greater than 90 wt% biodegradable components, and more preferably greater than 95 wt% biodegradable components. In another preferred embodiment, the filter media will have a wet burst strength of greater than 30 inches of water pressure (in H2O). In yet another preferred embodiment, the filter media will have a folding resistance of over 500 folds. In yet another preferred embodiment, the filter media will have a stiffness of over 5000 milligrams (mg). The filter media achieves bacterial removal of at least 6-log and virus removal of at least 3-log, preferably at least 4-log. It is to be noted that the filter media can have one or more of the aforementioned properties. In an embodiment, high levels of bacterial and viral removal are effected by this filter media due to a combination of the cationic binder and the pore size distribution.

[0031] The filter media preferably comprises biodegradable fibers and a cationic polymer. The biodegradable fibers may include cellulose, chitosan, cotton, hemp, polylactic acid, polylactic-glycolic acid (PLGA), poly-caprolactone (PCL), copolymers of polylactic-glycolic acid and poly-caprolactone (PCL-PLGA copolymer), polyhydroxy-butyrate-valerate (PHBV), polyorthoester (POE), polyethylene oxide-butylene terephthalate (PEO-PBTP), poly-D,L-lactic acid-p-dioxanone-polyethylene glycol block copolymer (PLA-DX-PEG), or the like, or a combination thereof.

[0032] Preferred biodegradable fibers comprise cellulose (hereinafter cellulosic fibers). In an preferred embodiment, the biodegradable fibers, especially the cellulosic6AMJ0051PCT(P4471)fibers, are used in the filter media in fibrillated and non-fibrillated fiber form. Fibrillation is a process where the fibers are mechanically or chemically treated to create fine, hair-like strands or fibrils on their surface. The fibrillated fibers preferably have fibrillation levels less than 300 ml Canadian Standard Freeness (CSF), preferably less than 200 ml CSF, preferably less than 100 ml CSF, preferably less than 75 ml CSF, and more preferably less than 50 ml CSF as specified by TAPPI test method T227 om-94 (Freeness of Pulp). The “fibrillation level” refers to the degree or extent to which the fibers have been split or fibrillated into smaller fibrils. Canadian Standard Freeness is a measure of the drainage rate of a fiber suspension, often used in the pulp and paper industry to evaluate the fibrillation level of fibers. Lower CSF values (below 100 ml) indicate a higher degree of fibrillation.

[0033] The fibrillated fibers may include parent fibers and fibrils. The parent fiber is the original, larger fiber from which the fibrils are derived. These fibers are typically long and continuous, forming the primary structural component before the fibrillation process begins. The parent fibers provide the main strength and bulk of the material. They are responsible for the overall integrity of the fiber mat or fabric.

[0034] The fibrillated fibers can be naturally occurring fibers, synthetic fibers or a combination of both. In an embodiment, preferred fibrillated fibers are synthetic cellulosic fibers such as viscose, rayon, lyocell, or the like. Preferred fibrillated cellulosic fibers are those made by direct dissolution and spinning of wood pulp in an organic solvent, such as an amine oxide, and are known as lyocell fibers. The fibrillated cellulose fibers may be fibrillated either during the fiber production process, or by being subjected to standard mechanical beaters, refiners and the like employed in the paper-making industry.

[0035] The fibrillated fibers preferably have an average parent fiber diameter of 5 to 30 micrometers, more preferably 10 to 20 micrometers and most preferably around 10 to 15 micrometers. The fibrils preferably have an average diameter of 1000 nanometersor less, more preferably 400 nanometers or less, and most preferably 100 nanometers or less. Some preferred embodiments will include fibrils having average diameters of 250 to 350 nanometers.

[0036] Average fiber diameter can be measured using Scanning Electron Microscopy (SEM) by averaging the measurements of over 50, preferably over 1007AMJ0051PCT(P4471)fibers. In this method, handsheet samples made exclusively of the fibers are placed in the SEM chamber, where an electron beam scans the samples, producing high-resolution images. These images are analyzed using specialized software to measure the diameters of individual fibers. By averaging these measurements, a representative average fiber diameter is obtained. Alternatively, the average fiber diameter can be calculated using the dtex / denier, fiber length and material density of the fiber, all of which are provided by the supplier.

[0037] The preferred average length of the fibrillated fibers is 0.4 to 8 millimeters, more preferably 1 to 6 millimeters. In addition, in preferred embodiments, less than 15% of the fibers have a length-weighted average fiber length (LWAFL) of greater than 2 millimeters. Fiber length is measured with any suitable equipment that follows ISO 16065-1 :2014 OR ISO 16065-2:2014. A suitable equipment can be for example, Morfi TECHPAP which follows the ISO 16065-2:2014 standard.

[0038] The fibrillated fibers are present in an amount of 30 to 70 wt%, preferably 35 to 65 wt%, and more preferably 38 to 62 wt%, based on the total weight of the biodegradable fibers. The composition ranges for the fibrillated and non-fibrillated fibers disclosed herein should not be viewed as limiting. Values outside the ranges can also be optimized for use if desired. In an embodiment, preferred fibrillated fibers include synthetic cellulose fibers. An example of commercially available fibrillated fibers are fibrillated lyocell fibers.

