Study on the Remediation of Cd Pollution by the Biomineralization of Urease-Producing Bacteria

Xingqing Zhao, Min Wang, Hui Wang, Ding Tang, Jian Huang and Yu Sun
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Xingqing Zhao: School of Environmental and Safety Engineering, Changzhou University, Changzhou 213164, China
Min Wang: School of Environmental and Safety Engineering, Changzhou University, Changzhou 213164, China
Hui Wang: School of Environmental and Safety Engineering, Changzhou University, Changzhou 213164, China
Ding Tang: School of Environmental and Safety Engineering, Changzhou University, Changzhou 213164, China
Jian Huang: School of Environmental and Safety Engineering, Changzhou University, Changzhou 213164, China
Yu Sun: School of Environmental and Safety Engineering, Changzhou University, Changzhou 213164, China

IJERPH, 2019, vol. 16, issue 2, 1-14

Abstract: Cadmium (Cd) is a highly toxic metal that can affect human health and environmental safety. The purpose of this study was to research the removal of Cd from an environmental perspective. In this article, four highly urease-active strains (CZW-2, CZW-5, CZW-9 and CZW-12) were isolated from an abandoned mine and their phylogenetic trees were analyzed. The maximum enzyme activities, the mineralized precipitate and the removal rates of these strains were compared. The results showed that CZW-2 had the highest urease activity at 51.6 U/mL, and the removal rates of CZW-2, CZW-5, CZW-9 and CZW-12 after 120 h were 80.10%, 72.64%, 76.70% and 73.40%, with an initial concentration of Cd of 2 mM in the Cd precipitation experiments. XRD (X-ray diffractometer), EDS (Energy dispersive spectrometer) and FTIR (Fourier transform infrared spectroscopy) analysis indicated that the mineralized precipitate was CdCO 3 . SEM (Scanning electron microscopy) analysis revealed that the diameter of the oval-shaped mineralized product ranked from 0.5 to 2 μm. These strains were used to remedy Cd-contaminated soil, and five different fractions of Cd were measured. Compared with the control, the results of spraying pre-cultured strains containing 2% urea to remove Cd from contaminated soils showed that the exchangeable fraction of Cd decreased by 53.30%, 27.78%, 42.54% and 53.80%, respectively, whereas the carbonate-bound fraction increased by 55.42%, 20.27%, 39.67% and 34.36%, respectively, after one month. These data show that these strains can effectively reduce the bioavailability and mobility of Cd in contaminated soils. The results indicate that biomineralization based on the decomposition of substrate urea can be applied to remedy heavy contaminated soil and water.

Keywords: biomineralization; urease; heavy metal; sequential extraction; bioremediation (search for similar items in EconPapers)
JEL-codes: I I1 I3 Q Q5 (search for similar items in EconPapers)
Date: 2019
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (4)

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