Bioremediation of Heavy Crude Oil Contamination

Abstract

Crude oil contamination is one of the major environmental concerns and it has drawn interest from researchers and industries. Heavy oils contain 24-64% saturates and aromatics, 14-39% resins and 11-45% asphaltene. Resins and asphaltenes mainly consist of naphthenic aromatic hydrocarbons with alicyclic chains which are the hardest to degrade. Crude oil biodegradation process, with its minimal energy need and environmentally friendly approach, presents an opportunity for bioremediation and as well for enhanced oil recovery to utilize heavy oil resources in an efficient manner. Biodegradation entails crude oil utilization as a carbon source for microorganisms that in turn change the physical properties of heavy crude oil by oxidizing aromatic rings, chelating metals and severing internal bonds/chains between molecules. Biodegradation does not necessarily lower quality of crude oil as there are cases where quality was improved. This paper provides information on heavy crude oil chemistry, bioremediation concept, biodegradation enzymes, cases of Microbial Enhanced heavy crude Oil Recovery (MEOR) and screening criteria towards a better understanding of the biodegradation application. Through the utilization of single microorganisms and consortia, researchers were able to biodegrade single pure hydrocarbon components, transform heavy crude oil fractions to lighter fractions, remove heavy metals and reduce viscosity of crude oil.

Microbial-Enhanced Heavy Oil Recovery under Laboratory Conditions by Bacillus firmus BG4 and Bacillus halodurans BG5 Isolated from Heavy Oil Fields

“…This study showed that isolates, B. firmus and B. halodurans were mostly utilizing aromatic fractions in the crude oil and fractionation of which led to increase in the amount of aliphatic compounds. Several enzymes such as oxidoreductase (laccases and cytochrome-P450 mono-oxygenase), xylene monooxygenase, catechol 2,3-dioxygenase, benzoyl-CoA reductase and others, are reported to play an important role in bacterial biodegradation of crude oil and polycyclic aromatic hydrocarbons [5]. We are further analyzing these bacterial isolates for presence of genes encoding for such enzymes, which are responsible for heavy crude oil biotransformation.…”

“…Crude oil is a fossil fuel which is considered as non-renewable energy source. It is composed of a mixture of different hydrocarbons (including alkanes/paraffins, alkenes/olefins, cycloalkanes/naphthenes, and aromatics), complex hydrocarbons (such as polycyclic aromatic hydrocarbons), resins, asphaltenes, along with certain other hetero-species, containing nitrogen, oxygen and sulfur [5]. Heavy crude oil is characterized by high density or specific gravity, more resistant to flow with an American Petroleum Institute (API) gravity of less than 20 • .…”

Bioremediation of Total Petroleum Hydrocarbons (TPH) by Bioaugmentation and Biostimulation in Water with Floating Oil Spill Containment Booms as Bioreactor Basin

“…Some researchers have used other methods by applying N:P:K nutrient ratios [ 18 , 19 ], food wastes [ 20 ]. Some researchers have applied it in the field [ 12 , 15 , 18 , 19 , 21 , 22 , 23 , 24 ]. A comprehensive and practical collection of guidelines for the application of this technology to seawater oil spill responders is urgently required to address questions such as when to use bioremediation, what bioremediation agents should be used, how to apply them, and how to track and evaluate the outcomes [ 25 ].…”

“…Heavy crude oils produce large quantities of difficult to process complex hydrocarbons, such as polynuclear aromatic compounds (PNA), PAHs, alkyl aromatic compounds, heteroatoms, and metal materials. Sulphur, oxygen, nitrogen, and metal atoms are typical heteroatoms in hydrocarbons [ 21 ].…”

Production and Characterization of Hydrocarbon Degrading Peroxidase from Rhizopus and Saccharomyces Species

“…Microorganisms have been considered as treasure of useful enzymes. Microorganisms possess specific enzyme systems that enable them to degrade and utilize hydrocarbons as their sole carbon and energy sources (Al-sayegh et al, 2016). Fungal isolates from polluted soil are able to use hydrocarbon present in that area as substrates for growth.…”