[0039] The non-fibrillated fibers also preferably comprise a cellulose. The non-fibrillated fibers can be naturally occurring fibers, synthetic fibers or a combination of both. The non-fibrillated fibers are preferably pulp fibers and more preferably comprise large diameter softwood fibers (e.g. Northern Bleached Softwood Kraft (NBSK), Southern Bleached Softwood Kraft (SBSK),, or a combination thereof). The non-fibrillated fibers can be from woody and non-woody plants. They can include hardwood and / or softwood fibers. Woody plants include, for example, deciduous (hardwood),coniferous trees (softwood), or the like, or a combination thereof. Non-woody plants include, for example, cotton, flax, esparto grass, kenaf, sisal, abaca, milkweed, straw, jute, hemp, bagasse, or the like, or a combination thereof.

[0040] Examples of softwood fibers include fibers obtained from chemical treatments like mercerization (e.g., HPZ fibers), northern bleached softwood kraft (e.g.,8AMJ0051PCT(P4471)fibers from Redwoods, Douglas firs, Western red cedar, or the like), southern bleached softwood kraft (e.g., fibers from slash pine, loblolly pine, or the like), or chemically treated mechanical pulps (e.g., CTMP fibers), or the like, or a combination thereof.Exemplary hardwood fibers include fibers obtained from eucalyptus, birch, aspen, beech, oaks, gum tees, or the like, or a combination thereof.

[0041] Using softwood fibers can add rigidity and stiffness to the media. The non-fibrillated fibers may have an average fiber diameter that is greater than the average fiber diameter of the fibrillated fibers.

[0042] The non-fibrillated fibers preferably have an average fiber diameter of 10 to 55 micrometers, more preferably 15 to 50 micrometers.

[0043] The non-fibrillated fibers preferably have an average fiber length, as measured with any suitable equipment that follows ISO 16065-1 :2014 OR ISO 16065-2:2014, of 0.3 to 8 millimeters, more preferably from 1 to 6 millimeters, more preferably from 3 to 6 millimeters.

[0044] In an embodiment, the non-fibrillated fibers have an average aspect ratio (calculated as average fiber length / average fiber diameter) of 3 to 800, preferably 5 to 700 and more preferably 10 to 600 and even more preferably 20 to 500.

[0045] The non-fibrillated biodegradable fibers are present in the filter media in an amount of 30 to 70 wt%, preferably 35 to 65 wt% and more preferably 38 to 62 wt%, based on a total weight of fibers in the filter media.

[0046] In a preferred embodiment, the total cellulosic content of the filter media is greater than or equal to 90 wt%, preferably greater than 95 wt%, based on a total weight of the filter media, i.e. the filter media comprises at least 90 wt%, preferably greater than 95 wt% cellulosic fibers. It is believed that the large fibrous content provides the media with the requisite strength, pleatability and stiffness. The media is also biodegradable and compostable (both in an open air landfill and in the home) due to the large cellulosic content.

[0047] As noted above, the filter media comprises a cationic binder in addition to the biodegradable fibers. The cationic binder provides the filter media with an electropositive charge on its surface, for example as measured using zeta potential, at a pH of 6 to 8.5 (the pH of drinking water), preferably at a pH of 6.5 to 8.0.9AMJ0051PCT(P4471)

[0048] The cationic polymer may comprise a thermoplastic polymer, a blend of thermoplastic polymers, a thermosetting polymer (e.g., a crosslinkable or crosslinked polymer), or a blend of a thermoplastic polymer with thermosetting polymers. The cationic polymer may comprise an oligomer, a homopolymer, a copolymer, a block copolymer, an alternating block copolymer, a random copolymer, a graft copolymer, a star block copolymer, a dendrimer, a polyelectrolyte (polymers that have some repeat groups that contain electrolytes), a polyampholyte (a polyelectrolyte having both cationic and anionic repeat groups), an ionomer, or the like, or a combination thereof.

[0049] In an embodiment, the cationic polymer is a crosslinkable polymer that undergoes crosslinking during the process of manufacturing the filter media. The cationic polymer in the final filter media product is typically crosslinked.

[0050] The cationic polymer may be any polymer bearing an overall positive charge, such as, for example, a polyethyleneimine (PEI), a polyamidoamine, a polylysine, a poly(allylamine), a poly(diallyldimethylammonium chloride), a poly(N-isopropyl acrylamide-co-acrylamide), a poly(N-isopropyl acrylamide-co-acrylic acid), a poly(L-lysine), a diethylaminoethyl-dextran copolymer, a poly-(N-ethyl-vinylpyridinium bromide), a poly(-dimethylamino)ethyl methacrylate), a poly(ethylene glycol)-co-poly(trimethylaminoethylmethacrylate chloride), an epichlorohydrin based polymer, a polyamide, an epichlorohydrin-dimethylamine copolymer, a polyamide-epichlorohydrin (PAE), or the like, or a combination thereof.

