Papers by Keyword: Metal Precipitation

Abstract: This paper presents a simple, reliable and extensible dynamic biofilm model. The model simulates the case of Sulfate-Reducing Bacteria (SRB) grown as biofilm on the surface of an inert support material in a completely mixed bioreactor. The principles of microbial stoichiometry and thermodynamics combined with microbial kinetic equations and chemical reactions have been implemented in AQUASIM software. Simulation results predict the biofilm growth, the reactor bulk volume solute concentrations and their corresponding profiles in the biofilm layer. The interaction of metal ions with biogenic sulfide is also discussed as decontamination means for a wastewater stream containing high metal and sulfate concentrations.

Abstract: Biosulfidogenesis (the generation of hydrogen sulfide by microorganisms) in acidic liquors was investigated using two metabolically-distinct bacteria. One was a novel acidophilic sulfate-reducing bacterium (isolate CL4) that grew at pH 3.0 and above using glycerol as electron donor, and the other was the type strain of Acidithiobacillus ferrooxidans which was grown at pH 2.5 using hydrogen (derived from dissolution of metallic iron) as electron donor and elemental sulfur as electron acceptor. Both bacteria were grown in pH-controlled bioreactors. Isolate CL4 mediated the selective precipitation of zinc in situ, while the At. ferrooxidans bioreactor operated as an off-line system, generating hydrogen sulfide that precipitated copper in a separate reaction vessel. The potential of using acidophilic sulfidogens for the selective recovery of metals from acidic waste streams is discussed.