Microbial Desulphurization of Combustion Coal and Environmental Control in Carbonization Coal : Emissions Reduction Techniques

Abstract

Coal use in electricity generation has attracted much attention recently mainly due to the sector been identified as the main source of sulphur dioxide (SO2) emissions globally. The combustion of coal releases sulphur dioxide emissions into the atmosphere that create air pollution and cause harmful effects on the ecosystem. In the current study, biodesulphurization of Waterberg steam coal was investigated using a bacterial consortium isolated from coal. Coal samples were obtained from the coal feed into the power plant mills, by auto sampling equipment. Coal samples with various particle size fraction of +4.60 mm, −4.60 + 2.30 mm, −2.30 + 1.00 mm and −0.85 mm were used in the biodesulphurization experiments. The characteristic properties of the coal samples were analysed by means of a number of techniques, including Leco S-628 Elemental analyser, UV Spectrophotometry, bomb calorimeter and X-Ray Fluorescence. The contribution of this study to the country's minimum emissions requirements and compliance could be outlined as follows: Coal was classified as medium sulphur coal when the sulphur content was detected in the range 1.15 – 1.49 wt.%. Four forms of sulphur - pyrite, mineral/sulphide sulphur, inorganic sulphates and organic sulphur were present in Waterberg coal with pyritic sulphur (≥ 0.51 wt.%) and organic sulphur (≥ 0.49 wt.%) accounting for the bulk of the total sulphur in coal.