SCIENCE IN THE NEWS DAILY

New Desalination Technique Yields More Drinkable Water

from Nature News

More than a third of the world already suffers from shortages of potable water--with a rise to 50 percent expected by 2025. Desalination of seawater can help coastal communities address local shortfalls, although the process is costly, and releasing leftover brine back to the ocean has environmental implications. Now a new system promises to produce more drinkable water with less salty effluent.

Kamalesh Sirkar, a New Jersey Institute of Technology (N.J.I.T.) distinguished professor of chemical engineering, says he has devised a direct-contact membrane distillation (DCMD) system that can efficiently wring drinking water out of up to 20 percent-salt-concentrated brine. (After about 25 percent, salt precipitates out of the solution in the membrane distillation system and could damage the membranes, pumps, lines and other components, Sirkar says.)

Normal seawater has a salt concentration of about 3.5 percent, which means the new system can reprocess the same seawater several times. "More water can be recovered with less residue," Sirkar says.