Boron removal from the permeate of a large SWRO plant in Eilat

The SWRO plant in Eilat for the production of 8000 m3/d was commissioned in June 1997. It was retrofitted in 1999, a retrofit which increased the production to 10,000 m3/d. Due to the recent modifications in WHO guidelines for boron limits in treated water, boron removal from the plants' permeate has become a critical demand. In addition, the aging of the membranes since June 1997 caused an increase in the chloride concentration in the permeate to more than 300 ppm and a decline in the plants' production from 10,000 m3/d down to 95,000 m3/d. Based on the above, and after extensive pilot planting, a second retrofit of the plant was performed during 2004, and commissioned in January 2005. The targets of the retrofit were reducing the boron concentration in the water transmitted to the community to 0.4 ppm maximum, reducing the chloride concentration to less than 150 ppm, and in addition increasing the net production back to 10,000 m3/d. The results obtained after 6 weeks of operation are better than expected. The paper is describing the performed retrofit, and analyzing the obtained results. Additionally, economic evaluation is presented. The results and the experience obtained in this plant and their consequent economic effect may be implemented in the very large sea water desalination plants. Discussion to the above is presented.