Oil Degradation Rate Research Articles

Dynamics of CO2 Evolution during Bioremediation of Clayey and Sandy Soils Contaminated with Used Lubricating Oil

The aim of the study was to evaluate the biodegradation of petroleum hydrocarbons in two Brazilian contaminated soil types (clayey S1 and sandy S2) at a loading rate of 30,000 and 45,000 mg/kg. A model soil of 300 g with used lubricating oil was amended with commercially available hydrocarbon degrading microbial consortium: Amnite p1300 as the bioaugmentation (T1), other treatments consist of nutrients amendments - (NH4)2SO4 and K2HPO4 (NPK) as biostimulation (T2), unammended soil - natural attenuation as (T3) and the control soil treated with sodium azide (NaN3) as (T4) were evaluated on the microbial community and the degradation of used lubricating oil. Three microcosm replicated flasks per treatment were incubated, and the performance of each treatment was examined by monitoring CO2 evolution, microbial activity, and oil degradation rate. In Soil 1, T1 produced the highest values of CO2 of (1600.20 mg/kg) and (1347.60 mg/kg) while the least values were recorded in the control (T4) with 89.52 and 102 mg/kg in oil contaminated with 3 and 4.5 % respectively. A similar trend was obtained in the bioaugmented treatment soil (S2) with the highest CO2 production in T1. The best percentage oil degradation was also recorded where the utmost CO2 production was obtained.

Comparative Studies on Modelling and Optimization of Soil Parameters on Crude Oil Contaminated Mangrove and Clay Soils Remediation Using Box-Behnken RSM

The combined effect of three selected soil parameters (moisture, nutrient, and pH) on the degradation rate of hydrocarbons inmangrove and clayey soils was successfully modeled using Box–Behnken design matrix of Response Surface Methodology (RSM). The method of study using the biostimulation technology aims to investigate, optimize and compare the relative effects of the selected soil variables and textures on the degradation rate of Bonny light crude oil in the soil samples. Two sets of sixteen experimental buckets containing 1 kg of contaminated soil were set up for each soil sample. The soil factors studied at three levelswas the independent variables. The residual (TPH) in the experimental buckets, monitored using gas chromatography/mass spectrometry was the dependent parameter. Results from each experimental unit showed a measurable reduction in TPH withtime. The statistical analyses of the experimental results and model predictions reveal that nutrient has a pronounced majorinfluence on crude oil degradation and that mangrove soil in comparison to clay soil favors faster crude oil degradation underatmospheric conditions. The predicted optimum parameters for nutrient, pH, and moisture were 0.143kg/kg soil, 6.7 and 0.23kg/kg soil, for the clay soil 0.160kg/kg soil, 8.00 and 0.140kg/kg soil for the mangrove soil. The predicted value of 81.48% forthe mangrove soil and 63.5% for the clay soil at the optimum with a regression coefficient of 99.35% and 99.09 is suggesting thatthe developed quadratic regression models are accurate and reliable

Isolation of Oil-degrading Bacteria and Treatment of Oil Wastewater

With the improvement of people’s living standards, the pollution caused by oil-rich kitchen wastewater has attracted people’s attention. In order to screen efficient soybean oil-degrading bacteria, six strains that could degrade soybean oil were isolated from the soil with soybean oil as the sole substrate. Among them, the strain CR5 and CR6 had strong ability to degrade soybean oil. After 10 days of culture, the degradation rates of strain CR5 (pH 2.42) and CR6 (pH 3.84) on soybean oil were 65.25%, 66.04% respectively. In order to study the salt tolerance of the strains, the degradation rates of soybean oil by CR5 were 16.36%, 3.85% and 7.36% after 5 days of cultivation at different salt concentrations (1.0%, 1.5%, 3.5%) and those of CR6 were 5.52%, 8.45%, 16.98%.

Recovery of contaminated marine environments by biosurfactant-enhanced bioremediation.

