How sulfur species can accelerate the biological immobilization of the toxic selenium oxyanions and promote stable hexagonal Se0 formation

B. Song, J. Weijma, C.J.N. Buisman, R.D. van der Weijden*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

6 Citations (Scopus)

Abstract

Toxic selenium oxyanions and sulfur species are often jointly present in contaminated waters and soils. This study investigated the effect on kinetics and resulting products for bio-reduction of selenium oxyanions in the presence of biologically produced sulfur resulting from bio-oxidation of sulfide in (bio)gas-desulfurization (bio-S0) and of sulfate. Selenite and selenate (~2 mmol L-1) bio-reduction was studied in batch up to 28 days at 30 oC and pH 7 using lactic acid and a sulfate-reducing sludge, 'Emmtec'. Bio-S0 addition increased the selenite removal rate, but initially slightly decreased selenate reduction rates. Selenite reacted with biologically generated sulfide resulting in selenium-sulfur, which upon further bio-reduction creates a sulfur bio-reduction cycle. Sulfate addition increased the bio-reduction rate for both selenite and sulfate. Bio-S0 or sulfate promoted hexagonal selenium formation, whereas without these, mostly amorphous Se0 resulted. With another inoculum, ‘Eerbeek’, bio-S0 accelerated the selenite reduction rate less than for ‘Emmtec’ because of lower sulfur and higher selenite bio-reduction rates. Bio-S0 addition increased the selenate reduction rate slightly and accelerated hexagonal selenium formation. Hexagonal selenium formation is advantageous because it facilitates separation and recovery and is less mobile and toxic than amorphous Se0. Insights into the interaction between selenium and sulfur bio-reduction are valuable for understanding environmental pathways and considerations regarding remediation and recovery.

Original languageEnglish
Article number129367
JournalJournal of Hazardous Materials
Volume437
DOIs
Publication statusPublished - 5 Sept 2022

Keywords

  • Bio-reduction
  • Hexagonal selenium
  • Selenium-sulfur
  • Sulfur bio-cycling

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