[0051] Preferred cationic polymers may include epichlorohydrin.Epichlorohydrin is advantageous because it reacts with hydroxyl groups, making it useful in crosslinking polysaccharides such as starch, cellulose, or polyvinyl alcohol (PVA). In polymers or biomaterials, epichlorohydrin can be used to introduce crosslinks that enhance mechanical strength, chemical resistance, and stability.

[0052] In an embodiment, the preferred cationic polymers include a crosslinkable epichlorohydrin based polymer, a crosslinkable polyamide, a crosslinkableepichlorohydrin-dimethylamine copolymer, a crosslinkable polyamide-epichlorohydrin (PAE), or a combination thereof.

[0053] The positively charged binder (e.g., the cationic polymer), may be bound covalently and / or electrostatically to the surface of the biodegradable fibers. In some embodiments, the positively charged binder is electrostatically bound to the surface of the10AMJ0051PCT(P4471)biodegradable fibers. For example, the positively charged binder, may bind electrostatically to the surface of the cellulosic fibers, which have an overall negative charge. In an embodiment, hydrogen bonding may occur between the positively charged binder and the biodegradable fibers. The electropositive nature of the filter media is due to the impregnation of the fibers by the positively charged binder and a reaction is not needed to induce the charge.

[0054] The cationic polymer may have a number average molecular weight (Mn) greater than 10,000 grams per mole, preferably greater than 20,000 g / mole and more preferably greater than 50,000 g / mole. In an embodiment, the cationic polymer may have a number average molecular weight (Mn) of less than 2,000,000 g / mole, preferably less than 1,000,000 g / mole.

[0055] The cationic polymer is preferably used in an amount of less than 10 wt%, preferably less than or equal to 5 wt%, preferably less than or equal to 2.5 wt%, and more preferably less than or equal to 2.0 wt%, based on a total weight of the filter media. The positively charged binder is present in an amount of greater than 1 wt%, preferably greater than 1.2 wt%, and more preferably greater than 1.5 wt%, based on a total weight of the filter media. When the positively charged binder is added in amounts greater than 1wt%, the filter media shows enhanced virus removal efficiencies of 3-log or above.

[0056] In one embodiment, in one method of producing the filter media, the fibrillated fibers and the non-fibrillated fibers (fibers having an aspect ratio of greater than or equal to 3:1) are mixed together in a pulper (in a paper machine) along with a suitable liquid (e.g., water) to form a fiber mixture.

[0057] In an embodiment, the liquid is preferably water. No particulate matter (having an aspect ratio of less than 3:1) is added to the pulper. There is no agitation or refining applied to the fiber mixture. The cationic polymer in a desired amount is added to the mixture in the pulper to form a slurry. The constituents in the slurry are allowed to mix together before the slurry is transferred to the headbox and further diluted. The diluted slurry is applied onto a wire conveyor in a papermaking machine (e.g., a fourdrinier or a rotoformer) to form a fibrous web. Vacuum is continuously applied during the aforementioned processes to remove the liquid (e.g. water) from the mixture and / or the slurry, thereby producing a fibrous web. The web thus formed, is subsequently dried to form the filter media and wound into a roll.11AMJ0051PCT(P4471)

[0058] The filter media is then cut into the desired sizes and pleated to form a filter that may be used for the removal of bacterial matter and / or viral matter from liquids such as water. The pore size is measured according to the American Society of Testing and Materials (ASTM) Standard 316-03 (2011).

[0059] In an embodiment, the cationic resin may be added to the fiber mixture at any point prior to drying in the wet end of the paper machine. In other words, the cationic resin may be added to the fiber mixture in the pulper (as described above) or downstream of the pulper in the headbox (of the paper machine) to form the slurry.

[0060] The resulting filter media has a maximum pore size of less than 5 micrometers, preferably less than 4 micrometers. In an embodiment, the resulting filter media has mean flow pore size less than 2 micrometers, preferably less than 1.4 micrometers.

[0061] For details of the specific types of biodegradable fibers, positively charged binders and weight ratios which are applicable in the method according to the present invention, reference is made to the above statements.

[0062] In an embodiment, the filter media displays a minimum of 3-log for virus removal and a minimum of 6-log for bacterial removal from water. The filter media typically has a thickness of 600 to 1000 micrometers, preferably 650 to 900 micrometers, and more preferably 675 to 875 micrometers, measured according to ISO 9073-2:1997.

[0063] In an embodiment, the filter media has a wet burst strength of greater than 30 in H2O, preferably greater than 50 in H2O, preferably greater than 70 in H2O and more preferably greater than 100 in H2O, when measured according to an internal test method, which is described below.

[0064] This is an internal test method and can be summarized as follows: A test sample of a suitable size is cut and clamped between two metal rings each of which are roughly 2.5 inches in diameter. The clamps hold the sample in place. Prior to the test, the sample is wetted with water. There is a column of water connected to the sample.The column is gradually filled with water, by using a suitable flowmeter (e.g. Gilmont flowmeter tube), thereby increasing the pressure exerted on the sample. The height of the water column is raised until water penetrates the material and it ruptures. The pressure at which rupture occurs is measured, typically in inches of water pressure (in H2O).12AMJ0051PCT(P4471)

[0065] In some instances, when the water level reaches the maximum column height and there is no rupture, a pressurized water tank is connected to the sample. The water flows into the sample and a gauge (e.g. Ashcroft Precision test gauge) measures the pressure reading. The pressure reading from the gauge at the point of rupture is recorded in inches of water pressure (in H2O).

