The Council for Scientific and Industrial Research (CSIR) is developing low-cost polymer-based adsorbents for the removal of toxic pollutants such as heavy metals, anions and organics from wastewater, which could be applied in the treatment of acid mine drainage (AMD).
AMD is the outflow of acidic water from mines; it contains toxic metals, has a reduced pH, and has a detrimental impact on water quality and the environment.
“It’s an ecological disaster and many environmentalists are trying to treat this,” CSIR nanocomposites development student Athi Nogqwazi said at the CSIR’s recent Tech Day, in Pretoria, adding that AMD diffused into drinking water and dams and was absorbed by plants.
To address these challenges, the CSIR has developed a range of polymer composite adsorbents that serve as advanced and highly sensitive media for the active removal of pollutants such as heavy metals, ions, organics and oils from water.
The absorbent technology being developed by the CSIR, known as nanoclay, could lead to more feasible alternative treatment technologies to address water quality issues, such as AMD.
“We can de-absorb heavy metals found in AMD using an acid concentrate and sell off some of the heavy metals found in the contaminated water that have been absorbed by the clay, because those metals have commercial value,” he said.
Nogqwazi further stated that the main contributors to the deteriorating water quality in the country were intensive mining and industrial activity, which caused acidity and increased metals content.
Chemical precipitation is typically used for removing heavy metals and anions from water; however, this method produces large volumes of sludge.