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Miscible carbon dioxide (CO2) flooding is a well-established and promising enhanced oil recovery (EOR) technique whereby residual oil is recovered by mixing with injected CO2 gas. However, CO2, being very light and less viscous than reservoir crude oil, results in inefficient sweep efficiency. Extensive research is ongoing to improve CO2 mobility control such as the development and generation of CO2/water foams. The long-term stability of foam during the period of flooding is a known issue and must be considered during the design stage of any CO2 foam flooding project. The foam stability can be improved by adding surfactants as stabilizers, but surfactants generated foams have generally a shorter life because of an unstable interface. Furthermore, surfactants are prone to higher retention and chemical degradation in the porous media, particularly under harsh reservoir conditions. Research has shown that nanoparticles (NPs) can act as an excellent stabilizing agent for CO2/water foams owing to their surface chemistry and high adsorption energy. The foams generated using NPs are more stable and provide better mobility control compared to surfactant-stabilized foams. One limitation of using NPs as foam stabilizers is their colloidal stability which limits the use of low-cost NPs. Combining surfactants and NPs for CO2 foam stabilization is a novel approach and has gained interest among researchers in recent years. Surfactants improve the dispersion of NPs in the aqueous phase and minimize particle aggregation. NPs on the other hand create a stable barrier at the CO2/water interface with the help of surfactants, thus generating highly stable and viscous foams. This paper presents a comprehensive review of the basic principles and applications of stabilized CO2 foams. A brief overview of CO2 foam flooding is discussed first, followed by a review of standalone surfactant-stabilized and NPs-stabilized CO2/water foams. The application of hybrid surfactant-NPs stabilized CO2 foams is then presented and areas requiring further investigation are highlighted. This review provides an insight into a novel approach to stabilize CO2/water foams and the effectiveness of the method as proved by various studies.

Hypothesis While surfactant solutions mobilize residual oil under optimal conditions by lowering the water–oil interfacial tension, emulsion phases outside of the optimum tend to be immobile. How are mobility and texture of such phases related, and how can the stability of these phases be understood? Can non-optimized surfactant solutions improve displacement processes through mobility control? Experiment Emulsification and miscibility during surfactant flooding were investigated in microfluidics with generic oil and surfactant solutions. The salt concentration was varied in an exceptionally wide range across the optimal displacement conditions. The resulting emulsion textures were characterized in situ by optical and fluorescence microscopy and ex situ visually and by Small-Angle X-ray Scattering. Findings During displacement, oil is increasingly solubilized and transported in a phase with a foam-like texture that develops from a droplet traffic flow. The extent and stability of these emulsion phases depend on the salinity and surfactant efficiency. The similarity with textures of classic foam phases is used to hypothesize the mechanisms that stabilize such macroemulsions in porous media. The observed microscopic displacement mechanisms can be traced back to foam formation, quality and transport. The resulting phases are of particular interest for mobility control during surfactant flooding, which, however, requires further investigation.

Due to the remarkable oil reduction in oil fields, enhanced oil recovery (EOR) techniques have been considered by a large number of scientists. In this study, the surfactant-polymer injection(SP) was firstly tested in a designed-micro model by using sand, gasoil and a crude oil to evaluate its performances, and then it was applied in the Y- field by involving a Single Well Chemical Tracer Test (SWCTT) to determinate the residual oil saturation (Sor) and the ability of the field to EOR. The results indicate that SP-flooding leads to the recovery of 95% of residual oil contained in 5 m radius.

In order to explore the influence of the micropore structure of the tight sandstone reservoir in the water driving characteristics, the studies on the Chang 6 tight sandstone reservoir of the middle-western part of Ordos Basin are carried out by various experiments such as cast-thin section analysis, scanning electron microscopy, high-pressure mercury injection and micro-water driving. The result shows that the permeability contribution curves of samples shift to the left as the sample permeability decreases, indicating that the greater the permeability, the greater the proportion of large pores. The permeability is mostly dominated by pores with the radius larger than R50–R60. There are big differences in the water driving type, oil-driven efficiency and residual oil distribution characteristics between reservoirs of different types. The type II reservoir is the major target of subsequent exploration and development, where water driving types consist of mesh and finger, leaving the residual oil mainly locked by water or isolated as oil drops. The size and distribution feature of pores are the key factors dominating the oil-driven efficiency.