[0066] In an embodiment, the filter media has a folding resistance of greater than 500 folds, preferably greater than 700 folds and more preferably greater than 900 folds, when measured according to TAPPI T511 lm-96, using a MIT tester.

[0067] In an embodiment, the filter media has a stiffness of greater than 10,000 milligrams (mg), preferably greater than 12,000 mg and more preferably greater than 13,000 mg, when measured according to TAPPI 543 om-00 using a GURLEYTMbending resistance tester.

[0068] In an embodiment, the filter media has a dry tensile strength of greater than 20 pounds per inch (psi), preferably greater than 25 psi and more preferably greater than 30 psi, when measured according to TAPPI Standard T-494-om88.

[0069] The filter media achieves bacterial removal of at least 5-log, preferably at least 6-log and more preferably at least 7-log and a virus removal of at least 3-log and more preferably at least 4-log, when measured according to an internal test method and can be summarized as follows:

[0070] Three 25 mm samples were cut for each filter media and then placed in Millipore filter holders. The samples were then flushed with 40 mL of RO water (with conductivity adjusted to ~35µS / cm and pH adjusted to between 7.5-7.8). After the flush, the samples were challenged with approximately 50 mL of adjusted water that had been polluted with virus (MS2 at 1.25 E5-1.75E5pfu / mL), bacteria (Raoultella terrigena at 1.2E6-1.4E6cfu / mL), and cyst surrogate (Fluoresbrite™ Plain YG 3.0 Microspheres at 1.25E5-1.75E5beads / mL). Influent concentrations were measured after dilution by 1000. Effluent samples were then plated properly for each microorganism in order to providefiltration percentage for each.

[0071] The effluent was also diluted to 1000X (100 µL of the challenge was added to 99 mL of phosphate buffered saline (with 1 mL of tryptic soy broth added to avoid lysis of the virus)). To determine virus removal, effluent samples were plated using double layer agar method described in Kropinski AM, Mazzocco A, Waddell TE, Lingohr13AMJ0051PCT(P4471)E, Johnson RP. Enumeration of bacteriophages by double agar overlay plaque assay. Methods Mol Biol.2009;501:69-76. doi: 10.1007 / 978-1-60327-164-6_7. PMID:19066811. The total volume of effluent and agar was 8mL. Plates were allowed to dry, inverted, and then incubated for 17-19 hours at 37 C before viruses were counted.

[0072] To determine bacteria counts, diluted effluent was plated via a pipette on a 100mm tryptic soy agar plate. The cyst count in the effluent was determined by placing 0.1 mL of diluted effluent on a 8mm microscope slide visualized under fluorescent microscope. The filter media disclosed herein is advantageous in that it may be used, for example, in gravity-flow applications, including both high and low-flow applications. Specifically, the media is suitable for high-flow applications with a rapid fluid flow-rate of greater than or equal to 7 mL / min.

[0073] In an embodiment, this biodegradable filter media may be used in combination with other layers, wherein the biodegradable media serves either as a pre-filter or a post-filter to the other layer(s). Preferably, the other layers are also biodegradable.

[0074] The filter media and the method of manufacturing it are exemplified in the following non-limiting examples.EXAMPLESExample 1

[0075] This example was conducted to demonstrate the manufacturing and properties of the filter media that is devoid of particulate media. The filter media contains only fibers and a binder. The example also compares the disclosed filter media (detailed as Working Example 1) with three different comparative filter media. The filter media along with their compositions are detailed below.

[0076] Working Example 1: A 50-50 weight blend of unrefined Grand Prairie Northern Bleached Softwood Kraft (NBSK) pulp (non-fibrillated fibers) and 10 ml CSFfibrillated lyocell fibers (L010-4 grade from EFT) (the fibrillated fibers) are mixed together in a pulper with water. No particulate matter (having an aspect ratio of less than 3:1) is added. The weight ratio of fibers to particulate matter is 100:0.

[0077] There is no refining applied. 2 wt% of POLYCUPTMpolyamide-epichlorohydrin (PAE) binder (the cationic polymer), based on the total weight of the14AMJ0051PCT(P4471)final filter media, is added at the pulper (or optionally may be added in the headbox) and are mixed together before the slurry is transferred to the headbox and further diluted with more water such that the total weight of the fibers in the suspension is less than 1wt%, typically around 0.1 to 1 wt%.

[0078] The diluted slurry is applied onto a wire conveyor in a papermaking machine (e.g., a fourdrinier or a rotoformer) to form a fibrous web. Vacuum is continuously applied during the above process to remove the water from the fibers, thereby resulting in a fibrous web. The web is subsequently dried to form the filter media and wound into a roll. The binder crosslinks during the drying.

