Membrane desalination plants from an energy–exergy viewpoint

Minimization of energy requirements in desalination processes is seen now as a necessary approach for future desalination plants. This concerns reducing the amount of produced sludge and saving of energy. Energy–exergy calculations might present a desirable approach for establishing a criterion based on which an optimum combination of desalination processes may be selected for operation. The thermodynamic property of exergy was combined with a mathematical model for multi-solute reverse osmosis systems to determine the optimum operating condition for an integrated nanofiltration (NF)–reverse osmosis (RO) seawater desalination plant. This simulation analysis shows promising results for the integrated NF–RO process. The analysis could further be extended to other desalination technologies including the state-of-the-art technology of membrane distillation.