Dow Signs Exclusive Licensing Agreement to Commercialize ZDD Desalination Process Technology

08-02-2006: The Dow Chemical Company announced that it has signed a licensing option and evaluation agreement with South Carolina-based ZDD, Incorporated, giving Dow exclusive rights to elect an exclusive license to ZDD, Incorporated's Zero Discharge Desalination (ZDD) process technology for desalination of seawater and brackish water.

The patent-pending ZDD process technology utilizes a unique combination of reverse osmosis or nanofiltration membranes and electrodialysis cells that enables water treatment facilities to recover potentially saleable salts and greater amounts of pure filtered water. According to the company, it also minimizes or eliminates the production of concentrated brine, the disposal of which represents a substantial cost associated with water treatment in coastal and, in particular, inland locations.

As part of the ZDD process, brine streams containing sparingly soluble salts are treated with electrodialysis to separate the anions and cations of the salts into two separate streams. These ions are then paired with appropriate cations and anions to form salts that are more soluble in the two streams. Additional pure water is recovered through this process from the separated brine streams and ultimately the concentrates are remixed and the insoluble salts that precipitate are separated and potentially sold.

ZDD technology was originally developed by Thomas A. Davis, Ph.D., Department of Chemical Engineering at the University of South Carolina and was licensed to ZDD, Incorporated by the University as part of its program to encourage commercialization of its technologies. Davis, research professor and Walker Rast, alumnus of the university, are currently the principals of ZDD, Incorporated. The University has filed two patents on the technology, one for use with seawater and the other for inland desalination and agricultural water treatment.