Making use of acid mine water

Two companies that are incubated at The Innovation Hub’s Climate Innovation Centre South Africa treat water in local mining sites to provide clean drinking water, contributing to a cleaner environment.

BN Aqua Solutions takes acidic mine water from underground and treats the contaminated water to drinking stage by using a waste product that is locally available. The company has built a prototype model at the CSIR, where it has conducted various tests proving it can provide clean drinking water.

What makes the project innovative is the use of waste material to treat the contaminated mine water. The result is not only clean drinking water, but also a reduction in waste material. BN Aqua Solutions reduces the environmental footprint currently caused by this unused metallurgical product. “This waste product is a by-product of a metallurgical process, and it has been stockpiled without use,” says Boitumelo Nkatlo, founder of BN Aqua Solutions. “We have found a cheaper solution to this problem and can also recover saleable minerals such as gypsum, magnetite and synthetic lime from the residual slag, which can help to offset the plant operating cost,” he adds.

ROC Water Technologies “It is foreseen that mine water can be treated to recover not only drinking water but also pigment, aluminium hydroxide, calcium carbonate, sodium carbonate and elemental sulfur,” says Professor Jannie Maree, founder of ROC Water Technologies.

ROC Water Technologies has designed an ROC (reverse osmosis/cooling) process that can treat acid mine water to recover drinking water and saleable products in its various stages. Ferric hydroxide is recovered in the first stage of the ROC process, where sodium carbonate increases the pH to 3.5. The remaining steps of the ROC process make provision for removing the remaining metals in the water by raising the pH to 7.5, followed by the recovery of drinking water and a brine stream through reverse osmosis.

“These companies improve the standard of water from mining sites in South Africa and help us tackle problems such as water scarcity with real, tangible solutions,” adds Pieter Holl, CEO of The Innovation Hub.

Professor Jannie Maree (left) with two of his PhD students

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