Performance of an ultra-low-pressure reverse osmosis membrane (ULPROM) for separating heavy metal: effects of interference parameters

An experimental investigation was conducted to study the performance of an aromatic polyamide (ES20) ultra-low-pressure reverse osmosis membrane (ULPROM) for separating divalent (Cu2+, Ni2+) and hexavalent (Cr6+) heavy metals from bulk solution. The influence of operating pressure, feed concentration, pH, and effect of other ions (Ca2+ and Mg2+) on the ULPROM performance was studied. The investigation was conducted for synthetic wastewater and wastewater from the heavy metal industry. Experimental results show that the rejection increases with increasing feed pressure, it is dependent on feed pH and is higher at higher pH. Increasing concentration of other ions slightly decreased the rejection of heavy metals. Generally, rejection of heavy metal is found to be greater than 95% for the ULPROM tested, which suggests the suitability of such membranes for industrial application for recovery of heavy metal and reclaiming wastewater.