Crude Oil Removal Research Articles

Study on the mechanism and recoverability of magnetically enhanced ionic liquid microemulsion for oily sludge treatment

Magnetic ionic liquid (MIL) 1-hexadecyl-3-methylimidazolium tetrachloroferrate (III) ([C16mim]FeCl4) with high surface activity and magnetic responsiveness was synthesized and chosen as surfactant for the preparation of MIL-microemulsion, which could be applied to the effective treatment of oily sludge based on its large specific surface area and good solubilization. Under the optimal conditions of MIL concentration of 3.0 wt%, stirring time of 40 min, stirring speed of 500 r/min and temperature of 25 °C, the residual oil rate reached up to 1.36%. Scanning electron microscope (SEM) and fourier infrared spectrometer (FT-IR) measurement proved the successful removal of crude oil. The interaction between [C16mim]FeCl4 and each component in crude oil was explored by interfacial tension (IFT) and quartz crystal microbalance with dissipation (QCM-D). The results demonstrated that MIL exhibited the lowest interfacial tension of 13.48 mN/m and the highest desorption rate of 28.18% with asphaltene. In addition, based on the magnetic responsiveness of MIL, the application of magnetic field made it possible for the recovery of MIL, which could be reused for the preparation of microemulsion. Even after 5 cycles, the residual oil content in the oily sludge remained below 1.92%. The controllable recovery and reuse of [C16mim]FeCl4 by external magnetic field expanded the application of MIL-microemulsion in the field of oily sludge treatment.

Superhydrophobic and robust photothermal/electrothermal PVDF-a/CNT-s@PDMS membrane for crude oil removal and dye adsorption

Recently, the crude oil spill has brought inevitable harm to the global ecological environment. Due to the high-viscosity crude oil, it is wise to take advantage of the photothermal/electrothermal effects of the membrane to separate the crude oil from the water. However, the functional separation membrane always suffers from low photothermal/electrothermal effects and poor stability. Herein, the vinyl polyvinylidene fluoride/mercapto carbon nanotubes@vinyl-terminated polydimethylsiloxane (PVDF-a/CNT-s@PDMS) membrane with fast photothermal/electrothermal effects and organic absorption property was successfully prepared by electrospinning and multi-layer loading method. The prepared PVDF-a/CNT-s@PDMS membrane resisted a variety of liquids and had stable superhydrophobicity (WCA = 156°). Furthermore, the membrane maintained superhydrophobicity even suffer from water and milk under the applied voltage condition. After 100 wear resistance tests, the membrane maintained stable superhydrophobicity and the separation rate remained unchanged. The surface temperature of the membrane rapidly approached to the maximum temperature in 30 s, showing a rapid photothermal/electrothermal effects, and the average separation rate of crude oil was 1185 kg m−2 h−1·bar−1. Meanwhile, the membrane exhibited outstanding efficiency for separate immiscible oil-water mixtures. Importantly, the incorporation of the sulfhydryl group enhanced the special ability of the composite membrane to adsorb organic dyes from oil phase. Therefore, the PVDF-a/CNT-s@PDMS membrane has a wide range of potential application in the domain of oil-water separation.

