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As the energy demand increases, there is a significant expansion and utilization of oil resources, resulting in the inevitable occurrence of environmental pollution. Oil has been identified as a prevalent soil contaminant, posing substantial risks to the soil ecosystems. The remediation of soil contaminated with oil is a formidable undertaking. Increasing evidence shows that chemical washing, a remediation technique employing chemical reagents like surfactants to augment the solubilization, desorption, and separation of petroleum hydrocarbons in soil, proves to be an efficacious approach, but the latest advances on this topic have not been systematically reviewed. Here, we present the state of knowledge about the surfactant-based chemical washing to remediate oil-contaminated soil. Using the latest data, the present article systematically summarizes the advancements on ex situ chemical washing of oil pollution and provides a concise summary of the underlying principles. The use of various surfactants in chemical washing and the factors influencing remediation efficiency are highlighted. Based on the current research status and knowledge gaps, future perspectives are proposed to facilitate chemical washing of oil-polluted soil. This review can help recognize the application of chemical washing in the remediation of oil-polluted soil. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Agro-Environment Science is the property of Journal of Agro-Environment Science Editorial Board and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This study explores the sorption capacity and field application of activated carbons (ACs) derived from plant residues for the remediation of oil-contaminated soils. ACs were prepared from rice husks, reed stalks, pine sawdust and wheat straw using two-stage pyrolysis and chemical activation with potassium hydroxide. The structural and physicochemical properties of these ACs were analyzed using BET surface area measurements, SEM analysis, Raman spectroscopy and FTIR spectroscopy. Sorption experiments at room temperature demonstrated that AC from rice husks (OSL) exhibited the highest sorption capacities for gasoline, kerosene and diesel fuel, with values of 9.3 g/g, 9.0 g/g and 10.1 g/g, respectively. These results are attributed to the well-developed microporous and mesoporous structures of OSL, as confirmed by SEM images and a BET surface area of 2790 m2/g. Field tests conducted at the "Zhanatalap" oil deposit showed that the ACs effectively reduced the oil content in contaminated soils from 79.2 g/kg to as low as 2.6 g/kg, achieving a purification degree of up to 67% within 16 days. This study highlights the critical role of structural properties, such as porosity and graphitization degree, in enhancing the sorption efficiency of ACs. [ABSTRACT FROM AUTHOR]

Conventional Fenton chemical oxidation was more difficult to directly oxid all alkanes of long, mid and short-chain alkanes in oil-contaminated soil. To investigate the direct and fast oxidation mechanism of all alkanes in the soil by the fast oxidation group using two different soils for the direct oxidation experiments. The results showed that the hydrophilic Fe-SOM rich in hydrophilic groups could directly oxidize all alkanes in the soil with a high removal rate of total petroleum hydrocarbons (TPH) (59.0%–72.5%). Similarly, for the oxidation of long-chain alkanes (C23-C30), the fast oxidation group in which the hydrophilic Fe-SOM was located had higher removal rates (52%-64%). Regarding long chain oxidation per unit hydroxyl radicals (•OH) intensity, the fast oxidation group was significantly higher than the slow oxidation group (1.3–4.2 times). The results revealed a well-linear fit (r2 = 0.97, 0.81) for total iron and FeOOH with hydrophilic groups such as C=O and C-O-C in the fast oxidation group regarding content. Hydrophilic Fe-SOM enabled the rapid decomposition (51% − 88%) of H2O2 in the presence of hydrophilic promoters such as humic acid (49%−79%). The hydrophilic groups and hydrophilic promoters made the •OH generated by decomposition collide and react with pollutants rapidly to maximize the •OH in the liquid phase. The TPH removal efficiency per the unit intensity of •OH in the fast oxidation group was 3.74 times higher than in the slow oxidation group. The long-chain removal efficiency was 4.2 times higher than that in the slow oxidation group. The above results indirectly proved that the oxidation reaction in the fast oxidation group occurred at the petroleum pollutants and also demonstrated that the technology is an in situ oxidation technology. This technology can directly oxidize all petroleum hydrocarbons in the soil and has excellent engineering application value. [ABSTRACT FROM AUTHOR]

Oil pollution is a common type of soil organic pollution that is harmful to the ecosystem. Bioremediation, particularly microbe-assisted phytoremediation of oil-contaminated soil, has become a research hotspot in recent years. In order to explore more appropriate bioremediation strategies for soil oil contamination and the mechanism of remediation, we compared the remediation effects of three plants when applied in combination with a microbial agent and biochar. The combined remediation approach of Tagetes erecta, microbial agent, and biochar exhibited the best plant growth and the highest total petroleum hydrocarbons degradation efficiency (76.60%). In addition, all of the remediation methods provided varying degrees of restoration of carbon and nitrogen contents of soils. High-throughput sequencing found that microbial community diversity and richness were enhanced in most restored soils. Some soil microorganisms associated with oil degradation and plant growth promotion such as Cavicella, C1_B045, Sphingomonas, MND1, Bacillus and Ramlibacter were identified in this study, among which Bacillus was the major component in the microbial agent. Bacillus was positively correlated with all soil remediation indicators tested and was substantially enriched in the rhizosphere of T. erecta. Functional gene prediction of the soil bacterial community based on the KEGG database revealed that pathways of carbohydrate metabolism and amino acid metabolism were up-regulated during remediation of oil-contaminated soils. This study provides a potential method for efficient remediation of oil-contaminated soils and thoroughly examines the biochar– bacteria–plant combined remediation mechanisms of oil-contaminated soil, as well as the combined effects from the perspective of soil bacterial communities. [ABSTRACT FROM AUTHOR]

This study aims to investigate the biosurfactant production capabilities of bacterial strains isolated from oil-contaminated soil samples. Employing a comprehensive methodological approach, we collected soil samples from thirty different fuel pumps and conducted an extensive screening of bacterial isolates using various tests such as hemolytic activity, emulsification index, blue agar plate method, and drop collapsing test. The results revealed significant biosurfactant production among certain isolates, specifically highlighting the effectiveness of two particular strains. This paper presents a detailed analysis of these strains, including their optimal growth conditions in terms of pH, temperature, carbon, and nitrogen sources. Our findings indicate a notable potential of these bacterial strains in biosurfactant production, with implications for environmental bioremediation, particularly in oil pollution contexts. The study also sheds light on the limitations encountered and underscores the originality of the research in exploring biosurfactant production in a novel context. This study contributes to the field by offering insights into the effective utilization of microbial strains for biosurfactant synthesis, which is crucial for sustainable and eco-friendly bioremediation practices. [ABSTRACT FROM AUTHOR]