Gas injection has been evaluated and implemented in the large carbonate oil field located offshore Qatar as water alternating gas or WAG. It has been seen that WAG is economically viable and a robust enhanced oil recovery (EOR) method for homogenous formations. However, using WAG in heterogeneous parts of the field has not been attempted due to issues like early gas breakthrough and unfavourable sweep efficiency. Hence, it was decided to design a foam-assisted WAG system that can provide the required conformance control to mitigate those issues and expand the use of WAG. A complete laboratory programme was carried out to screen the best foaming surfactant formulation that resulted in the selection of environmentally friendly, Alkyl polyglucoside (APG) surfactant. Surfactant testing involved foamability in porous media under oil-wet and water-wet conditions in presence of residual oil to gas flood. The chosen surfactant showed good foam strength in both cases with effective mobility reduction factors (MRF) above 20. The impact of mobile oil was also observed by co-injecting oil during linear core flood experiments, which clearly showed that good foam strength could be achieved in a lower flow fraction of mobile oil with foam. Additionally, boosting of foam strength using amphoteric Lauryl Betaine (LB) surfactant was also performed. The formulation with APG/LB (70%/30%) gives foam boosting of 2.5 times compared to foam strength using APG alone. Additionally, it was shown that altering wettability using a nonionic Tergitol surfactant (TGT-1) as pre-flush and then injecting APG-5 surfactant and methane resulted in foam strength, which is 1.5 times higher than observed in oil-wet conditions.

The C oilfield is located in the Bohai Bay Basin, a typical strong bottom water reservoir. Oilfield reservoir and oil–water distribution are complex. At present, the C oilfield has entered the high water cut development stage, and it is challenging to stabilize oil and control water. The reservoir with an imperfect well pattern has dominant bottom water ridge channels, uneven oil–water interface uplift, limited water drive sweep range, and low inter-well reservoir production degree. The oil layer between the horizontal section of the production well and the top of the reservoir cannot be effectively developed, and the remaining oil is enriched. Therefore, it is urgent to explore new energy supplement methods to improve inter-well and vertical remaining oil production in the C oilfield. In this study, the displacement medium is optimized through indoor experimental simulation. From the experimental results, the remaining oil between the sand bodies can be used in heavy oil reservoirs, and the residual oil between wells can be significantly utilized in the alternate displacement of gas and foam, and the recovery degree of the reservoir is increased by 12.44%. The remaining oil at the top of the reservoir can be used in the upper reservoir to increase the remaining oil in the top of the reservoir by injecting gas and foam alternately in the new reservoir. The final recovery of the reservoir is increased by 6.00%. This experimental study guides tapping the potential of the remaining oil in the offshore strong bottom water reservoir.

The main purpose of this work is to identify the hygroscopic equilibrium and also determine the product–water relationship in olive pomace. In this context, experimental, modeling and thermodynamic analysis of adsorption isotherms of four types of agricultural wastes (olive pomace), have been carried out. Two samples were separately de-oiled by the maceration method and the hydrothermal carbonization process. Besides, adsorption isotherms of these biomass samples were obtained experimentally at three oven temperatures (30, 40 and 50 °C). The findings showed that the de-oiled samples are more hydrophobic than those containing residual oil, especially when water activity (aw) values are higher than 0.4. Moreover, adsorption isotherms were modeled by five mathematical models available in the literature. In the thermodynamic point of view, the net isosteric heat and the differential entropy of adsorption were estimated for each sample. The highest value of the net isosteric heat (around 65 kJ mol−1) is obtained for no de-oiled samples. Also, it has been found that the development of monolayer adsorption requires more net isosteric heat to ensure the water molecules adhesion to the biomass surface unlike the formation of multilayer adsorption. In addition, the enthalpy/entropy compensation theory for all examined biomasses was confirmed, and their free energy values are positive (between 3479.8 and 4155.6 J mol−1). Finally, optimal water activity values were also estimated and ranged from 0.35 to 0.49.

