Based upon the expected 13.6% increase in population per decade over the next 20 years, most of which will take place in the nation's warm and sunny regions, water is clearly the issue that will dominate our future. Because all U.S. fresh water sources are already committed, plans are moving aggressively forward to put in place the desalination infrastructure to meet our county's needs for the next 50 years. The coastal areas will most likely use seawater as their main raw material source, while the interior of the country will most likely use impaired groundwater or brackish water.

The main technological challenge to desalination is the disposal of residue water that contains three to four times the salt content of the input water. A good deal of this material is currently being pumped into deep wells, but the feasibility of this approach is questionable for the future. A major challenge is the determination of best practices to dispose of or utilize the wastewater streams coming from large- scale desalination operations. This was recently highlighted in a previous blog as well as an article in the April issue of Water Conditioning & Purification Magazine , "A Glass Half Full," by Mort Satin.

In the March SI Report , we suggested that a desalination operation's waste can easily serve as the raw material for another unit operation ("The salt-making/desalination nexus"). Just as former cheese factory waste product, whey, became one of the most highly valued products in the food industry, we speculated that desalination waste streams might prove to be a new source of raw material for the salt industry.

Just this week we see that is exactly what has happened.

Business Wire reported that GE Water & Process Technologies is to design and construct a reverse osmosis seawater desalination plant in South Africa, which will provide 70,000 m3/day of fresh water. In a first, the plant will recover ultra-pure salt from the concentrated brine stream for the production of chlorine, caustic soda, and hydrochloric acid at the refinery.

The $220 million project is part of a larger investment to build a new chlorine refinery in the Coega Industrial Zone, Port Elizabeth, South Africa.

GE's seawater desalination and thermal evaporation technologies will create around 630,000 tonnes of 99.9% pure salt annually. Reclaiming salt from the desalination brine stream will not only improve the overall economics of the refinery project, but also ensure a reliable and locally available supply of high grade salt for use in the refining of chlorine.

This project will provide freshwater to help lessen water scarcity and use the brine waste stream as a valuable raw material for another unit operation.