Innovations in separations technology for the recycling and re-use of liquid waste streams

As the costs of wastewater disposal increase more emphasis is being placed upon the recovery and recycling of valuable chemicals contained within these streams. In this article, we review three separations technologies that facilitate such recycling. Solvent extraction is an established technique for recovery of heavy metals and other pollutants and is most useful in large and medium scale operations when solute concentrations are high. Membrane technology is a more recent development that can be used in conjunction with extraction solvents to extend the range of conditions under which such processes are viable. Finally, adsorption and ion-exchange processes provide the means for extracting valuable contaminants when the concentrations of such so lutes are low. (C) 2001 Elsevier Science B.V. All rights reserved.