In this study, a microcosm experiment was conducted to investigate the effects of Na2S2O8 preoxidation combined with biostimulation on petroleum-contaminated soil remediation. The response of microbial community during this process was explored using BIOLOG ECO microplate carbon utilization method and 16 s rDNA high-throughput sequencing. The results showed that use of 10 mg/g Na2S2O8 removed 19.8 % of the petroleum hydrocarbons, reduced soil biotoxicity and did not affect soil microbial activity compared to other concentrations. Therefore, sodium persulfate of ca. 10 mg/g was used to oxidize petroleum in soil before the biostimulation experiment with organic and inorganic fertilizers. Our finding showed that the content of total petroleum hydrocarbons (TPHs) in soil was reduced by 43.3 % in inorganic fertilizer treatment after 60 days. The results of BIOLOG ECO microplate carbon utilization analysis and 16 S rDNA high-throughput sequencing further confirmed that biostimulation quickly restored the microbial activities in oxidant treated soil. The main marker bacteria in chemical oxidation combined with biostimulation remediation were Arthrobacter and Paenarthrobacter, and their relative abundances were both significantly negatively correlated with the content of petroleum hydrocarbons in soil.

The scale of land pollution with oil waste necessitates the use of economical and effective methods of recultivation. Phytoremediation is one of the simplest methods, but it has a number of limitations, so additional preparation of the territory is often required before it is carried out. Preliminary electrical preparation and subsequent seeding of special phytoremediants are of interest. Passing a constant electric current through the soil volume under a low voltage removes toxicants from deep soil layers even with flooding. In addition, it reduces pollutant content in the upper layer, where the plants root system is located, which creates more favorable conditions for phytoremediants. Adequately selected types of plants will ensure additional soil cleaning, improve its structure and air exchange. The results of two research directions are presented. Experiments on the study of plant resistance to oil-contaminated soil substrate allowed establishing contamination thresholds at which it is advisable to sow a particular species, and to choose optimal phytoremediants. The study of the oil-containing soil cleaning in a monocathodocentric electrochemical installation with the fixation of main characteristics (oil products concentration, soil temperature, volt-ampere characteristics) allows us to develop technical measures to prepare territories for phytoremediation taking into account the relief features.

It is important to understand the shear behavior of oil-contaminated soils in many geotechnical problems, such as the analysis of pipelines and storage tanks affected by oil leakage. In this study, the shear behavior of a silt permeated with silicone oil/water (denoted by OS and WS, respectively) was investigated through direct shear tests. The residual shear strength was measured at various degrees of liquid saturation (65–100%) and net normal stresses (50 to 400 kPa). The oil and water retention curves were measured and used to explain the shear behavior. The results show that the residual friction angle of OS is 30% larger than that of WS. This is likely because OS and WS show aggregated and matrix structures, respectively, as evidenced by the Scanning Electron Microscope (SEM) test. The former structure includes more particle contacts than the latter one. These structural differences can be attributed to varying fluid properties, such as wettability, viscosity, and dielectric constant. When the volumetric degree of water saturation decreases, the total cohesion of WS increases substantially because of the strengthening effects of air-water interfaces on the soil skeleton. In contrast, the degree of oil saturation has minuscule effects on these variables, mainly because OS has a low oil retention ability and the air-oil suction remains very low (i.e., less than 2 kPa) during the desaturation process. [ABSTRACT FROM AUTHOR]

Currently, there is limited understanding of the structures and variabilities of bacterial communities in oil-contaminated soil within shale gas development. The Changning shale gas well site in Sichuan province was focused, and high-throughput sequencing was used to investigate the structures of bacterial communities and functions of bacteria in soil with different degrees of oil pollution. Furthermore, the influences of the environmental factors including pH, moisture content, organic matter, total nitrogen, total phosphorus, oil, and the biological toxicity of the soil on the structures of bacterial communities were analyzed. The results revealed that Proteobacteria and Firmicutes predominated in the oil-contaminated soil. α-Proteobacteria and γ‐Proteobacteria were the main classes under the Proteobacteria phylum. Bacilli was the main class in the Firmicutes phylum. Notably, more bacteria were only found in CN-5 which was the soil near the storage pond for abandoned drilling mud, including Marinobacter, Balneola, Novispirillum, Castellaniella, and Alishewanella. These bacteria exhibited resilience to higher toxicity and demonstrated proficiency in oil degradation. The functions including carbohydrate transport and metabolism, energy metabolism, replication, recombination and repair replication, signal transduction mechanisms, and amino acid transport and metabolism responded differently to varying concentrations of oil. The disparities in bacterial genus composition across samples stemmed from a complex play of pH, moisture content, organic matter, total nitrogen, total phosphorus, oil concentration, and biological toxicity. Notably, bacterial richness correlated positively with moisture content, while bacterial diversity showed a significant positive correlation with pH. Acidobacteria exhibited a significant positive correlation with moisture content. Litorivivens and Luteimonas displayed a significant negative correlation with pH, while Rhizobium exhibited a significant negative correlation with moisture content. Pseudomonas, Proteiniphilum, and Halomonas exhibited positive correlations not only with organic matter but also with oil concentration. Total nitrogen exhibited a significant positive correlation with Taonella and Sideroxydans. On the other hand, total phosphorus showed a significant negative correlation with Sphingomonas. Furthermore, Sphingomonas, Gp6, and Ramlibacter displayed significant negative correlations with biological toxicity. The differential functions exhibited no significant correlation with environmental factors but displayed a significant positive correlation with the Proteobacteria phylum. Aridibacter demonstrated a significant positive correlation with cell motility and cellular processes and signaling. Conversely, Pseudomonas, Proteiniphilum, and Halomonas were negatively correlated with differential functions, particularly in amino acid metabolism, carbohydrate metabolism, and membrane transport. Compared with previous research, more factors were considered in this research when studying structural changes in bacterial communities, such as physicochemical properties and biological toxicity of soil. In addition, the correlations of differential functions of communities with environmental factors, bacterial phyla, and genera were investigated. [ABSTRACT FROM AUTHOR]

