A process for removing heavy metal ions or cyanide ions from a waste water stream originating in a metal plating plant or a mine comprising the steps of pretreatment in which the waste water stream is first pretreated by removing particulates, fats and oils; filtration by means of a first sand filter to remove suspended particulates down to 50 microns, a second bag filter to remove suspended particulates down to 3.5 microns, a third micro filter to remove particulates down to 0.1 microns in size and a fourth ultrafilter to remove particulate down to a molecular weight of 10,000; concentration of the heavy metal ions in the waste water stream by means of a first stage nanofiltration unit and second stage nanofiltration unit or reverse osmosis membrane unit down to a molecular weight of about 200 with nanofiltration and less by reverse osmosis; increase the concentration of heavy metal species in the waste water stream to above 700 ppm; electrodialysis to further increase the concentration of heavy metal ions in the waste water stream to approximately 6000 ppm; electrolysis to remove heavy metal ions. Alternatively, ion exchange columns can be used to remove the heavy metal ions after the filtration and concentration in the nanofiltration membranes.
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