Oil Tank Bottom Sludge Research Articles

Hydrothermal Carbonization of Crude Oil Tank Bottom Sludge for Energy Applications

Hydrothermal Carbonization of Crude Oil Tank Bottom Sludge for Energy Applications

Screening oil tank bottom sludge microbial community for identification of native efficient hydrocarbon-degrading bacteria for bioremediation purposes

Screening oil tank bottom sludge microbial community for identification of native efficient hydrocarbon-degrading bacteria for bioremediation purposes

Analysis of surfactant production by Bacillus cereus GX7 and optimization of fermentation conditions

Although biosurfactants have many advantages compared to chemical surfactants, biosurfactants are still limited by problems such as low yields and high production costs. In the present study, a strain of Bacillus Cereus (GX7) isolated from an oil tank bottom sludge of Shengli Oil Field (China) was selected as a highly effective surfactant producer. The biosurfactant produced by GX7 was extracted, purified, and analyzed by TLC, FT-IR, and LC-MS/MS. The results showed that the biosurfactant was surfactin of lipopeptide surfactant. Single-factor experiments were used to optimize the fermentation process of the strain from two aspects: the composition of the fermentation medium (carbon source, nitrogen source) and the fermentation conditions (temperature, pH, inoculation amount, rotation speed, and fermentation time). The surface tension and emulsification index of the fermentation broth were used to evaluate the optimal fermentation conditions. The results showed that the best carbon and nitrogen sources were glucose and peptone, and the optimum temperature, inoculum amount, pH, rotation speed, and fermentation time were 30 ℃, 1%, 7.5, 150 rpm, and 48 h, respectively. After optimization, the surface tension and emulsification index of fermentation broth were 26.84 mN/m and 57.84%, respectively. Moreover, the results also prove that the biosurfactant produced by this strain has good stability in a wide range of temperature, pH, and salt concentration.

Effects of Ionic Liquid, 1-Ethyl-3-methylimidazolium Chloride ([EMIM]Cl), on the Material and Electrical Characteristics of Asphaltene Thin Films.

Asphaltene is a component of crude oil that has remained relatively unexplored for organic electronic applications. In this study, we report on its extraction technique from crude oil tank bottom sludge (COTBS) and its thin-film characteristics when 1-ethyl-3-methylimidazolium chloride ([EMIM]Cl) ionic liquid (IL) was introduced as dopants. The extraction technique yielded asphaltene with more than 80% carbon content. The IL resulted in asphaltene thin films with a typical root-mean-square surface roughness of 4 nm, suitable for organic electronic applications. The thin films each showed an optical band gap of 3.8 eV and a sheet resistance as low as 105 Ω/□. When the film was used as a conductive layer in organic field-effect transistors (OFET), it exhibited hole and electron conduction with hole (µh) and electron (µe) mobilities in the order of 10−8 and 10−6 cm2/Vs, respectively. These characteristics are just preliminary in nature. With the right IL, asphaltene thin films may become a good alternative for a transport layer in organic electronic applications.

Response surface methodology to optimize ultrasonic-assisted extraction of crude oil from oily sludge

This study is the first to use a response surface method to optimize the main parameters of ultrasonic-assisted recovery of oil from oily sludge. The solvent with the highest oil recovery (xylene) and most suitable process (Ultrasonic Assisted Extraction) were first selected based on the highest oil recovery rate. Then, single-factor experiments were performed to determine the best parameter range of solvent sludge ratio, frequency, duration, and temperature. Box-Behnken response surface methodology was used to study the influence of each variable on oil recovery. Solvent sludge ratio, frequency, and duration were found to have significant effects. The model optimization results show that the best conditions for Ultrasonic Assisted Extraction are as follows: a solvent to sludge ratio of 7.56:1, frequency of 31.48 kHz, duration of 23.67 min, and temperature of 45.87 °C. Under optimum conditions, the oil recovery predicted by the model and the actual oil recovery were 87.21 and 83.77%, respectively. The relative error between the predicted and actual values was 3.44%. These results indicate that the model results are reliable. Finally, the characteristics of the recovered oil and residue were analyzed. This research provides the possibility to utilize difficult-to-handle crude oil tank bottom sludge.

