Kinetics of phenol and m-cresol biodegradation by an indigenous mixedmicrobial culture isolated from a sewage treatment plant
Pichiah Saravanan , Kannan Pakshirajan , Prabirkumar Saha
DOI:
Received December 18, 2007,Revised March 12, 2008, Accepted , Available online
Volume 20,2008,Pages 1508-1513
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An acclimatized mixed microbial culture, predominantly Pseudomonas sp., was enriched from a sewage treatment plant, and its
potential to simultaneously degrade mixtures of phenol and m-cresol was investigated during its growth in batch shake flasks. A 22 full
factorial design with the two substrates at two di erent levels and di erent initial concentration ranges (low and high), was employed
to carry out the biodegradation experiments. The substrates phenol and m-cresol were completely utilized within 21 h when present at
low concentrations of 100 mg/L for each, and at high concentration of 600 mg/L for each, a maximum time of 187 h was observed
for their removal. The biodegradation results also showed that the presence of phenol in low concentration range (100–300 mg/L)
did not inhibit m-cresol biodegradation. Whereas the presence of m-cresol inhibited phenol biodegradation by the culture. Moreover,
irrespective of the concentrations used, phenol was degraded preferentially and earlier than m-cresol. A sum kinetics model was used
to describe the variation in the substrate specific degradation rates, which gave a high coe cient of determination value (R2 > 0.98) at
the low concentration range of the substrates. From the estimated interaction parameter values obtained from this model, the inhibitory
e ect of phenol on m-cresol degradation by the culture was found to be more pronounced compared to that of m-cresol on phenol. This
study showed a good potential of the indigenous mixed culture in degrading mixed substrate of phenolics.