Determining the pore structure characteristics and influencing factors of continental shale reservoir in the oil generation stage is of great significance for evaluating the shale oil reservoir space and analyzing shale oil enrichment mechanism. In this paper, shale from the first member of the Upper Cretaceous Qingshankou Formation (K2qn1) in the Songliao Basin was selected. X-ray diffraction (XRD), Rock-Eval pyrolysis, total organic carbon content (TOC), scanning electron microscopy (SEM), nitrogen gas adsorption (N2GA), and high-pressure mercury injection (HPMI) were used to clarify the composition characteristics of inorganic minerals and organic matter and determine the influencing factors of pore development in the K2qn1 shale. The results show that intergranular pores related to clay minerals and quartz, intragranular dissolution pores related to feldspar, and other mineral intragranular pores are developed. The organic matter pore is less developed, mainly composed of intragranular pores and crack pores of organic matter. Mesopores related to clay minerals are widely developed, rigid quartz particles can protect and support mesopores and macropores, and carbonate cementation can inhibit pore development. Although the TOC contents of shale are commonly less than 2.5%, it has a good positive correlation with porosity; TOC is greater than 2.5%, and the increase of residual oil fills part of the pores, leading to a decrease in porosity with the increase of TOC. Three types (types I, II, and III) of the reservoir space were classified by the combined pore size distribution diagram of N2GA and HPMI. By comparing the characteristics of pore structure parameters, it is found that Type I reservoir space is favorable for shale oil enrichment. It provides scientific guidance for shale oil exploration in the Songliao Basin.

Nowadays more emphasis is given to biodegradable polymers owing to their distinct properties. Biopolymers are natural, inexpensive, available, and environmentally friendly substitutes that are planned to substitute HPAM for enhanced oil recovery (EOR). In this research, grafted guar with different vinyl monomers prepared through a free radical emulsion polymerization reaction to enhance the drawbacks of native guar gum. Structure characterization was conducted by various spectroscopic techniques including (FTIR) spectroscopy, atomic force microscope (AFM), nuclear magnetic resonance (1H NMR), and thermal analysis established by TGA analysis. Rheological characteristics were tested at severe reservoir conditions. Laboratory flooding experiments performed by sandstone packed model. It is indicated from the rheological analysis that the modified composites have more temperature resistance, salt tolerance, and improved viscosity properties than native gum. The flooding data assumed that the prepared GG-g-AM& MMA and GG-g-AM, MMA&TEVS are suitable for EOR techniques where they can withstand the severe reservoir condition and achieve a recovery factor up to (47.7%) from residual oil by using GG-g-AM& MMA and (55.5%) of residual oil by using GG-g-AM, MMA&TEVS while native guar achieves only (27.7%).

A technique for determining the microstructural wettability of a carbonate rock using a scanning electron microscope (SEM) in the low-vacuum mode employing a special chamber and the results of respective experiments are described. To this end, the principle of the spontaneous formation of microscopic water droplets on the sample surface as a result of vapor condensation and measurement of the contact angle on SEM images is implemented. The possibility of determining the surface properties of dispersed particles with different mineral compositions is shown. Analysis of the surface properties of the pore space of oil-saturated rocks using a SEM makes it possible to specify the wetting properties in the pore space at the microscale level. These studies are of practical importance for petroleum geology. Detailed determination of the wettability makes it possible to predict the water cut of the produced products and provides additional possibilities for adopting special methods to decrease the amount of residual oil in the reservoir and increase the production of hydrocarbons.

The article comprises the selection of high-efficiency and cost-effective draining agents for the extraction of waste oil, which is becoming a global problem. The effectiveness of pushing residual oil with nitrogen in small cavities of the oil layer and in the capillary matrix was discussed. The theory of the mechanism of pushing residual oil in the porous cavities using nitrogen and it is important to test in the laboratory. The nitrogen is denser than oil; moreover it is gas which it can penetrate intensively at high pressures into cavities and capillary matrices, displacing residual oil from them along the cavities to the production wells. In this laboratory experiment was used core samples from the North Karamandybas field after drying and then they are saturated with oil in the vacuum with weighting each ones. Then, a specially designed device was used to push oil using the nitrogen. It was concluded that the experience of pushing oil in oil-saturated cores samples with nitrogen has yielded positive results, using this method will be increased the oil recovery of the formation in the field.

