Sulphate Reduction Processes in Biological Permeable Reactive Barriers: Column Experimentation and Modeling

In this work a mathematical model for simulating biological sulphate reduction processes was developed and validated by experimental data in fixed bed columns as lab-scale representations of permeable reactive barriers (PRBs). The model takes in consideration transport and adsorption of sulphate and heavy metals, sulphate bioreduction, bioprecipitation and chemical precipitation of metals. Firstly, the effect of sorption capacity of solid phase of column filling versus the effect of active biological mechanisms on solute removal was isolated denoting the significant contribution of sorption versus bioprecipitation of heavy metals. Subsequently, the mathematical model was validated using experimental data from laboratory column experiments and a good agreement between experimental data and simulation results was obtained. Sensitivity analysis of dynamic model showed that, after steady state was reached, parameter related to biological sulphate reduction affected the model output in the most significant way.