The need to remediate areas contaminated by petroleum products has led to the development of novel technologies for treating such contaminants in a non-conventional manner, that is, without the use of chemical or physical methods. Biosurfactants are amphipathic biomolecules produced by microorganisms that can be used in bioremediation processes in environments contaminated by petroleum products due to their excellent tensioactive properties. The aim of the present study was to produce a biosurfactant from Pseudomonas aeruginosa UCP 0992 cultivated in 0.5% corn steep liquor and 4.0% vegetable oil residue in a 1.2-L bioreactor employing a central composite rotatable design to optimize the cultivation conditions for maximum yield. The best results were achieved with aeration rate of 1.0 vvm and 3.0% inoculum at 225 rpm for 120 h, resulting in a surface tension of 26.5 mN/m and a biosurfactant yield of 26 g/L. Kinetic and static assays were then performed with the biosurfactant for the removal of motor oil adsorbed to sand, with removal rates around 90% and 80%, respectively, after 24 h. Oil degradation experiments with the bacterium and the combination of the bacterium and biosurfactant were also conducted to simulate the bioremediation process in sand and seawater samples (duration: 75 and 30 days, respectively). In both cases, oil degradation rates were higher than 90% in the presence of the biosurfactant and the producing species, indicating the potential of the biomolecule as an adjuvant in petroleum decontamination processes in the marine environment.

Synergistic degradation of crude oil by indigenous bacterial consortium and exogenous fungus Scedosporium boydii

The purpose of this study was to investigate the potential of defined co-culture of indigenous bacterial consortium and exogenous fungus Scedosporium boydii for biodegradation of crude oil. After 7 days of incubation, residual oil, n-alkanes and aromatic fraction were analyzed. The degradation rate of crude oil was increased from 61.06% to 81.45% by the defined co-culture according to the 3:1 inoculation ratio of bacteria to fungi. The microbial activity was enhanced markedly and the formation of biofilms was accelerated after suitable inoculation of Scedosporium boydii. High throughput analysis showed that bacterial evenness and diversity were increased and the relative abundance of Paraburkholderia tropica was increased observably from 7.67% to 56.13% in the defined co-culture. These results indicated that synergistic degradation of crude oil in the bacteria-fungi consortium may be advantageous for bioremediation of petroleum-contaminated site.

Study on immobilization of marine oil-degrading bacteria by carrier of algae materials.

This study investigated the immobilizations with of bacteria two kinds of algal materials, Enteromorpha residue and kelp residue. The lipophilicity of them were compared by diesel absorption rates. The immobilization efficiency of Bacillus sp. E3 was measured to evaluate whether these carriers would satisfy the requirement for biodegradation of oil spills. The bacteria were immobilized through adsorption with the sterilized and non-sterilized carriers to compare the differences between the two treatments. Oil degradation rates were determined using gravimetric and GC-MS methods. Results showed the absorption rates of Enteromorpha residue and kelp residue for diesel were 411 and 273% respectively and remained approximately 105 and 120% after 2h of erosion in simulated seawater system. After immobilized of Bacillus sp. E3, the oil degradation rates of them were higher than 65% after 21 days biodegradations. GC-MS analysis showed that two immobilizations degraded higher than 70% of the total alkane and the total PAHs, whereas the free bacteria degraded 63% of the total alkane and 66% the total PAHs. And the bacteria immobilized with the carriers degraded more HMW-alkanes and HMW-PAHs than the free bacteria. The bacteria immobilized by non-sterilized kelp residue showed a considerably higher degradation rate than that using sterilized kelp residue. A considerably higher cells absorption rate of immobilization was obtained when using kelp residue, and the preparation of immobilization was low cost and highly efficient. The experiments show the two algae materials, especially the kelp residue, present potential application in bioremediation of marine oil spills.

Compatibility between weak gel and microorganisms in weak gel-assisted microbial enhanced oil recovery

To investigate weak gel-assisted microbial flooding in Block Wang Long Zhuang in the Jiangsu Oilfield, the compatibility of weak gel and microbe was evaluated using laboratory experiments. Bacillus sp. W5 was isolated from the formation water in Block Wang Long Zhuang. The rate of oil degradation reached 178mg/day, and the rate of viscosity reduction reached 75.3%. Strain W5 could produce lipopeptide with a yield of 1254mg/L. Emulsified crude oil was dispersed in the microbial degradation system, and the average diameter of the emulsified oil particles was 18.54μm. Bacillus sp. W5 did not affect the rheological properties of the weak gel, and the presence of the weak gel did not significantly affect bacterial reproduction (as indicated by an unchanged microbial biomass), emulsification (surface tension is 35.56mN/m and average oil particles size is 21.38μm), oil degradation (162mg/day) and oil viscosity reduction (72.7%). Core-flooding experiments indicated oil recovery of 23.6% when both weak gel and Bacillus sp. W5 were injected into the system, 14.76% when only the weak gel was injected, and 9.78% with strain W5 was injected without the weak gel. The results demonstrate good compatibility between strains W5 and the weak gel and highlight the application potential of weak gel-assisted microbial flooding.

