Date of Award

12-2013

Document Type

Thesis

Degree Name

Master of Chemical Engineering (MChE)

Department

Chemical Engineering

First Advisor

Dr. Sulaiman Al-Zuhair

Second Advisor

Amer El -Dieb

Abstract

The characteristics and viability of polyvinyl alcohol (PVA) as a support material for biomass immobilization and utilization for the biodegradation of cresols have been evaluated. PVA gel pellets were prepared by repeated freezing-thawing method using different PVA compositions. The porous structures of the PVA pellets were examined using a Compound Microscope and SEM and revealed that the matrix structure and pore size distribution were affected by PVA composition. Mechanical properties of the PVA gel were also characterized to evaluate the PVA integrity as a matrix for immobilizing microbial cells and found to be dependent on the PVA mass composition. The prepared pellets were utilized for the immobilization of Pseudomonas putida and biodegradation of phenol over a long period of time. The results revealed that the capabilities of the biomass to degrade phenol increased with time and were depended on the PVA mass content and porous structure.

Batch and continuous experiments were also carried out to evaluate the biodegradation of cresols (o-, p- and m-cresol) using Pseudomonas putida immobilized in polyvinyl alcohol (PVA) gel in spouted bed bioreactor (SBBR). The effect of initial substrate concentration, temperature, pH and volume fraction of PVA particles on the biodegradation of each cresol isomer was evaluated. Continuous experiments were also carried to study the effect of other operating parameters such as air flow rate and residence time on the biodegradation efficiency. The biodegradation capabilities of P.putida were found to be highly affected by operating parameters and the dependency varied for each cresol isomer. In addition, the potential of P.putida in the biodegradation of binary and ternary mixtures of cresols was examined in the continuous process and compared with single component biodegradation. Batch experimental data for each system were used to evaluate the kinetics parameters in order to utilize them in modeling the continuous biodegradation process. The model predictions were in very good agreement with experimental results.

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