Mpeta M., Tendenedzai J.T., Tabana L., Tichapondwa S., Chirwa E., 2026, Kinetic Modelling of Microbial Au (III) Reduction by an Indigenous Bacterial Consortium, Chemical Engineering Transactions, 127, 295-300.
Gold mining effluents containing toxic Au (III) ions (typically 3–6 mg/L) present significant environmental and health risks. Conventional chemical recovery methods remain energy-intensive and generate secondary waste. This study developed and validated predictive kinetic models for microbial gold reduction using a specialized bacterial consortium. The consortium isolated from gold mine tailings comprised of Stenotrophomonas maltophilia, Klebsiella pneumoniae, Acinetobacter bereziniae, and Bacillus cereus. Aerobic batch bioreactors operating at 35°C compared synthetic wastewater (mineral salt medium (MSM) with HAuCl4 at different concentrations of 1.5, 3 and 6 mg/L. Au (III) depletion was quantified by ICP-OES and AAS, while Au (0) nanoparticle formation was verified via X- ray diffraction (XRD), Scanning Electron Microscopy (SEM) with Energy-Dispersive X-ray Spectroscopy (EDS) and Transmission Electron Microscopy (TEM), revealing predominantly spherical particles (15–70 nm). The bacterial consortium achieved 87-99 % Au (III) reduction in synthetic wastewater within 24 h. Experimental data were fitted to a pseudo-first-order model using AQUASIM software (0.726 > R² > 0.97), providing a predictive description of Au (III) depletion in environmentally relevant concentrations.