OPTIMIZATION BACTERIAL DENSITY AND FERTILIZER DOSAGE FOR BIOREMEDIATION OF OIL CONTAMINATED SANDY BEACH: A CASE OF CILACAP, INDONESIA

Bioremediation, involving biostimulation and/or bioaugmentation, is a promising method to overcome oil spills in Cilacap coastal waters. Cilacap coastal area has high risk on oil pollution. This study investigated the stimulatory effect of nitrogen concentration, bacterial density and the composition of bacterial culture in enhancing oil degradation in this area. The applications of 4 different concentrations of Slow Release Fertilizer (SRF) and 2 different densities of bacterial cells in the form of single (RCO/B/08_008) and mixed culture were employed in microcosm experiments for 28 days. The efficacy of combining bacterial culture and fertilizer application in various concentrations was also tested. Oil degradation, bacterial growth and environmental parameters were monitored periodically during the experiments. The results showed that oil degradation rate was more influenced by nutrient concentration (biostimulation) than bacterial number or culture composition (bioaugmentation) added. The efficacy of biostimulation in degrading oil was better than that of bioaugmentation. Biostimulation increased oil degradation up to 6.4 times higher than the control. The optimum of fertilizer concentration added was 7.5 mg N/g (C:N ratio of 1,000:75), which increased depletion rate both in biostimulation-only and the combination of biostimulation with bioaugmentation up to 6.4 and 7.5 times higher than the control, respectively. It is suggested that bioremediation of oil-contaminated sandy beach in Cilacap would be optimal by employing a combination of Slow Release Fertilizer at concentration having C/N ratio = 1,000 : 75 and RCO/B/08_008 culture at density of 0.5 x 108 cells/mL (100% homology with Alcanivorax sp. TE-9).

Chemical dispersants enhance the activity of oil- and gas condensate-degrading marine bacteria.

Application of chemical dispersants to oil spills in the marine environment is a common practice to disperse oil into the water column and stimulate oil biodegradation by increasing its bioavailability to indigenous bacteria capable of naturally metabolizing hydrocarbons. In the context of a spill event, the biodegradation of crude oil and gas condensate off eastern Canada is an essential component of a response strategy. In laboratory experiments, we simulated conditions similar to an oil spill with and without the addition of chemical dispersant under both winter and summer conditions and evaluated the natural attenuation potential for hydrocarbons in near-surface sea water from the vicinity of crude oil and natural gas production facilities off eastern Canada. Chemical analyses were performed to determine hydrocarbon degradation rates, and metagenome binning combined with metatranscriptomics was used to reconstruct abundant bacterial genomes and estimate their oil degradation gene abundance and activity. Our results show important and rapid structural shifts in microbial populations in all three different oil production sites examined following exposure to oil, oil with dispersant and dispersant alone. We found that the addition of dispersant to crude oil enhanced oil degradation rates and favored the abundance and expression of oil-degrading genes from a Thalassolituus sp. (that is, metagenome bin) that harbors multiple alkane hydroxylase (alkB) gene copies. We propose that this member of the Oceanospirillales group would be an important oil degrader when oil spills are treated with dispersant.

Bioremediation of oil-contaminated field by two Pseudomonas aeruginosa strains

We studied the remediation of petroleum-contaminated soils. Two Pseudomonas aeruginosa strains were screened from soil samples in the mine environment. The degradation rate of crude oil was 95.67% after 10 days by mixed culture of the two strains, which was 32% higher than that of single bacterium. It means that the two bacteria had synergistic effect on degrading crude oil. Based on the result, bacterial agent was prepared, and the oil pollution sites were artificially constructed to simulate the degradation of crude oil under different operating conditions. During the experiment, the petroleum hydrocarbon content of the sites after treating with the bacterial agent, decreased obviously in 60 days. The content decreased to among 0.1% and 0.3% from the initial 0.8% per gram of soil. Then, the site with organic manure as supplemental source of carbon and nitrogen had the highest degradation rate of 85.28%, compared to that without adding bacterial agent of only 25.85%.