Microbial remediation has been widely studied due to its low cost, low environmental impact and high efficiency ・ The research hotspots for microbial remediation are the selection of petroleum-degrading microorganisms and the removal effect of multiple microbial complex bacteria on petroleum components, but there are relatively few practical applications and mechanism studies on microbial technology・ This article sorts out various technical means and practical application research of microbial remediation of oil - contaminated soil, reports the mechanism of microbial remediation of petroleum pollutants, and puts forward the future research and development direction of microbial remediation. [ABSTRACT FROM AUTHOR]

The release of oil into the environment represents a pervasive problem stemming from oil exploration, accidents, transportation and releases from landfills, storage facilities or industrial plants. Compared to conventional and costly techniques, bioremediation is an attractive and promising alternative, as it can selectively degrade pollution without affecting the natural features of the site and the flora and fauna living there. In this study, the isolation, identification and characterization of autochthonous bacterial strains from a crude oil-contaminated soil sample was carried out under batch conditions over a period of 28 days. The initial colony forming units value for bacteria was 1.15 × 109/g of soil. The results show that the activity of bacteria was highest at a pH of 7.25. Based on morphology, biochemical tests and an analysis of MALDI TOF, isolated autochthonous bacterial species were identified as Bacillus megaterium, Bacillus licheniformis, Bacillus cereus and Pseudomonas chlororaphis. Since allochthonous bacteria are not highly efficient in a new environment due to their low adaptability and competition with indigenous microorganisms, these autochthonous microorganisms play a pivotal role in enhancing the bioremediation process on an applicable, industrial scale. This advancement aligns with the principles of sustainable development and the green economy, as purified soil is suitable for rational reuse in the environment. [ABSTRACT FROM AUTHOR]

As the energy demand increases, there is a significant expansion and utilization of oil resources, resulting in the inevitable occurrence of environmental pollution. Oil has been identified as a prevalent soil contaminant, posing substantial risks to the soil ecosystems. The remediation of soil contaminated with oil is a formidable undertaking. Increasing evidence shows that chemical washing, a remediation technique employing chemical reagents like surfactants to augment the solubilization, desorption, and separation of petroleum hydrocarbons in soil, proves to be an efficacious approach, but the latest advances on this topic have not been systematically reviewed. Here, we present the state of knowledge about the surfactant-based chemical washing to remediate oil-contaminated soil. Using the latest data, the present article systematically summarizes the advancements on ex situ chemical washing of oil pollution and provides a concise summary of the underlying principles. The use of various surfactants in chemical washing and the factors influencing remediation efficiency are highlighted. Based on the current research status and knowledge gaps, future perspectives are proposed to facilitate chemical washing of oil-polluted soil. This review can help recognize the application of chemical washing in the remediation of oil-polluted soil.

This study explores the sorption capacity and field application of activated carbons (ACs) derived from plant residues for the remediation of oil-contaminated soils. ACs were prepared from rice husks, reed stalks, pine sawdust and wheat straw using two-stage pyrolysis and chemical activation with potassium hydroxide. The structural and physicochemical properties of these ACs were analyzed using BET surface area measurements, SEM analysis, Raman spectroscopy and FTIR spectroscopy. Sorption experiments at room temperature demonstrated that AC from rice husks (OSL) exhibited the highest sorption capacities for gasoline, kerosene and diesel fuel, with values of 9.3 g/g, 9.0 g/g and 10.1 g/g, respectively. These results are attributed to the well-developed microporous and mesoporous structures of OSL, as confirmed by SEM images and a BET surface area of 2790 m2/g. Field tests conducted at the “Zhanatalap” oil deposit showed that the ACs effectively reduced the oil content in contaminated soils from 79.2 g/kg to as low as 2.6 g/kg, achieving a purification degree of up to 67% within 16 days. This study highlights the critical role of structural properties, such as porosity and graphitization degree, in enhancing the sorption efficiency of ACs.

Two Acinetobacter isolates were found in soil samples from motorbike repair workshop floors in Vietnam. The two Acinetobacter isolates were Gram-stain-negative, coccobacilli-shaped, aerobic, non-motile, non-hemolytic, oxidase-negative, and catalase-positive. They were designated as strains VNH17T and VNK23. Their growth was inhibited by NaCl concentrations of >3%, and they grew at an optimal temperature of 20–35 °C. Acidification of D-glucose and hydrolysis of gelatin were negative. They grew on β-alanine, ethanol, L-histidine, D-malate, and L-ornithine whereas L-arginine, citrate, L-glutamate, and L-phenylalanine were not utilized. Core genome-based phylogenetic analysis revealed that the two isolated strains formed a lineage within the genus Acinetobacter in the family Moraxellaceae, the closest relative was Acinetobacter pavus (91.70–91.95%), and were grouped within a hemolytic clade with other closely-related relatives. The DNA G+C content of VNH17T and VNK23 was 42.07% and 41.75%, respectively. The average nucleotide identity and in silico DNA-DNA hybridization relatedness values (74.41–91.61% and 20.6–45.40%, respectively) between the Acinetobacter isolates and phylogenetically related type strains were below the threshold values used for species delineation. Based on genomic, chemotaxonomic, phenotypic, and phylogenomic analyses, the isolated strains represent novel species in the genus Acinetobacter, for which the name Acinetobacter thutiue sp. nov. (type strain VNH17T = KACC 23003T = CCTCC AB 2023063T) is proposed. [ABSTRACT FROM AUTHOR]

