Environment News Service (ENS)

Environment News Service (ENS)

Thirsty Australia Advances Desalination Technology


Source: Environment News Service (ENS)

Melbourne, Australia - The delivery of energy efficient water desalination to drought-stricken Australia received a boost today with the establishment of a new collaboration between the government research agency CSIRO and nine Australian universities.

The research aims to advance water desalination as an alternative water supply option for Australia by increasing efficiency, and reducing the financial and environmental costs of producing desalinated water.

Australia, especially southern Australia, is short of water, and the country is experiencing the worst drought on record this year. Desalination of seawater is a possible additional supply, but it requires a lot of electricity, and is expensive, costing about A$1.10 per 1,000 liters (US$.90 per 264 gallons).

The new research effort, known as the Advanced Membrane Technologies for Water Treatment Research Cluster, is led by Professor Stephen Gray of Victoria University.

As a first step, the multi-disciplinary research team will carry out an evaluation of existing membranes and develop new energy efficient membranes.

'Many desalination and recycling programs rely on a process called reverse osmosis, where the water is forced through a semi-permeable membrane, removing salts and any other contaminants,' Gray explains.

'These membranes need regular replacement and cleaning, but they also require a large amount of energy to force water through what are nano-sized pores,' he says.

When contaminants such as salts are removed from water, some of them adhere to the surface of the membrane, building up on the surface, increasing the pressure and energy required to desalinate the water.

'Chemicals are used to clean the membranes, but membrane surfaces that are less sticky would reduce the pressure and energy required and the frequency of cleaning,' Gray says.

The researchers aim to improve membrane anti-fouling properties, increasing the ability of the membranes to clean themselves without chemicals.

The research will link with and inform related CSIRO research into membrane and carbon nanotube water filtration technologies.

Carbon nanotubes, molecules made of carbon atoms, are hollow and more than 50,000 times thinner than a human hair. Billions of these tubes serve as the pores in a desalination membrane.

The smooth inner walls of the nanotubes allow liquids and gases to rapidly flow through, while the miniscule pore size keeps out larger molecules.

Alan Gregory, urban water research leader at CSIRO, says, 'In combination with other research projects led by CSIRO, we aim to reduce by up to 50 percent the amount of energy required to desalinate seawater using membranes. This same technology will have benefits for the treatment and recycling of wastewater.'

CSIRO researchers are using nanotechnology to develop a new membranes for desalination with electrodialysis technology, which they say may lead to breakthrough technologies in cost-effective and highly efficient water recovery systems.

Nanotechnology for water desalination is a rapidly developing field. In the United States, researchers at Lawrence Livermore National Laboratory announced in May 2006 their creation of a membrane made of carbon nanotubes and silicon that may offer less expensive desalinization.

The CSIRO scientists are developing new 'inorganic-organic nanocomposite membranes for desalination by electrodialysis membrane process, which involves the incorporation of oxide nanoparticles into ion-conducting polymers to form new nanocomposites.'

'This also means we could potentially provide more secure water supplies while minimizing greenhouse gas emissions,' said Gregory.

Other partners in the membrane research program are the University of New South Wales, Monash University, the University of Melbourne, RMIT University, Curtin University of Technology, the University of Queensland, Deakin University, and Murdoch University.

Funding for the research was announced by Minister for Education, Science and Training Julie Bishop under the Flagship Collaboration Fund.

Desalination membrane advances cannot come soon enough for Australia, which is opening giant desalination plants already based on existing membrane technology, even if the water they produce is costly.

In April, the Water Corporation of Western Australia opened the 45 gigaliter Perth Seawater Desalination Plant. The US$290 million project will guarantee 17 percent of Western Australia's current water needs, regardless of rainfall or drought.

On Tuesday Western Australia Premier Alan Carpenter announced that a second desalination plant of the same size would be built at Binningup.

Meanwhile, the New South Wales Government of Premier Morris Iemma is moving forward with a huge desalination plant south of Sydney at Kurnell. The plant will use reverse osmosis technology with membranes that remove salts and other impurities from seawater to produce drinking water.

The environmental assessment for the construction and operation of a pipeline for Sydney’s desalination plant is open for public comment to Monday May 28.

As part of the desalination project, an 18 kilometer pipeline will be constructed from Kurnell, across Botany Bay, to Erskineville.

Sydney Water Managing Director Kerry Schott said the Kurnell plant would be 100 percent powered by green energy and would guarantee Sydney's water supply.

'Given the uncertainty of climate change and Sydney’s growing population, alternative sources of water need to be developed,' said Schott.

'The desalination plant will supply about seven percent of Sydney’s water supply by 2009 but it can be scaled up further if required,' he said. 'This gives us a supply of water that does not depend on rainfall.'

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