De-oiling characteristics and mechanism of oil-bearing sludge cleaned by CGAs

There hasn't been much study on using Colloidal Gas Aphrons (CGAs) to clean oily sludge. In addition, the efficacy and mechanism of CGAs-enhanced surfactant cleaning of oily sludge are not yet clear. Therefore, in this study, CGAs prepared from the compound surfactant solution were used to clean oily sludge in an oil field in Xinjiang. The performance of CGAs in terms of oil removal and particle size was both examined when building the surfactant compounding system. The removal abilities of CGAs from different crude oil components and an analysis of the chemical cleaning process of CGAs were studied. The results demonstrated that the interfacial tension was as low as 3.535 mN/m and the oil removal rate of CGAs was as high as 92.9% when the ideal ratio of sophorolipid (SL) to sodium dodecyl benzene sulfonate (SDBS) was 6: 4. The average particle size of CGAs was 90.57 µm at this ideal ratio. The Zeta potential and turbidity of the supernatant after CGAs cleaning was lower than those of chemical cleaning. Infrared analysis, two-dimensional fluorescence analysis, and thermogravimetric methods were used to characterize the oily sludge after CGAs cleaned. According to the analysis's findings, CGAs' enormous specific surface area allows them to adsorb more petroleum pollutants and improved the ability of those pollutants to migrate between the water phase and other phases of the atmosphere. Also, CGAs are particularly successful in adhering to petroleum-based pollutants in oil sludge for the removal of light constituents like n-alkanes and aromatic hydrocarbons due to the synergistic effects of hydrophobic and electrostatic effects on the functional surface of CGAs. This work provides useful information on the mechanism of the enhanced removal of crude oil from oily sludge by CGAs and provides a new idea for oily sludge cleaning.

Maize cob (Zea mays) as natural biomass sorbent for crude oil biosorptive removal from contaminated seawater: Taguchi process optimization and biosorptive removal mechanism.

Crude oil pollution poses a serious threat to the aquatic environment. Hence, there is an increasing interest in developing an efficient cleaner process technique for oil spill cleanup via agricultural biomass waste-organic sorbent utilization. This work evaluated the effects of independent biosorptive removal at three varying levels (initial concentration of crude oil (Z1, 7.8-15.6 g/L), seawater-oil temperature (Z2, 25-45 °C), sorbent dose (Z3, 1-3 g), and sorbent particle size diameter (Z4, 1.18-4.72 mm)) on the biosorptive removal efficiency and biosorptive capacity performance of maize cob sorbent for crude oil biosorptive removal from seawater. Experiments were designed based on Taguchi orthogonal array experimental design (L9(34)) to study the effects and process optimization. The results revealed that the maize cob sorbent's crude oil biosorptive removal efficiency is related to Z1, Z3, and Z4, while the biosorptive capacity is related to Z1 and Z3. The optimum biosorptive removal efficiency and the biosorptive capacity values were 96.53% and 12.64 g/g, respectively, achieved at optimum factors of Z1 (7.8 g/L), Z3 (3 g), and Z4 (1.18 mm), as well as at Z1 (15.6 g) and Z3 (1 g). The isotherm and kinetic data, respectively, followed the Langmuir isotherms and the pseudo-second-order kinetics with a maximum monolayer biosorptive capacity of 23.31 g g-1. The mechanism of biosorptive crude oil removal was by physical sorption and film diffusion control. Therefore, the maize cob represents an inexpensive and effective natural sorbent for oil spill removal from water bodies.

Simultaneous immobilization enhances synergistic interactions and crude oil removal of bacterial consortium

Oil spillage has serious adverse effects on marine environments. The degradation of crude oil by microorganisms may be an effective and sustainable approach. In this study, the removal of crude oil from seawater by immobilized bacterial consortium was performed and the enhancement of crude oil degradation efficiency by varying immobilization methods and inoculum volume ratio was examined. The nonpathogenic and heavy metal-tolerant bacterial consortium of Sphingobium naphthae MO2-4 and Priestia aryabhattai TL01-2 was immobilized by biofilm formation on aquaporousgels. The simultaneous immobilization of strains MO2-4 and TL01-2 showed better crude oil removal efficiency than independent immobilization, which indicated positive interactions among consortium members in the mixed-culture immobilized systems. Moreover, the immobilized consortium at a 2:1 (MO2-4:TL01-2) inoculum volume ratio showed the best crude oil removal capacity. The immobilized consortium removed 77% of 2000 mg L−1 crude oil in seawater over 7 days. The immobilized consortium maintained crude oil removal efficacy in semicontinuous experiments. In addition, the immobilized consortium was used to remediate seawater contaminated with 1000 mg L−1 crude oil in a 20 L wave tank. After 28 days, the crude oil degradation efficiency of immobilized consortium was approximately 70%, and crude oil degradation through natural attenuation was not observed. Moreover, the genomic features of strains MO2-4 and TL01-2 are reported. Genomic analyses of both strains confirmed the presence of many genes involved in hydrocarbon degradation, heavy metal resistance, biosurfactant synthesis, and biofilm formation, supporting the biodegradation results and characterizing strain properties. The results of this work introduce the potential benefit of simultaneous immobilization of bacterial consortia to improve efficiency of crude oil biodegradation and has motivated further investigations into large-scale remediation of crude oil-contaminated seawater.