In order to investigate the response of soil physicochemical properties and indigenous microbial community structures to oil pollution in different regions, and to systematically clarify the commonalities and differences of the effects of external environmental factors on microbial community structure and diversity in oil-contaminated soils around the world, this study collected oil-contaminated and clean soils from four regions in China with distinct geographic locations and climate differences (temperature and rainfall). The total petroleum hydrocarbon content and soil physicochemical properties were analyzed by gas chromatography and conventional chemical testing methods. Meanwhile, 16S rRNA Illumina high-throughput sequencing technology and statistical methods were used to study the microbial community structure composition and diversity of soils at different depths, and the results were compared with literature data from other oil-polluted areas around the world. The results evidenced that oil pollution in different regions would affect soil physicochemical properties, especially total organic carbon. Microbial community analysis showed that external environmental factors had similarity on the phylum level on the microbial community composition and diversity, both dominated by Proteobacteria and Actinobacteria. However, there were significant differences at the genus level. The dominant bacterial genera in contaminated soils from Zhejiang (103–130 mg/kg), Liaoning (2640–8660 mg/kg), Guangdong (43–87 mg/kg), and Xinjiang (16–1100 mg/kg) were Lysobacter, Sphingomonas, Burkholderia–Caballeronia–Paraburkholderia, and Nocardioides, respectively. Combined with literature reports, we found that the microbial community composition in oil-polluted soils worldwide (Asia, Europe, North America, South America, Africa, Oceania) is consistent with the results of this study. The microbial community diversity laws of oil-contaminated soils summarized in this study at multiple spatial scales provide information for the biological remediation and microbiological evaluation standards of oil-contaminated soils. [ABSTRACT FROM AUTHOR]

Oil-contaminated soil is detrimental to the ecosystem. There are various methods for purifying and controlling oil-contaminated soil. Among these, the use of oil absorbent geotextiles is considered a new method, and its performance requires more research. The separating by geotextiles has the advantages such as absence of chemicals in the separation process, less energy, simple control and implementation. This study presents an environmentally friendly sustainable solution using spacer geotextile layers to absorb crude oil and improve the geotechnical properties of contaminated soil. The variables include contamination percentage, number of fibrous substrate layers, soil overhead load pressure and duration of exposure to contaminated soil. The response variable is the internal friction coefficient of soil obtained from the direct shear test. By comparing soil samples containing geotextiles with samples without geotextiles, it was concluded that spacer geotextile layers could increase the internal friction coefficient of the soil and thus lead to improved soil properties. Increasing the number of geotextile layers, loading and the presence time of geotextile layers in the soil had increased the internal friction angle. But as the oil percentage in the soil increases, the internal friction angle of the soil decreases. Also, in this study, a linear regression model has been used to investigate the effect of existing parameters and the model was in good agreement with the experimental data. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the mechanism of sustainable biodegradation of long-alkanes with moderate pre-oxidation in soil. Moderate pre-oxidation was performed with two consecutive doses of 1.35 mL 30% of H2O2 (225 mM) in two soil. After moderate pre-oxidation, the experiment of sustainable biodegradation of long-alkanes during 80 d was conducted. Then, long-alkanes relative activity coefficient (K), NH4+-N allocation (G) and the performance of hydrocarbon degraders (E) was calculated. Long-alkanes were sustainably biodegraded with moderate pre-oxidation (1765 mg/kg, 2438 mg/kg and 2672 mg/kg). Long-alkanes biodegradation (8723 mg/kg) with moderate pre-oxidation was 2.5 folds of excessive pre-oxidation. The average increment in long-alkanes biodegradation with moderate pre-oxidation was 30–38% as K values improved (0.28–0.48). The bacterial destruction D decreased to 14–17% and hydrocarbon degraders activity increased to 0.065 mol CO2/kg with moderate pre-oxidation. Basidiomycota and Acinetobacter sp. showed high tolerance with moderate pre-oxidation and remained dominant strains throughout the bioremediation. NH4+-N consumption played an essential role as nutrients in growth of hydrocarbon degraders (Basidiomycota and Acinetobacter sp.). Then, high and sustained E was achieved with decreased D and elevated hydrocarbon degraders activity, resulting in high K. So, long-alkanes sustainably increasing biodegraded under high E assisted with elevated G with moderate pre-oxidation. [ABSTRACT FROM AUTHOR]

In recent years, oil spills and leakages have often occurred during oil exploration, transportation, handling, usage, and processing, causing serious global environmental problems. Microbially-induced carbonate precipitation (MICP) is an emerging green, environmentally friendly, and sustainable technology that has proven to be a promising alternative for soil stabilisation. This paper provides a comparison between the mechanical performance of oil-polluted sand treated with biocement and traditional Portland cement. A series of laboratory tests, including permeability, unconfined compressive strength (UCS), and triaxial consolidated undrained (CU) tests, was conducted. Even though oil contamination deteriorates the bonding strength of treated soil for both biocement and Portland cement soils, the biocement-treated oil-contaminated sand was found to achieve higher strength (up to four times) than cement-treated soil in the presence of similar content of cementing agent. After eight treatment cycles, the UCS value of oil-contaminated sand treated with biocement reached 1 MPa, demonstrating a high potential for oil-contaminated soil stabilisation in regions of oil spills and leakages. [ABSTRACT FROM AUTHOR]

This study investigated the function and mechanism of Fenton pre-oxidation on the long lasting degradation of all alkanes in soil contaminated by petroleum. The findings demonstrated that the biological removal amount of all alkanes in the respiratory regulation group reached 4083.46 mg/kg, which was twice that of the non-regulation group, and the removal amount gradually increased in the four stages of bioremediation. In addition, the removal amount of all alkanes in the non-regulated group did not change much and showed a downward trend, indicating that long lasting degradation of all alkanes could be achieved by the respiratory regulation group, and the biodegradation cycle was saved by 251 days compared with the non-regulated group. Furthermore, the total number of bacteria in the respiratory regulation group (6.73 log CFU/g) was significantly higher than that in the non-regulation group (2.25 log CFU/g). Pseudomonas became the dominant genus in the respiratory regulation group with an average relative abundance of 32.17 %. In the respiratory regulation group, a large amount of ammonia nitrogen (1703.62 mg/kg) was consumed during the degradation process, which stimulated the tricarboxylic acid cycle respiratory metabolism process of Pseudomonas and accelerated the hydrocarbon conversion. This may be the reason why the long lasting degradation of all alkanes in soil could be achieved by the respiratory regulation group. [Display omitted] • 67.52 % of all alkanes were removed by respiratory regulation group. • The large consumption of ammonia nitrogen strengthened the respiration process of bacteria after Fenton pre-oxidation. • A long lasting degradation system with Pseudomonas as the dominant genus was formed. [ABSTRACT FROM AUTHOR]

