The development of the spiral-wound reverse osmosis(RO) modules

Abstract

The four-inch diameter spiral-wound RO membrane elements have been developed succesfully. The membrane element (type-SRC-401) is 965 millimeter long. A demonstrating prototype, designated SRO-80-1000, has been designed and fabricated by using the type-SRC-401 spiral-wound membrane elements. This paper describes in detail capital specifications about this membrane element and the operating performance of the prototype. The SRC-401 membrane element incorporating cellulose acetate (CA) membrane provides water productivity of 3.5–4.5m 3/day and salt rejection of 85–90%, at an applied pressure of 30kg/cm 2, tap water as raw water and feed temperature of 25 C. The prototype is now first spiral-wound RO pure-water installation which was designed and fabricated in China. It consists of five modules. The prototype for producing primary pure-water has operated more than 3000 hours in a plant. The operating results show that its performance is stable, average salt rejection is about 90% with water productivyt 30–35m 3/day, recovery more than 70%, and the flux decline slope of (−0.01) or so. This installation can be used to produce ultra-pure water for electronic industry and high pressure boiler by combining with ion-exchange demineralizer, and to get potable water from brackish water with low salinity and so on.