Spectroscopic analysis of synthetic lubricating oil

Analysis and evaluation of the degradation rate of the synthetic lubricating oil in diesel vehicle engines under the operating effect were carried out by exploiting: Electron Paramagnetic Resonance (EPR) and Infrared Fourier Transform (FTIR).EPR measurements of the degraded samples reveal that the spectra shape depends on the nature of the used oil and stable free radicals that are produced. Almost a linear correlation between the concentration of these radicals and the degradation rate, expressed in the number of kilometers traveled by vehicle, is observed. The results of FTIR measurements revealed the production of organic compounds from degradation.Both EPR and FTIR techniques seem to be effective for analyzing the quality of the lubricating oil and the evaluation of its rate of degradation.

Isolation, Identification and Degradation Characteristics of Oil Degrading Bacterial Strain

Objective: The aim of study is to obtain a strain which can effectively degrade oil. Methods: By enrichment, domestication and separation of culture from the sample which comes from Qianjiang Guanghua Oilfield, the pure culture (G-40) was selected from the medium supplemented with oil as the sole source of carbon. The G-40 was preliminarily identified and classified by morphological observation, physiological and biochemical determination and sequence analyses of 16S rDNA. Effects of temperature, pH, oil concentration, salt concentration, inoculation amount, N and P source on the degradation of the oil were studied by single factor test. Meanwhile, the effects of temperature, pH, oil concentration and salt concentration were optimized by orthogonal design. Result: G-40 was isolated and identified as Brevibacillus laterosporus. The orthogonal design showed that the degradation rate of oil could reach 20.81%, 24.34% and 31.15% at 10 d, 20 d and 40 d under the optimal conditions which was 35℃, initial pH 7.3, oil concentration 0.6%, salt concentration 0.5%, inoculum amount 8%, the optimal N and P was (NH4)2SO4 and K2HPO4. Conclusion: This study provides microbial resources for bioremediation of petroleum contaminated soil.

Microbial response to oil enrichment in Gulf of Mexico sediment measured using a novel long-term benthic lander system

Weathered crude oil sank to the seafloor following the Deepwater Horizon disaster in 2010, removing this oil from further physical and photo-chemical degradation processes and leaving benthic processes as the mechanisms for altering and remediating this hydrocarbon source. To quantify potential microbial oil degradation rates at the seafloor, and associated changes in sediment microbial community structure and pore fluid composition, we used a benthic lander system to deploy novel sediment flow-through chambers at a natural hydrocarbon seep in the Gulf of Mexico (at a depth of 1226 m in lease block GC600) roughly 265 km southwest of the Deepwater Horizon wellhead (at 1500 m depth). Sediment amended with 20% unweathered crude oil had elevated rates of sulfate reduction over the course of the 5-month-long experiment as compared to an unamended control, yielding potential rates of sulfate reduction (600–800 mmol m–2 d–1) among the highest measured in hydrocarbon-influenced seafloor sediment. Oil amendment also stimulated methane production towards the end of the experiment, and led to slightly higher cell densities without significant changes in microbial community structure, based on 16S rRNA gene sequence libraries and fatty acid profiles. Assuming a link between sulfate reduction and hydrocarbon degradation, these results suggest that electron acceptor availability may become limiting in heavily oiled deep-sea environments, resulting in minimal degradation of deposited oil. This study provides unique data on seafloor sediment responses to oil deposition, and reveals the value of using observatories to fill the gap in understanding deep-sea microbial processes, especially for ephemeral and stochastic events such as oil spills.

Compatibility Study Between Synthetic Oil and Vitrified Wastes for Direct Thermal Energy Storage

Compatibility tests were conducted between synthetic oil and potential solid filler materials in a thermocline tank built at the PROMES-CNRS laboratory. These experiments consisted of placing the oil and the solid materials together in small crucibles (2.3 L) and performing compatibility tests at 300 °C and accelerated ageing tests at 330 °C for 500 h. The mutual influence of the oil and the solid materials was assessed through different measurements: X-ray diffraction and scanning electron microscopy. The influence of the solid on the oil was assessed by measuring thermo-physical and chemical properties. While no significant degradation of the oil is measured at 300 °C, at 330 °C, an increase in the oil degradation rate was observed. Its density, thermal conductivity and specific heat did not change, but its viscosity showed a significant increase. However, after accelerated ageing tests at 330 °C, the oil still shows good heat transfer performance. The solid crystalline structure did not change during the test but some of the samples seemed to absorb oil.

