, Volume 22, Issue 2, pp 253-265
Date: 25 Jul 2010

Enhanced degradation of phenol by Pseudomonas sp. CP4 entrapped in agar and calcium alginate beads in batch and continuous processes

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Phenol is one of the major toxic pollutants in the wastes generated by a number of industries and needs to be eliminated before their discharge. Although microbial degradation is a preferred method of waste treatment for phenol removal, the general inability of the degrading strains to tolerate higher substrate concentrations has been a bottleneck. Immobilization of the microorganism in suitable matrices has been shown to circumvent this problem to some extent. In this study, cells of Pseudomonas sp. CP4, a laboratory isolate that degrades phenol, cresols, and other aromatics, were immobilized by entrapment in Ca-alginate and agar gel beads, separately and their performance in a fluidized bed bioreactor was compared. In batch runs, with an aeration rate of 1 vol−1 vol−1 min−1, at 30°C and pH 7.0 ± 0.2, agar-encapsulated cells degraded up to 3000 mg l−1 of phenol as compared to 1500 mg l−1 by Ca-alginate-entrapped cells whereas free cells could tolerate only 1000 mg l−1. In a continuous process with Ca-alginate entrapped cells a degradation rate of 200 mg phenol l−1 h−1 was obtained while agar-entrapped cells were far superior and could withstand and degrade up to 4000 mg phenol l−1 in the feed with a maximum degradation rate of 400 mg phenol l−1 h−1. The results indicate a clear possibility of development of an efficient treatment technology for phenol containing waste waters with the agar-entrapped bacterial strain, Pseudomonas sp. CP4.