Long term experience in the operation of nanofiltration pretreatment unit for seawater desalination at SWCC SWRO plant

摘要

Saline Water Conversion Corporation is the pioneer in developing applications and operation of nanofiltration (NF) pretreatment for seawater desalination which was developed by its research arm, namely, the Saline Water Desalination Research Institute. Initial work on a pilot plant scale, resulted in its application in one of the commercial seawater reverse osmosis (SWRO) plants at Ummlujj currently in operation since September 2000. During this long term of operation of NF-SWRO system, a number of improvements were made on the system operation based on operational experiences as well as research, which ultimately resulted in smooth operation of the same. This long-term operation revealed that it is possible to operate NF at 65% recovery at pH = 6 utilizing only low feed pressure of <25 bar. This led to increase in SWRO production by 42%. Also, no chemical cleaning or membrane replacement was required for SWRO membranes. These achievements make the NF-SWRO process economically attractive and feasible. This paper provides an overview of long-term operation of NF-SWRO plant as well as different research programs which were undertaken and results obtained following the application of the same. Major obstacles in the smooth operation of the NF pretreatment and future direction of improvement and research to be adopted are also addressed.