Adsorption and bio-degradation of phenol by chitosan-immobilized Pseudomonas putida (NICM 2174)

Biodegradation of phenol by Pseudomonas putida (NICM 2174), a potential bio degradent of phenol has been investigated for its degrading potential under different conditions. Pseudomonas putida (NICM 2174) cells immobilized in chitosan were used to degrade phenol. Adsorption of phenol by the chitosan immobilized matrix Flayed an important role in reducing the toxicity of phe nol. In the present work, results of the batch equilibrium adsorption of ph enol on chitosan from its aqueous solution at different particle sizes (0.1 77 mm, 0.384 mm, 1.651 mm) and initial concentration of phenol (20, 40, 60, 80, 100, 120, 140, 160, 180, 200 mg/l) have been reported. The adsorption isotherms are described by Langmuir, Freundlich and Redlich-Peterson types of equations. These indicate favourable adsorption with chitosan. From the adsorption isotherms, the adsorption capacity, energy of adsorption, number of layers and the rate constants were evaluated. In batch kinetic studies the factors affecting the rate of biodegradation of phenol, were initial ph enol concentration (0.100 g/l, 0.200 g/l, 0.300 g/l), temperature (30 degre es C, 34 degrees C, 38 degrees C) and pH (7.0, 8.0, 9.0). Biodegradation ki netic data indicated the applicability of Lagergren equation. The process f ollowed first order rate kinetics. The biodegradation data generally fit th e Lagergren equation and the intraparticle diffusion rate equation from whi ch adsorption rate constants, diffusion rate constants and diffusion coeffi cients were determined. Intraparticle diffusion was found to be the rate-li miting step. Cell growth contributed significantly to phenol removal rates especially when the degradation medium was supplemented with a utilizable c arbon source.