[0079] Comparative Example A: Fibrillated Lyocell fiber (40ml CSF, 6mm), PET fibers (2.8d X 6mm) and microglass fibers were mixed into a pulper with water.Aluminium powder and caustic (50% NaOH) are added under heat into the pulper. A reaction occurs in the pulper, where nano-alumina particles are formed and adhere to the surface of the fibers. Once the reaction is complete, sulfuric acid is added to neutralize the reaction.

[0080] A wet-strength binder (Kymene 557H) and latex binder (Lubrizol Hycar 26540) are added to the pulper. The constituents are allowed to mix together before the slurry is transferred to the headbox and further diluted with more water such that the total weight of the fibers and particles in the slurry is less than 1wt%, typically around 0.1 to 1wt%. The diluted slurry is applied onto a wire conveyor in a papermaking machine (e.g., a fourdrinier or a rotoformer) to form a fibrous web. Vacuum is continuously applied during the above process to remove the water from the fibers, thereby resulting in a fibrous web. The web is subsequently dried to form the filter media and wound into a roll. The filter media comprises 0.6 wt% wet-strength binder, 1.8% latex binder, 42.9 wt% nano-alumina, 6.7 wt% fibrillated lyocell, 15.0 wt% PET fibers and 33.0 wt% microglass fibers, based on the total weight of the filter media.

[0081] Comparative Example B: Fibrillated Lyocell fibers (40ml CSF, 6mm),softwood fibers, PET fibers (0.1 dtex (diameter) X 3mm length) and microglass fibers are added to a pulper with water. Aluminium powder and caustic (50% NaOH) are added under heat into the pulper. A reaction occurs in the pulper wherein nano-alumina particles are formed and adhere to the surface of the fibers. Once the reaction is complete, sulfuric acid is added to neutralize the reaction.15AMJ0051PCT(P4471)

[0082] A wet-strength binder (Kymene 557H) and latex binder (Lubrizol Hycar 26540) are added to the pulper. The constituents are mixed together before the slurry is transferred to the headbox and further diluted with more water such that the total weight of the fibers and particles in the slurry is less than 1wt%, typically around 0.1 to 1wt%. The diluted slurry is applied onto a wire conveyor in a papermaking machine (e.g., a fourdrinier or a rotoformer) to form the filter media. Vacuum is continuously applied during the above process to remove the water from the fibers, thereby resulting in a fibrous web. The web is subsequently dried to form the filter media and wound into a roll. The filter media comprises 0.6 wt% wet-strength binder, 1.2 wt% latex binder 14.7 wt% nano-alumina, 28.7 wt% softwood fibers, 14.7 wt% fibrillated lyocell, 15.5 wt% PET fibers and 24.6 wt% microglass fibers, based on the total weight of the filter media.

[0083] Comparative Example C: Fibrillated Lyocell fibers (Lenzing 80°SR), PET fibers (2.8d X 6mm) and microglass fibers are added to a pulper with water. Aluminium powder and caustic (50% NaOH) are added under heat into the pulper. A reaction occurs in the pulper wherein nano-alumina particles are formed and adhere to the surface of the fibers. Once the reaction is complete, sulfuric acid is added to neutralize the reaction.

[0084] A wet-strength binder (Kymene 557H), silver powder (AgIon LGK 10T) and latex binder (Lubrizol Hycar 26540) are added to the pulper, in that order. The constituents are mixed together before the slurry is transferred to the headbox and further diluted with more water such that the total weight of the fibers and particles in the slurry is less than 1 wt%, typically around 0.1 to 1 wt%. The diluted slurry is applied onto a wire conveyor in a papermaking machine (e.g., a fourdrinier or a rotoformer) to form the filter media. Activated carbon is also added at the headbox of the paper making machine. Vacuum is continuously applied during the above process to remove the water from the fibers, thereby resulting in a fibrous web. The web is subsequently dried to form the filter media and wound into a roll. The filter media comprises 0.5 wt% wet-strength binder, 1.4 wt% silver powder, 2.9 wt% latex binder, 33.8 wt% nano-alumina, 29.0 wt%activated carbon, 4.6 wt% fibrillated lyocell, 7.7 wt% PET fibers and 20.1 wt% microglass fibers, based on the total weight of the filter media.

[0085] The various ratios of the ingredients and the physical properties of the respective filter media are shown in the Table 1 below.16AMJ0051PCT(P4471)Table 1COMPOSITIONComparative Comparative Comparative Working (wt% based on total weight of filter ample C Example 1- -- 49.0%4.6% - - -- 49.0%- -7.7% -7.7% -- -12.4% -2.9% -0.5% -- 2.0%33.8% -29.0% -1.4% - 100.0% 100.0%Wt% of fibers*, based on total weight of web (filter media) 54.7% 83.4% 32.5% 98.0% Wt% of biodegradable fibers, based on total weightof filter 6.7% 43.3% 4.6% 98.0% media17AMJ0051PCT(P4471)N / A (contains N / A (containsRatio of fibrillated biodegradable fibers: unfibrillated only fibrillated only fibrillated50:50 degradablefibers)3.4% 2.0% 0.5% 2.0%34.3% 2.0% 228.5 228.5 680 770 2 2.3 1.1 1.6 2.5 2.127736 >32000 (no aminated supporting h support) layer) 13.8 34.7 40 1653 965 Log Virus Removal > 3 > 2 > 3 > 3 Rapidity (mL / min) 10 50 4 8.25 * fibers are defined as material with aspect ratio about 3:1 and length > 0.2mm.18AMJ0051PCT(P4471)

[0086] As shown in the table, the Comparative examples A, B and Care made with less than 85 wt% fibers and contain less than 50wt% biodegradable fibers. These media have low stiffness and folding resistance and hence cannot be pleated without the use of an additional support layer. Interestingly, the inventive media demonstrates high removal rates of bacteria, cyst and virus with a much lower amount of electropositive charged material, showing a better performance than Sample B and similar performance as Sample A.

