Integration of membrane technologies to enhance the sustainability in the treatment of metal-containing acidic liquid wastes. An overview

• Mining and hydrometallurgical industries as large generators of acidic liquid wastes. Current management options do not contemplate their valorisation. Membrane technologies provide resource recovery options. New membranes with enhanced properties for long-term industrial operation. The mining generate effluents characterised by a high acidity (pH < 3) content metals (e.g. Fe, Al, Cu Zn, among others) non-metals As, Sb, Bi), which confers them toxicity that makes necessary treatment. conventional treatments such streams mainly rely on neutralisation/precipitation, solvent extraction, ion-exchange adsorption. However, these are often feasible because consumption chemicals the generation volumes sludge. On other hand, due to exhaustion natural resources, circular economy schemes increasingly promoted valuable elements Cu, rare earth elements) from waste an alternative already over-exploited mine sites. Within this new paradigm, integration membrane gaining importance valorisation since they possibility of: i) reducing volume be treated, ii) favour selective separation metal ions acids, and, iii) concentration in streams. promoting dissolved components reuse acid, disposal Among different technologies, nanofiltration (NF), diffusion dialysis (DD), reverse osmosis (RO), electrodialysis (ED), forward (FO) distillation (MD) most promising ones tackle challenges promote circularity.