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Experimental Removal of Aromatic Hydrocarbons by Thermophilic Bacteria in a Fixed Bed Reactor

Bokaee, Shima | 2009

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 39886 (06)
  4. University: Sharif University of Technology
  5. Department: Chemical and Petroleum Engineering
  6. Advisor(s): Borghei, Mehdi; Vossoughi, Manouchehr; Zeinali, Majid
  7. Abstract:
  8. According to the environmental lows and standards, wastewater of petroleum industries such as refineries and petrochemical that include many petroleum compounds like aromatic and aliphatic hydrocarbons, must be treated up to desirable limit, before entering the collecting network. Using microorganisms is one of the fundamental ways of biodegradation of these polluted compounds. Since phenolic compounds are the main components of raw petroleum, strains that are capable of tolerating phenol and usage of this poisonous hydrocarbon are specifically important. Therefore, in this study the potentiality of the indigenous thermophilic bacterium Nocardia otitidiscaviarum strain TSH1, for degradation of phenol in a packed column bioreactor was investigated. In a batch experiment the maximum growth of this strain is optimized at 50 ºC, a pH of 7 and phenol concentration of 600 ppm with free cells. However, strain TSH1 has still got the ability of degrading phenol at the concentration of 900 ppm. The Haldane equation was adopted in order to describe the relation between the specific growth rates (μ) and S0. Kinetic constants of the Haldane equation were μm = 0.36 h-1, Ks = 14.27 mg/l and Ki = 356 mg/l. Immobilization of cells on Monolith supports was carried out in batch-recirculation reactor. The experiments showed good ability of monolith supports in formation of biofilm. Maximum phenol biodegradation rate was 2.88 g/l.d at 2 ml/min. Our study also indicated that immobilization had reached the tolerance limit of the cells towards phenol from 900 ppm (in the suspended culture), to 2000 ppm. In continuous system the influence of dilution rate and influent phenol concentration on steady state performance of the bioreactor was studied. Almost 100% degradation of 200, 400 and 600 ppm influent phenol could be achieved at D = 0.36 and 0.6 h-1. At these dilution rates and at concentrations of 800 and 1000 ppm the percentage degradation has reduced to around (98% and 96%) and (96.8% and 86%) respectively. Maximum phenol degradation rate was 14 g/l.d for 600 ppm at D = 1.2 h-1.

  9. Keywords:
  10. Aromatic Compounds ; Fixed Bed Reactor ; Biofilm Reactors ; Thermophilic Bacteria ; Monolith

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