Multi-layered composite filter media and pleated filter element constructed therefrom

Abstract

A multi-layered pleated filter element for filtering drinking water is disclosed which includes at least one upstream glass fiber layer for pre-filtration, a nanofiber membrane layer for bacteria retention, and at least one downstream positively charged microporous membrane layer for virus retention.

What is claimed is: 
     
         1 . A multi-layered composite filter media comprising:
 a) at least one pre-filtration layer;   b) a bacteria retention layer; and   c) at least one virus retention layer.   
     
     
         2 . A multi-layered composite filter media as recited in  claim 1 , wherein the at least one pre-filtration layer is a glass fiber pre-filtration layer. 
     
     
         3 . A multi-layered composite filter media as recited in  claim 1 , wherein the bacteria retention layer is a nanofiber membrane layer. 
     
     
         4 . A multi-layered composite filter media as recited in  claim 3 , wherein the nanofiber membrane layer is formed of an electrospun polymer resin. 
     
     
         5 . A multi-layered composite filter media as recited in  claim 3 , wherein the electrospun polymer resin is Polyacrylonitrile (PAN). 
     
     
         6 . A multi-layered composite filter media as recited in  claim 3 , wherein the nanofiber membrane layer includes a substrate made of polyethylene terephthalate (PET). 
     
     
         7 . A multi-layered composite filter media as recited in  claim 6 , wherein the nanofiber membrane layer has an average thickness of about between 170 to 210 μm. 
     
     
         8 . A multi-layered composite filter media as recited in  claim 7 , wherein the nanofiber membrane has a thickness of about between 30 and 60 μm and the substrate has an average thickness of about between 140 to 150 μm. 
     
     
         9 . A multi-layered composite filter media as recited in  claim 1 , wherein the at least one virus retention layer is a positively charged microporous media layer. 
     
     
         10 . A multi-layered composite filter media as recited in  claim 9 , wherein the positively charged microporous media layer includes a porous substrate with a cross-linked polymer coating. 
     
     
         11 . A multi-layered composite filter media as recited in  claim 10 , wherein the porous substrate of the at least one virus retention layer is made of glass fiber. 
     
     
         12 . A multi-layered pleated filter element comprising:
 a) at least one upstream glass fiber layer for pre-filtration;   b) an interior nanofiber membrane layer for bacteria retention; and   c) at least one downstream positively charged microporous media layer for virus retention.   
     
     
         13 . A multi-layered pleated filter element as recited in  claim 12 , wherein the nanofiber membrane layer is formed of an electrospun polymer resin. 
     
     
         14 . A multi-layered pleated filter element as recited in  claim 13 , wherein the electrospun polymer resin is Polyacrylonitrile (PAN). 
     
     
         15 . A multi-layered pleated filter element as recited in  claim 13 , wherein the nanofiber membrane layer includes a substrate made of polyethylene terephthalate (PET). 
     
     
         16 . A multi-layered pleated filter element as recited in  claim 13 , wherein the at least one positively charged microporous media layer includes a porous substrate with a cross-linked polymer coating. 
     
     
         17 . A multi-layered pleated filter element as recited in  claim 16 , wherein the porous substrate of the at least one virus retention layer is made of glass fiber. 
     
     
         18 . A multi-layered pleated filter element as recited in  claim 12 , including first and second glass fiber layers for pre-filtration. 
     
     
         19 . A multi-layered pleated filter element as recited in  claim 12 , including first, second and third positively charged microporous media layers for virus retention. 
     
     
         20 . A filter cartridge comprising:
 a) a housing having an inlet region for the ingress of an unfiltered fluid and an outlet region for the egress of filtered fluid; and   b) a multi-layered pleated filter element disposed within the housing and including:
 i) at least one upstream layer for pre-filtration; 
 ii) an interior nanofiber membrane layer for bacteria retention; and 
 iii) at least one downstream positively charged microporous media layer for virus retention. 
   
     
     
         21 . A filter cartridge as recited in  claim 20 , wherein the pleated filter element is a radially pleated filter element with an outer periphery and an inner periphery. 
     
     
         22 . A filter cartridge as recited in Clam  21 , wherein the upstream pre-filtration layer is positioned at the inner periphery of the pleated filter element. 
     
     
         23 . A filter cartridge as recited in Clam  21 , wherein the downstream virus retention layer is positioned at the outer periphery of the pleated filter element. 
     
     
         24 . A filter cartridge as recited in  claim 20 , wherein the housing includes a cover portion having the inlet region, and wherein the inlet region is in fluid communication with the inner periphery of the filter element. 
     
     
         25 . A filter cartridge as recited in  claim 20 , wherein the pleated filter element is potted on an interior surface of the cover portion. 
     
     
         26 . A filter cartridge as recited in  claim 20 , including first and second glass fiber layers for pre-filtration. 
     
     
         27 . A filter cartridge as recited in  claim 20 , including first, second and third positively charged microporous media layers for virus retention. 
     
     
         28 . A filter cartridge as recited in  claim 20 , wherein the outlet region includes a plurality of circumferentially spaced apart outlet ports formed about an upper peripheral edge of the housing.