Multi-path split cell spacer and electrodialysis stack design

Abstract

An electrodialysis method and apparatus include a source of concentrate fluid, a source of dilute fluid, a collector of treated concentrate fluid, a collector of dilute fluid, an anode and a cathode. A plurality of generally planar spacers are interleaved with a plurality of membranes to define a plurality of cells providing electrically conductive fluid connection between the anode and the cathode. Each of the spacers comprises a gasket that defines a first aperture and a second aperture. Each of said first and second apertures define an independent cell between interleaved membranes. The symmetrical, multiple split cell spacer configuration channels fluid flow through two or more narrow and elongated paths. The split cell arrangement allows for operation of the stack in parallel or in series. The invention improves the ion removal efficiency of a given membrane area, requires significantly less energy than other electrodialysis systems and substantially reduces stack assembly, materials and fabrication costs.

Having thus described the aforementioned invention, we claim:  
     
         1 . In an electrodialysis system comprising a source of concentrate fluid, a source of dilute fluid, a collector of treated concentrate fluid; a collector of used dilute fluid, an anode, a cathode, a plurality of generally planar spacers, a plurality of membranes interleaved with said spacers to define a plurality of cells providing electrically conductive fluid connection between said anode and said cathode, each of said spacers comprising: 
 a gasket defining a first aperture and a second aperture, each of said first and second apertures defining an independent cell between interleaved membranes.    
     
     
         2 . The apparatus of  claim 1  wherein said apertures have the shape of an abbreviated rectangle having squares removed from two diagonally opposed corners.  
     
     
         3 . The apparatus of  claim 2  wherein all corners of said apertures are rounded.  
     
     
         4 . The apparatus of  claim 1  wherein a conduit provides flow communication between said first aperture and said second aperture.  
     
     
         5 . The apparatus of  claim 1  wherein one or more bolts extend through said spacers between said first aperture and said second aperture.  
     
     
         6 . The apparatus of  claim 5  wherein said bolts are coated with an electrically resistant material.  
     
     
         7 . A method of electrodialysis treatment comprising providing a source of concentrate fluid, providing a source of dilute fluid, providing a collector of treated concentrate fluid; providing a collector of used dilute fluid, providing an anode, providing a cathode, securing a plurality of generally planar spacers and a plurality of membranes interleaved with said spacers to define a plurality of cells, providing electrically conductive fluid connection between said anode and said cathode, wherein each of said spacers comprises a gasket defining a first aperture and a second aperture, each of said first and second apertures defining an independent cell between two common interleaved membranes.  
     
     
         8 . A method in accordance with  claim 6  wherein said apertures have the shape of an abbreviated rectangle having squares removed from two diagonally opposed corners.  
     
     
         9 . The method of  claim 8  wherein all corners of said apertures are rounded.  
     
     
         10 . The method of  claim 8  and further comprising the step of providing flow communication from said first aperture to said second aperture.  
     
     
         11 . An electrodialysis system comprising a source of concentrate fluid, a source of dilute fluid, a collector of treated concentrate fluid; a collector of used dilute fluid, an anode, a cathode, a plurality of generally planar spacers, a plurality of membranes interleaved with said spacers to define a plurality of cells providing electrically conductive fluid connection between said anode and said cathode, each of said spacers comprising: 
 a gasket defining an aperture defining an independent cell between interleaved membranes, said aperture having the shape of an abbreviated rectangle having squares removed from two diagonally opposed corners.    
     
     
         12 . The apparatus of  claim 11  wherein all corners of said apertures are rounded.