Impact of microbial activities on the mineralogy and performance of column-scale permeable reactive iron barriers operated under two different redox conditions

Van Nooten, Thomas; Lieben, François; Dries, Jan; Pirard, Eric; Springael, Dirk; Bastiaens, Leen

doi:10.1021/ES070027J

Title

Impact of microbial activities on the mineralogy and performance of column-scale permeable reactive iron barriers operated under two different redox conditions

Author

Van Nooten, Thomas

Lieben, François

Dries, Jan

Pirard, Eric

Springael, Dirk

Bastiaens, Leen

Abstract

The present study focuses on the impact of microbial activities on the performance of various long-term operated laboratory-scale permeable reactive barriers. The barriers contained both aquifer and Fe0 compartments and had received either sulfate or iron(III)-EDTA to promote sulfatereducing and iron(III)-reducing bacteria, respectively. After dismantlement of the compartments after almost 3 years of operation, DNA-based PCR-DGGE analysis revealed the presence of methanogenic, sulfate-reducing, metalreducing, and denitrifying bacteria within as well as up- and downgradient of the Fe0 matrix. Under all imposed conditions, the main secondary phases were vivianite, siderite, ferrous hydroxy carbonate, and carbonate green rust as found by scanning electron microscopy (SEM) combined with energy dispersive X-ray analysis (EDX), and X-ray diffraction (XRD). Under sulfate-reduction promoting conditions, iron sulfides were formed in addition, resulting in 7 and 10 times higher degradation rates for PCE and TCE, respectively, compared to unreacted iron. These results indicate that the presence of sulfate-reducing bacteria in or around iron barriers and the subsequent formation of iron sulfides might increase the barrier reactivity.

Language

English

Source (journal)

Environmental science and technology / American Chemical Society. - Easton, Pa

Publication

Easton, Pa : 2007

ISSN

0013-936X [print]

1520-5851 [online]

DOI

10.1021/ES070027J

Volume/pages