In situ remediation of Cr(VI) contaminated groundwater by ZVI-PRB and the corresponding indigenous microbial community responses: a field-scale study

The performance of a permeable reactive barrier (PRB) for the in situ remediation of hexavalent chromium [Cr(VI)] contaminated groundwater, and the resulted responses in the indigenous microbial community, were investigated in a field-scale study. The PRB consisted of a mixture of zero-valent iron (...

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Bibliographic Details
Published in:	The Science of the total environment 2022-01, Vol.805, p.150260-150260, Article 150260
Main Authors:	Wang, Qing, Song, Xin, Wei, Changlong, Jin, Peng, Chen, Xing, Tang, Zhiwen, Li, Kang, Ding, Xiaoyan, Fu, Heng
Format:	Article
Language:	eng
Subjects:	Cr(VI) reduction Groundwater Indigenous microbial community Permeable reactive barrier Zero-valent iron
Online Access:	Get full text
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Summary:	The performance of a permeable reactive barrier (PRB) for the in situ remediation of hexavalent chromium [Cr(VI)] contaminated groundwater, and the resulted responses in the indigenous microbial community, were investigated in a field-scale study. The PRB consisted of a mixture of zero-valent iron (ZVI), gravel and sand. The results showed that the PRB segment with 20% active reaction medium (ZVI) was able to successfully reduce Cr(VI) via chemical reduction from 27.29–242.65 mg/L to below the clean-up goal of 0.1 mg/L, and can be scaled-up under field conditions. It was found that the ZVI induced significant changes in the indigenous microbial community structure and compositions in the area of the PRB and those areas downgradient. The competitive growth among Cr(VI)-reducing bacteria (the reduced abundance of Hydrogenophaga, Pseudomonas, Exiguobacterium and Rhodobacter, along with the enrichment of Rivibacter and Candidatus_Desulforudis) were observed in PRB. In addition, Cr(VI)-reducing bacteria (Hydrogenophaga, Pseudomonas, Exiguobacterium and Rhodobacter) were enriched in the downgradient of PRB, indicating that Cr(VI) can be further bio-reduced to Cr(III). The Cr(VI) bio-reduction could serve as a secondary mechanism for further removal of Cr(VI) from contaminated groundwater, suggesting that the actual lifetime of a PRB can be prolonged, which is important for the design and economic assessment of a PRB. Further analysis revealed that pH, dissolved oxygen, Cr(VI) level, the oxidation-reduction potential, and temperature were the main environmental factors influencing the subsurface microbial community compositions. [Display omitted] •ZVI in PRB successfully reduced high concentrations of Cr(VI) to Cr(III) in situ.•ZVI induced competitive growth of the Cr(VI)-reducing bacteria in the PRB.•Enrichment of Cr(VI)-reducing bacteria was observed downgradient of the PRB.•Cr(VI) bioreduction could serve as a secondary mechanism for Cr(VI) removal.
ISSN:	0048-9697 1879-1026