Two Acinetobacter isolates were found in soil samples from motorbike repair workshop floors in Vietnam. The two Acinetobacter isolates were Gram-stain-negative, coccobacilli-shaped, aerobic, non-motile, non-hemolytic, oxidase-negative, and catalase-positive. They were designated as strains VNH17T and VNK23. Their growth was inhibited by NaCl concentrations of >3%, and they grew at an optimal temperature of 20–35 °C. Acidification of D-glucose and hydrolysis of gelatin were negative. They grew on β-alanine, ethanol, L-histidine, D-malate, and L-ornithine whereas L-arginine, citrate, L-glutamate, and L-phenylalanine were not utilized. Core genome-based phylogenetic analysis revealed that the two isolated strains formed a lineage within the genus Acinetobacter in the family Moraxellaceae, the closest relative was Acinetobacter pavus (91.70–91.95%), and were grouped within a hemolytic clade with other closely-related relatives. The DNA G+C content of VNH17T and VNK23 was 42.07% and 41.75%, respectively. The average nucleotide identity and in silico DNA-DNA hybridization relatedness values (74.41–91.61% and 20.6–45.40%, respectively) between the Acinetobacter isolates and phylogenetically related type strains were below the threshold values used for species delineation. Based on genomic, chemotaxonomic, phenotypic, and phylogenomic analyses, the isolated strains represent novel species in the genus Acinetobacter, for which the name Acinetobacter thutiue sp. nov. (type strain VNH17T = KACC 23003T = CCTCC AB 2023063T) is proposed.

Environmental problems associated with soil contamination by oil products have become more and more acute over the years. They require effective and rational technical and economic solutions. The electrochemical method is one of the solutions for remediating oil-contaminated soils. Experimental and theoretical studies made it possible to develop the physicochemical and technological foundations of a new resource-saving and energy-efficient electrochemical process for cleaning soils from oil, oil products, and highly mineralized waters in situ without labor-intensive and expensive excavation operations or the use of special chemical reagents. It was theoretically and experimentally confirmed that there is a decrease in contaminant concentrations after soils of different types are treated with small direct currents taking terrain into account. The trend revealed allowed us to propose electrode arrangements to ensure that soils are evenly treated by creating a nearly homogeneous electric field. The arrangements factor is uneven contamination of the territory being treated and its relief. Based on such arrangements, installations for effective soil remediation with reduced energy consumption were developed for the implementation of the electrochemical method. For various modifications of these installations selected depending on pollution and terrain, the use of a single electric power source is possible. In areas with depressions, monocathode (cathodocentric) circuits can be used, where one cathode is located in the center and anodes are located along the perimeter. Methods for calculating the key technical, energy, and economic parameters of electrochemical remediation are proposed. They include current and voltage, the parameters and number of electrodes in the arrangement, properties of the soil mass being cleaned, features of the distribution of the pollutants over the territory, and the required degree of remediation. [ABSTRACT FROM AUTHOR]

A biopreparation consisting of the cells of Azospirillum brasilense strain SR80 immobilized on wood biochar was characterized. Sorption of oil by biochar and its colonization by Azospirillum were studied in liquid medium. Oil sorption by biochar was found to decrease in the presence of microbial cells. Within the 22–45°C temperature range, the highest oil biodegradation efficiency by biochar-immobilized and suspended cells was observed at 22 and 38°C, respectively. These data were confirmed by soil experiments. Under conditions of a laboratory pot experiments, the biochar-immobilized microbial culture in combination with two plants (Sorghum bicolor and Medicago falcata) exhibited the highest oil removal efficiency compared to other variants. The introduced strain A. brasilense SR80 exhibited high survival in tilled soil during two-month incubation, as was confirmed by molecular biological assays. Suspended Azospirillum cells exhibited higher oil-oxidizing activity than the immobilized ones in a field experiment under real-life conditions of a hot dry summer. The present work shows high dependence of bioremediation technologies upon environmental factors and indicates the need for thorough investigation of the processes involved. [ABSTRACT FROM AUTHOR]

Electrochemical cleaning of oil-contaminated soils is a promising area of environmental safety, as it can be easily organized even in locations remote from settlements. For this purpose, a power source and a system of electrodes are necessary as equipment. It is possible to use an electric generator if there are no power supply lines nearby. The material of electrodes affects the features of redox processes, which can affect the energy consumption and the degree of soil cleansing from oil or oil products. Therefore, the correct choice of electrode materials is one of the important tasks in the field of engineering electrochemical methods of purification. Changes in the main parameters (humidity, temperature, degree of acidity) in an oil-contaminated model soil, similar in composition to one of the oil fields, were investigated. Measurements of parameters when using graphite and metal electrodes were carried out at several fixed sections of the interelectrode space depending on the treatment time. The established patterns of parameter changes in the purification of oil-contaminated soils allow us to draw conclusions about the stages of the electrochemical process, its speed, and energy efficiency. The results obtained form a basis for designing industrial facilities for soil treatment.

