Gravity filter

Abstract

Embodiments of a gravity filter for potable water comprise a loose filter bed comprising ion exchange resin particles and activated carbon particles, and a porous non-woven filter substrate disposed downstream of the loose filter bed, wherein the porous non-woven filter substrate comprises an impregnated heavy metal scavenger.

What is claimed is: 
     
         1 . A method of filtering water comprising:
 introducing water into a gravity filter; and   filtering the water in the gravity filter;   wherein the gravity filter comprises:
 a loose filter bed comprising an ion exchange resin and activated carbon; and 
 a porous non-woven filter substrate disposed downstream of the loose filter bed, the porous non-woven filter substrate comprising a fibrous material impregnated with heavy metal scavenger particles and further comprising an average pore size of from about 5 μm to about 15 μm; 
 wherein the heavy metal scavenger particles consist of one or more of amorphous titanium silicate, a zirconium oxide, and a zirconium hydroxide, and the fibrous materials consists of one or more of polyolefin fibers, polyester fibers, glass fibers, and cellulose fibers. 
   
     
     
         2 . The method of  claim 1 , wherein the ion exchange resin is a weak acid cationic exchange resin, a strong cation exchange resin, or combinations thereof. 
     
     
         3 . The method of  claim 1 , wherein the ion exchange resin is a copolymer of acrylic acid. 
     
     
         4 . The method of  claim 1 , wherein the ion exchange resin is a sulfonic acid resin. 
     
     
         5 . The method of  claim 1 , wherein the fibrous material is further impregnated with activated carbon. 
     
     
         6 . The method of  claim 1 , wherein the porous non-woven filter substrate comprises a binder. 
     
     
         7 . The method of  claim 6 , wherein the binder comprises a hydrophobic binder, a hydrophilic binder, or combinations thereof. 
     
     
         8 . The method of  claim 1 , wherein the heavy metal scavenger particles are amorphous titanium silicate. 
     
     
         9 . The method of  claim 8 , wherein the porous non-woven substrate comprises from about 18 to about 30% by weight of the amorphous titanium silicate. 
     
     
         10 . The method of  claim 1 , wherein the fibrous material consists of cellulose fibers and glass fibers and optionally one or more of polyolefin fibers and polyester fibers. 
     
     
         11 . The method of  claim 1 , wherein the loose bed comprises about 20 to about 70% by weight of the ion exchange resin. 
     
     
         12 . The method of  claim 1 , wherein the loose bed comprises about 30 to about 70% by weight of the activated carbon. 
     
     
         13 . A method of filtering water comprising:
 introducing water into a gravity filter; and   filtering the water in the gravity filter;   wherein the gravity filter comprises:
 a filter housing; 
 a loose filter bed disposed in the filter housing and comprising a weak acid ion exchange resin and activated carbon; and 
 a porous nonwoven filter substrate disposed downstream of the loose filter bed inside the filter housing, wherein the porous nonwoven filter substrate comprises glass fibers impregnated with amorphous titanium silicate particles and further comprising an average pore size of from about 5 μm to about 15 μm. 
   
     
     
         14 . The method of  claim 13 , wherein the gravity filter further comprises a scrim layer above the loose filter bed. 
     
     
         15 . The method of  claim 13 , wherein the porous non-woven filter substrate comprises a binder. 
     
     
         16 . The method of  claim 13 , wherein the binder comprises a hydrophobic binder, a hydrophilic binder, or combinations thereof. 
     
     
         17 . The method of  claim 13 , wherein the porous non-woven substrate further comprises cellulose fibers. 
     
     
         18 . The method of  claim 13 , wherein the porous non-woven substrate comprises from about 18 to about 30 percent by weight of the amorphous titanium silicate.