Patent ID: 6187162
Filing Date: 2001-02-13
Classification: B01D,B01J,C02F

Abstract:
Electrodeionization apparatus for purifying water including calcium and carbon dioxide and its hydrates comprisinga first stage electrodeionization system followed by a second stage electrodeionization system,each said system includinga cathode,an anode spaced from said cathode, a plurality of alternating anion permeable membranes and cation permeable membranes between said cathode and anode defining concentrating and diluting flow channels, each said channel being defined between an adjacent pair of said membranes,said first stage electrodeionization system including one member of the group consisting of a cation exchange resin and an anion exchange resin in a diluting flow channel, said second stage electrodeionization system including at least the other of said cation exchange resin and said anion exchange resin in a diluting flow channel,the outflow of water from said diluting flow channels in said first stage electrodeionization system being connected to be fed as the inflow for said diluting flow channels in said second stage electrodeionization system, the outflow of brine from each said concentrating flow channel in said first stage electrodeionization system being isolated from the inflow for any said concentrating flow channel in said second stage electrodeionization system, whereby said calcium and carbon dioxide and its hydrates tend to be removed in different stages so as to deter calcium carbonate precipitation in said concentrating flow channel.