Evaluation of microbial systems for bioremediation of petroleum refinery effluents in Nigeria

The potential of various organisms to catabolize and metabolize organic compounds has been recognized as potentially effective means of disposing of hazardous wastes. Phenolic compounds has long been recognized as one of the most recalcitrant and persistent substance in petroleum refinery effluents. This is a cause of some concern because of the high toxicity and of this compound. Bioremediation of phenolic compounds has been recognized as a potential solution for the disposal of phenolic compounds due to its scale ability, cost effectiveness and simplicity. The two species of Pseudomonas , P. aeruginosa and P. fluorescence were studied for their bioremediation potential on Refinery effluent with respect to phenol biodegradation in a batch reactor. Phenol was degraded completely by the two species. While P. aeruginosa completely mineralize phenol at the 60th hour of cultivation, only 75% (23 mg/l) of phenol was degraded by P. fluorescence; complete degradation was achieved at the 84th hour of fermentation. There was highly positive correlation between phenol biodegradation and the microbial growth. (r = +0.994 and r = +0.980 at P≤0.05 for P. aeruginosa and P. fluorescence, respectively). The maximum specific growth rate (μmax) and inhibitory constant (Ki); 0.019(h-1) and 30.89 mg/l, and 0.011 (h-1) and 33.43 mg/l were obtained from Haldane model for P. aeruginosa and P. fluorescence, respectively. The study revealed the high potency of these strains and the possibility of using them in bioremediation of petroleum refinery and petrochemical waste waters