טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
Ph.D Thesis
Ph.D StudentAntizar Ladislao Blanca
SubjectEffect of Biomass Dynamics on the Fate of Chlorophenols
in Porous Media under Bioremediation Conditions
DepartmentDepartment of Civil and Environmental Engineering
Supervisor Professor Emeritus Noah Galil (Deceased)


Abstract

The impact of biomass dynamics on the biodegradation, biosorption and transport of phenols in a bioremediation context was evaluated in this study.

At the pilot plant-scale, results from column studies demonstrated that phenol, 2-chlorophenol, 2,4,6-trichlorophenol and pentachlorophenol followed first order biodegradation kinetics, and the biodegradation rates were correlated to the hydrophobicity of the phenols when they were bioremediated as single pollutants. This correlation showed that the biodegradation rate increases with decreasing hydrophobicity. A relationship between the hydrophobicity of phenols and the biodegradation rate determined from the experiments is proposed as a predictive relationship.

The comparative study of the biosorption capacity of phenol, 2-chlorophenol, 2,4,6-trichlorophenol and pentachlorophenol by acclimated resident biomass characterized by Freundlich isotherms showed that: (i) the physiological state of the biomass (active, inactive) may affect the biosorption of 2,4,6-trichlorophenol and pentachlorophenol, but not phenol; and that (i) the equilibrium sorption capacity is influenced by the pH of the aqueous solution and the hydrophobicity of the phenols. A relationship between the hydrophobicity of phenols and the equilibrium sorption capacity determined from the experiments is proposed as a predictive relationship.

Higher biodegradation rates were observed at lower initial shock loadings of 2,4,6-trichlorophenol and higher recirculation rates. Higher substrate loading rates and higher recirculation rates created an increase in biomass density in the columns which resulted in: (i) lower biodegradation rates, due to mass transfer limitations, (ii) lower free biomass mobility, (iii) lower hydraulic conductivity of the porous media due to biomass accumulation, (iv) uniform spatial reduction of hydraulic conductivity, due to biomass compaction.

A complex interrelationship between the flow-rate, cumulative load, kinetics of biodegradation, hydraulic conductivity and biosorption is then implied in the present study. The findings present here have important implications for representation of bioremediation in computer modeling and in the design of bioremediation strategies.