Application of reverse osmosis process associated with EDTA complexation for nickel and copper removal from wastewater

In this study, low-pressure reverse osmosis was analyzed to remove heavy metal ions (nickel and copper) from highly diluted feed flows. Given the ability of these ions to form complexes with EDTA, the effectiveness of a preliminary stage of complexation was also evaluated. The experimental system consisted of a reactor with commercial flat membrane of polyamide and cross flow. Studies employing solutions of single ions and also mixture of ions in different concentration ranges reached removals of 99%. The complexing agent forms a larger complex than the single ion in aqueous phase, thus increasing ion removal in terms of final concentration in permeate. Experiments made at different pressures showed the increase in pressure has an effect on increasing rejection and permeate flow, but the applied pressure of 0.5 MPa is sufficient to achieve 98.5% removal of metal ions and a flow of about 13 L/h m2.