Mathematical Modelling of the Effects of Aerobic and Anaerobic Chelate Biodegradation on Actinide Speciation

J. E. Banaszak, J. M. VanBriesen, Bruce Rittmann, D. T. Reed

Research output: Contribution to journalArticle

11 Citations (Scopus)

Abstract

Biodegradation of natural and anthropogenic chelating agents directly and indirectly affects the speciation, and hence, the mobility of actinides in subsurface environments. We combined mathematical modelling with laboratory experimentation to investigate the effects of aerobic and anaerobic chelate biodegradation on actinide [Np(IV/V), Pu(IV)] speciation. Under aerobic conditions, nitrilotriacetic acid (NTA) biodegradation rates were strongly influenced by the actinide concentration. Actinide-chelate complexation reduced the relative abundance of available growth substrate in solution and actinide species present or released during chelate degradation were toxic to the organisms. Aerobic bioutilization of the chelates as electron-donor substrates directly affected actinide speciation by releasing the radionuclides from complexed form into solution, where their fate was controlled by inorganic ligands in the system. Actinide speciation was also indirectly affected by pH changes caused by organic biodegradation. The two concurrent processes of organic biodegradation and actinide aqueous chemistry were accurately linked and described using CCBATCH, a computer model developed at Northwestern University to investigate the dynamics of coupled biological and chemical reactions in mixed waste subsurface environments. CCBATCH was then used to simulate the fate of Np during anaerobic citrate biodegradation. The modelling studies suggested that, under some conditions, chelate degradation can increase Np(IV) solubility due to carbonate complexation in closed aqueous systems.

Original languageEnglish (US)
Pages (from-to)445-451
Number of pages7
JournalRadiochimica Acta
Volume82
Issue number1
StatePublished - 1998
Externally publishedYes

Fingerprint

Actinoid Series Elements
biodegradation
Actinides
Biodegradation
chelates
Complexation
degradation
Nitrilotriacetic Acid
experimentation
releasing
citrates
organisms
Degradation
radioactive isotopes
Poisons
Carbonates
carbonates
chemical reactions
Substrates
solubility

Keywords

  • Actinides
  • Biodegradation
  • Biological effects
  • Chelates
  • Coupled modelling
  • Speciation

ASJC Scopus subject areas

  • Inorganic Chemistry
  • Nuclear Energy and Engineering

Cite this

Mathematical Modelling of the Effects of Aerobic and Anaerobic Chelate Biodegradation on Actinide Speciation. / Banaszak, J. E.; VanBriesen, J. M.; Rittmann, Bruce; Reed, D. T.

In: Radiochimica Acta, Vol. 82, No. 1, 1998, p. 445-451.

Research output: Contribution to journalArticle

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