Copyright of Experimental Technology & Management is the property of Experimental Technology & Management Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The U.S. Environmental Protection Agency's (EPA) Superfund—the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) database—has collected and built an open-source database based on nearly 2000 US soil remediation cases since 1980, providing detailed information and references for researchers worldwide to carry out remediation work. However, the cases were relatively independent to each other, so the whole database lacks systematicness and instructiveness to some extent. In this study, the basic features of all 144 soil remediation projects in four major oil-producing states (California, Texas, Oklahoma and Alaska) were extracted from the CERCLA database and the correlations among the pollutant species, pollutant site characteristics and selection of remediation methods were analyzed using traditional and machine learning techniques. The Decision Tree Classifier was selected as the machine learning model. The results showed that the growth of new contaminated sites has slowed down in recent years; physical remediation was the most commonly used method, and the probability of its application is more than 80%. The presence of benzene, toluene, ethylbenzene and xylene (BTEX) substances and the geographical location of the site were the two most influential factors in the choice of remediation method for a specific site; the maximum weights of these two features reaches 0.304 and 0.288. [ABSTRACT FROM AUTHOR]

Loessial soil is moisture-sensitive soil susceptible to settle when fully saturated. In this study, efforts were made to investigate the effect of oil pollutants on mechanical behavior of soil. The loess soil was contaminated by 2,4,6,8 and 10% dry weight of lamp oil and gasoline. Atterberg limits, direct shear, unconfined compressive strength (UCS) and scanning electron microscope (SEM) tests were performed to evaluate the behavior of oil-contaminated collapsible soils. The results of Atterberg tests showed that the plasticity of the soil decreased, due to the reduction in the thickness of the absorbed surface layer and double water layer. According to the direct shear test, with increasing contamination up to 10% of lamp oil and gasoline, the cohesion of the soil was decreased from 14.5 kPa to 7.3 kPa and 7 kPa, respectively, which was due to the reduction in soil plasticity and diffuse double-layer. Because of the lubrication of soil particles, the internal friction angle of soil was reduced from 18.5° to 13.6° and 13.9° for 10% lamp oil and gasoline. UCS of contaminated soil increased in low strains due to the apparent cohesion of hydrocarbons and it decreased 31% for gasoline and 53% for lamp oil at high strains due to the softening behavior of the contaminated soil. SEM test revealed that hydrocarbons covered the soil particles and changed the soil fabrication to dispersed skeleton. Generally, collapsible soil contaminated with different lamp oil and gasoline contents showed a decrease in shear strength and UCS with increasing oil content. [ABSTRACT FROM AUTHOR]

Crude oil continues to impact many nations as it is among the major sources of fuel. Its role in making life in modern societies comfortable cannot be overemphasized as it is readily available and easy to use. Contamination resulting from its use in industries such as mining, transportation and petroleum especially soil contamination cannot be overlooked. Soil pollution resulting from oil contamination can be seen as being among the twenty-first-century vulnerabilities because if not well taken care of the consequences can be devastating. Soil contamination is of interest in most societies because it affects both the environment and humans. This review highlights common sources of soil pollution and their effects, oil waste disposal methods, soil remediation techniques that are well established and those still in their infancy. Such techniques include bioremediation such as phytoremediation and landfarming, where percent removal of contaminated soils was reported from 68% to 89 % in 40 days to 1 year, respectively; physical methods such as excavation and incineration (75-86% removal); chemical methods such as oxidation (48 % by Fenton process); and photocatalysis (67% using titanium dioxide). The choice of remediation in mining, transportation and petroleum industries depends on the urgency and hazardous effects of the pollutant. In Zambia, Mopani Copper Mines uses landfarming as a means to mitigate large amounts of soil contaminated with oil wastes, but the process is slow. In the proposed research, photocatalysis coupled with adsorption of oil on clay will be used to assess the effectiveness of this emerging technology to quicken the degradation of oil in soils. Clay will be incorporated with metal ions and with hydrophobic groups to enhance light absorption and oil-clay interaction, respectively. Photochemical remediation techniques for remediation of soils polluted with oil have attracted considerable interest as the processes are reported to enhance the degradation of oils in soil compared to the biological and physical methods. The extent of photo-degradation of oil waste will be evaluated using the Soxhlet technique by determining the percent residual oil. The importance of remediating contaminated soil in any nation cannot be overemphasized as consequences of not remediating this precious resource might be devastating. Since economic development through industrialization will continue, there is need to constantly improve on methods of mitigating the impact of wastes on the environment, especially in developing countries, where engineering of cheap, nontoxic materials for soil remediation is paramount. ========================================================================================== COPYRIGHTS©2021 The author(s). This is an open access article distributed under the terms of the Creative Commons Attribution (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, as long as the original authors and source are cited. No permission is required from the authors or the publishers. ==========================================================================================

Objectives : In this research work, we investigated the biocatalytic potency of orange and watermelon garbage enzymes in the remediation of used motor oil-contaminated soils. The optimization of the biocatalytic remediation process was evaluated through D-optimal of response surface methodology (RSM) design of design expert. Methods : The optimization of the biocatalytic process was evaluated with D-optimal model of response surface methodology (RSM) design, where input variables in the system were garbage enzymes solutions of orange and watermelon peels (biocatalysts) and two different pollution levels. The two levels of pollution factor considered were 5 and 10 % (w/w) oil pollution levels and used as independent variables; while the response of the system was in oil and grease (O&G) removal as dependent variables that were monitored under 6-week remediation process. Results and Discussion : The result indicated that the model was highly significant and good predictors of the response fate of oil and grease (O&G) removal by the orange and watermelon garbage enzymes, as indicated by their coefficients of determination: R2 = 0.90627 and R2 = 0.88365 at p < 0.05, respectively. Therefore, it was observed from the numerical optimization carried out that 54.2 and 53.8 % O&G removal was achieved with orange garbage enzymes at 5 and 10 % pollution level respectively after six weeks. On the other hand, 54.7 and 55.2 % O&G removal was accomplished with the same pollution level respectively under the influence of watermelon garbage enzymes after six weeks of the remediation process. Conclusion : In response to what was achieved in this research work, the enzymes produced from the orange and watermelon garbage removed oil in terms of O&G from used motor oil-contaminated soils biocatalytically and hence could be applied in the remediation of oil contaminated soils.

