Assessing the hydrocarbon degrading potential of indigenous bacteria isolated from crude oil tank bottom sludge and hydrocarbon-contaminated soil of Azzawiya oil refinery, Libya

Abstract

The disposal of hazardous crude oil tank bottom sludge (COTBS) represents a significant waste management burden for South Mediterranean countries. Currently, the application of biological systems (bioremediation) for the treatment of COTBS is not widely practiced in these countries. Therefore, this study aims to develop the potential for bioremediation in this region through assessment of the abilities of indigenous hydrocarbonoclastic microorganisms from Libyan Hamada COTBS for the biotreatment of Libyan COTBS-contaminated environments. Bacteria were isolated from COTBS, COTBS-contaminated soil, treated COTBS-contaminated soil, and uncontaminated soil using Bushnell Hass medium amended with Hamada crude oil (1 %) as the main carbon source. Overall, 49 bacterial phenotypes were detected, and their individual abilities to degrade Hamada crude and selected COBTS fractions (naphthalene, phenanthrene, eicosane, octadecane and hexane) were evaluated using MT2 Biolog plates. Analyses using average well colour development showed that ~90 % of bacterial isolates were capable of utilizing representative aromatic fractions compared to 51 % utilization of representative aliphatics. Interestingly, more hydrocarbonoclastic isolates were obtained from treated contaminated soils (42.9 %) than from COTBS (26.5 %) or COTBS-contaminated (30.6 %) and control (0 %) soils. Hierarchical cluster analysis (HCA) separated the isolates into two clusters with microorganisms in cluster 2 being 1.7- to 5-fold better at hydrocarbon degradation than those in cluster 1. Cluster 2 isolates belonged to the putative hydrocarbon-degrading genera; Pseudomonas, Bacillus, Arthrobacter and Brevundimonas with 57 % of these isolates being obtained from treated COTBS-contaminated soil. Overall, this study demonstrates that the potential for PAH degradation exists for the bioremediation of Hamada COTBS-contaminated environments in Libya. This represents the first report on the isolation of hydrocarbonoclastic bacteria from Libyan COTBS and COTBS-contaminated soil.

Dissipation of Phenanthrene and Anthracene from Soil with Increasing Salt Content Amended with Wastewater Sludge

“…Approximately 49% of the PHEN and 26% of ANTHR added to soil was removed from within 56 days. It is well known that autochthonous microorganisms can remove PAHs from soil [31] -even in the presence of salt [32]. In a previous experiment, 99% PHEN and 85% ANTHR were removed from an agricultural soil [23].…”

Assessment of the Hydrocarbon Degrading Abilities of Three Bioaugmentation Agents for the Bioremediation of Crude Oil Tank Bottom Sludge Contaminated Libyan Soil

“…Three bacterial isolates previously isolated and identified in a previous study [24] (Table 1) were selected for use based on their hydrocarbon degrading properties. These isolates (designated as 4M14, 4M12 and IB16A) were obtained from stocks of pure cultures maintained at -80°C in 50% glycerol and streaked individually on nutrient agar plates (Acumedia, Lansing, Michigan 48912) (26 g/ l adjusted to pH 7.4).…”

“…The identities of the three hydrocarbonoclastic bacteria had been determined in earlier studies [24]. The isolates were selected depending on the highest hydrocarbon degradation potential.…”

“…Successful bioremediation outcome is expected to accelerate the acceptance and utilization of this technology for the treatment of contaminated environments in Mediterranean countries. Earlier work on a Libyan soil contaminated with COTBS had led to the isolation of 49 hydrocarbonoclastic bacterial isolates of which seven isolates were selected for further evaluations based on their high hydrocarbon degrading properties [24]. Out of these seven isolates, 3 were selected as the best COTBS degraders for use in this study.…”

Effect of Different Organic and Inorganic Nitrogen Sources on the Kinetics of the Breakdown of Crude Oil Using Pseudomonas

“…In other words, the organisms can be seen to obey the MichealisMentens assumptions and equation: Pseudomonas sp. are hydrocarbonoclastic bacteria that are naturally endowned with the ability to breakdown compounds with carbon backbone chain (Mansur et al, 2014).…”