Thabo Mohlala
A research project to decontaminate and rehabilitate water polluted by the coal mining activities in eMalahleni, Mpumalanga, has received a major financial boost from the Water Research Commission (WRC).
The project was established in 2019 and will receive be funded to the tune of R2.7 million. Chemical and Water and Sanitation researchers will be leading the initiative. It will operate under the theme: “Treatment of mine water for the recovery of drinking water and saleable products,” andaims to explore cost-effective ways of refining mine waste and other industrial wastes into drinking water and saleable products.
The project involves Johannes Maree, professor in the University of Limpopo (UL)’s department of water and sanitation as project Leader. He is ably assisted by two PhD candidates in chemistry as research assistants, namely Conny Mokgohloa and Tumelo Mogashane. Also included are researchers from the University of Pretoria (UP) and ROC Water Technologies which offers research and development support to postgraduate students involved in the water project.
Professor Maree said the project demonstrate that drinking water and saleable products such as pigment can be recovered from iron-rich acid mine water. “The process offers a cost-effective solution to the treatment of mine and other industrial effluents to mitigate South Africa’s water shortage challenges. In this regard, 500 millilitres of mine water per day could be purified into quality drinking water through the project,” said Professor Maree.
The project is conducted at the Khwezela Colliery in eMalahleni, Mpumalanga province where a 1m3/h demonstration plant is operated to demonstrate that the Reverse Osmosis/Cooling (ROC) process can be used to allow zero waste of mining water.
Expected to end in 2022, the project has found out that acid mine water is a national problem with negative health effects and makes water not to be suitable for downstream users, and it also results in the death of animals.
Water and sanitation senior lecturer at UL, Dr Munyaradzi Mujuru, who is also taking part in the project said that after piloting the project in Witbank, the next step is to move it to the commercialisation stage. Dr. Mujuru said: “The project is in the process of registering a patent for UP and UL and this will benefit the water industry. Hence, there is a need for testing the findings of this research project with other types of effluents from various industries.”
Conny Mokgohloa, one of the research assistants, explained that acid mine water contains high quantities of toxic substances that have harmful effects on ecology and the health of living beings. She said converting it from harmful to a healthy state makes the project more exciting.
Her colleague, Tumelo Mogashane concurred. He said he believes that the most interesting part of the project involves the extraction of heavy metals and toxic contaminants from the acid mine water to recover drinkable water. Said Mogashane: “With the experience acquired from this project, we can develop cost-effective desalination techniques to produce clean water while producing minimum waste.”
The Department of Trade, Industry and Competition (the dtic) through the Technology and Human Resources for Industry Programme (THRIP) also supports the initiative. In early 2012 residents of the town of Carolina were advised after heavy rains hit the area that the water had become unsafe for drinking, cooking including washing clothes.
The advice was based on the investigation carried out by Wits University team which comprised Terence McCarthy, emeritus professor of mineral Geochemistry in the School of Geosciences, and Dr Marc Humphries, an environmental Geochemist in the School of Chemistry., the problem is not only confined to the Mpumalanga, investigated the disaster. Among other findings, McCarthy said the main cause of the pollution was acid mine drainage (AMD), which he described as a major problem not only confined to Mpumalanga. “The AMD is happening everywhere there is mining activity – albeit slowly, he said. McCarthy said the Vaal River system is also in danger of being contaminated, adding that the major culprits are the coal and gold mines. Because of their location in the upper portions of the Vaal River catchment, noted McCarthy, their footprint on the water supply is huge.