In this study, a microcosm experiment was conducted to investigate the effects of Na 2 S 2 O 8 preoxidation combined with biostimulation on petroleum-contaminated soil remediation. The response of microbial community during this process was explored using BIOLOG ECO microplate carbon utilization method and 16 s rDNA high-throughput sequencing. The results showed that use of 10 mg/g Na 2 S 2 O 8 removed 19.8 % of the petroleum hydrocarbons, reduced soil biotoxicity and did not affect soil microbial activity compared to other concentrations. Therefore, sodium persulfate of ca. 10 mg/g was used to oxidize petroleum in soil before the biostimulation experiment with organic and inorganic fertilizers. Our finding showed that the content of total petroleum hydrocarbons (TPHs) in soil was reduced by 43.3 % in inorganic fertilizer treatment after 60 days. The results of BIOLOG ECO microplate carbon utilization analysis and 16 S rDNA high-throughput sequencing further confirmed that biostimulation quickly restored the microbial activities in oxidant treated soil. The main marker bacteria in chemical oxidation combined with biostimulation remediation were Arthrobacter and Paenarthrobacter , and their relative abundances were both significantly negatively correlated with the content of petroleum hydrocarbons in soil. [Display omitted] • The contaminated soil was pre-oxidized with sodium persulfate (Na 2 S 2 O 8). • Changes of soil microbial community structure during peroxidation. • The main markers of soil microorganisms were arthrobacter and Arthrobacter was Arthrobacter and Paenarthrobacter. • Effects of different fertilizer treatments on the removal of petroleum hydrocarbons. [ABSTRACT FROM AUTHOR]

Oil-contaminated soil is a major societal problem for humans and the environment. In this study, the pyrolysis method was applied to oil-contaminated soil used as a landfill and gas station site in Korea. The removal efficiency of the main components of oil-contaminated soils, such as total petroleum hydrocarbons (TPH), polyaromatic hydrocarbons (PAHs), unresolved complex mixture (UCM), and alkylated PAHs (Alk-PAHs) were measured, and the effect of temperature, treatment time, and moisture content on pyrolysis efficiency was studied. In order to evaluate the risk of soil from which pollutants were removed through pyrolysis, integrated ecotoxicity was evaluated using Daphnia magna and Allivibrio fischeri. The chemical and biological measurements in this study include contaminants of emerging concerns (CECs). Results showed that the pyrolysis was more efficient with higher treatment temperatures, moisture content, and treatment times. In addition, toxicity was reduced by 99% after pyrolysis, and the degree of toxicity was evaluated more sensitively in Allivibrio fischeri than in Daphnia magna. This study shows that weathered oil-contaminated soil can be effectively treated in a relatively short time through pyrolysis, as well as provides information on efficient conditions and the assessment of ecotoxicity. [ABSTRACT FROM AUTHOR]

A light yellow-coloured, non-motile, aerobic, Gram-stain-negative, and rod-shaped bacterial strain DKR-2T was isolated from oil-contaminated experimental soil. The strain was catalase and oxidase positive, and grew at 0–1.5% (w/v) NaCl concentration, at temperature 10–35 °C, and at pH 6.0–9.5. The phylogenetic analysis suggested that the strain DKR-2T was affiliated to the genus Kaistella, with the closest species being Kaistella haifensis DSM 19056T (97.6% 16S rRNA gene sequence similarity). The principle fatty acids were iso-C15:0, summed feature 9 (iso-C17:1ω9c and/or C16:0 10-methyl), and antiso-C15:0. The sole menaquinone was MK-6 and major polar lipid was phosphatidylethanolamin. The DNA G+C content was 39.5%. The dDDH (in silico DNA–DNA hybridization) and ANI (average nucleotide identity) values between strain DKR-2T and K. haifensis DSM 19056T were 22.4% and 79.3%, respectively. In addition, both dDDH and ANI values between strain DKR-2T and other phylogenetically related neighbours were < 25.0% and < 77.0%, respectively. In overall, the polyphasic taxonomic data presented in this study clearly indicated that strain DKR-2T represents a novel species in the genus Kaistella, for which the name Kaistella soli sp. nov. is proposed. The type strain is DKR-2T (=KACC 22070T=NBRC 114725T). [ABSTRACT FROM AUTHOR]

The present study aimed to investigate the biodegradability of the native species isolated from a site contaminated with crude oil (Karun Gas Oil Production Company, Iran). According to the findings, the species isolated from bacillus could grow at the concentrations of 1 and 3% of crude oil within the pH range of 3-5 and at various temperatures. Bacillus sonorensis had higher efficiency at the concentration of 1%, temperature of 30 °C, and near-neutral pH compared to the second species. Therefore, it could be used in biological remediation processes through the reduction of biosurfactant and surface tension to a certain extent (24.87 mN/m) compared to the control samples (59 mN/m). Furthermore, the chemical analysis showed that the bioremediation efficiency of chrysene, fluorene, naphthalene, dibenz(a, h)anthracene, and pyrene was 35.85, 39.56, 27.14, 28.45, and 27.5% within four days, respectively. With the reduction of the surface tension, aromatic compounds could be better decomposed compared to aliphatic compounds.

Microbial sources are regularly used as reliable biocatalysts sources which are often used in the process and production industry. Demands for such organisms with greater capacity of intended enzyme production are on the rise. Lipase is important enzyme used in the biotechnological process of hydrolysis of fats in almost all the relevant industries We have utilized the local oil-contaminated soil resources to search for efficacious bacterial strains that have excellent lipase activity. We were successful in identifying two such bacterial sources, namely, Bacillus subtilis strain RCPS3 and Bacillus fumarioli strain RCPS4, responsible for lipase production from oil effluent contaminated soil of Telangana. This is the first report of these two strains from this part of India that are involved in lipase production. The strains were isolated, optimized, and purified using standard microbiology protocols and were characterized at the molecular level using the biomarker 16s ribosomal RNA genes of the strains. The identified and isolated bacterial strains were confirmed as Bacillus subtilis strain RCPS3, and Bacillus fumarioli strain RCPS4 through molecular and computational characterization.

The article discusses some features of the method of reagent encapsulation in conditions of negative temperatures. An installation layout has been created that makes temperature measurement of the encapsulated material in the process of reagent encapsulation. During the experiment, the duration of maintaining the temperature necessary for preparing the next portion is determined. A comparison is made of the methods for supplying carbon dioxide to the installation during reagent encapsulation. As a result of the experiment, a more profitable way of supplying carbon dioxide to the installation is determined.

