Biodegradation Kinetic Studies of Phenol and p-Cresol in a Batch and Continuous Stirred-Tank Bioreactor with Pseudomonas putida ATCC 17484 Cells

The biodegradation of phenol, p-cresol, and phenol plus p-cresol mixtures was evaluated using Pseudomonas putida ATCC 17484 in aerobic batch reactors. Shake-flask experiments were performed separately using growth medium with initial nominal concentrations of phenol (50-600 mg L-1) and p-cresol (50-600 mg L-1) as well as phenol (50-600 mg L-1) plus p-cresol (50-600 mg L-1). The complete degradation of phenol and p-cresol was achieved within 48 h and 48-56 h, respectively, for all initial concentrations of phenol and p-cresol. The maximum cell growth rate using phenol (mu(max,P) = 0.45 h(-1)) was much faster than that using p-cresol (mu(max,C) = 0.185(-1) h). The larger K-i value for phenol (310.5 mg L-1) revealed that the P. putida cells had a higher resistance to phenol inhibition compared with p-cresol (243.56 mg L-1). A mixture of phenol and p-cresol in batch experiments resulted in the complete removal of phenol within 52-56 h for initial phenol concentrations of 50-500 mg L-1. The time needed to remove p-cresol completely was 48-56 h for initial p-cresol concentrations of 50-500 mg L-1. In the continuous-flow immobilized cells reactor, the degradation efficiency for phenol and p-cresol was 97.6 and 89.1%, respectively, at a stable condition.

Automated summary

Pseudomonas putida ATCC 17484 showed efficient degradation of phenol and p-cresol in aerobic batch reactors, with phenol being degraded faster than p-cresol. The coexistence of phenol and p-cresol resulted in complete removal of phenol within 52-56 hours and p-cresol within 48-56 hours in batch experiments. In continuous-flow immobilized cells reactor, the degradation efficiency for phenol and p-cresol was 97.6% and 89.1% respectively.