Evaluation of microbial reduction of Fe(III)EDTA in a chemical absorption-biological reduction integrated NOx removal system

Wei Li, Cheng Zhi Wu, Shi Han Zhang, Ke Shao, Yao Shi

Research output: Contribution to journalArticlepeer-review


A chemical absorption-biological reduction integrated process can be used to remove nitrogen oxides (NOx) from flue gas. In such a process, nitric oxide (NO) can be effectively absorbed by the ferrous chelate of ethylenediaminetetraacetate (Fe(II)EDTA) to form Fe(II)EDTA-NO, which can be biologically regenerated by denitrifying bacteria. However, in the course of these processes, part of the Fe-(II)EDTA is also oxidized to Fe(III)EDTA. The reduction of Fe(III)EDTA to Fe(II)EDTA depends on the activity of iron-reducing bacteria in the system. Therefore, the effectiveness of the system relies on how to effectively bioreduce Fe-(III)EDTA and Fe(II)EDTA-NO in the system. In this paper, a strain identified as Escherichia coli FR-2 (iron-reducing bacterium) was used to investigate the reduction rate of Fe-(III)EDTA. The experimental results indicate that Fe(II)-EDTA-NO and Fe(II)EDTA in the system can inhibit both the FR-2 cell growth and thus affect the Fe(III)EDTA reduction. The FR-2 cell growth rate and Fe(III)EDTA reduction rate decreased with increasing Fe(II)EDTA-NO and Fe(II)-EDTA concentration in the solution. When the concentration of Fe(II)EDTA-NO reached 3.7 mM, the FR-2 cell growth almost stopped. A mathematical model was developed to explain the cell growth and inhibition kinetics. The predicted results are close to the experimental data and provide a preliminary evaluation of the kinetics of the biologically mediated reactions necessary to regenerate the spent scrubber solution.

Original languageEnglish (US)
Pages (from-to)639-644
Number of pages6
JournalEnvironmental Science and Technology
Issue number2
StatePublished - Jan 15 2007
Externally publishedYes

ASJC Scopus subject areas

  • Chemistry(all)
  • Environmental Chemistry


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