Mark Wilf Ph. D. EFFECT OF NEW GENERATION OF LOW PRESSURE, HIGH SALT REJECTION MEMBRANES ON POWER CONSUMPTION OF RO SYSTEMS

The performance of commercial composite reverse osmosis membranes has been continuously improving, since its introduction in the late seventies. An additional significant improvement of membrane performance has been achieved at the beginning of 1995, when new composite polyamide brackish water RO membrane technology has been introduced. The new membrane material is characterized by a very high specific water flux, about double the flux of the previous generation of polyamide composite brackish membranes while maintaining low salt transport. The nominal salt rejection of the new membranes is similar to the conventional composite polyamide brackish membranes. Higher specific permeate flux results in a lower feed pressure requirement in the RO system and lower power consumption. However, in order to fully utilize the power saving potential of the new technology, at some conditions of feed salinity, temperature and operating parameters, the design of RO system equipped with new membranes has to be modified, as compared to the design of system with conventional membranes. This paper will discuss characteristics of the new membrane technology, evaluate the impact of improved membrane performance on RO system design and the resulting power consumption of the RO process. The potential for additional improvement of membrane performance will be analyzed as well.