Although the pump is a relatively small part of the overall cost of an RO system, expenses resulting from downtime and inefficiency quickly can diminish the productivity of the system and your return on investment. Due to the corrosive atmosphere and high demands on these sea water RO systems, special attention is required in the pump selection process. There are several key factors that will help to ensure optimum pump and system performance.
In 1957 The Dow Chemical Corp. addressed the negatives of using bromine by creating a brominated ion exchange resin, which opened up the use of bromine in offshore water treatment applications.2 Today, polybromide resin is used in many offshore water treatment systems. The fact that bromine can be added to water that previously has been chlorinated makes polybromide resin a practical solution to accommodate the multiple sources of water in offshore applications.
Five large municipal water agencies have combined to advocate a significantly increased federal role in encouraging desalination. The group sees desalination as a viable, cost-effective way of making seawater and brackish groundwater reliable sources to supplement national drinking water supplies.
On average there are 50 to 75 significant desalination projects per year in the United States with an average capacity of approximately 1 million gallons per day. The majority of these projects utilize membrane processes such as nanofiltration (NF) or reverse osmosis (RO).
Although China ranks sixth in the world in total water resources, there is a shortage. The average water resources per capita is 2,300 m3, making it only one fourth of the world average per capita, while the unit plantation area of water resources is only one half the world’s average value.
Groundwater resources throughout northern China are drying up at an astonishing rate.
Part one of this article appeared in the February issue and described how nanofiltration, reverse osmosis and electrodialysis reversal are being run side-by-side at the Brackish Water Demonstration Facility in California.
The Diablo Canyon Power Plant at Avila Beach in California utilizes seawater for both cooling water and makeup water for steam generation. Ionics, Inc., Watertown, Mass., designed and built and now operates a complete water treatment system serving the high-purity water needs of this power plant. Over the past eight years, the seawater treatment section has demonstrated excellent long-term performance as a result of strong design, consistent maintenance and qualified operators.
In Port Hueneme, California, a state-of-the-art desalination facility uses three brackish water desalination technologies: reverse osmosis (RO), nanofiltration (NF) and electrodialysis reversal (EDR), operated side-by-side to produce over three million gallons per day (mgd) of high quality drinking water. The Brackish Water Reclamation Demonstration Facility (BWRDF) is the cornerstone of the Port Hueneme Water Agency’s (PHWA) Water Quality Improvement Program. In addition to providing desalted water for local use, the BWRDF also serves as a full-scale research and demonstration facility.
After a hurricane in the 1960s caused salt water from the Atlantic Ocean to seep into private wells-effectively destroying the drinking water-Kill Devil Hills in Dare County, N.C., took action. Today, four water treatment facilities provide safe, clean and healthy fresh water for residents and tourists.
Two technologies currently are used by Dare County for the treatment of water. The first is a conventional ion exchange method that softens well water. The second is a reverse osmosis (RO) procedure that desalts brackish groundwater from wells drilled down 300 to 400 feet.
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