Potential of some microbial isolates on diesel hydrocarbons removal, bio surfactant production and biofilm formation.

Potential of Arthrobacter citreus B27Pet, Bacillus thuringiensis B48Pet and Candida catnulata to produce biosurfactant using four different carbon sources (naphthalene, hexadecane, diesel and petroleum crude oil) was investigated. Removal of petroleum crude oil from aqueous culture and degradation of diesel were also determined using single and mixed culture of strains. The biofilm existence in single and mixed culture of strains was considered using naphthalene, hexadecane and diesel in culture medium. Cell surface hydrophobicity of A. citreus was higher than other isolates which also showed maximum surface tension reduction and emulsification index. As a whole, remarkable biosurfactant production occurred using petroleum crude oil as a carbon source in medium. A. citreus was found to be more robust than other tested strains in removal efficiency of crude oil due to its biosurfactant production capability. Statistically significant positive correlation was observed between biofilm existence and surface tension using diesel and hexadecane as carbon source. Overall diesel biodegradation efficiency by the mix culture of three applied strains was about 75% within a short period of time (10 days) which was accompanied with high biofilm production.

Simultaneous removal of crude oil and heavy metals by highly adapted bacterial strain Cutibacterium sp. NL2 isolated from Algerian oilfield.

Investigating the ability of bacteria to simultaneously enhance hydrocarbon removal and reduce heavy metals' toxicity is necessary to design more effective bioremediation strategies. A bacterium (NL2 strain) isolated from an Algerian oilfield was cultivated on crude oil as sole carbon and energy sources. Molecular analyses of the 16S rRNA gene sequence placed the strain within the Cutibacterium genera. This isolate was able to tolerate up to 60% of crude oil as sole carbon source. Chemical analyses (GC-MS) evidenced that strain NL2 was able to degrade 92.22% of crude oil (at optimal growing conditions: pH 10, 44 °C, 50 g L-1 NaCl, and 20% of crude oil (v/v) as sole carbon source) in only 7 days. NL2 isolate was also able to produce biosurfactants with reduction of surface tension of growing media (29.4 mN m-1). On the other hand, NL2 strain was able to tolerate high lead (Pb) and copper (Cu) concentrations (up to 60 mM). In fact, NL2 cultivated in the presence of 20% of crude oil, and 0.48 mM of Pb was able to reduce Pb concentration by a 41.36%. In turn, when cultivated on high Pb concentration (15 mM), the strain was able to remove 35.19% of it and 86.25% of crude oil, both in a time frame of 7 days. Our findings suggest that Cutibacterium strain NL2 is able to efficiently use and remove a wide range of crude oil substrates in presence of high Pb concentration. Accordingly, NL2 strain is of extreme interest from a biotechnological standpoint.