Process optimization for the recovery of oil from tank bottom sludge using microwave pyrolysis

Petroleum refining generates hazardous sludge with polyaromatic hydrocarbons and heavy metals. The main objective of the study was to evaluate the performance of microwave pyrolysis for the recovery of oil from furnace oil sludge. The characteristics of furnace oil tank bottom sludge such as pH, moisture, viscosity, and volatile hydrocarbon content were determined. Thermal Gravimetric Analysis has been done to determine the cracking and degradation range of oily sludge. Gas Chromatography-Mass Spectrometry was used to fingerprint the hydrocarbon. Pyrolysis experiments were conducted in lab-scale pyrolysis set up with different susceptors and sludge in a specific weight ratio. The process parameters like microwave power, sludge: susceptor ratio were optimized to increase the oil yield. Graphite mixed sludge in 1:5 ratio at 450 W power shown higher oil yield. The calorific value of oil and char were determined as 44,442.9 and 16,686.58 kJ /kg. Physicochemical characteristics of oil such as flash point, density, and kinematic viscosity are 94 °C, 874.9, kg/m3, and 4.063 cSt. Cetane index and sulfur content were measured as 40.9, 6.85 g/kg respectively. The gas analysis had shown the presence of H2, CO2, CO, and CH4 compounds. Char contains a higher percentage of carbon, Fe, Al, Ni, Pb, Cd, and S compounds.

Biodegradation of oil tank bottom sludge using a new two-phase composting process: kinetics and effect of different bulking agents

In this study, the effect of adding various bulking agents on the performance of a two-phase composting method in bioremediation of petroleum compounds from oily sludge was surveyed. The utilized system included the primary stage composting (PSC) using 6 windrow piles and the secondary stage composting (SSC) using 6 in-vessel bioreactors. Various amounts and combinations of immature compost, mature compost, and green waste were blended with oil tank bottom sludge (OTBS). Then, the mixture was added to the PSC and SSC experiments and composted for a period of 12 and 6 weeks, respectively. The results showed that the degradation percentages of total petroleum hydrocarbons in the PSC and SSC experiments were 63.56–84.50% and 57.59–88.95%, respectively. The removal efficiency reached through the two-phase system was higher than that of the single-stage process. Biodegradation was fitted to the first- and second-order kinetic with the rate constants of 0.076–0.389 day−1 and 0.006–0.176 g kg−1 day−1, respectively. The bacteria identified from the composting mixtures were Bacillus sp., Pseudomonas sp., Staphylococcus sp., and Klebsiella sp. It was concluded that the two-stage composting system, as an inexpensive and efficient method, is practically applicable for remediation of OTBS.

Ionic Liquid-Enhanced Solvent Extraction for Oil Recovery from Oily Sludge

An ionic liquid (IL), 1-ethyl-3-methyl-imidazolium tetrafluoroborate ([Emim][BF4]), was investigated for its effectiveness on enhancing oil recovery from hazardous crude oil tank bottom sludge usin...

Oil recovery from tank bottom sludge using rhamnolipids

Oil sludge has become a major impediment to the development of the petroleum and petrochemical industries with the growth of oil production worldwide. In this research, rhamnolipid biosurfactant produced by Pseudomonas aeruginosa was used to recover oil from oil tank bottom sludge. The optimum value of the fermentation broth (with rhamnolipid biosurfactant concentration of 5.4 g/L) addition was a volume fraction of 2% (v/v). Optimal temperature (65 °C), liquid/solid ratio (3:1), washing time (3 h), and agitation intensity (300 rpm) for oil recovery were determined. Wastewater from oil recovery was flocculated with 400 mg/L polyaluminum chloride for reuse. The moisture of the recovered oil was (0.42 ± 0.12) %, which could directly enter into the refinery process. The solid particles in the oil sludge exhibited a porous structure that adsorbed a significant amount of oil and increased the difficulty of oil recovery. Results showed that the fermentation broth of P. aeruginosa can be used to recover oil from oil sludge and has potential industrial applications.

