Low scale potential water treatment

Abstract

An electrochemical treating device having low scale potential is disclosed. The device has a variety of configurations directed to the layering of the anionic exchange and cationic exchange. The treatment device can also comprise unevenly sized ion exchange resin beads and/or have at least one compartment that provides a dominating resistance that results in a uniform current distribution throughout the apparatus.

What is claimed is: 
     
         1 - 24 . (canceled) 
     
     
         25 . An electrodeionization apparatus having at least one compartment with at least one outlet port defined by a distributor having a plurality of apertures, comprising:
 a first layer of particles in the compartment bounded by ion selective membranes, the particles comprising media having a first effective diameter less than the smallest dimension of the apertures; and   a second layer of particles in the compartment downstream of the first layer, the second layer of particles having a second effective diameter greater than the first effective diameter and greater than the smallest dimension of the apertures.   
     
     
         26 . The electrodeionization apparatus of  claim 25 , further comprising a third layer of particles disposed upstream of the first layer of particles. 
     
     
         27 . The electrodeionization apparatus of  claim 26 , wherein the third layer comprises particles having about the same effective diameter as the particles of the second layer. 
     
     
         28 . The electrodeionization apparatus of  claim 25 , wherein the second layer comprises ion exchange resin. 
     
     
         29 . The electrodeionization apparatus of  claim 25 , wherein the first layer comprises an ion exchange resin. 
     
     
         30 . The electrodeionization apparatus of  claim 25 , wherein the third layer comprises ion exchange resin. 
     
     
         31 - 64 . (canceled) 
     
     
         65 . The electrodeionization apparatus of  claim 25 , wherein the first layer of particles has an effective diameter that is at least the dimension of the interstices between the second layer of particles. 
     
     
         66 . The electrodeionization apparatus of  claim 26 , wherein the second layer of particles has an effective diameter that is at least the dimension of the interstices between the third layer of particles. 
     
     
         67 . The electrodeionization apparatus of  claim 25 , wherein the first layer of particles has at least one of an effective diameter and a smallest dimension that is less than the smallest dimension of the apertures of the distributor. 
     
     
         68 . The electrodeionization apparatus of  claim 26 , wherein the second layer of particles has at least one of an effective diameter or a smallest dimension that is less than the smallest dimension of the apertures of the distributor. 
     
     
         69 . The electrodeionization apparatus of  claim 26 , wherein at least one of the first layer of particles, the second layer of particles, and the third layer of particles comprises close packed spheres. 
     
     
         70 . The electrodeionization apparatus of  claim 69 , wherein the close packed spheres have interstitial spaces of about 0.4 times the radius of the spheres.