Simultaneous nitrate and chromium removal mechanism in a pyrite-involved mixotrophic biofilter

文献类型： 外文期刊

第一作者： Zhang, Haigeng

作者： Zhang, Haigeng;Zhang, Yulei;Xu, Zhongshuo;Zhou, Panpan;Wang, Yuhui

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关键词： Nitrate; Cr(VI); Pyrite; Mixotrophic; Biofilter

期刊名称：ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH （ 影响因子：5.8； 五年影响因子：5.4 ）

ISSN： 0944-1344

年卷期： 2023 年 30 卷 59 期

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收录情况： SCI

摘要： Microbially mediated NO3--N and Cr(VI) reduction is being recognized as an eco-friendly and cost-effective remediation strategy. Iron sulfide mineral, as a natural inorganic electron donor, has a strong influence on NO3--N and Cr(VI) transformation, respectively. However, little is known about the simultaneous nitrate and chromium removal performance and underlying mechanism in an iron sulfide mineral-involved mixotrophic biofilter. This study demonstrated that the NO3--N and Cr(VI) removal efficiencies were stable at 62 +/- 8% and 56 +/- 10%, and most of them were eliminated in the 0-100-mm region of the biofilter. Cr(VI) was reduced to insoluble Cr(III) via microbial and chemical pathways, which was confirmed by the SEM-EDS morphology and the XPS spectra of biofilm and pyrite particles. SO42- was as a main byproduct of pyrite oxidation; however, the bacterial SO42- reduction synchronously occurred, evidenced by the variations of TOC and SO42- concentrations. These results suggested that there were complicated and intertwined biochemical relations between NO3--N/Cr(VI)/SO42-/DO (electron acceptors) and pyrite/organics (electron donors). Further investigation indicated that both the maximal biomass and greatest denitrifiers' relative abundances in microbial sample S1 well explained why the pollutants were removed in the 0-100-mm region. A variety of denitrifiers such as Pseudoxanthomona, Acidovorax, and Simplicispira were enriched, which probably were responsible for both NO3--N and Cr(VI) removal. Our findings advance the understanding of simultaneous nitrate and chromium removal in pyrite-involved mixotrophic systems and facilitate the new strategy development for nitrate and chromium remediation.

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