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Title: Isotopic evidence of nitrate degradation by a zero-valent iron permeable reactive barrier: Batch experiments and a field scale study
Author: Grau Martínez, Alba
Torrentó Aguerri, Clara
Carrey Labarta, Raúl
Soler i Gil, Albert
Otero Pérez, Neus
Keywords: Desnitrificació
Hidrologia d'aigües subterrànies
Groundwater hydrology
Issue Date: 11-Jan-2019
Publisher: Elsevier B.V.
Abstract: Permeable reactive barriers (PRBs) filled with zero-valent iron (ZVI) are a well-known remediation approach to treat groundwater plumes of chlorinated volatile organic compounds as well as other contaminants. In field implementations of ZVI-PRBs designed to treat these contaminants, nitrate consumption has been reported and has been attributed to direct abiotic nitrate reduction by ZVI or to denitrification by autochthonous microorganisms using the dissolved hydrogen produced from ZVI corrosion. Isotope tools have proven to be useful for monitoring the performance of nitrate remediation actions. In this study, we evaluate the use of isotope tools to assess the effect of ZVI-PRBs on the nitrate fate for the further optimization of full-scale applications. Laboratory batch experiments were performed using granular cast ZVI and synthetic nitrate solutions at pH 4-5.5 or nitrate-containing groundwater (pH = 7.0) from a field site where a ZVI-PRB was installed. The experimental results revealed nitrate attenuation and ammonium production for both types of experiments. In the field site, the chemical and isotopic data demonstrated the occurrence of ZVI-induced abiotic nitrate reduction and denitrification in wells located close to the ZVI-PRB. The isotopic characterization of the laboratory experiments allowed us to monitor the efficiency of the ZVI-PRB at removing nitrate. The results show the limited effect of the barrier (nitrate reduction of less than 15-20%), probably related to its non-optimal design. Isotope tools were therefore proven to be useful tools for determining the efficacy of nitrate removal by ZVI-PRBs at the field scale.
Note: Versió postprint del document publicat a:
It is part of: Journal of Hydrology, 2019, vol. 570, p. 69-79
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ISSN: 0022-1694
Appears in Collections:Articles publicats en revistes (Mineralogia, Petrologia i Geologia Aplicada)

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