Solar-driven evaporation is promising in oily wastewater treatment, in particular for emulsions, but conventional evaporators suffer from pore blocking by residual oil or contamination by volatile oil compounds in the condensed water. In the current research, we develop a suspended membrane evaporator integrating solar evaporation with oil-in-water emulsion separation. The heating and evaporating interface is separated from the rejecting interface to avoid oil escape and improve heat management. A temperature gradient forms on the membrane surface that can promote evaporation performance by combining both solar and environmental evaporation. Such an evaporator achieves a maximum evaporation rate of 1.645 kg/(m2·h) as well as an apparent evaporation efficiency of 111.9%. Moreover, the superhydrophilic and superoleophobic membrane shows excellent oil repellence and emulsion rejection, which can achieve an oil removal efficiency above 98.8% in oil-in-water emulsion separation, and high evaporation rate recovery in cycling tests. A scaled-up membrane evaporator array produces ∼8 kg/(m2·d) of clean water from oily wastewater in outdoor experiments, further demonstrating the strong purification performance of this evaporator in oily wastewater treatment.

Waterflooding experiments were conducted in micro-models (microscopic scale) and on plunger cores from low permeability, extra-low permeability and ultra-low permeability reservoirs in the Ordos Basin under different displacement pressures using the NMR techniques to find out pore-scale oil occurrence state, oil production characteristics and residual oil distribution during the process of waterflooding and analyze the effect of pore structure and displacement pressure on waterflooding efficiency. Under bound water condition, crude oil mainly occurs in medium and large pores in the low-permeability sample, while small pores and medium pores are the main distribution space of crude oil in extra-low permeability and ultra-low permeability samples. During the waterflooding, crude oil in the medium and large pores of the three types of samples are preferentially produced. With the decrease of permeability of the samples, the waterflooding front sequentially shows uniform displacement, network displacement and finger displacement, and correspondingly the oil recovery factors decrease successively. After waterflooding, the residual oil in low-permeability samples is mainly distributed in medium pores, and appears in membranous and angular dispersed phase; but that in the extra-low and ultra-low permeability samples is mainly distributed in small pores, and appears in continuous phase formed by a bypass flow and dispersed phase. The low-permeability samples have higher and stable oil displacement efficiency, while the oil displacement efficiency of the extra-low permeability and ultra-low permeability samples is lower, but increases to a certain extent with the increase of displacement pressure.

Although thermal desorption is popular in remediation of contaminated soils, it is both energy-intensive and prone to deteriorate soil reuse. Meanwhile, less attention is paid to its chemical conversion. Here, the factors affecting the lube oil remediation efficiency are investigated, and the charring behaviors are explored from the perspective of chemical composition conversion in off-gas and treated soils. The impacts of heating temperatures on lube oil removals are significant, while those exerted by heating time and carrier gas velocity are minor. Heating at 350 °C for 30 min reduces the lube oil concentration from 74,840.60 to 4804.29 mg kg−1 by 93%, which is lower than the Chinese risk intervention value of 5000 mg kg−1. The SOC contents decrease gradually from 1.22 to 0.94% at 200–500 °C, still significantly higher than that of clean soils. Comparison between residual SOC ratios and residual oil concentration ratios indicates that partial residual organic carbon comes from some newly produced carbonaceous products in treated soils. GC–MS analysis of off-gas products confirms that polycondensation of lube oil is greater than cracking at 350 °C, while the case is just on the opposite at 500 °C. The micromorphology of the char formed is obtained by SEM. XPS analysis shows that chemical bonds between carbon-containing functional groups are broken and derived char is formed from lube oil and original organic matter after heating, being favorable for soil reusability. In short, indirect thermal desorption is efficient and sustainable for the remediation of lube oil-contaminated soils.

The effect of the preparation of raw materials (aqueous suspensions of the mixtures of biomass and oil residues) for gasification on the results of gasification and the composition and properties of the resulting synthesis gas was studied. It was found that combined mechanical activation of the suspensions/emulsions of oil and vegetable raw materials makes it possible to obtain synthesis gas with a high ratio of H2 : CO = 1.9–2.3 and a low soot content upon gasification. Synthesis gas can be separated and used for catalytic conversion into valuable organic products. The features of the preparation of homogeneous highly dispersed suspensions by mixing biomass and oil residues, in particular, a synergistic effect upon mixing biomass and oil raw materials, were revealed.