Large scale bioaugmentation of soil contaminated with petroleum hydrocarbons using a mixed microbial consortium

Singapore is a highly industrialised country with an important oil industry resulting in a significant environmental impact, creating vast amounts of hydrocarbon waste that needs to be remediated. Here we report on the commercial scale bioremediation of a soil contaminated with processed petroleum hydrocarbons at a petroleum facility located offshore from Singapore. Initial laboratory results indicated the efficacy of an adapted consortium in terms of degradation of petroleum hydrocarbons, with complete degradation of the contaminants occurring after 21days. Microbial counts confirmed a bacterial increase during the degradation and an ecotoxicological assessment using Brassica rapa confirmed a reduction in the toxicity of the treated soil. In field studies for example, initial processed petroleum hydrocarbon concentrations of 26,240; 622,657; and 978,399mgkg−1 in 250 tonnes of soil were degraded to <1000mgkg−1 in 9, 12 and 17weeks, respectively following the bioaugmentation treatment. A 100% germination rate of Brassica rapa was also observed in the field for all the treated soil batches except for soils further contaminated with oil tank bottom sludge. Moreover, further total petroleum hydrocarbons (TPH) analysis performed 3years after the treatment confirmed that their concentrations have remained low (7–35mgkg−1) all over the site. To the author's knowledge, this is among the first studies to report large scale successful bioaugmentation of TPH-contaminated soil in Singapore.

An effective soil slurry bioremediation protocol for the treatment of Libyan soil contaminated with crude oil tank bottom sludge

Petroleum hydrocarbons are the most widespread contaminants in the environment. Soil contamination with crude oil tank bottom sludge (COTBS) represents a significant risk to both human and environmental health. Current traditional approaches only partially resolve the issue as they are inefficient, expensive, not environmentally friendly and leave behind unwanted products; hence, there is an urgent need to develop an environmentally friendly and cost effective solution to address this issue, especially in developing countries. The aim of this study was to develop a slurry phase bioremediation protocol for the treatment of Libyan soil contaminated with crude oil tank bottom sludge (COTBS) at a minimum soil:water ratio using indigenous bacterial isolates. Two hydrocarbonoclastic bacterial isolates, Pseudomonas spp. (4M12) and Pseudomonas xanthomarina (4M14), were used in three different strategies, namely:- bioaugmentation (BA), biostimulation (BS) and biostimulation-bioaugmentation (BS-BA) to assess their ability to reduce the total petroleum hydrocarbon concentration (TPH) in COBTS contaminated Libyan soil. The results indicated that a substantial reduction in TPH was observed in all three treatments, with the BS-BA treatments showing the highest reduction (96–97%, from 30,703 to 860 and 1020 mg kg−1), followed by the BS treatment (92–93% reduction). In contrast, control microcosms showed only a 17.15% reduction (30,667 mg kg−1) in TPH concentration. The results from CO2 respiration, community fingerprinting (DGGE) and metabolic profiling (Biolog assay) confirmed increased activity in the BS/BA treatment. For example, BS-BA treatments produced the highest levels of CO2 after 90 d incubation (0.075 mg day−1 g soil−1 and 0.072 mg day−1 g soil−1) respectively, some 244–258% higher than the control (0.020 mg day−1 g soil−1). This study confirms the potential benefit of the BS-BA approach and the ability of Pseudomonas spp. isolates to significantly reduce the TPH concentration in soil contaminated with COTBS. This approach can be utilized at the commercial scale, as it has lower water requirements than traditional slurry treatments.

