The effect of microbial FE(III) reduction on smectite flocculation

Jin Wook Kim, Yoko Furukawa, Hailiang Dong, Steven W. Newell

Research output: Contribution to journalArticle

27 Citations (Scopus)

Abstract

This study was undertaken to investigate the changes in flocculation properties of Fe-rich smectite (nontronite, NAu-1) suspensions, including settling velocity, aggregate size and floc architecture associated with microbial Fe(III)-reduction in the smectite structure. The dissimilatory Fe-reducing bacterium Shewanella oneidensis MR-1 was incubated with lactate as the electron donor and structural Fe(III) as the sole electron acceptor for 3, 12, 24 and 48 h in an anaerobic chamber. Two controls were prepared; the first was identical to the experimental treatments except that heat-killed cells were used (non-reduced control), and the second control was the same as the first except that the incubation was carried out in an aerobic environment. The extent of Fe(III) reduction for the 48 h incubation was observed to reach up to 18%. Neither the non-reduced control nor the aerobically inoculated sample showed Fe(III) reduction. Compared with the non-reduced control, there was a 2.7 μm increase in mean aggregate size and a 30-fold increase in average settling velocity in the bioreduced smectite suspensions as measured using a Micromeritics Sedigraph®. The aerobically inoculated smectite showed a similar aggregate-size distribution to that of the non-reduced control. Significant changes in physical properties of smectite suspensions induced by microbial Fe(III) reduction were measured directly using transmission electron microscopy. The floc architecture of bioreduced smectite revealed less open structures compared to those of a non-reduced control. The aspect ratio (thickness/length) of individual smectite particle increased from 0.11 for the non-reduced control to 0.18 on average for the bioreduced smectite suspensions. The effects of pH on the clay flocculation were minimal in this study because the value of pH remained nearly constant at pH = 7.0-7.3 before and after the experiments. We therefore suggest that the increase in net negative charge caused by microbial Fe(III) reduction significantly promoted clay flocculation by increasing the electrochemical attraction in the smectite suspensions.

Original languageEnglish
Pages (from-to)572-579
Number of pages8
JournalClays and Clay Minerals
Volume53
Issue number6
DOIs
Publication statusPublished - 2005 Dec 1

Fingerprint

flocculation
smectite
Flocculation
Suspensions
aggregate size
cell aggregates
settling velocity
clay
Shewanella oneidensis
incubation
electrons
nontronite
effect
Smectite
electron
Electrons
lactates
transmission electron microscopy
Aspect ratio
Lactic Acid

All Science Journal Classification (ASJC) codes

  • Water Science and Technology
  • Soil Science
  • Geochemistry and Petrology
  • Earth and Planetary Sciences (miscellaneous)

Cite this

Kim, Jin Wook ; Furukawa, Yoko ; Dong, Hailiang ; Newell, Steven W. / The effect of microbial FE(III) reduction on smectite flocculation. In: Clays and Clay Minerals. 2005 ; Vol. 53, No. 6. pp. 572-579.
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The effect of microbial FE(III) reduction on smectite flocculation. / Kim, Jin Wook; Furukawa, Yoko; Dong, Hailiang; Newell, Steven W.

In: Clays and Clay Minerals, Vol. 53, No. 6, 01.12.2005, p. 572-579.

Research output: Contribution to journalArticle

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