Mesoporous carbon spheres modified polyurethane sponge/phase change material composites: Photothermal conversion, thermal storage and efficient recovery of high-viscosity crude oil

Efficient recovery of crude oil spills is still a great challenge for worldwide due to its high-viscosity and low-fluidity. Although the application of solar-heated absorbents in accelerating crude oil recovery has achieved significant progress, solar irradiation intensity is greatly dependent on time, location and weather conditions, which greatly restrict their practical application. In order to solve this problem, a novel phase change material (PCM)-included polyurethane (PU) sponge with simultaneous solar energy conversion and storage capacity was prepared and used for crude oil removal from spill. As the oil adsorption material matrix, the polyurethane (PU) sponge was combined with mesoporous carbon spheres (MCS) first and further encapsulated myristic acid (MA) as latent heat storage material to obtain PU/MCS/MA composite PCMs. The high latent heat value (129.27 J g−1), large porosity, excellent solar-thermal conversion and storage capacity make PU/MCS/MA show remarkable in-situ oil viscosity reduction and it can absorb about 1.08 g cm−3 of crude oil under sunlight. Importantly, due to the encapsulation of MA, PU/MCS/MA can achieve efficient thermal storage to reduce the viscosity of crude oil via releasing latent heat at special circumstances. This study provided a potential strategy for the efficient utilization of clean energy and crude oil spills pollution treatment.

Application of Tea Waste/Alginate/Nanoparticles Iron Bio-nanocomposite Beads for Removal of Crude Oil

Application of Tea Waste/Alginate/Nanoparticles Iron Bio-nanocomposite Beads for Removal of Crude Oil

Efficient and eco-friendly mixed bacterial consortium for petroleum wastewater treatment: Effect of the bio-augmentation and biosurfactant addition on hydrocarbon biodegradation

In the present investigation, we aimed to study biological petroleum wastewater treatment. A bioprocess based on the use of a mixed bacterial consortium along with the addition of Biosurfactant (BioS) and bioaugmentation with BioS producing strains were evaluated. The consortium was the combination of two bacterial strains with the capacity to metabolize hydrocarbons, Baci and B201. Two other strains BH1 and BSS2 selected for their ability to degrade hydrocarbons as well as to produce BioS were also exploited. The effect of ex-situ and in-situ produced BioS on hydrocarbon biodegradation were compared. Obtained results demonstrated a moderate capacity to remove crude oil from contaminated water of about 47% for the consortium. The best improvement of hydrocarbon biodegradation of about 84% was obtained when adding BH1 derived BioS solely. However, ex-situ produced BioS exhibited better results. Regarding the wastewater characteristics, we note a decrease of the COD/BOD5 Ratio to reach 2.64. Thus, the wastewater became easily biodegradable. The described bioprocess is of great interest for the bioremediation of petroleum effluents. BioS addition as well as bioaugmentation enhanced crude oil removal.

Two-Phase Partitioning Bioreactor for the Treatment of Crude Oil- Contaminated Aqueous Solution

A new application of a combined solvent extraction and two-phase biodegradation processes using two-liquid phase partitioning bioreactor (TLPPB) technique was proposed and developed to enhance the cleanup of high concentration of crude oil from aqueous phase using acclimated mixed culture in an anaerobic environment. Silicone oil was used as the organic extractive phase for being a water-immiscible, biocompatible and non-biodegradable. Acclimation, cell growth of mixed cultures, and biodegradation of crude oil in aqueous samples were experimentally studied at 30±2ºC. Anaerobic biodegradation of crude oil was examined at four different initial concentrations of crude oil including 500, 1000, 2000, and 5000 mg/L. Complete removal of crude oil was achieved biphasic bioreactor after 3 weeks compared to 73-82% in the monophasic bioreactor for the same time period.

Advancing hyper-crosslinked materials with high efficiency and reusability for oil spill response

Developing materials with high efficiency for recovering oil to mitigate the environmental impact of oil spills has always been a challenging task. A commercial melamine formaldehyde sponge was coated with an optimised superhydrophobic/superoleophilic hyper-crosslinked polymer and applied to the removal of crude oil from oil-in-water emulsions for the improvement of oil spill clean-up processes. The high surface area, porosity, hydrophobicity, and selectivity of oil over water made the hyper-crosslinked polymer coated sponge (HPCS) an ideal sorbent for efficient oil/water separation. The system was able to strip crude oil from water emulsions of 1000 ppm to a negligible level of 2 ppm oil with minimal amounts of the HPCS material. More importantly, the HPCS material could be reused via a simple mechanical compression process, and the uptake capacity was retained over ten cycles. For five cycles of oil adsorption/mechanical compression the HPCS was able to provide water filtrate with oil concentrations of under 15 ppm. This is an effective and economical recovery system, removing the need for consistent solvent washing and drying processes. These results suggest that the HPCS is a promising material for oil/water separation and recovery under challenging conditions.

