Multi-stage water treatment system and method for operating the same

A method for treating water contaminated with metal ions in order to remove said metal ions therefrom comprising the steps of:

• providing a supply of water contaminated with metal ions;
• providing at least one nanofiltration membrane capable of preventing a portion of said metal ions from passing therethrough;
• passing said water contaminated with said metal ions through said nanofiltration membrane in order to produce a retentate which does not pass through said nanofiltration membrane and a permeate which passes through said nanofiltration membrane;
• providing a supply of porous polymer beads each comprising a metal ion extracting agent therein, said metal ion extracting agent comprising at least one organic biomass composition;
• passing said permeate through said polymer beads in order to remove any residual metal ions from said permeate which were not removed by said nanofiltration membrane, said passing of said permeate through said polymer beads causing said residual metal ions in said permeate to be retained within said beads by said metal ion extracting agent in order to yield a supply of purified water;
• and
• passing at least one acid solution through said polymer beads after said passing of said permeate therethrough in order to remove said residual metal ions from said polymer beads, said residual metal ions being transferred from said polymer beads to said acid solution during said passing of said acid solution through said polymer beads in order to produce an acidic waste solution.

A method for treating water contaminated with metal ions in order to remove said metal ions therefrom comprising the steps of:

• providing a supply of water contaminated with metal ions;
• providing at least one nanofiltration membrane capable of preventing a portion of said metal ions from passing therethrough;
• passing said water contaminated with said metal ions through said nanofiltration membrane in order to produce a retentate which does not pass through said nanofiltration membrane and a permeate which passes through said nanofiltration membrane;
• providing a supply of porous polymer beads each comprising a metal ion extracting agent therein, said metal ion extracting agent comprising at least one organic biomass composition;
• passing said permeate through said polymer beads in order to remove any residual metal ions from said permeate which were not removed by said nanofiltration membrane, said passing of said permeate through said polymer beads causing said residual metal ions in said permeate to be retained within said beads by said metal ion extracting agent in order to yield a supply of purified water;
• passing at least one acid solution through said polymer beads after said passing of said permeate therethrough in order to remove said residual metal ions from said polymer beads, said residual metal ions being transferred from said polymer beads to said acid solution during said passing of said acid solution through said polymer beads in order to produce an acidic waste solution;
• and
• passing at least one alkali solution through said polymer beads after said passing therethrough of said acid solution.