Anglo American was the first company to transform waste water from its coal mines into something 80 000 people drink. Now it is seen as a model.

Purifying contaminated water from three sites in South Africa has proved so successful that Anglo’s plant in Witbank is doubling in size and being replicated elsewhere in the country by BHP Billiton and Glencore Xstrata.

While the $130 million (R1.3 billion) plant will not upend the $600bn world water industry, Anglo’s treatment centre provides as much as 12 percent of the area’s municipal drinking supply and serves as a template for how the industry could treat waste in the future. It also shows how companies and municipalities are finding new ways to confront an increasingly water-stressed planet.

Mines often treat waste water to some extent. But until the Emalahleni water reclamation plant, none of the water was of drinking quality.

This plant “is a model”, said Marius Keet, the acting head of the Department of Water Affairs in Gauteng. “It’s a good example of how it should be done.”

That said, the technology is not cheap and the company must still store a leftover brine from the treatment process, a residue that can be toxic.

BHP and Glencore are among those following with similar treatment works as the industry juggles its needs with water scarcity and environmental concerns about coal.

Coal from Anglo and other mining operators provides 40 percent of world’s energy. Coal consumption climbed 54 percent between 2000 and 2011, increasing carbon emissions.

The 30 million litre-a-day reverse osmosis plant recovers 99.5 percent of the mine’s waste water, which will increase to 100 percent after the expansion is completed this year.

Seawater desalination plants had recovery rates of between 60 percent and 70 percent, said Thubendran Naidu, the hydrology manager at Anglo’s Emalahleni plant.

Cleaning mine waste water to a higher quality allows companies to continue producing coal, keep their water licences and reduce the acidity that corrodes equipment.

“The company would have to treat the mining waste water before draining it into rivers or land anyway so this way they also did something good,” said Adrian Viljoen, formerly an engineer at Keyplan, now Aveng, which built the facility.

“The only extra cost was the pipework to deliver the water to the municipality.”

Much of Anglo and other miners’ efforts has been driven by government regulation. Mines are required to secure water licences and part of the approval includes a water-treatment plan after the mine closes as well as proper handling of the concentrated brine.

While Anglo had no immediate plans to build similar plants in its thermal coal business, it was considering water treatment operations in its platinum and copper businesses, according to water manager Richard Garner.

Glencore is building a water treatment plant in the Middelburg coal-mining area to improve the mine waste water to an approved level so it can flow into waterways. The plant would be commissioned later this year with a capacity of 20 million litres of water a day, it said. BHP is investing in the Middelburg water plant.

Glencore owns a water-treatment plant similar to Anglo’s that began operations in 2010 with a 15 million litre-a-day capacity. It supplies about 20 percent of the drinking water to Hendrina residents. - Bloomberg