The hydrogenation and co-hydrogenation behaviors of Hami coal and Tahe residue were investigated in an autoclave, and the feasible technical route for co-hydrogenation was explored. The experimental results showed that Hami coal had good hydroliquefaction performance and the suitable reaction temperature was 445°C. At 445°C and 9 MPa, the coal conversion rate reached 98.74%, and the oil yield reached 68.54%. The hydrogenation tests of Tahe residue showed obvious coking tendency at the lower temperature, and it was difficult to achieve lightening. At 430°C, the conversion rate of Tahe residue was only 66.38%, the light oil yield was only 50.01%, and its coking rate was as high as 9.45%. The coking rate increased with the reaction temperature. When the mixtures of Hami coal and Tahe residue were co-hydrogenated directly, the conversion rate of the raw materials was lower, and the coke phenomenon was obvious. At the coal/oil ratio was 40/60, the conversion rate was 97.79%, and oil yield was 73.36%. Adding hydrogen solvents into the co-hydrogenation system could effectively inhibit coke formation, increase the conversion rate, and lighten co-hydrogenation products. When the amount of coal was 45% and Tahe residue was 20%, the conversion rate of raw materials was 98.38% and the oil yield was 74.82%.

For low-permeability sandstone reservoirs, CO2 huff and puff is an effective method for increasing oil recovery. Commonly, sandstone formations with low permeability have diverse pore and throat sizes and a complex pore-throat structure, which essentially affects the flow characteristics of CO2 and oil in the formation and further the CO2 huff and puff performance. It is necessary to understand the recovery degree of various microscale pore sizes under different operational parameters during CO2 huff and puff in tight sandstones. In this work, several experiments of cyclic CO2 injection are conducted with sandstone core samples with low permeability. Before and after the injection, the T2 spectra of the sandstone cores are compared using the NMR technique. We then discuss the micro residual oil distribution and recovery degree in different pores, such as micropores (100 ms). It is found that the recovery degree in the different pores increases as the pore size increases. Oil can be recovered more easily from macropores and medium pores during the cyclic CO2 injection. The oil contained in micropores is relatively difficult to extract considering a high capillary force under immiscible conditions. It is found that the total recovery degree increases with the increase in soaking time. However, such a recovery degree increment in small pores is not as large as that achieved in medium and large pores. With the CO2 injection volume increase, the total recovery degree increases. When the CO2 injection volume is less than 1.5 PV, it is challenging to extract the oil from micropores and small pores. As the cycle number increases, the cyclic oil recovery decreases, and most of the oil is produced in the first cycle. This suggests that under the experimental conditions of this study, the cycle number of CO2 huff and puff shall not be more than 3. This work is important to further understand the CO2 huff and puff process for improving oil recovery in sandstone reservoirs with low permeability.

Water-alternating-gas (WAG) injection is recommended as a means of improving gas mobility control. This paper describes a series of coreflood tests conducted to investigate the potential for continuous gas injection and WAG injection in ultra-high water-cut saline reservoirs. The mechanisms of immiscible water-alternating-nitrogen injection on residual oil distribution are analyzed, and pore-scale analysis is conducted. The effect of injection parameters on residual oil distribution and recovery efficiency is also evaluated. Coreflood results show that tertiary oil recovery efficiency is significantly higher using WAG injection than continuous gas injection during the ultra-high water-cut period. Pore-scale visualization illustrates the movement of gas through the waterflooded channels into the pore space previously occupied by water and residual oil, which then becomes trapped. Injected gas breaks the force balance of microscopic residual oil and reduces residual oil saturation. This mobilizes the displaced/collected residual oil into large waterfilled pores and blocks several water channels. WAG flooding can decrease free-gas saturation and increase trapped-gas saturation significantly, resulting in decreased relative permeabilities of gas and water. The experimental results indicate that appropriate WAG design parameters could enhance recovery by 15.62% when the injected pore volume of water and gas in the cycle is 0.3 PV at a gas/water injection ratio of 2:1. The results from this study will allow researchers and reservoir engineers to understand and implement immiscible WAG injection as an enhanced oil recovery method in ultra-high water-cut stage reservoirs. Cited as: Kong, D., Gao, Y., Sarma, H., Li, Y., Guo, H., Zhu, W. Experimental investigation of immiscible water-alternating-gas injection in ultra-high water-cut stage reservoir. Advances in Geo-Energy Research, 2021, 5(2): 139-152, doi: 10.46690/ager.2021.02.04

