Recent developments in reduction of sulphur emissions from selected Waterberg coal samples used in South African power plants

Abstract

Sulphur content in the coal is the most notorious environmental contaminant, which produces sulphur dioxide (SO2) during combustion. In this study, the sulphur content of the parent coal samples reduced through biodesulphurization treatment and its influence on the SO2 emissions concentration in a power plant was monitored. Coal samples were screened to a particle size fraction of – 0.85 mm, – 2.30 + 1.00 mm, – 4.60 + 2.30 mm and +4.60 mm prior to biodesulphurization treatment. Data used in this study comprised of average 2 daily interval sulphur content and SO2 emissions concentrations for the period 0 to 20 Days. The finer fraction of – 0.85 mm showed a significant reduction of sulphur content from 1.45 wt% to 0.50 wt% which translate to SO2 emissions concentration reduction from 3716 mg/Nm3 to 1280 mg/Nm3. However, when the temperature was increased from 23 ± 3 °C to 30 ± 2 °C, further reduction of SO2 emissions to 1023 mg/Nm3 was realized. Biodesulphurization treatment demonstrated to lower SO2 emissions by 72.4% and reduce ash content by some 33%. Moreover, pyrite was observed in vitrinite and inertinite, both syngenetically and epigenetically. The current study offers the possibility of reducing SO2 emissions in South African power plants through biodesulphurization treatment.