Regenerative Capacitive Electro-Desalination System (RECED)

The U.S. Environmental Protection Agency (EPA) Office of Water (OW) is seeking innovative technologies to improve the performance and reliability of small drinking water systems. In response, Physical Optics Corporation (POC) proposes to develop a novel Regenerative Capacitive Electro-Desalination System (RECED) to enable the use of reduced-quality water sources, such as weakly saline brackish water, or even ocean and seawater, as part of the drinking water system’s intake. This will provide much needed water source diversification to small-size drinking water systems, eliminating their sole dependency on the locally available ground or surface freshwater supply. The proposed system is based on the recent development at POC of a unique, man-portable desalinator unit that demonstrated efficient, electrically driven desalination of brackish water and seawater, producing excellent quality drinking water output at salinity levels below 250 ppm total dissolved solids (TDS). With the proposed continued development of this new technology, POC will not only address the EPA’s need for better performing small drinking systems, but will enter a multi-billion dollar desalination system market that has experienced significant growth in the recent years due to the continuing lack of freshwater resources worldwide. POC will demonstrate the feasibility of RECED by analytically and numerically modeling the system and building a bench-top test prototype based on the simulation results. Because of its demonstrably superior performance, the proposed system, once fully developed, can potentially capture a share of the market that is addressed today by osmotic desalination devices.

RECED will extend the current field of water desalination technologies for extremely compact, highly productive and reliable devices and installations for worldwide deployment. Due to its scalability, the technology is not only relevant for deployment within community-sized small drinking water systems, but can also be applied to the development of smaller-sized desalination devices used by outdoorsmen, sailors, first responders, emergency personnel, etc.

Recent developments in new nano-structured materials and compact, powerful energy sources, as well as continuing decline in the cost of renewable power generation, enable creation of self-powered portable desalination systems; thus, people in remote, fresh-waterless areas would benefit from a novel deionizing technology that could provide a ready supply of purified drinking water. In RECED, POC will implement a series of innovative technical solutions, which include using commercially available, non-degrading, high-performance nano-materials that guarantee years-long continuous operation with minimal maintenance requirements. Another technological innovation is the use of energy-saving regenerative operating principle that allows a substantial degree of energy recovery during the desalination cycle, thus reducing the overall power budget. These assessments are supported by the experimental evidence from testing the previously fabricated small-scale desalinators/deionization systems, based on the same physical principles.

The new system, lacking the high-pressure components of conventional reverse osmosis (RO) units, is cheaper, has a smaller footprint, and is easier to install and use. Its operation is automatic and self- sustainable, with higher uptime and shorter maintenance downtime, providing improved performance and reliability over current water treatment plants. RECED technology also offers significant advantages over the thermal desalination approach, especially when applied to the smaller, community-size installations of small drinking water systems. POC’s approach will produce dramatically increased levels of drinking water output per watt of electric power consumed, and will decrease the initial investment required for enabling a desalination component as part of a drinking water supply system to a level that is affordable for the smaller system operators. To POC’s knowledge, no other technology is currently available to deliver the mix of high throughput, energy efficiency, and low cost, offered by RECED.