Reduction of Fe(III)EDTA by Klebsiella sp. strain FD-3 in NOx scrubber solutions

Abstract

Biological reduction of Fe(III) to Fe(II) is a key step in nitrogen oxides (NOx) removal by the integrated chemical absorption–biological reduction method, which determines the concentration of Fe(II) in the scrubbing liquid. A new Fe(III)EDTA reduction strain, named as FD-3, was isolated from mixed cultures used in the integrated NOx removal process and identified as Klebsiella sp. by 16S rDNA sequence analysis. The reduction abilities of FD-3 and the influence of nitrogen-containing compounds (Fe(II)EDTA–NO, NO3- and NO2-) and sulfur-containing compounds (SO42-, SO32-) on the Fe(III)EDTA reduction were investigated. The results indicated that strain FD-3 could reduce Fe(III)EDTA efficiently. NO3-, NO2- and Fe(II)EDTA–NO inhibit the reduction of Fe(III)EDTA and could also serve as electron acceptor for strain FD-3. SO32- inhibited Fe(III)EDTA reduction while SO42- had no obviously effect on Fe(III)EDTA reduction. The relationship between cell growth and Fe(III)EDTA reduction could be described by the models based on Logistic equation.