The impact of metal transport processes on bioavailability of free and complex metal ions in methanogenic granular sludge

J. Bartacek, F.G. Fermoso, F. Vergeldt, E. Gerkema, J. Maca, H. van As, P.N.L. Lens

Research output: Contribution to journalArticleAcademicpeer-review

10 Citations (Scopus)

Abstract

Bioavailability of metals in anaerobic granular sludge has been extensively studied, because it can have a major effect on metal limitation and metal toxicity to microorganisms present in the sludge. Bioavailability of metals can be manipulated by bonding to complexing molecules such as ethylenediaminetetraacetate (EDTA) or diethylenetriaminepentaacetate (DTPA). It has been shown that although the stimulating effect of the complexed metal species (e.g. [CoEDTA]2-) is very fast, it is not sustainable when applied to metal-limited continuously operated reactors. The present paper describes transport phenomena taking place inside single methanogenic granules when the granules are exposed to various metal species. This was done using magnetic resonance imaging (MRI). The MRI results were subsequently related to technological observations such as changes in methanogenic activity upon cobalt injection into cobalt-limited up-flow anaerobic sludge blanket (UASB) reactors. It was shown that transport of complexed metal species is fast (minutes to tens of minutes) and complexed metal can therefore quickly reach the entire volume of the granule. Free metal species tend to interact with the granular matrix resulting in slower transport (tens of minutes to hours) but higher final metal concentrations.
Original languageEnglish
Pages (from-to)1875-1881
JournalWater Science and Technology
Volume65
Issue number10
DOIs
Publication statusPublished - 2012

Keywords

  • waste water treatment
  • bioreactors
  • anaerobic conditions
  • granular sludge
  • bioavailability
  • metals
  • toxicity
  • magnetic resonance imaging
  • magnetic-resonance
  • dynamics
  • immobilization
  • biofilm
  • nickel

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