Reduction of bromate by biogenic sulfide produced during microbial sulfur disproportionation

Monserrat Chairez, Antonia Luna-Velasco, Jim A. Field, Xiumin Ju, Reyes Sierra-Alvarez

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25 Scopus citations


Bromate (BrO3-) is a carcinogenic contaminant formed during ozonation of waters that contain trace amounts of bromide. Previous research shows that bromate can be microbially reduced to bromide using organic (i. e. acetate, glucose, ethanol) and inorganic (H2) electron-donating substrates. In this study, the reduction of bromate by a mixed microbial culture was investigated using elemental sulfur (S0) as an electron donor. In batch bioassays performed at 30°C, bromate (0. 30 mM) was completely converted to bromide after 10 days and no accumulation of intermediates occurred. Bromate was also reduced in cultures supplemented with thiosulfate and hydrogen sulfide as electron donor. Our results demonstrated that S0-disproportionating microorganisms were responsible for the reduction of bromate in cultures spiked with S0 through an indirect mechanism involving microbial formation of sulfide and subsequent abiotic reduction of bromate by the biogenic sulfide. Confirmation of this mechanism is the fact that bromate was shown to undergo rapid chemical reduction by sulfide (but not S0 or thiosulfate) in abiotic experiments. Bromate concentrations above 0. 30 mM inhibited sulfide formation by S0-disproportionating bacteria, leading to a decrease in the rate of bromate reduction. The results suggest that biological formation of sulfide from by S0 disproportionation could support the chemical removal of bromate without having to directly use sulfide as a reagent.

Original languageEnglish (US)
Pages (from-to)235-244
Number of pages10
Issue number2
StatePublished - Apr 2010


  • Bromate reduction
  • Bromide
  • Elemental sulfur
  • Sulfide
  • Sulfur disproportionation

ASJC Scopus subject areas

  • Pollution
  • Bioengineering
  • Environmental Engineering
  • Microbiology
  • Environmental Chemistry


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