Aerobic batch degradation of phenol using immobilized Pseudomonas putida

Alginate concentrations between 2 and 4% had little effect on the degradation rate of phenol by alginate-immobilized Pseudomonas putida. Ten-degree shifts from 25°C resulted in approximately 30% slower degradation. Maximal degradation rates were favored at pH 5.5–6.0. The response of degradation rate to increased air flow in the bubble column used was almost linear and an optimal higher than 16 vol vol−1 was indicated, although free cells appeared in the reaction medium above 12 vol vol−1. When the initial phenol concentration was raised, degradation rate was not significantly affected until levels higher than 1200 mg ml−1 where performance was markedly reduced. Increasing the ratio of total bead volume to medium volume gave progressively smaller increases in degradation rate. At a medium volume to total bead volume ratio of 5:1, the maximum degradation rate was 250 mg L−1 h−1.