Document Type : Original Research Paper
Authors
1
Shahid Chamran University of Ahvaz
2
Department of Biology, Faculty of Sciences, Shahid Chamran University of Ahvaz, Ahvaz, Iran
3
Natural Resources and Environmental Engineering, Faculty of Chemistry, Razi University of Kermanshah, Kermanshah, Iran
10.22059/poll.2025.397632.3000
Abstract
This study evaluated the effectiveness of microbial-induced carbonate precipitation (MICP) in immobilizing heavy metals, using the most resistant bacterial strain isolated from petroleum-contaminated soil. Among the 16 strains isolated from soil near oil wells in Khuzestan, Iran, Citrobacter sp. strain PO2 was identified as the most effective in stabilizing a mixture of highly toxic heavy metals. The strain has been deposited in the NCBI database under accession number PP864728. The analysis was performed using inductively coupled plasma optical emission spectrometry (ICP-OES), scanning electron microscopy (SEM), and energy-dispersive spectroscopy (EDS) techniques. The results showed that the isolated bacterium removed 96.08% of copper, 97.47% of zinc, 99.89% of lead, 72.60% of cadmium, and 60.59% of nickel from a medium containing a mixture of heavy metals at a concentration of 800 mg/L, after 24 hours of incubation at 30 °C. At a concentration of 1500 mg/L, the bacterial strain removed 93.56%, 94.64%, and 97.59% of copper, zinc, and lead, respectively, from the mixed heavy metal solution, while no significant removal of cadmium and nickel was observed at this concentration. At a concentration of 1200 mg/L, bacterial removal efficiencies were 22.07% for cadmium and 6.29% for nickel, respectively. The toxicity of the heavy metals was ranked as follows: Pb > Cu = Zn > Cd > Ni. The MICP process thus represents a promising biological approach for stabilizing heavy metals, offering significant potential for applications in ecological restoration.
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