Bioregeneration of Granular activated carbon (GAC) contaminated with phenolic compounds

Ahangar, Ata Ollah | 2010

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 40911 (06)
  4. University: Sharif University of Technology
  5. Department: Chemical and Petroleum Engineering
  6. Advisor(s): Vossoughi, Manouchehr; Borghei, Mehdi
  7. Abstract:
  8. This project surveys bioregeneration of granular activated carbons contaminated with phenolic compounds. To carry out this survey, the procedure of phenol absorption on the surface of activated carbon was studied and their adsorption isotherms were calculated. In the first step, newly activated carbon was contaminated with phenol solution and optimum amount of carbon in phenol elimination was 0.5g. Then, the effect of time contact on phenol elimination was studied and eventually 1 hour of time contact was determined as the equilibrium time of phenol adsorption. In the second step, kinetics of adsorption of phenol and different stages of adsorption were studied. The results of this study showed that, compared to the previous stage, adsorption procedure of phenol followed first-order kinetics and in each stage, the rate constant of reaction speed was reduced while the time for reaching equilibrium increased, so much so that after six stages of adsorption, adsorption procedure was stopped and activated carbon had got saturated. Rate constants of the six procedures of adsorption were: 0.023, 0.0116, 0.0055, 0.0023 and 0.0006 1/min, respectively. In the third stage, all results from phenol adsorption on GAC were fitted by Langmuir and Freundlich isotherm and, eventually, Langmuir isotherm (R2 = 0.9905), compared with Freundlich isotherm (R2 = 0.9761), was more suitable. After drawing diagram and linear regression, Langmuir isotherm constants were Qm = 49.72 and KL = 0.1099 and Freundlich isotherm constants were Kf = 6.5942 and n = 2.0425. In the forth stage, bioregeneration procedure of the contaminated GAC was studied. In this stage, a microorganism which could biodegradate contamination was needed. Among all microorganisms a thermophilic bacterium, Nocardia otitidiscaviarum strain TSH1, was known as the best microbe for degredation of phenol. For regeneration, contaminated carbons were exposed to the selected microbe and the efficiency of elimination of phenol was determined. Eventually, after 7 days, the efficiency of degredation reached 63.41 percent. Redegredation of carbons which previously had been degredated, was also done and it showed that after 7 days, the efficiency had reached 22 percent. Therefore, bioregredation method is just effective for the firs time but for the consequent bioregredation this method alone will not be that effective.

  9. Keywords:
  10. Granular Activated Carbon ; Phenolic Compounds ; Adsorption ; Isotherm ; Bioregeneration

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