The reference and analysis of a double-element type hollow fiber RO module in seawater desalination

Abstract Toyobo succeeded in developing a single-pass seawater desalination RO module composed of hollow fiber type membranes made of cellulose triacetate in 1978, and then in 1979 began production of the first commercially available double-element module. This double-element module has many advantages suitable for seawater desalination. It has high chlorine tolerance and high salt rejection, derived from the properties of the membrane material, and it is highly resistant to fouling and scaling matters due to the unique flow pattern and fiber bundle configuration. These advantages help to explain why the Toyobo double-element module has been used so successfully at the many seawater desalination plants around the world. In this report we show the simulated water flow rate, bulk concentration, concentration polarization coefficient and concentration at the membrane surface in double-element modules and present actual operating data from desalination plants in Chigasaki (Japan), Seraya (Singapore),and Helgoland (Germany). Using these monitoring data we analyzed RO performance, A value and B value, thereby demonstrating the advantages of the Toyobo double-element module.