title: Investigation of Acidithiobacillus ferrooxidans in pure and mixed-species culture for bioleaching of Theisen sludge from former copper smelting.
abstract: OBJECTIVE
  The aim of this study was to investigate the potential of bioleaching for the treatment of an environmentally hazardous waste, a blast-furnace flue dust designated Theisen sludge.
  
  
  RESULTS
  Bioleaching of Theisen sludge was investigated at acidic conditions with Acidithiobacillus ferrooxidans in pure and mixed-species culture with Acidiphilium. In shaking-flask experiments, bioleaching parameters (pH, redox potential, zinc extraction from ZnS, ferrous- and ferric-iron concentration) were controlled regularly. The analysis of the dissolved metals showed that 70% zinc and 45% copper were extracted. Investigations regarding the arsenic and antimony species were performed. When iron ions were lacking, animonate (Sb(V)) and total arsenic concentration were highest in solution. The bioleaching approach was scaled up in stirred-tank bioreactors resulting in higher leaching efficiency of valuable trace elements. Concentrations of dissolved antimony were approx. 23 times, and of cobalt, germanium, and rhenium three times higher in comparison to shaking-flask experiments, when considering the difference in solid load of Theisen sludge.
  
  
  CONCLUSIONS
  The extraction of base and trace metals from Theisen sludge, despite of its high content of heavy metals and organic compounds, was feasible with iron-oxidizing acidophilic bacteria. In stirred-tank bioreactors, the mixed-species culture performed better.
  
  
  CONCLUSIONS
  To the best of our knowledge, this study is the first providing an appropriate biological technology for the treatment of Theisen sludge to win valuable elements.
authors.affiliation: Institute of Biosciences, TU Bergakademie Freiberg, Freiberg, Germany.
authors.forename: C
authors.initials: C
authors.lastname: Klink
authors.affiliation: Institute of Biosciences, TU Bergakademie Freiberg, Freiberg, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Eisen
authors.affiliation: Department Analytical Chemistry, UFZ - Helmholtz Center for Environmental Research, Leipzig, Germany.
authors.forename: B
authors.initials: B
authors.lastname: Daus
authors.affiliation: Helmholtz Institute Freiberg for Resource Technology, Freiberg, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Heim
authors.affiliation: Institute of Biosciences, TU Bergakademie Freiberg, Freiberg, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Schlömann
authors.affiliation: Institute of Biosciences, TU Bergakademie Freiberg, Freiberg, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Schopf
mesh_terms: D042763:Acidithiobacillus / Q000145:classification / Q000378:metabolism*; D019149:Bioreactors; D003247:Conservation of Natural Resources / Q000379:methods*; D003300:Copper / Q000737:chemistry; D019216:Metals, Heavy / Q000737:chemistry / Q000378:metabolism*; D010802:Phylogeny; D059027:Recycling; D012722:Sewage / Q000737:chemistry* / Q000382:microbiology*
chemical_list: D019216:Metals, Heavy; D012722:Sewage; D003300:Copper
keywords: Theisen sludge; acidophilic bacteria; bioleaching of valuable trace elements; stirred-tank bioreactors; toxic organic compounds