Full Length Research Paper

Optimization of process variables for the microbial degradation of phenol by Pseudomonas aeruginosa using response surface methodology

S. E. Agarry^1*, B. O. Solomon² and   S. K. Layokun²

¹Biochemical Engineering Research Unit, Department of Chemical Engineering, Ladoke Akintola University of Technology, Ogbomoso, Nigeria.

²Biochemical Engineering Research Unit, Department of Chemical Engineering, Obafemi Awolowo University, Ile-ife, Nigeria.

*Corresponding author. E-mail: sam_agarry@yahoo.com.

Accepted 17 June, 2008

Removal efficiency of phenol from aqueous solutions was measured using a freely suspended monoculture of indigenous Pseudomonas aeruginosa. Experiments were performed as a function of temperature (25– 45^oC), aeration (1.0 – 3.5 vvm) and agitation (200 – 600 rpm). Optimization of these three process parameters for phenol biodegradation was studied. Statistically designed experiments using response surface methodology was used to get more information about the significant effects and the interactions between the three parameters. A 2³ full-factorial central composite designed followed by multistage Monte-Carlo optimization technique was employed for experimental design and analysis of the results. The optimum process conditions for maximizing phenol degradation (removal) were recognized as follows: temperature 30.1^oC, aeration 3.0 vvm, and agitation 301 rpm. Maximum removal efficiency of phenol was achieved (94.5%) at the optimum process conditions.

Key words: Pseudomonas aeruginosa, phenol, biodegradation, regression model, statistical optimization.