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Analysis of the bacterial sulphur system
Journal article   Open access   Peer reviewed

Analysis of the bacterial sulphur system

R.M. Candy, K.R. Blight and D.E. Ralph
Advanced Materials Research, Vol.825, pp.190-193
2013
DOI: https://doi.org/10.4028/www.scientific.net/AMR.825.190
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Abstract

Heterogeneous bacterial sulphur systems are inherently complicated. However, developing an understanding of the influence of environmental factors such as pH, I and PCO2 is important for a number of fields. Examples of these include minimising acid mine drainage and maximising metal recovery from low-grade sulphide minerals. Measuring the effect of these factors on sulphur (S) oxidation is complicated by the presence and nature of solid phase elemental S. The rate and extent of S oxidation can be determined indirectly via the reaction product, H2SO4, which was quantified using pH measurements in this study. The method was critically dependent on the quality of pH data but proved effective in providing rate constants for the catalysed S oxidation reaction and yield (biomass/substrate) estimates in the range pH > 1.5. Increasing I over the range 0.176 - 0.367 mol L-1 decreased bacterial cell yields but increased the rate of sulphur oxidation significantly. Partial pressures of CO2 in the range of 0.039 - 1.18% v/v produced no significant effect on the rates of S oxidation or bacterial cell yields. Bacterial cell yields were not affected in the pH range 1.5 - 2.5, however the rate of S oxidation increased significantly from pH 2.0 - 2.5. In the range pH < 1.5 the batch cultures progressed and although no reliable pH data were recorded, cell yields decreased from 7.43 × 1012 to 2.05 × 1012 cells mol-1 at pH 1.5 to1.0 respectively.

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