Abstract
The use of coal in South Africa, primarily for the generation of electricity, is probably not going to change significantly in the next few decades owing to the abundance of coal resources and a lack of suitable alternatives to coal. However, the use of this fossil fuel is one of the prime anthropogenic activities which may result in severe environmental pollution through the release of greenhouse gases, toxic metals (Cd, Cr, Pb, Zn), and metalloids (As, Se). An element of particular interest that derives from coal combustion is selenium (Se). Selenium is essential to living organisms at concentrations between 20 µg/L to 100 µg/L per day. Levels greater than 200 µg/L per day are toxic and toxicity depends on its chemical form or species. This study aimed to establish the total dissolved Se and inorganic Se species in wastewaters from selected ESKOM (South African electricity public utility) coal-fired power plants and natural waters from selected rivers. The Se levels were also determined in wastewater from a coal-mine in Lower Germiston. From a mass balance perspective, selenium was also determined in raw coal samples. A microwave-assisted digestion procedure (using HNO3/H2O2) was used for the dissolution of coal samples and a Standard Reference Material (SARM 20) used to check the accuracy of the total Se data.
M.Sc. (Chemistry)