New technique extracts value from industrial ponds
ON a satellite map of any of SA’s big mines or refineries, there will be a series of blue-green pools. From afar, they look almost pretty, but they are brine ponds filled with a soupy sludge of water contaminated with the byproducts of industrial processes.They pose an environmental hazard to groundwater supplies, and as industries grow, so the storage headache grows.Brine has traditionally been regarded as waste, but Alison Lewis, University of Cape Town (UCT) engineering and built environment dean, sees it differently. "The stuff in the waste is actually the stuff you spent a fortune digging out the ground, or buying as a reagent, or adding as a catalyst: it is a resource," she says.Lewis has conducted pioneering research into how to extract these contaminants in an efficient way, using a surprisingly simple process that exploits water’s unique "iceberg" properties.The technique, known as eutectic freeze crystallisation, transforms brine into potable water and salts such as calciu...
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