Bioremediation Potential of Algae (Chlorella vulgaris) in Crude Oil Contaminated Sediment

Aim: To evaluate the bioremediation potential of algae (Chlorella vulgaris) in crude oil contaminated sediment.
 Study Design: The study employs three (3) experimental designs using flat rubber, statistical analysis of the data and interpretation makes up the study design.
 Place and Duration of Study: New Calabar River, Choba, Obio Akpor Local Government Area, Rivers State, Nigeria, was used for this study. New Calabar River lies between longitude 6°53.13E and latitude 4°53.52N in Choba. Bioremediation monitoring process lasted for 56 days; analyses were carried out at 14 days’ interval.
 Methodology: Three (3) experimental set up were employed using a using flat rubber basin, each set up contained 2500g of sediment and was contaminated with 250ml of Crude Oil except Control 1 uncontaminated sediment (Us). The set up was augmented with the Chlorella vulgaris (CHL) except the control 1 and 2 (Us and Cs). Sediment profile like Temperature, pH, Nitrogen, Phosphorus, Potassium, electrical conductivity, moisture content, total organic carbon, soil organic matter and total hydrocarbon content (THC) before contamination was determined using standard analytical methods while parameters like Temperature, pH, Nitrogen, Phosphorus, Potassium and Total Hydrocarbon Contents (THC) were monitored throughout the experimental period. Microalgae and Hydrocarbon utilizing algae (HUA) were monitored throughout the experimental period using standard microbiological methods. Percentage Bioremediation was estimated from amount of THC reduction from day 1 (initial) of monitoring. Statistical analysis was carried out for microbiological and physicochemical parameters when treated using Statistical ANOVA to ascertain significant difference of mean values between various treatments.
 Results: Results revealed the amount of hydrocarbon removed and % bioremediation efficiency after 56 days of monitoring with different treatment on the set up is given in a decreasing order as follows: (initial contamination value of 10525mg/kg) Cs+Chl (7700mg/kg; 73.15%) > control (Cs) contaminated without amendment of organisms (6345mg/kg 60.28%) > and Us uncontaminated sediment 1969.96 mg/kg. The total hydrocarbon content (THC) of the treated setup decreased from (10525mg/kg initial contamination value) at the start of bioremediation to Cs+Chl (7700mg/kg: 73.15%) at the end of bioremediation. The highest count of microalgae (log10cfu/g) for each set up during the monitoring were as follows; day 0 Us (7.65) day14 Cs (7.63) day28 Us (7.70) day42 Cs+Chl (7.60) day56 Cs (7.30). It was observed that peak count was on day28 (7.70) and a decline was on day56 (7.30). The highest Hydrocarbon Utilizing Algae (Log10cfu/g) count for each set up during the monitoring were as follows; day 0 Cs+Chl (5.23) day 14 Cs+Chl (5.30) day28 Cs (5.23) day42 Cs+Chl (4.77) > day56 Cs (5.07). Decline was observed on day 42 and peak count was on day 14.
 Conclusion: Results from the study revealed that Chlorella vulgaris is capable of degrading hydrocarbon components. There was a faster utilization of hydrocarbon by set up with Chlorella vulgaris than control. Though incomplete removal of crude oil was observed in THC concentration value. This suggests that an improvement in the process is required. Such improvement could include biostimulation of the polluted sample or some chemical pretreatment of the sample. From the study, bioremediation can be said to be a viable and effective response to sediment contamination with crude oil.

