Treating Bahrain zone c groundwater using the EDR process

Abstract

Developing and applying efficient water desalination technologies for treatment of Zone C groundwater appears to be an essential factor in maintaining an adequate water supply for the Island of Bahrain. The quality of this source (approximately 11,000 ppm total dissolved solids) will increase capital and operating costs of desalting systems as compared to units currently operating on the Zone B brackish water sources in Bahrain. The EDR process has been used effectively for the treatment of a 10,000 ppm source near the Mediterranean -coast-Analyses of the data for the first eighteen months have shown system operation to be very stable. The ability of the EDR process to operate efficiently and reliably on this high TDS brackish water supply, without chemical conditioning of the feed, has been demonstrated. Conceptual design studies have shown that this technology is directly applicable to Zone C desalination requirements. This paper reviews the pertinent operating characteristics of the Mediterranean installation and projects estimated operating parameters and costs for Bahrain Zone C water treatment. Factors contributing to the improvement in EDR system operating efficiency which make treatment of the Zone C type water feasible are: • New aliphatic membranes which improve electrical efficiency • A special electrode Clean-In-Place system which reduces acid consumption for periodic stack cleaning • A new time phased reversal system which increases the efficiency of polarity reversal in the multistage units needed to desalt 10–12,000 ppm TDS feed waters Overall, it can be concluded that the EDR process does offer an attractive, economical alternative for the Zone C desalination requirements.