Membrane Operations for the Recovery of Valuable Metals from Industrial Wastewater

Abstract

The development of separation technologies, which also permit the recovery of valuable compounds from industrial wastewaters, reports economic and environmental benefits. In particular, the selective recovery of metals from end-of-life products is an essential strategy to avoid the depletion of natural sources, especially for less abundant metals such as rare earths (REs) and platinum-group metals (PGMs). Although several technologies have been applied in the recovery of metals from wastes, solvent extraction reported the best performance in terms of selectivity when complex matrixes are treated. Regarding solvent extraction, the use of membrane contactors raises against the conventional contactors due to their diverse advantages such as the high interfacial area/volume ratio, the prevention of emulsion formation, the modular design that simplifies the process scale-up and the lower operation cost. This work evaluates the benefits of membrane-based solvent extraction technologies to recover metallic compounds from waste materials through three different cases of study: (i) zinc recovery from spent pickling solutions, (ii) PGMs recovery from depleted car catalytic converters and (iii) rare earths recovery from waste electrical and electronic devices.