Modelling performance evaluation of microbial desulphurization of Waterberg steam coal in CSTR

Abstract

The first part of this study used microbial desulphurization process as a pre-combustion technique for sulphur content reduction in Waterberg steam coal. This is simulated at the laboratory scale where Continuously Stirred Tank Reactor (CSTR) acts as a biological reaction chamber. Experimental tests were performed by varying coal particle size distribution of -0.85 mm, +1.00 mm, +2.30 mm and 4.60 mm in order to determine the influence and optimum condition for desulphurization process. The second part of this study deals with developing a model based on reaction kinetics, simulate microbial desulphurization process in CSTR system and validate the model under various experimental conditions. Kinetics study and parameter estimations were evaluated and optimized using the Simulation Programme for Aquatic Systems (AQUASIM) 2.0 Software. The average kinetic parameters in the bioreactor were determined for both without inhibition: kd = 1.65 x 10-3 (h-1), Ks = 1.23 x 10-4 mgL-1, X0 = 523 mgL-1 and χ2 = 0.524 and with inhibition, KI = 371 mgL-1 for finer coal particle size. Equally important, these kinetic parameters were determined by means of optimization. Consideration should be given that the developed model may be applied to only wider range of sulphur content range studied.