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

Bioremediation is a widely used environmental friendly treatment method for petrogenic hydrocarbon contaminated soils but its application to the treatment of crude oil tank bottom sludge (COTBS) contaminated soil is limited especially in Mediterranean countries such as Libya. Therefore in this study, the hydrocarbon degrading abilities of three bioaugmentation agents Pseudomonas sp (4M12), Pseudomonas xanthomarina (4M14) and Arthrobacter nitroguajacolicus (1B16A) (isolated from COTBS polluted soils) applied as part of a biostimulation-bioaugmentation (BS/BA) strategy were assessed in COTBS contaminated Libyan soils. Biostimulated (BS) and natural attenuation (NA) microcosms were also set up for comparative purposes. Gas chromatograph mass spectrometer (GC- MS) analysis revealed a total soil petroleum hydrocarbon (TPH) and polycyclic aromatic hydrocarbon (PAHs) content of 30,703 mg kg-1 and 13,816 mg kg-1 respectively. Two carcinogenic fractions (naphthalene and benzenamine, 4, 4`methylenbis [2-methyl-]) and 4 mutagenic fractions (pyrene, phenanthrene, fluorene and anthracene) were detected. Substantial PAH degradation occurred in 4M14 and 4M12 samples within 15 days in contrast to up to 23 days in 1B16A, NA. However, substantial reduction in TPH (> 97%) was only observed in 4M12 and 4M14 inoculated microcosms within 15 days compared to 25-30 days in 1B16A inoculated, BS and NA microcosms. 4M14 inoculated microcosms were most efficient at complete removal (D100) of all carcinogenic and mutagenic fractions; 4M14 (9-10 days), 4M12 (9-15 days), 1B16A (15-23 days), BS (18-21 days) and NA (18-22 days). Pseudomonas xanthomarina was therefore shown as the best candidate for use in a BS/BA approach for treating COTBS contaminated Libyan soils. This study shows the importance of pre-screening bioaugmentation agents for the removal of carcinogenic and mutagenic fractions prior to use; in order to carry out safe, efficient and sustainable COTBS bioremediation in Libya.

Recovery and Characterization of Oil from Waste Crude Oil Tank Bottom Sludge from Azzawiya Oil Refinery in Libya

In this work we present the results of quantitative and qualitative analyses of oil obtained from crude oil tank bottom sludge (COTBS) generated from Azzawiya oil refinery in Libya. The aim of the study was to recover and evaluate oil from waste oily sludge and to compare it with parent oil (Hamada crude oil) in order to assess the commercial potential of recycling the oil. The benefits would be two-fold, firstly to improve oil utilisation efficiency and secondly in reducing the environmental contamination associated with the petrogenic hydrocarbon industry. Oily COTBS and extracted oil were characterised and key properties were measured including water and oil content, light and heavy hydrocarbon content, solid content and organic matter content for COTBS and water content, density, specific gravity, API (American Petroleum Institute) gravity, viscosity, salt and ash content for the extracted oil. Solvent (hexane) extraction confirmed that the oily sludge contained 42.08% (± 1.1%) oil composed of light hydrocarbons (30.7 ± 0.07%) and heavy hydrocarbon (69.3 ± 0.4%) fractions. The water and solid contents were 2.9% (± 0.2%) and 55.02% (± 0.6%) respectively. The properties of the recovered oil were assessed; gas chromatograph spectrophotometer (GC-MS) results indicated that the oil contained 139 different hydrocarbon fractions with a total petroleum hydrocarbon (TPH) concentration of 29,367 mgkg-1 and a polycyclic aromatic hydrocarbons (PAH) concentration of 11,752 mgkg-1. Several parameters of the oil were measured and compared to the parent oil (Hamada crude oil) including density, specific gravity, viscosity, salt and ash content. The API of the extracted oil (33.03) was lower than the parent oil (38.8) due to a reduced light hydrocarbon (LHC) content. TGAFTIR hyphenation shows both mass loss of hydrocarbons— low, medium and high molecular mass over a range of temperatures between 60°C and 450°C. crude oil extract exhibited a non-Newtonian behaviour (shear thinning) for the shear rate sweep between 10 and 500/s. dynamic shear rheology data showed that the extracted oil exhibit more like a solid than liquid. Overall the findings of the study confirmed that COTBD has a significant amount of oil similar in properties to Hamada crude oil. This large amount can be reclaimed and recycles. Depending on this essay, a commercial process could be performed which in parallel will reduce the environmental contamination with hydrocarbons.

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

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.

Exploiting the intrinsic hydrocarbon-degrading microbial capacities in oil tank bottom sludge and waste soil for sludge bioremediation

