Novel regeneration of mixed bed ion exchange resins for seawater desalination

A process for the treatment of wastewater containing a dissolved electrolyte comprising the steps of:

• a. Passing a continuous flow of the electrolyte wastewater through a mixed bed ion exchange column containing, strong acid and strong base resin, in which the ion exchange groups are initially saturated with NH4+ and HCO3− ions, to produce an ammonium bicarbonate solution containing essentially desorbed NH4+ and HCO3− ions until the resin is exhausted;
• b. Heating the ammonium bicarbonate solution produced in the previous step to a temperature between 60-80° C. or to a lower temperature under reduced pressure to completely remove the ammonium bicarbonate solute as CO2 and NH3 gases, to produce treated product water;
• c. Combining the released gases CO2 and NH3 with some portion of the treated product water to make an ammonium bicarbonate solution;
• d. Concentrating the said ammonium bicarbonate solution by subjecting it to higher pressure and temperature to produce a super saturated ammonium bicarbonate regenerant solution;
• e. Regenerating the exhausted resin in the ion exchanger column by passing the supersaturated ammonium bicarbonate regenerant solution by exchanging ammonium and bicarbonate ions in the regenerant solution with ions of the electrolyte in the exhausted resin while being heated to decompose the supersaturated ammonium bicarbonate regenerant to raise the partial pressures of both ammonia and carbon dioxide which drives the regeneration process;
• f. Draining out the concentrated waste solution from the ion exchange column;
• and
• g. Repeating the steps of a to f.

An apparatus for the treatment of an ionic solution by ion exchange comprising:

• a mixed bed ion exchange column containing, strong acid and strong base resin, in which the ion exchange groups are initially saturated with NH4+ and HCO3− ions, to produce treated water containing essentially desorbed NH4+ and HCO3− ions until the resin is exhausted;
• A means for heating the treated water containing desorbed NH4+ and HCO3− ions to between 60-80° C. or to a lower temperature under reduced pressure to completely remove the ammonium bicarbonate solute as CO2 and NH3 gases, to produce product water;
• or at lower temperatures under reduced pressures;
• A means for combining the released gases CO2 and NH3 with some portion of the produced product water to make an ammonium bicarbonate solution;
• A means for concentrating the said ammonium bicarbonate solution by subjecting it to higher pressure and temperature to produce a super saturated ammonium bicarbonate regenerant solution;
• A means for regenerating the exhausted resin in the ion exchanger column by passing the supersaturated ammonium bicarbonate regenerant solution for exchanging ammonium and bicarbonate ions in the regenerant solution with ions in the exhausted resin while being heated to decompose the supersaturated ammonium bicarbonate regenerant to raise the partial pressures of both ammonia and carbon dioxide which drives the regeneration process.
• A means for draining out the concentrated waste solution from the ion exchange column, using either applied pressure or residual pressure from the regenerant process.