Removal of Heavy Crude Oil from Wastewater Using Activated Carbon Obtained from Oak Seed Husk Biodegradable Lignocellulosic Biomass

Removal of Heavy Crude Oil from Wastewater Using Activated Carbon Obtained from Oak Seed Husk Biodegradable Lignocellulosic Biomass

Study the characteristics of porcellanite rocks and applied as a sorbent for removing crude oil

ABSTRACT The utilization of porcellanite rocks as a natural inorganic sorbent for crude oil sorption was investigated in this study. The experiments were achieved in batch operation, the efficiency of porcellanite was studied with different quantities of sorbent weight, grain size, mixing times and temperature. The effect of oil–water mixture pH on the sorption effectiveness of porcellanite at various pH value was tested. Porcellanite was chemically treated with HCl and NaOH to enhance the effectiveness of oil removal. The results show that porcellanite had good sorption effectiveness for crude oil at various pH and temperature. The maximum crude oil removal (82.2%) was obtained at a mixing duration of 20 min at room temperature and 3 g raw porcellanite with grain size 250 µm. Under optimized conditions, the raw porcellanite was found to adsorb about 82.2% of oil in the prepared sample. The study demonstrated that porcellanite has significant potential as a low-cost sorbent for oil spill cleanup.

Hydrophobic sandwich-like PVDF/rGO/PDMS composite membrane with fast electrothermal/photothermal response for crude oil removal

Functional membranes with electrothermal/photothermal effects are considered an effective method for separating water/viscous crude oil mixtures. However, the loading of photothermal and electrothermal particles in polymeric membranes with poor compatibility will deteriorate the membrane performance, leading to the unstable photothermal/electrothermal effects. Therefore, we prepared a hydrophobic sandwich structure polyvinylidene fluoride/reduced graphene oxide/polydimethylsiloxane (PVDF/rGO/PDMS) composite membrane using a two-step electrospinning process, which improved the binding force between the photothermal/electrothermal particles and the matrix with the composite membrane exhibiting super fast electric heating and photothermal effect. The temperature of the composite membrane surface rapidly reached to 162.5 °C within 30 s at 25 V. In addition, the addition of graphene (GO) improved the mechanical properties of the composite membrane. Meantime, the composite membrane possessed stable hydrophobicity and lipophilicity, which was beneficial for separating water/viscous crude oil mixtures. Owing to the controllable pore structure and special wetting behavior, the water-in-oil emulsion was successfully separated. Importantly, the separation rates of the water/crude oil mixtures under the electrothermal effect was 2340 kg·m−2·h−1·bar−1. Thus, this study provides a new method for preparing hydrophobic sandwich-like PVDF/rGO/PDMS composite membrane with electrothermal/photothermal effects, which has significant potential for engineering applications in high-viscosity crude oil removal and water-in-oil emulsion separation.

In English

Oil and oil products enters surface waters as a result of man-made disasters, caused, in particular, by military operations. In order to prevent ecological catastrophe, it is necessary to remove hydrocarbons from water surface. The paper is devoted to the development of materials for the extraction of non-polar liquids from aqueous media. Magnetic sorbents based on non-carbonized biopolymers (both plant cellulose and keratin) are proposed. Biopolymer matrices of different morphology on the level of fiber bundles were used for the composite preparation. Dependent on origin, the matrices are characterized by different morphologies at the level of fiber bundles: they are straight (cellulose obtained from wood and corn cobs), helical (cellulose of tea leaves or scaly (keratin from animal wool). Magnetite particles were inserted into biopolymer matrices after the removal of non-cellulose and non-keratin inclusions from them. The samples were investigated with SEM and FTIR techniques, magnetite was identified with XRD analysis. The most homogeneous distribution of magnetic particles, a size of which is less than 1 mm, was found for the matrix obtained from corn cobs. This composite contained the least amount of iron (0.24 mass. %), namely this sample demonstrates the best flotation. The sorbent based on cellulose from tea leaves contained 71% of iron: the particles sink almost completely. The capacity towards non-polar liquids was estimated as follows (g g–1): 1.6–8.6 (vegetable oil), 10.5–16.4 (crude oil), 9.8–14.5 (kerosene). After the removal of crude oil from water surface, no film of this liquid was visually observed. The value of chemical oxygen demand was » 0.2 mgO2 dm–3, this is less than the demand for drinking water. Moreover, the sorbent can be easy removed from water surface with magnet. As found, the sorbents can be used for removal of toxic metal ions from water. As found, magnetic particles improves sorption of Pb2+ ions but decrease Cd2+ sorption. Thus, the sorbents with small content of inorganic modifier can be used for the removal of oil and oil products from water surface. The sorbents, which demonstrate bad flotation, can be used for the recovery of inorganic ions. The advantages of biopolymer-based sorbents over known material is a simple preparation procedure that involves cheap and available feedstock. Moreover, the sorbents can be easy separated from aqueous phase with magnet.

