Concern about how surface- and groundwater are polluted by acid mine drainage (AMD) has prompted an Eskom Expo for Young Scientists finalist to create a cost-effective and environment-friendly baffle unit that increases the retention time in water treatment facilities.
“South Africa is driven by a strong mining industry, resulting in the discharge of highly acidic water into the country’s water systems. The flow of the acidic water causes AMD, which is formed when pyrite is exposed during mining operations and comes into contact with oxygenated water,” says finalist from Ladysmith High School grade 8 learner Thajna Sewparsad.
As a result, she adds, the oxidation of pyrite is characterised by the generation of sulphuric acid and dissolved iron.
Consequently, Sewparsad’s invention of the baffle unit is based on laboratory trials, which were conducted to determine the volume of calcium hydroxide needed to neutralise AMD water to a pH 7 level.
Having taken a sample of AMD, Sewparsad says, she used calcium hydroxide on the AMD water in order to increase the pH level, which would, in turn, cause a precipitation of calcium sulphate. Also, the experiment aimed at oxidising the iron present in the AMD so that it formed ferric hydroxide.
The baffle unit system was shown to present an ideal solution for AMD.
“Not only did it work, but it proved to be a beneficial system as it is an open system – it is stationary, requires less maintenance, boasts easy sludge removal, needs no electricity to function, the inflow is controlled through gravity, and no qualified staff are needed to work on the unit,” she points out.
She also indicates that, should baffle units be used on mining sites, it would be ideal to have sludge-drying beds or small slime dams, as well as weep holes that will allow for the draining of access water contained in the sludge to take place.
After drainage, the sludge will contain mainly calcium sulphate – which is also known as agri cultural lime. This means that the calcium sulphate can then be used on agricultural lands before planting, which makes it a viable option for land rehabilitation.
“This process also creates jobs for local communities as the dried sludge can be collected and sold to local farmers to use in their soil before planting,” Sewparsad highlights.
Being adamant that the baffle unit will present a solution for the AMD crisis in the country, she notes that she hopes more government departments take note of her project so that further research may be conducted. In this way, the solution will develop further to support the efficiency of the unit.
Highly impressed by the talented young scientists in the country, Science and Technology Minister Naledi Pandor mentioned during the Expo, which was held earlier this month, that through such innovations, she believed South Africa was strengthened as young learners continued to showcase their scientific abilities.
State-owned electricity utility Eskom chairperson Zola Tsotsi stated during the Expo that, through such innovation, the “shackles of poverty are broken and wealth is created” as the learners have the power to create a better future for the poor through their innovations.
The three-day Expo presented 88 gold awards, 176 silver awards, 253 bronze awards and 151 highly commended awards to the learners, who came from all nine provinces in the country and various other countries in the world.
This year also witnessed a total of 477 female participants and 345 male participants.
“South Africa wants to establish itself as a hub of science research and excellence. As a result, we need to produce outstanding scientists, researchers and technicians and attract top talent from around the world. “By hosting young scientist through the expo, we are exposing them to the world of science in South Africa and are starting to make the vision a reality,” said Eskom Expo executive director Parthy Chetty.