Scientist Naomi McSweeney works on her project to identify a new type of bacteria.
Scientist Naomi McSweeney works on her project to identify a new type of bacteria. Contributed

Bacteria makes a meal of bauxite

FORMER Yeppoon woman Naomi McSweeney has discovered a new species of naturally-occurring bacteria that has the potential to save the alumina and aluminium industries millions of dollars.

Naomi, 26, is now a leading scientist and discovered the new bacteria species during a collaborative project between Alcoa of Australia, CSIRO and the University of Western Australia.

What she found was a potentially new genus of Proteobacteria and a new species of the known genus Halomonas.

The bacteria can successfully break down and remove sodium oxalate, an organic impurity produced during the refining of low-grade bauxite into alumina.

The work was recently presented for the first time in public through Fresh Science, a national competition for early-career scientists.

Naomi, the daughter of Yeppoon businesswoman Ros Adamus, was one of 16 winners from across Australia.

At a typical refinery, sodium oxalate forms by the tonne during the production of alumina. It can affect the colour and the quality of the final product.

“Oxalate can be removed by combustion, but this process releases excess carbon dioxide,” Naomi said.

“The impurity may also be stored but this represents a major cost to refineries so treatment is a preferred option.”

Alcoa of Australia has designed and installed an innovative large-scale bioreactor which has the capability to remove about 40 tonnes a day of sodium oxalate produced at its Kwinana refinery south of Perth in Western Australia.

“Using bacteria to break down and remove oxalate is a better, more sustainable alternative.”

The bacterial process breaks down the sodium oxalate and produces significantly less carbon dioxide whilst avoiding the need to store the impurity.

Naomi has worked with researchers from Alcoa’s global Technology Delivery Group and the CSIRO’s Light Metals Flagship to identify the main bacteria involved in degrading the oxalate within the bioreactor.

“Oxalates, and bacteria that feed on them, are common in nature – for example in our food, in our guts and in the root systems of plants such as rhubarb,” Naomi said.

The bacteria doing most of the work in the bioreactor have never been found before.

To enhance the efficiency of the bio-removal process, the researchers are now determining the best conditions for growing these bacteria.

Alcoa is seeking to apply the process to other refineries around the world, and hopes it will be able to use it to treat previously stockpiled oxalate.

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