6	More on desalination
	US Water News reports the following article from their October, 2001 issue: DESALINATION WILL BE SOLUTION TO FUTURE WORLD-WIDE SHORTAGES

“Every so often a story appears in the media concerning future water shortages in countries around the world. The articles sometimes say that billions of people around the world face the threat of water shortages and many countries will soon be forced to rely on water supplies from ‘new sources’. In many instances, that new source of water will be desalinated water. Half a billion people in 31 countries suffered from water scarcity in 1995, Singapore’s acting Environmental Minister Lim Swee Say recently told participants at an international water conference held in his country. ‘By 2025, about 3 billion people in 48 countries are expected to face water shortages,’ Lim said. And by the year 2050, this will increase to 4 billion people in 54 countries, according to figures from Population Action International.

Water is quickly becoming the world’s most important resource for economic development—and water shortages could heighten the risk of international conflicts. Just recently, Egypt announced that once its population grows to 90 million from its present population of 69 million—projected by 2025—the Nile river will no longer be able to support the country’s need for water. Egypt shares the Nile River with Sudan under a 1959 agreement.

Desalination may well be the only practical solution to worldwide water shortages in the future. But the high cost of desalination historically has made it less attractive alternative when considering new sources of water for large population centers. Several coastal cities in Florida and California currently have desalination plants, and the Tampa Bay Regional Water Authority has recently broken ground on what it claims will be the most advanced desalination plant in the world.

The most common method of desalting water is through distillation—boiling water and collecting the condensate steam— which is expensive because it requires a lot of energy to heat the water. The cost can be lowered by combining desalination facilities with electrical power plants and using the plants ‘waste heat’ to distill water. More recently, stronger and thinner membranes have been developed for filtering seawater that are also making desalination cheaper. Thinner membranes mean lower pressure and hence lower energy consumption, reducing cost.

Over the past 20 years various research teams have attempted to develop advanced commercial energy recovery devices to overcome these efficiency limitations. These devices have used combinations of pistons, bladders, valves and timers, and some worked well initially but suffered high maintenance problems.

More recently, a new device for desalinating water has been developed using a relatively simple ducted rotor that transfers the pressure energy directly from the saltwater reverse osmosis brine to the incoming feed stream, according to HOH Technologies. The idea now has evolved into a 4-inch diameter, patented commercial device, called a Pressure Exchanger.

The Pressure Exchanger (PE) devices were first sold commercially in 1997. The all-ceramic moving and mating parts of the PE have shown exceptionally low, and even zero wear in high-pressure brine applications, says HOH. The slowly rotating PE (1,500 RPM) has proven to be a low maintenance component in commercial desalination plants, according to the company. Because the PE transfers energy directly from the brine to the feed without high-speed rotating shaft efficiencies, the PE achieves actual efficiencies of 91 to 95 percent within a broad range, HOH officials report. Reduced energy and capital costs means it is possible to produce potable water from seawater at a cost below $1 per cubic meter in many locations worldwide, according to HOH.

There will likely be vast improvements in desalination techniques in the coming years as researchers continue to work on the problem of high energy costs associated with the technique used to produce fresh water from seawater. A major breakthrough in finding a new and revolutionary low-cost source of energy would remove the final barriers for providing fresh water to cities and villages far into the future”

Quoted from our last Smart News Volume 1, No.3;

“As more and more desalination and reverse osmosis systems become the norm for alternative drinking water supplies, there will be more and more the need to be able to compliment their use by addressing optimum corrosion control of the distribution piping carrying these water supplies. One product, SeaQuest has proven to maintain optimum corrosion control in conjunction with produced water of such high quality. Because SeaQuest does not rely on any minerals (soft or hard) to provide corrosion control, there is no need for any additional corrosion control treatments, such as added pH control…one company, one product, one solution”