Elastomeric depth filter

Abstract

The present disclosure provides a depth filter medium comprising at least one elastomeric nonwoven web strengthened by combination with one or more structural support layers. The resulting material is particularly useful in the field of filtration, wherein particulates captured within the elastomeric nonwoven web can be readily released, such as by applying pressure to the web through backwashing. The elastomeric nonwoven web advantageously can stretch under such pressure and return substantially to its original structure and shape upon the removal of the pressure, rendering the filter available for reuse.

1 .- 22 . (canceled) 
     
     
         23 . A method of filtering a liquid to remove particulate matter therefrom comprising:
 contacting a liquid comprising particulate matter with a depth filter medium to remove a portion of the particulate matter from the liquid by depth filtration or a combination of depth filtration and surface filtration; and   backwashing the depth filter medium such that at least a portion of the particulate matter captured by the depth filter medium is removed from the depth filter medium, allowing for its reuse in filtration,   wherein the depth filter medium comprises:
 a first, upstream structural support layer comprising a first porous material; 
 an elastomeric nonwoven web attached to the first structural support layer, wherein the elastomeric nonwoven web comprises elastomeric fibers and has a mean flow pore size of about 15 microns or less; 
 and wherein said first structural support layer has a mean flow pore size greater than the mean flow pore size of the elastomeric nonwoven web. 
   
     
     
         24 . (canceled) 
     
     
         25 . The method of  claim 23 , wherein the depth filter medium comprises a second structural support layer comprising a second porous material having a mean flow pore size greater than the mean flow pore size of the elastomeric nonwoven web and a mean flow pore size smaller than the mean flow pore size of the first porous material, said elastomeric nonwoven web being positioned between said first and second structural support layers,
 wherein the liquid is contacted with the depth filter medium such that the first structural support layer is upstream and the second structural support layer is downstream during use.   
     
     
         26 . The method of  claim 23 , wherein the backwashing comprises removing the depth filter medium from the liquid and passing pressurized water backwards through the depth filter medium. 
     
     
         27 . The method of  claim 23 , further comprising surface washing the depth filter medium to remove particulate matter retained by surface filtration. 
     
     
         28 . The method of  claim 23 , wherein the backwashing is conducted so as to recover the initial water permeability of the depth filter medium at initial applied pressure drop. 
     
     
         29 . The method of  claim 23 , wherein the depth filter medium further comprises a second, downstream structural support layer comprising a second porous material having a mean flow pore size greater than the mean flow pore size of the elastomeric nonwoven web, said elastomeric nonwoven web being positioned between said first and second structural support layers. 
     
     
         30 . The method of  claim 29 , wherein the second porous material has a mean flow pore size smaller than the mean flow pore size of the first porous material. 
     
     
         31 . The method of  claim 29 , wherein the second structural layer is selected from a woven material or a mesh having a uniform pore size. 
     
     
         32 . The method of  claim 28 , wherein the mean flow pore size of the second structural support layer is about 30 microns or less. 
     
     
         33 . The method of  claim 23 , wherein the first structural support layer is selected from a woven material or a mesh having a uniform pore size. 
     
     
         34 . The method of  claim 23 , wherein the mean flow pore size of the first structural support layer is about 30 microns or less. 
     
     
         35 . The method of  claim 23 , wherein the elastomeric fibers are meltblown or spunbonded fibers. 
     
     
         36 . The method of  claim 23 , wherein the elastomeric nonwoven web has a mean flow pore size of less than about 5 microns. 
     
     
         37 . The method of  claim 28 , wherein the elastomeric fibers comprise a propylene-based elastomer. 
     
     
         38 . The method of  claim 23 , wherein the elastomeric nonwoven web comprises two or more elastomeric nonwoven sheets laminated together. 
     
     
         39 . The method of  claim 23 , wherein the elastomeric nonwoven web has a basis weight of about 500 g/m 2  or less. 
     
     
         40 . The method of  claim 23 , wherein the elastomeric nonwoven web has a basis weight of about 200 g/m 2  or less. 
     
     
         41 . The method of  claim 23 , wherein the first structural support layer comprises a woven material or a mesh having a mean flow pore size of about 30 microns or less; and the elastomeric nonwoven web comprises a single layer of elastomeric nonwoven material or a laminate of multiple layers of elastomeric nonwoven material, the elastomeric nonwoven web having a mean flow pore size of about 10 microns or less and a basis weight of about 200 g/m 2  or less. 
     
     
         42 . The method of  claim 23 , wherein the depth filter medium has a structural frame attached thereto. 
     
     
         43 . The method of  claim 23 , wherein the liquid is wastewater.