Combined Influence of High Pressure and High Temperature on the Removal of Crude Oil from Water during Laboratory-Scale Gas Flotation

Combined Influence of High Pressure and High Temperature on the Removal of Crude Oil from Water during Laboratory-Scale Gas Flotation

Enhanced crude oil degradation by remodeling of crude oil-contaminated soil microbial community structure using sodium alginate/graphene oxide/Bacillus C5 immobilized pellets

Bioaugmentation (BA) of oil-contaminated soil by immobilized microorganisms is considered to be a promising technology. However, available high-efficiency microbial agents remain very limited. Therefore, we prepared a SA/GO/C5 immobilized gel pellets by embedding the highly efficient crude oil degrading bacteria Bacillus C5 in the SA/GO composite material. The optimum preparation conditions of SA/GO/C5 immobilized gel pellets were: SA 3.0%, GO 25.0 μg/mL, embedding amount of C5 6%, water bath temperature of 50°C, CaCl2 solution concentration 3% and cross-linking time 20 h. BA experiments were carried out on crude oil contaminated soil to explore the removal effect of SA/GO/C5 immobilized pellets. The results showed that the SA/GO/C5 pellets exhibited excellent mechanical strength and specific surface area, which facilitated the attachment and growth of the Bacillus C5. Compared with free bacteria C5, the addition of SA/GO/C5 significantly promoted the removal of crude oil in soil, reaching 64.92% after 30 d, which was 2.1 times the removal rate of C5. The addition of SA/GO/C5 promoted the abundance of soil exogenous Bacillus C5 and indigenous crude oil degrading bacteria Alcanivorax and Marinobacter. In addition, the enrichment of hydrocarbon degradation-related functional abundance was predicted by PICRUSt2 in the SA/GO/C5 treatment group. This study demonstrated that SA/GO/C5 is an effective method for remediating crude oil-contaminated soil, providing a basis and option for immobilized microorganisms bioaugmentation to remediate organic contaminated soil.

Influence of power generation period on the oily sludge bio-electrical system.

The single-chamber bio-electrical systems can degrade oily sludge in sediments while generating electricity from the microbial fuel cells (MFCs) and their characteristics in energy and environmental effects have attracted wide international attention in recent years. To explore the influence of the power generation period on the oily sludge bio-electrical system, an oily sludge bio-electrical system was constructed. The output voltage, polarization curve, power density curve, crude oil removal rate and microflora were detected during different power generation periods, respectively. The results of this study showed that under the stable power generation period, the power generation and oily sludge degradation performance of MFC are higher than the voltage rise period and voltage attenuation period. Besides, the oily sludge bio-electrical system during the stable period contained more electricity-producing bacteria than the other two periods. The voltage in the stable period of oily sludge bio-electrical system is about 280 mV, the electromotive force is 493.1 mV and the power density is 134.93 mW·m-3. It lays a foundation for the improvement of degradation of crude oil and power generation performance in oily sludge bio-electrical system.