Hydrocarbon exploration in Angola commenced in 1910 with its first oil recovered in 1955. The proven reserves in Angola are estimated to reach up to 13 billion barrels (2.1 billion m3). Most of the Angolan oil fields are mature or maturing and some are or may be abandoned due to unprofitable recovery limit beyond the conventional type of oil production. The oil recovery is mainly by primary and secondary recovery methods. Apart from the issue of maturity, there is increasing energy demand due to population growth and difficulties in discovering and developing new fields as alternatives to the current oil fields. For incremental and sustained production rate of these fields and in addition to instability of oil prices and concerns about future oil supply, Angola has started to work towards developing affordable and efficient technologies capable of recovering residual oil in reservoirs as well as extend the life of many current fields which can be achieved through the implementation of enhanced oil recovery (EOR). Therefore, this paper discusses the EOR planning strategy from project selection, project implementation and optimization, and field abandonment. It further highlights the mutual benefits that may be derived from a cross-collaboration between the government and other stakeholders in Angola.

Various types of Enhanced Oil Recovery (EOR) methods have generally been used to recover the residual oil left in the pores after secondary recovery processes. Surfactant flooding has been in use f...

Gas flooding is a promising way to enhance oil recovery in unconventional oil reservoirs, but accurate identification of the distributions of movable and residual oil during gas flooding is difficu...

One of the common challenges of applying foam for enhanced oil recovery is the foam instability in the presence of crude oil and nonwater-wet surfaces. In this experimental study, we systematically distinguish the effect of rock surface wettability from that of crude oil saturation on foam rheology under reservoir conditions. Neutral-wet Berea and reservoir sandstone cores are prepared by aging with crude oil, followed by the wettability index measurements. Transient foam generation and steady-state foam quality scans are conducted in neutral-wet cores, with/without water-flood residual oil. Nuclear magnetic resonance imaging is also utilized to measure the remaining oil saturation at the end of the foam-flood. It is shown that strong foam can be generated in a neutral-wet core with no residual oil because of the solubilization of the adsorbed crude oil components and the wettability alteration toward more water-wet conditions. However, in a neutral-wet core containing residual oil, foam generation is initially hindered. Foam generation occurs after injecting several pore volumes of surfactant solution and increasing the superficial velocity to overcome the minimum pressure gradient required for in situ foam generation. The findings from this study suggest that surface wettability in the presence of bulk oil saturation significantly affects transient foam generation. The final steady-state foam strength becomes comparable to the water-wet and oil-free case once the residual oil saturation is adequately reduced.

The article deals with the issues of improving the quality of highly watered well production fluid processing using chemical demulsifier reactants at crude oil processing facilities; the analysis of the use of the reactants at the Samotlor field has been made. The article presents the results of the study of the effectiveness of the "Hercules 2202 grade A" and "SNPH-4460-2" demulsifiers in comparison with the indicators of oil and bottom water processing achieved in the presence of the reactants used at existing facilities; their optimal consumption has been determined. The study has shown that the selected demulsifiers provide the required quality of the oil and water under processing at the considered oil processing facilities and can be used along with the basic reactants for these facilities. On the basis of total indicators, the best results have been achieved using "Hercules 2202 grade A" with the improved indicators of water cut and residual oil content in water by 33.9 % and 2.8 % while reducing the reactant consumption by 9.7 % compared to the basic demulsifier.

