Yale University researchers believe that improving the efficiency of water desalination could be the answer to solving the world's growing demand for freshwater.
According to the researchers, water desalination can be more efficient if it steps in the pre- and post-treatment stages of desalination were improved.
The traditional way of desalinating water, is to push the saltwater at a high pressure through a membrane which removes minerals from it, a process which is also known as reverse osmosis.
The researchers pointed out that pre-treatment step such as adding chemical agents to the water to clean it could be avoided partially or completely if the membrane does not build up organic matter on its surface.
The researchers mentioned two chemicals in particular - boron and chlorine - whose removal is needed before desalinated water is usable, especially if desalinated water is to be used for agricultural purposes.
Boron is a chemical element that can be toxic to both humans and plants in certain concentration levels. It occurs naturally in seawater proportional to salinity and is also used in soap and detergents, agricultural fertilize and wastewater.
Chlorine is commonly added to water as a disinfectant to remove bacteria, viruses and microorganisms. The chlorine compound chloride is also present in sea water. The two can be toxic in large doses and too much chlorine in normal filter membranes renders them useless requiring a dechlorination pretreatment.
The researchers noted that 70 percent of the world's water is used for agriculture; if desalinated water is to fill this need, boron and chloride needs to be removed.
Menachem Elimelech and William Philip, the authors of the study, calculated that a membrane capable of filtering out boron and chloride would result in substantial energy and cost savings.
"All of this will require new materials and new chemistry, but we believe this is where we should focus our efforts going forward. The problem of water shortage is only going to get worse, and we need to be ready to meet the challenge with improved sustainable technology," said Mr. Elimelech.
However, he cautioned that desalination should only be considered a last resort in the effort to provide fresh water, suggesting that long-term research is needed to determine the impact of seawater desalination on the aquatic environment.
Mr. Elimelech led an earlier university project in January 2007 which built a pilot-scale desalination plant, The pilot plant used forward osmosis desalination which they claim has higher recovery and less brine discharge than conventional desalination systems.
source: APEC-VC Korea
