Evaluation Of Biodegradation Ability Of Bacterial Consortium In Comparison With Combination Of It With Plant Species For Their Phytoremediation Potential

Abstract

Oil and its derivatives spills have been a major issue across decades due to transport, import, Export and accidents with its wider use in industry and it is difficult to be biodegraded. Many techniques were developed to clean up petroleum contaminated soil, among all of them, the biological treatments are more efficient and economic compared to chemical and physical ones. Bioremediation is applied as a treatment technology that is cost-effective, ecologically friendly and efficient for the decontamination of hydrocarbon pollution. In this study, crude oil contaminated soil samples were collected from oil extraction fields in Libya. The bacterial strains were isolated using selective media (agar containing crude oil). Isolated bacteria were identified using microbial features and selective media and then used in biodegradation experiment of 0.5% and 1% of crude oil contaminated soil. The bacterial concentration was adjusted to 1.5 x 108 scf/ml before supplementing in the soil. Three plants were chosen to perform experiment (Malva punilora, Ricinus communis and Triticum repens) on 0.5% and 1% crude oil contaminated soil. The chosen species were implanted directly in the contaminated soil together with prepared bacterial consortia. Soil sample (triplicate) was taken from each experiment at zero time, after 15 days, and 30 days of experiment, hexane was added to the soil samples and the absorbance was measured using spectrophotometer at 360 nm. As a result, two bacterial strains proved to be oil biodegrades were isolated and identified as Escherichia coli and other bacillus bacteria. The percentage of crude oil removal by bacteria was more than 60% in the soil contaminated by 0.5% of crude oil after 15 and 30 days of experiment, while it was 30% at 1% crude oil contaminated soil after 15 days and increased to be 75% after 30 days of experiment. The experiment included combination between plants and bacteria resulted in the 90% of removal by Triticum repens and bacterial mixture at 0.5 crude oil after 30 days, and 80% of removal for 1% contaminated soil using the same plant. In general, both techniques were effective in crude oil removal. Triticum repens showed good results in crude oil removal. This suggests more field application of this plant on crude oil contaminated oil