The effect of agitation on reverse osmosis desalination

✍ Scribed by J. Lora; J.M. Arnal

• Publisher: Elsevier Science
• Year: 1990
• Tongue: English
• Weight: 648 KB
• Volume: 79
• Category: Article
• ISSN: 0011-9164
• DOI: 10.1016/0011-9164(90)85010-8

✦ Synopsis

Chemical and physical phenomena such as precipitation fouling and concentration polarisation are of notorious influence on the performance and lifetime of reverse osmosis (RO) membranes and other similar ones .

In analogy to other mass transfer operations we have considered agitation as a means of improving the RO process and have designed a patented selfstirred module, suitable for plate-and-frame operation . The plate acts as a membrane support, and the space accorded by the frame serves as agitation chamber. A flat-blade turbine with appropriate baffles rotates with the liquid flow, its proper construction preventing damage to the membranes . No external access for any axis is required, thus avoiding complication of the setup . The rotation speed of the turbine is a linear function of inlet flow .

RO separation of water from dissolved salts with this self-stirred module has been investigated. Both brackish (1,000 ppm) and seawater (35,000 ppm) have been tested .

The improved appearance of the surface, clean and free of fouling, reflected the marked improvement in fluxes, about 90% for brackish water and some 140% for seawater, when compared with unstirred operation . Also, with stirring, some increased salt rejection was noted .

Clearly this improvement would apply to other similar membrane processes as well .