[0087] The compostability of the above samples were tested, using the modified OK home compost test method described above. Comparative examples A, B and C did not disintegrate in 6 months, while the working example was fully compostable (i.e. the samples were digested with no visual residue) in 151 days.Example 2

[0088] This example was conducted to demonstrate the pore sizes when the ratio fibrillated fibers to non-fibrillated fibers in the filter media is varied. Similar to Working Example 1, blends of unrefined Grand Prairie Northern Bleached Softwood Kraft (NBSK) pulp (non-fibrillated fibers) and 10 ml CSF fibrillated lyocell fibers (L010-4 grade from EFT) (fibrillated fibers) are mixed together in water. The samples contained only fibrous matter (with no particles).2 wt% Polycup PAE binder, based on the total weight of the filter media, was added to the fiber suspension. The examples were formed in the laboratory as follows: the fibers and the PAE binder are added to Labtech Standard Disintegrator Model 500-1 at dilution rate of approximately 10 g of pulp per 2000 mL water. The suspension is disintegrated for 10000 revolutions, and then added to 8x8 inch Williams Apparatus handsheet mold. The suspension is then diluted further to approximately 10 g of pulp in 6000 mL water, agitated additionally by hand and drained onto a wire to form a fibrous web. The fibrous web is then removed from the wire by hand. Excess moisture is removed by pressing with blotting papers and the examples are subsequently dried on laboratory hot plate to form the example filter media. The fibrillated lyocell content varied between 25 to 75 wt%, based on the total weight of the fibers. All examples were made at a grammage of 228gsm, similar to Example 1. The composition of therespective filter media and the minimum, maximum and mean pore sizes were measured and are listed in the Table 2.19AMJ0051PCT(P4471)Tableters) wbased Max 5.4 4.75 1.83 2.05 2.051.95 60 40 0.81 1.25 2.5 70 30 0.76 1.09 1.83 85 15 0.67 1.02 2.18

[0089] From the Table 2, it was found that keeping the fibrillated Lyocell content between 30 to 70 wt% is desirable to produce media which had pores small enough to keep out larger contaminants (max pore size of less than or equal to 5 micrometers) while also having sufficient permeability to water (i.e., water flows through the media at a sufficiently high flowrate of over 8 milliliters per minute (mL / min)). As may be seen from the data above, the mean pore size is less than or equal to 2 micrometers in combination with a max pore size of 1.8 to 5 microns and this corresponds to 30 to 70 wt% fibrillated lyocell in Table 2.

[0090] In an aspect, a biodegradable filter media comprises a mixture of biodegradable fibers and a positively charged binder; where the positively charged binder is present in an amount of less than 5 wt%, where the biodegradable fibers are present in an amount of greater than 90 wt%, and where the filter media comprises a total non-biodegradable content in an amount of less than 10 wt%, based on a total weight of the filter media.

[0091] The mixture of biodegradable fibers and the positively charged binder is a homogeneously dispersed mixture.

[0092] In another embodiment, the biodegradable fibers are selected from the group consisting of cellulosic fibers, chitosan fibers, cotton fibers, hemp fibers, polylactic acid fibers, polylactic-glycolic acid (PLGA) fibers, poly-caprolactone (PCL) fibers, fibers made of copolymers of polylactic-glycolic acid and poly-caprolactone (PCL-PLGA copolymer), polyhydroxy-butyrate-valerate (PHBV) fibers,polyorthoester (POE) fibers, polyethylene oxide-butylene terephthalate (PEO-PBTP) fibers, poly-D,L-lactic acid-p-dioxanone-polyethylene glycol block copolymer (PLA-DX-PEG) fibers, or a combination thereof.

[0093] In another embodiment, the biodegradable fibers comprise fibrillated and non-fibrillated fibers.20AMJ0051PCT(P4471)

[0094] In yet another embodiment, the fibrillated fibers are present in an amount of 30 to 70 wt%, preferably 35 to 65 wt%, and most preferably 38 to 62 wt%, based on a total weight of the biodegradable fibers and where the non-fibrillated fibers are present in an amount of 30 to 70 wt%, preferably 35 to 65 wt%, and most preferably 38 to 62 wt%, based on a total weight of the biodegradable fibers.

[0095] In yet another embodiment, the biodegradable fibers have an aspect ratio of greater than 3:1, preferably greater than 5:1, preferably greater than 10:1, and more preferably greater than 20:1.

