Using bacteria to mine metals in saltwater.

 In places like Singapore, where fresh water is scarce, one method to obtain drinking water is to filter out the salt from seawater. The usual process for doing this is known as reverse osmosis. Using membrane filtration technology, the salt is filtered out and chucked back into the sea. But this is an expensive, energy intensive process which is causing environmental damage to our oceans.

Biomining

Research engineer, Damian Palin, says, “The technology in reverse osmosis is reaching a plateau in terms of the amount of energy used versus the fresh water produced. Another drawback is the resulting brine which is produced. This is a super salty solution which is generally pumped back out into the environment with dire consequences.”

But Palin has come up with a solution: instead of chucking the brine back into the sea, why not use it as a resource in itself?

All you need is a bacterial strain which is able to precipitate minerals, water and food such as sugar

Palin explains, “I became fascinated by biological precipitation or biomineralization, which is a process where organisms form minerals under low energetic conditions – bacteria can do this as a form of defence on their cell surface and so I began to think about microbally inspired low energy production processes employing this technique.”

Harnessing nature

The idea at its heart is quite simple as all you need to do is provide the right setting and let nature take its course. He says, “All you need is a bacterial strain which is able to precipitate minerals, water and food such as sugar.”

This form of biomining means that various minerals can be extracted without having to apply heat or use toxic chemicals, both of which are environmentally unsound. Currently, Palin is testing different bacterial strains to see what minerals they extract from the brine.

So far we have achieved proof of concept and the findings of our experiments have been submitted for publication

He says, “To date I have worked with bacterial strains that are able to precipitate calcium carbonate and various magnesium carbonates, but it seems that certain strains have a degree of control over the minerals and hence the metals they precipitate. Understanding these processes may allow a revolution in manufacturing and material production techniques.”

Billion dollar industry

Singapore is aiming to produce 900 million litres of desalinated water a day by 2060. Palin believes that mining the leftover brine for metals could be a billion dollar industry. It is a nascent concept however, and a lot more testing is required to see if it really could be commercially viable. Palin says, “There has been lots of interest but the technology is very much in its infancy. So far we have achieved proof of concept and the findings of our experiments have been submitted for publication.”

Though it may be wise to remain cautious this early on in testing, the very idea of harnessing what occurs naturally and utilizing waste is an ingenious concept that could serve as a model for other forms of industry.


Check out the video below to see microbally induced mineral precipitation in action:


 

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