A major hindrance to the effective use of fungi in bioremediation is their inherent slow growth. Despite this, Aspergillus spp. may be used effectively. Our experiments demonstrate that bacteria, although inefficient in hydrocarbon degradation, may be effectively used in a consortium to overcome the lag in fungal utilization of petroleum hydrocarbons. Crude petroleum oil (160 mg; at 8 g/L) in minimal medium was inoculated with a previously isolated biofilm-forming consortium (Aspergillus sp. MM1 and Bacillus sp. MM1) as well as monocultures of each organism and incubated at 30 ℃ under static conditions. Residual oil was analyzed by GC-MS. Crude oil utilization of Aspergillus-Bacillus biofilm was 24 ± 1.4% in 3 days, increased to 66 ± 7% by day 5 and reached 99 ± 0.2% in 7 days. Aspergillus sp. MM1 monoculture degraded only 14 ± 6% in 5 days. However, at the end of 7 days, it was able to utilize 98 ± 2%. Bacillus sp. MM1 monoculture utilized 20 ± 4% in 7 days. This study indicates that there is a reduction of the fungal lag in bioremediation when it is in association with the bacterium. Although in monoculture, Bacillus sp. MM1 is inefficient in crude oil degradation, it synergistically enhances the initial rate of crude petroleum oil degradation of the fungus in the consortium. The rapid initial removal of as much crude oil as possible from contaminated sites is vital to minimize detrimental impacts on biodiversity.

The oilseed pressing process for the production of vegetable oils creates large amounts of cakes as by-products that contain high-added-value substances such as proteins and lipids. This work targets the chemical characterization of flax cake (FC), camelina cake (CC), and sunflower cake (SC) in order to evaluate the composition of proteins and residual oil, which are two of the main components, and to assess further technological applications of these biowastes. The use of a deep eutectic solvent (DES) was developed for protein extraction as a green alternative to conventional organic solvents. The lipid component, on the contrary, was extracted with n-hexane, which is typically used in oil industries. Several analytical techniques were used to characterize the cakes and the extracts (thermogravimetric analysis, attenuated total reflectance-Fourier transform infrared spectroscopy, elemental analysis; HPLC-ESI-Q-TOF/MS). In general, proteins were extracted with DES and precipitated with water, obtaining a higher yield for FC and CC. An improvement in extraction was obtained by increasing the temperature of the treatment. Different acyl glycerides profiles were identified in the residual oils obtained by solvent extraction from the cakes.

Exhaust emissions from shipping are a major contributor to particle concentrations in coastal and marine areas. Previously, the marine fuel sulfur content (FSC) was restricted globally to 4.5 m/m%, but the limit was changed to 3.5 m/m% at the beginning of 2012 and further down to 0.5 m/m% in January 2020. In sulfur emission control areas (SECA), the limits are stricter: the FSC restriction was originally 1.50 m/m%, but it decreased to 1.00 m/m% in July 2010 and again to 0.10 m/m% in January 2015. In this work, the effects of the FSC restrictions on particle number concentrations (PNCs) and particle number size distributions (NSDs) are studied in the Baltic Sea SECA. Measurements were made on a small island (Utö, Finland; 59∘46′50 N, 21∘22′23 E) between 2007 and 2016. Ship plumes were extracted from the particle number size distribution data, and the effects of the FSC restrictions on the observed plumes as well as on the ambient concentrations were investigated. Altogether, 42 322 analyzable plumes were identified during the 10-year measurement period. The results showed that both changes in the FSC restrictions reduced the PNCs of the plumes. The latter restriction (to 0.10 m/m% in January 2015) also decreased the ambient particle number concentrations, as a significant portion of particles in the area originated from ship plumes that were diluted beyond the plume detection limits. The overall change in the PNCs of the plumes and ambient air was 27 and 32 %, respectively, for the total FSC change from 1.50 m/m% to 0.10 m/m%. The decrease in the plume particle number concentration was caused mostly by a decrease in the concentration of particle sizes of between approximately 33 and 144 nm. The latter restriction also reduced the geometric mean diameter of the particles, which was probably caused by the fuel type change from residual oil to distillates during the latter restriction. The PNC was larger for the plumes measured at daytime than for those measured at nighttime, likely because of the photochemical aging of particles due to UV light. The difference decreased with decreasing FSC, indicating that a lower FSC also has an impact on the atmospheric processing of ship plumes.