Australian salinity crisis could become money-spinner

According to the Commonwealth Scientific and Industrial Research Organisation (CSIRO), the extraction of valuable minerals and chemicals for industry from saline groundwaters would help to reduce their impact on the landscape and on agriculture. Such a scheme would also help to create regional industries and jobs, says the organisation.

However, if nothing is done to halt the current trend of increasing salinity, in 50 years time water in the city of Adelaide to the west of the region would be undrinkable, say CSIRO scientists.

“Substances dissolved in our salty groundwaters can be used in the making of fertilisers, light metals, plastics, industrial chemicals, oil refining, pesticides, glass, fibre glass, ceramics, bleach, soaps, detergents, dyes, inks, sewage treatment, sugar refining, alcohol brewing – the list is almost endless,” said Dr Hal Aral of CSIRO Minerals.

“Salinity is undoubtedly an extremely grave national problem, but sometimes we focus more on the problem than on the opportunities it offers us,” said Aral.

The raw materials could be extracted from groundwater using natural evaporation and solar energy, says Aral and colleague Dr Graham Sparrow. For instance, ordinary salt can be crystallised out of groundwater by evaporation, then used to make chlorine, hydrochloric acid, sodium hydroxide, sodium metal, soda ash, sodium bicarbonate and table salt.

Once the salt is removed, the remaining water, known as ‘bittern’, still contains compounds such as magnesium, potassium, sulphates, boron, strontium, bromine and iodine. These include epsum salts, worth AU$400-800 a tonne, to fertiliser ingredients, cement ingredients and many other chemicals with even higher values, says CSIRO. Bittern can also be used directly in the mining industry as a dust suppressant.

The scheme would also link in with plans to develop major titanium and mineral sands industries in the Basin, with chemicals extracted from the salt being used in the processing of local titanium. The region has the potential to create a AU$300 billion (£109 billion) titanium industry, says Chief of CSIRO Minerals Dr Rod Hill.

“The Murray Darling Basin could, potentially, become the centre of an Australian sustainable chemical industry – drawing on a vast natural resource, and integrating production so that one industry uses the waste products of another,” said Aral.

“We also believe that large-scale removal of salt from the Basin will have a beneficial impact on salinity, as well as generating wealth needed to combat landscape salinity, making it less of a drain on the national coffers,” he said. “Investment in these new industries will bring new businesses and skills to inland Australia, nurture local communities, increase access to better services for residents, and generate more secure long-term employment.”

Currently we are working with companies in the Murray Basin to recover salts from the saline waters and to process then to higher value products,” Dr Sparrow explained to edie. “The technology used to recover the salts by evaporation is not novel as companies such as Dead Sea Works in Israel and Great Salt Lakes Minerals Corporation in Utah do it commercially – albeit with better quality waters then in the Murray Darling Basin. These current efforts have some Federal Government financial support at present and can be considered to be demonstration projects. When successful I am sure other operations will be set up.”

Saline water ponds in the area can also be used for generating renewable energy. The ponds have distinct layers with different salt content, with the most saline at the bottom, which is prevented from circulating. “In a sunny environment – e.g. in the Murray Basin – the saltiest water at the bottom of the pond traps and holds solar radiation, and as a result the bottm layers heat up and may reach temperatures of 70-80°C,” said Sparrow. “This heat trapped in the water may be recovered by means of a heat exchanger that is positioned in the bottom of the pond and has a fluid circulating through it. At the surface the heat is recovered for the hot fluid, and may be used to generate electricity.”

The problem of salinity in Australia is not isolated to the Murray Darling Basin. At the beginning of 2000, fears were raised over the effect on salinity of Australia’s high tree felling rate, which has become the fifth fastest in the world (see related story). However, in an attempt to lower the local water table, grants are now offered in the Murray Darling region for tree planting which are being widely taken up by residents.