In this study, biological methods (biostimulation and bioaugmentation) were used to treat oil tank bottom sludge contaminated soils to total petroleum hydrocarbon (TPH) levels suitable for landfill disposal. The sludge’s hydrocarbon-degrading microbial capacities were initially compared to those from other contaminated environments using culture-based methods. Results indicated that a fungus, Scedosporium dominated the sludge microbial community. Its application in a nutrient formulation resulted in greater reduction in oil tank bottom sludge viscosity (44 %) and residual soil hydrocarbon compared to hydrocarbonoclastic microorganisms from other sources (26.7 % reduction in viscosity). Subsequent field-based experiments showed greater TPH reduction (54 %) in fungal-nutrient-treated sludge–waste soils than in naturally attenuated controls (22 %) over 49 days. 16S ribosomal ribonucleic acid and internal transcribed spacer region-based polymerase chain reactions and denaturing gradient gel electrophoresis analyses showed minimal effects on the microbial communities during this time. TPH reduction to landfill disposal levels occurred at a slower rate after this, falling below the 10,000 mg kg−1 legislated TPH disposal threshold earlier in amended samples (91.2 %; 9,500 mg kg−1) compared to the control (82 %; 17,000 mg kg−1) in 182 days. The results show that the intrinsic hydrocarbon-degrading microbial capacities in sludge are better suited for sludge degradation than those from other sources. The substantial TPH reduction observed in control samples demonstrates the beneficial effects of natural attenuation with waste soils for oil tank sludge treatment. Microbial capacities in sludge and treated waste soils can therefore be successfully employed for treating oil tank bottom sludge.

A model for predicting solid particle behavior in petroleum sludge during centrifugation

An efficient model is proposed for predicting the behavior of solid particles in petroleum sludge during centrifugation, from the particle size distribution and petroleum viscosity. Petroleum sewage sludge (PSS) and oil-tank bottom sludge (OBS), respectively collected from a sewage reservoir containing petroleum waste water and a petroleum oil storage tank, were studied. The solid particle removal and oil recovery rates were measured to assess the efficiency of the model. The model predicted that solid particles could be separated into three groups during centrifugation, with critical separation sizes of 69.2 and 80.3μm for the PSS and 91.2 and 110.3μm for the OBS, and that particles larger than the smaller critical separation size could be removed from each sludge efficiently at room temperature without pretreatment. The predicted cumulative particle removal rates using a three-stage centrifugation process were 50%, 61%, and 70%, for the three PSS-particle size ranges (in ascending order), which agreed well with experimental measurements (54%, 65%, and 75%, respectively). The experimental water/oil emulsion recovery rates were 86%, 81%, and 75%, respectively. Preheating enhanced the solid particle removal rate by 29% for PSS whose viscosity decreasing quickly with increasing temperature. Adding a solvent increased the solid particle removal rates to 90% for the PSS and 82% for the OBS, but caused the water/oil emulsion recovery rates to decrease to 69% for the PSS and 67% for the OBS. The model and experimental results suggest that the optimum centrifugation time should be determined after assessing the petroleum viscosity and the solid particle size distribution.

Removal of Oil Tank Bottom Sludge by Novel Biosurfactant, JE1058BS

Maintenance of crude oil storage tanks requires periodical washing of the tanks before ordinary repairs can be made to these systems. In this study, crude oil derived sludge in the oil storage tank was treated with various surfactants to disperse the sludge into a miscible fraction, including JE1058BS, a new biosurfactant produced by Gordonia sp. strain JE-1058. Phylogenetic analysis of the 16SrRNA sequence of the strain JE-1058 identified Gordonia polyisoprenivorans. The sludge was efficiently removed by dispersion with biosurfactant at concentrations of 1-10 g/L, with stable dispersion at 10 g/L for 3 weeks. Addition of the BS caused no significant changes except for water content in the physicochemical factors such as density, viscosity, and sulfur/nitrogen content, suggesting that the novel biosurfactant JE1058BS is useful for oil tank bottom sludge treatment.

Extraction of Hydrocarbons from Crude Oil Tank Bottom Sludges using Supercritical Ethane

A custom‐built, solvent recirculating, supercritical fluid extraction (SFE) apparatus was used to study the extraction of hydrocarbons from a crude oil tank bottom sludge (COTBS) with supercritical ethane. The SFE experiments were carried out varying the pressure (10 MPa and 17.20 MPa) and temperature (35°C and 65°C). The yield of the extracted hydrocarbon fraction increased with increase in extraction pressure at constant temperature, and decreased with increase in extraction temperature at constant pressure. The maximum extraction yield was obtained at the pressure and temperature conditions that lead to the highest solvent density. The extracted hydrocarbon fraction was a significantly upgraded liquid relative to the original untreated COTBS.