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Biorecovery of heavy metals from oil waste water by adapted Thiobacillus Ferrooxidans

Molaei, Sima | 2009

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 40346 (06)
  4. University: Sharif University of Technology
  5. Department: Chemical and Petroleum Engineering
  6. Advisor(s): Yaghmaei, Soheila
  7. Abstract:
  8. Acidophilic microorganisms such as Thiobacillus ferrooxidans have the capability to carry out process of biorecovery of heavy metals. Its principle is the microbial production of the sulphuric acid and simultaneous recovery of metals. Acidithiobacillus ferrooxidans derives the energy for their metabolism from ferrous iron oxidation process which can be affected by the presence of heavy metals in the medium. In this study the ability of Acidithiobacillus ferrooxidans, on the biorecovery of heavy metals in shake flask has been investigated The adaptation of the Acidithiobacillus ferrooxidans to a kind of heavy metal such as Nickel, Cobalt, Vanadium, Molybdenum, Tungsten and the mixture of the prime four metals in the medium was developed through serial subculturing. Adaptation is easily carried out by continually growing the bacteria in an environment containing increasing concentrations of the toxic metal such that a culture tolerant to the toxic metal proliferates. Adapted strains to these metals exhibited better biorecovery results compared to the wild strains in the biorecovery of heavy metals. Effects of several process variables such as pH, Eh, bacterial concentration in solution and ferrous and ferric iron concentration for the specific bacterial growth rate, were also investigated. It was evident that concentrations of nickel, cobalt and vanadium had little effect on the oxidation of ferrous iron or the cell growth of A.ferrooxidans, whereas Mo and W ions were very inhibitory towards the Fe2+oxidation ability of A.ferrooxidans. W was found to cause the largest inhibition followed by Mo, V, Co and Ni. However, during Fe2+ oxidation in the combination of Ni, Co, V and Mo, it was showed that the presence of Mo as an inhibitory metal for A.ferrooxidans, has not much negative influence on the oxidation of ferrous iron and it could tolerate even up to higher concentration of molybdenum in combination with other metals.

  9. Keywords:
  10. Recovery ; Heavy Metals ; Thiobacillus Ferrooxidans ; Adaptation

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