Davis' desalination technology licensed by Dow

Dow Chemical Co. has agreed to commercialize a desalination process developed by Dr. Tom Davis, a research professor of chemical engineering.

Dow signed a licensing agreement with ZDD Inc. of Columbia for the exclusive rights to commercialize the patent-pending ZDD (Zero Discharge Desalination) technology.

"This is an example of how the university is working to transfer technology from the lab to industry," said Davis, who joined USC's research faculty in 2001. "Dow has an international reputation as a leader in the water-purification industry. The ZDD technology is a good fit for Dow's business."

ZDD Inc. was founded by USC alumnus Walker Rast, chairman and CEO of the company; his wife, Ruth Rast, president; and Davis, the company's chief technology officer.

Lisa Rooney, director of the USC Intellectual Property Office said this license agreement adds to the growing list of university technologies that are entering the commercial marketplace.

"It is a great example of how university research adds value to products that will benefit society," she said.

Desalination is the process of removing salt from water or a salty solution. The remaining concentrate is largely unusable because of its high salt content. Dumping the concentrate in a lake or stream is not acceptable, so the desalination industry has either pumped it into a deep well or sent it to a detention pond where the water evaporates, leaving behind a mixture of salts with limited commercial use.

Davis' technology is expected to expand the commercial use of this mixture when it comes from raw groundwater because it contains gypsum, which is used by home builders in wallboard.

"Instead of a waste product, it will have commercial use and value," Davis said.

The technology that Davis developed uses a combination of reverse osmosis, an economical way to purify water, and another process that separates calcium and sulfate, two components of gypsum, from water. The process creates two separate streams of salt, one with calcium chloride and the other with sodium sulfate. These streams are mixed to create calcium sulfate (gypsum), which can be harvested for the building industry.

Davis said New Mexico is a potential location for the ZDD technology because of its groundwater has an abundance of gypsum. ZDD Inc.'s research is supported by Sandia National Laboratories in New Mexico and the Bureau of Reclamation of the U.S. Department of the Interior.

"This technology will benefit many cities and communities throughout the western United States where groundwater is limited and often tainted," said Rast, who earned a bachelor's degree in mechanical engineering from USC in 1959.

Rast, who brings four decades of business experience to ZDD Inc., was chairman and CEO of the Keyes Fibre Co. (the Chinet Co.), which operated in 27 countries. The Rasts, who had retired to Hilton Head Island, are moving to Columbia to work more closely with USC engineering faculty who have projects with commercial potential.

Davis, who recently presented information about his desalination technology at a conference in Anaheim, Calif., and his research team are testing the ZDD process in California, where irrigation water also is high in gypsum.

Davis holds 13 patents for products and technology developed while working for Milliken in Spartanburg, the Southern Research Institute in Birmingham, Ala., and Exxon in New Jersey.