Australian Researchers Aim for Greener Desalination
时间：2011-10-08 07:45:56
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Researchers in Sydney are leading a new international effort to make desalination1 more environmentally friendly. Current techniques tend to use excessive amounts of energy or are heavily reliant on chemicals. The University of Technology in Sydney is working with teams from Singapore, Saudi Arabia and South Korea to improve the filtration process to make it more efficient and gentler on the environment.
Removing salt from water
Desalination is often seen as an expensive and energy-intensive way to remove salt from water. In Australia - the world’s driest inhabited continent where rainfall has become increasingly
erratic2 - desalination plants treat seawater that can produce almost half of the supplies needed by the major cities.
“There is a significant increase in the trend for the desalination market," explained
Professor Vigi Vigneswaran from the University of Technology in Sydney. He says the science has growing international value.
"Whether we like it or not, with the global warming problems, the desalination will become a very important technology - one of the important technologies - other than the water reuse and storm water harvesting," Vigneswaran said.
New techniques
One of the projects that researchers in Sydney are pursuing is improving the
membranes4 used in pre-treatment systems in desalination plants.
These thin films often become
clogged5, reducing their efficiency and increasing the amount of energy used to take the salt out of seawater.
The team in Sydney is developing new biological filters that do not become so congested and will not need chemicals that absorb contaminants.
Researcher
Christian6 Kazner says more effective filtration will cut energy usage.
“Membranes are very sensitive to everything which is contained in the water,"
noted7 Kazner. "It will be stopped by the
membrane3 and grow on the surface of the membrane, whether it is salts, you have scaling, it is blocked. Or whether it is organic contaminants they really collect on the surface and if you have microbes they can grow on that organic material. As much as you remove those contaminants before you filter it you improve the performance of the membrane, you reduce the energy demand and finally you can extend the lifetime of the membrane.”
Forward osmosis
While conventional desalination systems rely on a process called reverse osmosis that uses pressure to force water through membranes, work is also being done on an alternative process. Forward osmosis needs far less energy and allows water to effectively be sucked through the filters.
Scientists in Sydney believe this method could reduce energy consumption in the desalination process by up to 90 percent.
Other projects being developed include mobile salt-removal systems for remote
Aboriginal8 communities where supplies from groundwater wells are contaminated by high concentrations of saline and nitrates.
The aim is to export ideas and innovation overseas, especially smaller desalination units for use in developing countries, where safe and sustainable water supplies remain a distant dream for many.
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