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University
31 August 2021

THE USE OF PERVIOUS CONCRETE OFFERS A PROMISING ALTERNATIVE METHOD FOR THE TREATMENT OF POLLUTED OR

Dr Shabalala's research interests include mine water treatment, water quality monitoring and wastewater treatment. She has worked on various research projects including surface and groundwater sampling and monitoring, acid mine drainage treatment; socio-economic impacts of mine closure; heavy metal contamination, and health risks of soils and vegetables grown near mining areas.

The thesis for her PhD produced four published research articles and three conference presentations. Dr Shabalala tells us more about how her study will contribute to the reduction of environmental problems related to mine effluent discharge. 

What prompted your thesis?

The production of Acid Mine Drainage (AMD) usually contains high concentrations of metals, sulphates, salts, and radioactive materials which, if left untreated, can contaminate ground and surface watercourses, damaging the health of plants, humans, wildlife, and aquatic species.

Traditionally, the treatment of AMD consists of its neutralization with limestone or similar materials. However, the high cost of AMD remediation has resulted in the search for alternative liming substitutes which are low cost, readily available, and easily regenerated. My thesis seeks to provide a solution to these challenges through the investigation of a pervious concrete permeable reactive barrier (PRB) as an alternative treatment method for acidic mine water.

The research was aimed at showing that pervious concrete can be effective in treating acidic mine water by efficiently removing undesirable contaminants in the polluted water. Upon treatment, the mine water would meet the water quality standards for discharge of effluents to the environment and can be re-used without causing adverse impacts on the environment.

The applicability of pervious concrete reactive barrier treatment technology in South Africa has not been developed and is not well understood, therefore the findings of this study contribute to significant advances in understanding of the methods and potential application of concrete PRBs. The knowledge gained could be used to inform policy and decision making in responding to the AMD threat and to influence legislations affecting waste management.

What do your research findings mean?

My findings demonstrate that the use of pervious concrete offers a promising alternative method for the treatment of polluted or acidic mine water. The versatility of pervious concrete is anticipated to generate potential remedial measures that not only clean-up contaminated water and soils but also provide the technology for reclamation of disused land due to mining.

The study provides the scientific basis for innovative use of pervious concrete technology, towards reducing water stress and supporting irrigated agriculture. Mine water reuse can be a viable source of agricultural water supply that could contribute to the conservation of water resources and to reduction of environmental problems related to effluent discharge into water bodies.

Pervious concrete permeable reactive barrier system is a potentially novel and effective AMD treatment system. Concrete is a predominant construction material. Its cost-effectiveness may be exploited to provide economic treatment of AMD.

How will your research help to combat water scarcity in South Africa?

Mine water treated with pervious concrete can be a viable source of agricultural water supply that could contribute to the conservation of water resources and to reduction of environmental problems related to effluent discharge into water bodies. The pervious concrete technology could be used towards reducing water stress and supporting irrigated agriculture.

Furthermore, my research shows that pervious concrete can be effective in treating polluted mine water to meet the national limits applicable to the discharge of wastewater into a water resource without causing adverse impacts. Thus, the pervious concrete-treated mine water could also be used to replenish water systems.

Water pollution is a major global concern, will your research findings play a role in addressing this issue?

The scale of the AMD problem in South Africa and worldwide is enormous. AMD is associated with deterioration of soils, surface, and groundwater quality. Current technologies for the active treatment of AMD have the disadvantages of high capital cost, high operation and maintenance costs, making their implementation unsustainable.

The use of pervious concrete- reactive barriers offers a sustainable alternative treatment solution with cost-benefit advantages and the potential to remove heavy metals present in polluted mine water.

@ Story by Cleopatra Makhaga. Picture Supplied.