Effect of natural and synthetic surfactants on crude oil biodegradation by indigenous strains

Hydrocarbon pollution is a worldwide problem. In this study, five surfactants containing SDS, LAS, Brij 30, Tween 80 and biosurfactant were used to evaluate their effect on crude oil biodegradation. Hydrocarbon degrading bacteria were isolated from oil production water. The biosurfactant used was a kind of cyclic lipopeptide produced by Bacillus subtilis strain WU-3. Solubilization test showed all the surfactants could apparently increase the water solubility of crude oil. The microbial adhesion to the hydrocarbon (MATH) test showed surfactants could change cell surface hydrophobicity (CSH) of microbiota, depending on their species and concentrations. Microcalorimetric experiments revealed these surfactants exhibited toxicity to microorganisms at high concentrations (above 1 CMC), except for SDS which showed low antibacterial activity. Surfactant supplementation (about 0.1 and 0.2 CMC) could improve degradation rate of crude oil slightly, while high surfactant concentration (above 1 CMC) may decrease the degradation rate from 50.5% to 28.9%. Those findings of this work could provide guidance for the application of surfactants in bioremediation of oil pollution.

Phyto-enhanced remediation of soil co-contaminated with lead and diesel fuel using biowaste and Dracaena reflexa: A laboratory study

In phytoremediation of co-contaminated soil, the simultaneous and efficient remediation of multiple pollutants is a major challenge rather than the removal of pollutants. A laboratory-scale experiment was conducted to investigate the effect of 5% addition of each of three different organic waste amendments (tea leaves, soy cake, and potato skin) to enhance the phytoaccumulation of lead (60 mg kg(-1)) and diesel fuel (25,000 mg kg(-1)) in co-contaminated soil by Dracaena reflexa Lam for a period of 180 day. The highest rate of oil degradation was recorded in co-contaminated soil planted with D. reflexa and amended with soy cake (75%), followed by potato skin (52.8%) and tea leaves (50.6%). Although plants did not accumulate hydrocarbon from the contaminated soil, significant bioaccumulation of lead in the roots and stems of D. reflexa was observed. At the end of 180 days, 16.7 and 9.8 mg kg(-1) of lead in the stems and roots of D. reflexa were recorded, respectively, for the treatment with tea leaves. These findings demonstrate the potential of organic waste amendments in enhancing phytoremediation of oil and bioaccumulation of lead.

INTEGRATION OF BIODEGRADATION AND MIGRATION OF HYDROCARBONS IN A 2D PETROLEUM SYSTEMS MODEL: APPLICATION TO THE POTIGUAR BASIN, NE BRAZIL

Biodegradation is probably the most important in‐reservoir alteration process and is responsible for the majority of the known heavy oil accumulations. In the present study, biodegradation processes were integrated within a forward basin and petroleum systems model applied to the Potiguar Basin, NE Brazil. This basin was chosen because it has been studied in detail and data from previous investigations are publically available. In order to account for processes occurring during the biodegradation of hydrocarbons, the evolution of fluid properties was simulated through time. In the model, a new approach was developed in order to determine the intensity of microbial activity and the evolution of the oil‐water contact, the zone within which biodegradation is confined. The numerical results obtained by applying the forward simulator to a 2D model of the Potiguar Basin fit the observed data concerning the composition and quality of the oil in a series of oilfields. These accumulations are located along the NE‐SW oriented “Carnaubais trend” and show progressive biodegradation along the migration path from the offshore kitchen area. Our results show that the biodegradation trend observed along the cross‐section can in general be explained by the fact that reservoirs are successively filled as a result of spilling from previous reservoirs, with continuous hydrocarbon degradation occurring within the reservoirs. This charge history resulted in differences in the composition of oils transported from upstream to downstream reservoirs, and in the evolution over time of the ratio between biodegradation and reservoir filling rates. Thus, in addition to residence time in the biodegradation temperature window, the rate of reservoir infill, the rate of oil degradation and the migration pathways are key factors controlling biodegradation. This study also demonstrates how the approach developed within our petroleum system simulator, which integrates both migration and biodegradation, may improve the assessment of oil quantity, quality and migration timing.

