A method for minimizing wastewater discharge generated in an ion exchange regeneration system activated after service flow of a service solution is discontinued, said ion exchange regeneration system comprising a cation exchange bed packed with cation exchange resin and an anion exchange bed packed with anion exchange resin, said method comprising the steps of:
- (a) introducing a cation regenerant solution to said cation exchange bed containing a remaining service solution, in a direction opposite to said service flow, to expel the service solution remaining in said cation exchange bed from said cation exchange bed, and saving the expelled effluent from said cation exchange bed;
- (b) continuing introduction of said cation regenerant solution to said cation exchange bed to regenerate said resin, and separating an effluent, which is expelled from said cation exchange bed, from the ion exchange regeneration system;
- (c) introducing a displacement rinse to said cation exchange bed containing a remaining cation regenerant solution, in a direction opposite to the service flow, to expel the cation exchange solution remaining in said cation exchange bed from said cation exchange bed;
- (d) continuing introduction of said displacement rinse to said cation exchange bed to displace the cation regenerant solution further remaining in said cation exchange bed, with said displacement rinse, and saving an effluent of said displacement rinse to be used as a cation regenerant solution in the subsequent cycle, said effluent having a chemical concentration;
- (e) increasing the concentration of said effluent to be used as a cation regenerant solution;
- (f) circulating the displacement solution remaining in said cation exchange bed and the service solution remaining in said anion exchange bed in a loop formed by said cation exchange bed and said anion exchange bed in series in the same direction as the service flow, to permit the exhausted anion exchange resin packed in said anion exchange bed to adsorb the cation regenerant solution still remaining in said cation exchange bed;
- (g) introducing an anion regenerant solution to said anion exchange bed after step (f), in a direction opposite to said service flow, to expel the solution remaining in said anion exchange bed from said anion exchange bed, and saving an effluent from said anion exchange bed;
- (h) continuing introduction of said anion regenerant solution to said anion exchange bed to regenerate said resin, and separating an effluent, which is expelled from said anion exchange bed, from the ion exchange regeneration system;
- (i) introducing a displacement rinse to said anion exchange bed containing a remaining anion regenerant solution, in a direction opposite to the service flow, to expel the anion exchange solution remaining in said anion exchange bed from said anion exchange bed;
- (j) continuing introduction of said displacement rinse to said anion exchange bed to displace the anion regenerant solution further remaining in said anion exchange bed, with said displacement rinse, and saving an effluent of said displacement rinse to be used as an anion regenerant solution in the subsequent cycle, said effluent having a chemical concentration;
- (k) increasing the concentration of said effluent to be used as an anion regenerant solution;
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- (l) circulating a final rinse in a loop formed by said cation exchange bed and said anion exchange bed in series in the same direction as the service flow, until regeneration is completed.