Yum, more nickel please

RUSTENBERG, SOUTH AFRICA-This country's newest nickel treatment plant has impressive green credentials. It has no emissions other than oxygen, uses no fossil fuels, and even looks pretty. That's because Berkheya coddii is indeed a plant, absorbing nickel through its roots.

The Anglo American Platinum Corpo.ration has put this tall perennial to work cleaning up nickel-contaminated soils surrounding a base-metals refinery near Rustenberg. Their phytoremediation effort removes toxic nickel for as little as $60,000 a hectare-less than one tenth the cost of more conventional clean-up methods. Equally important, the old-fashioned remediation techniques-such as excavating soil for acid leaching-leave the ground sterile, while phytoremediation enriches the soil.

The metal is toxic to most plants, but this rare species evolved on a tiny patch of nickel-rich soil in northeastern South Africa. After three years of growth, one five-foot plant contains much more nickel than ... well ... a roll of nickels. Bundies of leaves and stems are tossed into a nearby smelter, yielding approximately 14 kilograms of nickel per hectare.

The platinum company is so pleased with its early results that it has sent scouts to central Africa's copper belt to look for copper-hungry plants that could alleviate soil contamination caused by that metal. Elsewhere in the world, researchers are attempting to take this technology to the next level: finding or genetically engineering plants that can absorb enough metal for commercial production.

The alchemists of the 21st century would do well to study botany.

-Don Boroughs

Copyright American Society for Engineering Education Nov 1999
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