A pioneering research project to clean up a flooded Cornish tin mine is using algae to harvest the precious heavy metals in its toxic water, while simultaneously producing biofuel.
If the project, which is at a very early stage, is proven to work, it could have huge environmental benefits around the world.
The GW4 Alliance, which brings together the universities of Bath, Bristol, Cardiff and Exeter, in collaboration with Plymouth Marine Laboratory (PML), the Coal Authority and waste management group Veolia, is taking untreated mine water samples from the Wheal Jane tin mine in Cornwall and growing algae in them in a laboratory.
The alliance is exploring whether the algae is effective in removing harmful materials, such as arsenic and cadmium, from the mine water. Researchers hope to convert the algae into a solid from which heavy metals can be extracted and recycled for use in the electronics industry. The remaining solid waste will then be used to make biofuels.
“It’s a win-win solution to a significant environmental problem,” said Dr Chris Chuck from the University of Bath’s Centre for Sustainable Chemical Technologies. “We’re putting contaminated water in and taking out valuable metals, clean water and producing fuel.”
The Wheal Jane mine, near Truro, closed in 1992. But the Department for Environment, Food & Rural Affairs is still spending £2m a year on cleaning it up and combating its polluting effects. The project to clean up its acidic water using algae is thought to be the first of its kind in the world.
Dead algae has been used to filter water but the Wheal Jane project uses live algae found at the site to “remediate” its toxic water.
The scientists had initially been interested in the ability of reeds in the flooded area around the mine to absorb toxic substances. But then they started examining the algae on the reeds and realised that it had special properties.