Document Type : Original Research Paper
Department of Biotechnology & Bioengineering CINVESTAV-IPN, Instituto Politécnico Nacional 2508, San Pedro Zacatenco, 07360 México, D.F.
Chemical and Biochemical Engineering Division, Tecnológico de Estudios Superiores de Ecatepec, Tecnológico, 55210, Valle de Anáhuac, Ecatepec de Morelos, Estado de México
In this work, an unstructured-type mathematical model was developed to simulate
cadmium (Cd2+) removal by Desulfovibrio alaskensis 6SR, which is a recently described sulfate
reducing bacterium, whose capacity for removing heavy metals are being studied. Three processes
are considered in the model: 1) the sulfate reduction process, 2) the consumption of lactate as
carbon source, and 3) the metal removal. The model was tested with different initial Cd2+ concentrations
(50, 100, 170, and 190 mg/L), and it accurately predicted the behavior of experimental data with
satisfactory correlation coefficients (R2>0.97). In addition, the model showed that the H2S production
rate and initial concentration of Cd2+ are key operating variables in a bioreactor. Desulfovibrio
alaskensis 6SR was able to remove more than 99.9% of cadmium in a batch process, where the initial
concentration was 170 mg/L. The model, applied to a continuous process, predicted a maximum Cd2+
removal of 99.1% with the same initial concentration. Also, the model predicted the inhibitory effect
of initial Cd2+ concentrations above 190 mg/L. The mathematical model developed can be used for
optimization and control purposes.