[0096] In yet another embodiment, the filter media comprises the biodegradable fibers in an amount of greater than 95 wt%, based on the total weight of the filter media.

[0097] In yet another embodiment, the fibrillated fibers comprise synthetic cellulose fibers.

[0098] In yet another embodiment, the non-fibrillated fibers comprise pulp fibers, fibers from woody and non-woody plants, especially softwood fibers and / or hardwood fibers, or a combination thereof.

[0099] In yet another embodiment, the positively charged binder comprises a cationic polymer.

[0100] In yet another embodiment, the cationic polymeric resin is crosslinkable.In yet another embodiment, the filter media has an electropositive charge on the surface at a pH of 6 to 8.5.

[0101] In yet another embodiment, the cationic polymer comprises an epichlorohydrin based polymer, a polyamide, an epichlorohydrin-dimethylamine copolymer, a polyamide-epichlorohydrin copolymer, a polyethyleneimine (PEI), a polyamidoamine, a polylysine, a poly(allylamine), a poly(diallyldimethylammonium chloride), a poly(N-isopropyl acrylamide-co-acrylamide), a poly(N-isopropyl acrylamide-co-acrylic acid), a poly(L-lysine), a diethylaminoethyl-dextran copolymer, a poly-(N-ethyl-vinylpyridinium bromide), a poly(-dimethylamino)ethyl methacrylate), a poly(ethylene glycol)-co-poly(trimethylaminoethylmethacrylate chloride), or a combination thereof.

[0102] In yet another embodiment, the positively charged binder is present in an amount of less than or equal to 2.5 wt%.

[0103] In yet another embodiment, the filter media has a mean pore size of up to 2 micrometers.

[0104] In yet another embodiment, the filter media has a maximum pore size of up to 5 micrometers.21AMJ0051PCT(P4471)

[0105] In yet another embodiment, the filter media has a thickness of 600 to 1000 micrometers.

[0106] In yet another embodiment, the filter media is biodegradable based on industrial biodegradability standard EN13432:2000 and / or meets OK home-compost standards.

[0107] In yet another embodiment, the filter media displays a minimum of 3-log for virus removal and a minimum of 6-log for bacterial removal from water.

[0108] In yet another embodiment, the filter media has a stiffness greater than 10,000 mg, a dry tensile strength greater than 20lb / in, a wet burst strength greater than 30 in H2O and / or a folding resistance of greater than 500 folds.

[0109] In yet another embodiment, the filter media is free of particles that comprise alumina.

[0110] In yet another embodiment, the filter media is an article that does not contain a supporting layer.

[0111] In yet another embodiment, a method of manufacturing a biodegradable filter media comprises blending together water, biodegradable fibers and a positively charged binder to form a slurry; where the positively charged binder is present in an amount of less than 5 wt%, where the biodegradable fibers are present in an amount of greater than 90 wt%, and where the filter media comprises a total non-biodegradable content in an amount of less than 10 wt%, based on a total weight of the filter media; transporting the slurry to a headbox of a paper-making machine; applying the slurry onto a wire conveyor in the papermaking machine to form a fibrous web;applying a continuous vacuum during the applying of the slurry onto the wire conveyor; and drying the fibrous web to manufacture the filter media.

[0112] In another embodiment, the positively charged binder is crosslinkable and is crosslinked during the transporting, the applying the slurry onto a wire conveyor and / or the applying of a continuous vacuum.

[0113] In an embodiment, the filter media of any of the preceding embodiments is used as a water filter.

[0114] In another embodiment, the method comprises passing water to be filtered through a filter media of any one of the foregoing embodiments.

[0115] It should be appreciated that any element, part, section, subsection, or component described with reference to any specific embodiment above may be incorporated with, integrated into, or otherwise adapted for use with any other embodiment described herein unless specifically noted otherwise or if it should render the embodiment device non-functional.22AMJ0051PCT(P4471)Likewise, any step described with reference to a particular method or process may be integrated, incorporated, or otherwise combined with other methods or processes described herein unless specifically stated otherwise or if it should render the embodiment method nonfunctional.Furthermore, multiple embodiment devices or embodiment methods may be combined, incorporated, or otherwise integrated into one another to construct or develop further embodiments of the invention described herein. Any of the foregoing aspects and embodiments may therefore be combined in any manner with another aspect or embodiment disclosed herein.

[0116] While the invention has been described with reference to some embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiments disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.23

Claims

AMJ0051PCT(P4471)What is claimed is:

1. A biodegradable filter media comprising:a mixture of biodegradable fibers and a positively charged binder;where the positively charged binder is present in an amount of less than 5 wt%, where the biodegradable fibers are present in an amount of greater than 90 wt%, and where the filter media comprises a total non-biodegradable content in an amount of less than 10 wt%, based on a total weight of the filter media.

