Advanced RO Membrane Technology Based on Scientific Research for Seawater and Brackish water Desalination

摘要

Global climate change and water shortage are serious issues we face. Sea Water RO (SWRO) membrane is one of the most powerful tools for solving the global water shortage, because seawater is the hugest water resource in the world. High energy saving and high water quality have been required in SWRO membrane desalination. From the viewpoint of energy saving, SWRO membrane with high water permeability is more preferable since lower pressure operation becomes to be possible. As for the water quality, boron removal is one of the most important issues, because it is known that reproductive toxicity was shown in per oral administration to laboratory animals, furthermore, boron is a typical substance which is difficult to be removed by RO membrane. Since there is a trade-off relation (Figure. 1) between the water permeability and the boron removal, the developments of seawater RO membranes are executed according to three courses: i) Extremely high boron removal performance, ii) High water permeability with high boron removal performance and iii) Extremely high water permeability. In order to obtain further excellent performances which are suitable for respective courses, scientific researches with a point on the solute transport mechanism in RO membrane are needed. RO membrane technologies have made great progress in last 50 years. In seawater and brackish water desalination field, both energy saving and water quality improvement have been two major subjects. Today, the energy consumption in RO membrane seawater desalination process becomes less than one tenth, compared to those of 1970's, by progress of membrane and process technologies. However, advanced membranes and processes are still demanded to achieve lower cost, lower energy consumption and higher water quality. In order to obtain further excellent performance, we have been executing fundamental research for RO membranes on investigating physical and chemical properties through PALS(Positron annihilation lifetime spectroscopy) study, Computer chemistry and TEM (Transmission electron microscopy) analysis, which has resulted in the advanced RO membranes with high flux, high rejection, excellent chemical durability and so on.