Aim: The research aims to assess the biodegradability of crude oil polluted aquatic environment using indigenous hydrocarbon degrading bacteria.
Place and Duration of Study: The research was conducted in the Environmental Management and Toxicology Laboratory, Federal University of Petroleum Resources, Effurun, Delta State.
Methodology: Hydrocarbon degrading bacteria species were isolated from hydrocarbon contaminated soils, screened and used for the degradation of crude oil. 5% and 10% crude oil were used to spike the test microcosm. Physicochemical parameters such as, pH, turbidity, total petroleum hydrocarbon (TPH) and bacterial counts of the bioremediated crude oil contaminated water were monitored on Day 0, 7 and 14. The biodegradation of the crude oil was done with the various bacteria isolates singly and as a consortium. Standard methods of American Public Health Association (APHA) and American Society for Testing and Materials (ASTM) were used for the analysis.
Results: The isolates identified and used for the biodegradation process were, Azomonas sp., Enterococcus sp., Klebsiella sp. and Rhizobactersp. On day 14, in the microcosms with 5% crude oil contamination, Azomonas sp. recorded the highest turbidity reading of 328 ± 2.0 NTU, while Rhizobacter sp. recorded the least with 57.67 ± 0.58 NTU. The bacterial countswere between 7.68 ± 0.002 CFU/ml and 8.05 ± 0.10x 107 CFU/ml for Rhizobacter sp. and Azomonas sp. respectively.The crude oil was also degraded most in the microcosm treated with Azomonas sp. with a residual TPH concentration of 0.0013± 0.005 mg/l.For the 10% crude oil contaminated microcosms, TPH was also biodegraded most by Azomonas sp. with a value of 0.0026 ± 0.002mg/l. Turbidity readings were between 82 ± 1.0 NTU and 375.33 ± 0.57 NTU for Rhizobacter sp. and Azomonas sp. respectively. Bacterial counts were between (7.71± 0.012)x 107CFU/ml – (8.13± 0.001) x 107CFU/ml for Rhizobacter sp. and Azomonassp. respectively.
Conclusion:There wasincreased microbial countsand decrease of residual crude oil concentration, indicating degradation of the crude oil by all the isolates.However, Azomonas sp. recorded the highest TPH degradation for both the 5% and 10% crude oil contaminated microcosms.Thus, findings from the research indicate that hydrocarbon degrading bacteria exist in our environment and can be used in the remediation of aquatic polluted environment.
Histopathological effects and biomarker response of earthworms, Eisenia fetida, after exposure to crude oil contaminated soils
