ABSTRACT
Masato Nishimura Osaka Industrial Research Association, Osaka, Japan
Kiyoshi Koyama Osaka Municipal Technical Research Institute, Osaka, Japan
I. INTRODUCTION Reverse osmosis and ultrafiltration are separation processes in which a pres sure gradient across a semipermeable membrane is the driving force. The desa lination of water by passing it through a membrane that is permeable to water and nonpermeable to dissolved salts under pressure was known and named re verse osmosis some 50 years ago. In 1953, Reid [1] proposed the possibility of water desalination by the reverse osmosis process and examined the membrane permeabilities for many types of synthetic membranes. In 1957, Reid and Bre ton [2,3] reported that cellulose acetate derivative membranes performed well as a semipermeable membrane, but that the water flux of the membrane was too low for practical use.
