Oasys develops energy-efficient osmosis for desalination

U.S.-based Oasys said it has developed a low-cost, low-energy desalination and purification technology for seawater, wastewater and industrial waste streams.

The Yale University spin-out is currently seeking venture funding for its 'engineered osmosis,' a technology the company says reduces the energy needed to purify water to one-tenth of what's required by current desalination systems.

Many desalination systems employ reverse osmosis, which uses pressure or heat to force water through a semipermeable membrane.

Oasys is using forward osmosis, in which a draw solution of high concentration induces a net flow of water through the membrane, also called an osmotic pressure gradient. That process has low energy requirements but can sometimes require a second step of purification, using energy-intensive reverse osmosis or the direct removal of draw solutes.

Oasys said it has identified a concentrated solution that can be removed easily and completely during the second step of purification. That solution is ammonia and carbon-dioxide gases dissolved in water.  

Oasys said its forward osmosis system uses a common membrane and a re-usable solution. The company estimates its process will cost $0.37 to $0.44 per cubic meter at commercial scale.

Oasys was founded by Yale Professor Menachem Elimelech and graduate students Robert McGinnis and Jeffrey McCutcheon. The CEO is Aaron Mandell.

At the end of 2007, there were more than 13,080 desalination plants worldwide, but just 119 in the U.S., according to the International Desalination Association, a nonprofit organization that promotes the technology.

The high energy and infrastructure cost of reverse osmosis inhibited adoption of desalination in the U.S. because municipalities were able to easily and cheaply pump water in from surrounding rivers and regions (see Largest desalination plant in Western world gets go-ahead).