Method for the purification of water by ion exchange

Claim 1

THE METHOD OF TREATING BRACKISH WATER CONTAINING A SUBSTANTIAL PROPORTION OF ALKALINE EARTH METAL SALTS COMPRISING PASSING THE WATER THROUGH A "CALCIUM EXCHANGER" WHEREIN ALKALINE EARTH METALS ARE REMOVED AND REPLACED BY CATIONS SELECTED FROM THE GROUP CONSISTING OF ALKALI METALS AND AMMONIUM IONS, THEN THROUGH A HYDROGEN EXCHANGER WHEREIN THE ALKALI METAL AND AMMONIUM IONS ARE REMOVED AND REPLACED BY HYDROGEN IONS, AND THEN THROUGH AN ANION EXCHANGER WHEREIN THE ACIDS ARE REMOVED FROM THE WATER UNTIL SAID EXCHANGERS ARE AT LEAST PARTIALLY EXHAUSTED, AND THEREAFTER REGENERATING SAID EXCHANGERS BY PASSING AN AQUEOUS SOLUTION OF A REGENERANT SELECTED FROM THE GROUP CONSISTING OF ALKALI METAL AND AMMONIUM HYDROXIDE AND CARBONATE THROUGH THE ANION EXCHANGER IN A DIRECTION OPPOSITE TO THAT IN WHICH THE WATER FLOWED THERETHROUGH DURING THE EXHAUSTION THEREOF AND SO LONG AS AN EFFLUENT FREE OF BOTH CARBONATE AND HYDROXIDE IS DISCHARGED THEREFROM, THEN PASSING SAID EFFLUENT THROUGH THE CALCIUM EXCHANGER TO REGENERATE SAME, AND PASSING AN AQUEOUS ACID SOLUTION THROUGH THE HYDROGEN EXCHANGER TO REGENERATE IT.