Present State and Prospective of Reverse Osmosis and Nano–Filtration Membranes

Abstract

The water shortage and pollution have been in serious situation in the world, especially in Asia and Africa, and will be more serious in USA, China and EU in the near future. In order to solve such water problems, rseverse osmosis (RO) and nanofiltration (NF) membranes have been developed and applied for the production of safe water. RO membranes were developed in 1960's for seawater desalination, and improved for the higher performance and the lower cost, which realized large number of RO desalination plants to produce drinking water such as in the Middle East, Caribbean Islands, and the Mediterranean. In addition, the new RO membranes with low fouling properties were developed recently, and have been applied to the wastewater reclamation plants. On the other hand, NF membranes have been used for softening the hard water and for removing the toxic materials such as organic solvent and agricultural chemicals in the environment. The RO and NF membranes are expected to improve for the higher performance such as selectivity, water permeability and durability, which enables the lower cost water treatment, and it will be achieved by the advanced polymer science and processing technologies.