Alesia F., Chirwa E., 2015, Optimisation Process of Sulphur Recovery Using a Two-Step Biological System, Chemical Engineering Transactions, 45, 607-612.
The production of elemental sulphur (S0) during treatment of Acid Mine Drainage is regarded as a sustainable solution since the produced elemental sulphur can be re-used for bioleaching processes or as fertilisers. Biological treatment of AMD primarily relies on the activity of sulphate reducing bacteria which reduce sulphate to sulphide in the presence of organic matter thus allowing the precipitation of the metals and increase in pH. However, excess of sulphide remains in the system and if not removed, can be oxidised to sulphate. The objective of the study was to optimise the oxidation process of sulphide to elemental sulphur in a batch reactor with glucose as the supplied carbon source. The study also describes the sulphide oxidation process to elemental sulphur as a Monod-type model with best-fit model parameters estimated. Up to 95 % of elemental sulphur was formed at pH 8 and Eh -80 mV. The mass balance calculations confirmed the results. The redox potential was observed to have a greater effect to the oxidation process compared to pH. This was later confirmed by the modelling results.
