科研之友
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摘要
In order to improve the efficiency of Cr(Ⅵ) bioreduction and fixation and to achieve rapid and effective removal of Cr(Ⅵ) pollutants in groundwater, the method of adding clay minerals and electron shuttle was adopted. The effects of iron-bearing clay mineral NAu-2 alone, electron shuttle AQDS alone and their both on the bioreduction and fixation of Cr(Ⅵ) with different concentrations of 0.1~2.0 mmol·L?1 in groundwater by metal-reducing bacteria Shewanella oneidensis MR-1 were explored. The results showed that NAu-2 alone addition have no effect on the promotion of Cr(Ⅵ) bioreduction, while AQDS alone addition could promote the bioreduction of Cr(Ⅵ) with different concentrations of 0.1~2.0 mmol·L?1, and the enhancement factor reached 1.33~3.90. With simultaneous addition of NAu-2 and AQDS, the enhancement of bioreduction was significantly elevated for Cr(Ⅵ) with different concentrations, and the enhancement factor reached 2.02~10.49. In addition, compared with the synergistic effects for bioreduction of Cr(Ⅵ) with different concentrations by MR-1 under the coexistence of AQDS and NAu-2, synergistic effect didn't occur at low Cr(Ⅵ) contents of 0.1~0.5 mmol·L?1 with the synergistic factor lower than 1.0; while a significant synergistic effect occurred at medium and high Cr(Ⅵ) contenta of 0.8~2.0 mmol·L?1 with the synergistic factor higher than 1.0, and at the concentration of 1.2 mmol·L?1, the most significant synergistic effect occurred with the synergistic factor=2.98. This indicated that there were big differences in synergistic effect for the bioreduction of Cr(Ⅵ) among the medium and high concentrations. This study provides new remediation thought and reference data for the Cr(Ⅵ) contaminated sites through investigating the process and mechanism of Cr(Ⅵ) migration and transformation in the NAu-2, AQDS and MR-1 coexisting complex system under different concentrations of Cr(Ⅵ).
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