The world is facing drought. Many countries are suffering from lack of water or polluted water. Desalination techniques can convert seawater, brackish or polluted water into drinkable water. Solutions based on evaporation techniques and membrane processes can be applied, yet the cost is still high for those with economies that are based on simple agriculture. Proximity to the ocean facilitates seawater desalination. Desalination of brackish water and the treatment of sewage water and industrial wastewater is the key for solving environmental problems while helping to resolve the water shortage situation. Those solutions are based on long evolution of the appropriate separation processes, a key issue in Chemical Engineering.

More R&D is needed in order to further reduce the cost of producing water in order to enable wide spread and affordable usage of desalination. Two main desalination directions survived the long evolution process: reverse osmosis and evaporation processes. Heat and mass transfer beside fluid dynamics are playing a significant role in the evolution of these processes. Competition and similarities exist between the different processes: product cost and market penetration, problems associated with concentration polarization, techniques used to improve the transfer mechanisms, and finally, directions for future research and development. The presentation will highlight some of the important achievements and future directions in water desalination.