2. The filter media of Claim 1, where the biodegradable fibers are selected from the group consisting of cellulosic fibers, chitosan fibers, cotton fibers, hemp fibers, polylactic acid fibers, polylactic-glycolic acid (PLGA) fibers, poly-caprolactone (PCL) fibers, fibers made of copolymers of polylactic-glycolic acid and poly-caprolactone (PCL-PLGA copolymer), polyhydroxy-butyrate-valerate (PHBV) fibers, polyorthoester (POE) fibers, polyethylene oxide- butylene terephthalate (PEO-PBTP) fibers, poly-D,L-lactic acid-p-dioxanone-polyethylene glycol block copolymer (PLA-DX-PEG) fibers, or a combination thereof.

3. The filter media of any one of the preceding claims, where the biodegradable fibers comprise fibrillated and non-fibrillated fibers.

4. The filter media of Claim 3, where the fibrillated fibers are present in an amount of 30 to 70 wt%, preferably 35 to 65 wt%, and most preferably 38 to 62 wt%, based on a total weight of the biodegradable fibers and where the non-fibrillated fibers are present in an amount of 30 to 70 wt%, preferably 35 to 65 wt%, and most preferably 38 to 62 wt%, based on a total weight of the biodegradable fibers.

5. The filter media of any one of the preceding claims, where the biodegradable fibers have an aspect ratio of greater than 3:1, preferably greater than 5:1, preferably greater than 10:1, and more preferably greater than 20:1.

6. The filter media of any one of the preceding Claims, where the filter media comprises the biodegradable fibers in an amount of greater than 95 wt%, based on the total weight of the filter media.24AMJ0051PCT(P4471)7. The filter media of any one of the preceding Claims, where the fibrillated fibers comprise synthetic cellulose fibers.

8. The filter media of any one of the preceding Claims, where the non-fibrillated fibers comprise pulp fibers, fibers from woody and non-woody plants, especially softwood fibers and / or hardwood fibers, or a combination thereof.

9. The filter media of any one of the preceding Claims, where the positively charged binder comprises a cationic polymer.

10. The filter media of any one of the preceding Claims, where the cationic polymeric resin is crosslinkable.

11. The filter media of any one of the preceding Claims, where the cationic polymer comprises an epichlorohydrin based polymer, a polyamide, an epichlorohydrin-dimethylamine copolymer, a polyamide-epichlorohydrin copolymer, a polyethyleneimine (PEI), a polyamidoamine, a polylysine, a poly(allylamine), a poly(diallyldimethylammonium chloride), a poly(N-isopropyl acrylamide-co-acrylamide), a poly(N-isopropyl acrylamide-co-acrylic acid), a poly(L-lysine), a diethylaminoethyl-dextran copolymer, a poly-(N-ethyl-vinylpyridinium bromide), a poly(-dimethylamino)ethyl methacrylate), a poly(ethylene glycol)-co-poly(trimethylaminoethylmethacrylate chloride), or a combination thereof.

12. The filter media of any one of the preceding Claims, where the positively charged binder is present in an amount of less than or equal to 2.5 wt%.

13. The filter media of Claim any one of the preceding Claims, having a mean pore size of up to 2 micrometers.

14. The filter media of Claim any one of the preceding Claims, having a maximum pore size of up to 5 micrometers.

15. The filter media of any one of the preceding, having a thickness of 600 to 1000 micrometers.25AMJ0051PCT(P4471)16. The filter media of any one of the preceding Claims, wherein the filter media is biodegradable based on industrial biodegradability standard EN13432:2000 and / or meets OK home-compost standards.

17. The filter media of any one of the preceding Claims, wherein the filter media displays a minimum of 3-log for virus removal and a minimum of 6-log for bacterial removal from water.

18. The filter media of any one of the preceding Claims, wherein the filter media has a stiffness greater than 5000 mg, a dry tensile strength greater than 30lb / in, a wet burst strength greater than 30 in H2O and / or a folding resistance of greater than 500 folds.

19. The filter media of any one of the preceding Claims, wherein the filter media is free of particles that comprise alumina.

20. An article comprising the filtration media of one of the preceding Claims, where the article does not contain a supporting layer.

21. A method of manufacturing a biodegradable filter media, the method comprising:blending together water, biodegradable fibers and a positively charged binder to form a slurry; where the positively charged binder is present in an amount of less than 5 wt%, where the biodegradable fibers are present in an amount of greater than 90 wt%, and where the filter media comprises a total non-biodegradable content in an amount of less than 10 wt%, based on a total weight of the filter media;transporting the slurry to a headbox of a paper-making machine;applying the slurry onto a wire conveyor in the papermaking machine to form a fibrous web;applying a continuous vacuum during the applying of the slurry onto the wire conveyor; anddrying the fibrous web to manufacture the filter media.

22. The method of the preceding claim, wherein the positively charged binder is crosslinkable and is crosslinked during the transporting, the applying the slurry onto a wire conveyor and / or the applying of a continuous vacuum and / or drying of the fibrous web.26AMJ0051PCT(P4471)23. The method of any one of the preceding claims, wherein the positively charged binder is crosslinkable and is crosslinked preferably during the drying of the fibrous web24. Use of a filter media of any one of the Claims 1 to 19 or an article of Claim 20 as a water filter.

25. A method of filtering water, the method comprising passing water to be filtered through a filter media of any one of the Claims 1 to 19 or an article of Claim 20.27

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