Characterization and application of a novel bioemulsifier in crude oil degradation by Acinetobacter beijerinckii ZRS

Bioemulsifiers can be applicated in a variety of areas such as bioremediation and microbial-enhanced oil recovery. The present study was aimed at bioemulsifier production, optimization, stability studies, and applications of the bioemulsifier produced by one of these strains, Acinetobacter beijerinckii ZRS. When Acinetobacter beijerinckii ZRS is cultured with hexadecane as a carbon source, it produces a novel extracellular emulsifying agent that does not cause remarkable reductions in surface tension. In order to enhance bioemulsifier production, response surface methodology was applied to optimize the culture medium. The bioemulsifier was subjected to thin-layer chromatography, Fourier transform infrared spectroscopy (FTIR), gel filtration chromatography, matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF), and nuclear magnetic resonance (NMR), which allowed for the identification of a novel polymeric bioemulsifier. The bioemulsifier retained its properties at a wide range of pH values, high temperatures and high salinities (up to 5% [w⁄v] Na(+) and 24% Ca(2+)). To deduce the role of this bioemulsifier in a coastal zone oil spill, the propagation of oil-degrading bacteria on oil-coated grains of gravel immersed in seawater was investigated in beach-simulating tanks. The bioemulsifier played a positive role in the degradation of these hydrocarbons and increasing the light crude oil degradation rate of the bacterial strain from 37.5 to 58.3% within 56 days. Therefore, this bioemulsifier shows strong potential to be used for bioremediation of oil pollution in marine environments.

Marsh plants mediate the influence of nitrogen fertilization on degradation of oil from the Deepwater Horizon spill

Coastal wetlands are commonly exposed to hydrocarbon pollutants derived from extraction disasters like the Deepwater Horizon oil spill. Naturally occurring microbes can degrade oil, but the rate of oil degradation depends heavily on the key chemical and biological factors. The goal of this study was to determine the influence of interactions between marsh plants and nitrogen (N) on the degradation of oil from the Deepwater Horizon oil spill. Oil disappearance was measured with gas chromatography (GC) focusing on the change in C18 n‐alkane‐to‐phytane ratio of oil, and instantaneous oil degradation rates were measured using an instantaneous carbon isotopic partitioning method. N addition often stimulates oil decomposition in soil slurries, but the effect of N in our mesocosms depended on plant species. N addition accelerated oil degradation in Spartina alterniflora mesocosms but slowed oil degradation in Spartina patens mesocosms. Across all plant and N treatments, oil degradation related to plant root growth. In many ecosystems including marshes, N addition has been shown to diminish root growth by reducing the need for nutrient foraging. Where N addition reduces root growth, N may ultimately exacerbate oxygen scarcity in marsh soils possibly negating or reversing the positive, direct effects that N has on oil degradation. Based on these findings, fertilization strategies that maximize marsh plant root growth will be the most effective at increasing the microbial degradation of oil and will have the greatest potential to mitigate the impacts of oil in marsh ecosystems.

Biodiversity and degradation potential of oil-degrading bacteria isolated from deep-sea sediments of South Mid-Atlantic Ridge

The indigenous oil-degrading bacterial consortia MARA and MARB were enriched from the deep-sea sediments of South Mid-Atlantic Ridge (MAR) with crude oil as sole carbon and energy sources. Biodiversity and community analyses showed that members of α-Proteobacteria were the key players in consortium MARA, whereas those of γ-Proteobacteria were the key players in consortium MARB, which were studied by MiSeq sequencing method. Gravimetric method estimated the oil degradation rates of MARA and MARB to be 63.4% and 85.8%, respectively, after 20d. Eleven cultivable oil degraders with different morphologies were isolated. These strains were identified as Alcanivorax, Bacillus, Dietzia, Erythrobacter, Marinobacter, Nitratireductor, and Oceanicola based on 16S rRNA gene sequences. Three strains belonging to Dietzia exhibited the highest oil degradation capability. Results indicated that the intrinsic biodegradation capacity of oil contaminants by indigenous microbial communities exists in South MAR sediments.