Abstract Purpose Bioremediation is widely considered the most desirable procedure for remediation of oil-contaminated soil. Few studies have focused on the relationships among microbial community, functional genes of biodegradation, and geochemical processes during field bioremediation, which provide crucial information for bioremediation. Methods In the current study, the microbial community and functional genes related to hydrocarbon and nitrogen metabolism, combined with the soil physico-chemical properties, were used to diagnose a set of bioremediation experiments, including bioaugmentation, biostimulation, and phytoremediation, at the field scale. Result The results showed that the added nutrients stimulated a variety of microorganisms, including hydrocarbon degradation bacteria and nitrogen metabolism microorganisms. The functional genes reflected the possibility of aerobic denitrification in the field, which may be helpful in biodegradation. Biostimulation was found to be the most suitable of the studied bioremediation methods in the field. Conclusion We offer a feasible approach to obtain useful bioremediation information and assist with the development of appropriate remediation procedures. The findings improve our knowledge of the interactions between microorganisms and edaphic parameters.

Abstract Potential reuse of oil-contaminated soils guidance policies are demonstrating ways to reuse these materials in engineering applications. However, the engineering properties of these materials are highly altered after contamination. Alternatively, chemical stabilization treatments can improve oil-contaminated soil properties for its reuse in geotechnical applications. This study investigates the effect of a diesel contamination on a coarse-grained soil and assesses the viability of a lime treatment. Laboratory tests included pH, Atterberg limits, compaction, unconfined compression strength (UCS), California Bearing Ratio (CBR) and tensile strength, RX-diffraction and scanning electron micrographs before and after lime treatment. Tests were performed on natural soil, diesel-contaminated soils (2, 4, 8, 12, and 16% of diesel) and lime treated diesel-contaminated soils (2, 4, 6 and 8% of lime). Diesel drastically changed soil plasticity and strength properties. Lime stabilization of diesel-contaminated soils was efficient to recapture soil natural properties with low lime contents. The influence of oil and lime in soil mechanical properties and mineralogical characteristics was evidenced in this study. The presence of oil drastically altered soil mechanical properties. Crystallization of calcite was present in both natural and oil-contaminated soils treated with lime, increasing particles flocculation. The presence of oil favored dolomite formation. Lime was significate in enhancing oil-contaminated soil mechanical properties, such as UCS, indirect tensile strength and CBR, mainly due to carbonation reactions. Oil-contaminated soil mixtures showed increase in mechanical properties after lime treatment and curing period.

Features of change of phytotoxic influence of the soil polluted with oil at the use of a complex biological product based on strains of microorganisms Bacillus amyloliquefaciens subsp. plantarum NSh-2 and Bacillus subtilis NSh-4 in the laboratory were investigated. The level of destruction of petroleum hydrocarbons at different combinations of pollutant and biological product concentrations was determined, as well as in the absence of oil pollution to ensure the assessment of the biological product’s impact on the environment. Soil phytotoxicity was assessed by the method of biotesting using radish seeds of the Sora variety by the ratio of seedling height and the obtained mass of organic matter. [ABSTRACT FROM AUTHOR]

An orange-coloured, rod-shaped, and aerobic bacterial strain DKR-6 T was isolated from oil-contaminated experimental soil. The strain was Gram-stain-negative, catalase and oxidase positive, and grew at temperature 10–42 °C, at pH 5.5–9.5, and at 0–3.0% (w/v) NaCl concentration. The phylogenetic analysis and 16S rRNA gene sequence analysis suggested that the strain DKR-6 T was affiliated to the genus Noviherbaspirillum, with the closest species being Noviherbaspirillum massiliense JC206T (96.3% sequence similarity). The chemotaxonomic profiles revealed the presence of phosphatidylethanolamine, phosphatidylglycerol, diphosphatidylglycerol, and phosphatidylcholine as the principal polar lipids; C16:0, C17:0 cyclo, summed feature 3 (C16:1ω7c and/or C16: 1ω6c), and summed feature 8 (C18:1ω7c/or C18:1ω6c) as the main fatty acids; and Q-8 as a sole ubiquinone. The DNA G + C content was 61.6%. The polyphasic taxonomic features illustrated in this study clearly implied that strain DKR-6 T represents a novel species in the genus Noviherbaspirillum, for which the name Noviherbaspirillum pedocola sp. nov. is proposed with the type strain DKR-6 T (= KACC 22074 T = NBRC 114727 T). [ABSTRACT FROM AUTHOR]

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The research was conducted on the territory of Nadvirna oil and gas district of South-Hvizdetsky oil field of Ivano-Frankivsk region during 2016-2020. The production activity at the research site was stopped 45 years ago. Energy crops the Miscanthus (Miscanthus giganteus) and switchgrass (Panicum virgatum) were planted and sown on model research plots with an estimated area of 25 m2 in triplicate. The miscanthus was planted manually according to the scheme 0.50 × 0.70 m. According to studies on the oil-contaminated soils, with the introduction of different sedimentation rates wastewater, the content of the Lead when growing the miscanthus increases with the introduction of SS 40 t/ha and N10P14K58 (option 6) and is 4.30 mg/kg of soil. However, when growing the switchgrass with the same fertilizer application, the Lead content is 3.97 mg/kg of soil, which is 0.33 mg/kg of soil less than growing the miscanthus. The concentration coefficients of the gross forms of the Lead vary in the range of 1.01-1.09 during the cultivation of the miscanthus. The concentration coefficient of the gross forms of the Cadmium varies in the range of 1.09-1.56, the maximum remains in the options for the introduction of the sewage sludge at a rate of 40 t/ha and N10P14K58. The concentration coefficients of the gross forms of the Lead for growing the switchgrass 20-40 t/ha (option 4-6) are equal to 1.02-1.15. The concentration coefficient of the gross forms of the Cadmium varies between 1.18 and 1.49. [ABSTRACT FROM AUTHOR]

Crude oil continues to impact many nations as it is among the major sources of fuel. Its role in making life in modern societies comfortable cannot be overemphasized as it is readily available and easy to use. Contamination resulting from its use in industries such as mining, transportation and petroleum especially soil contamination cannot be overlooked. Soil pollution resulting from oil contamination can be seen as being among the twenty-first-century vulnerabilities because if not well taken care of the consequences can be devastating. Soil contamination is of interest in most societies because it affects both the environment and humans. This review highlights common sources of soil pollution and their effects, oil waste disposal methods, soil remediation techniques that are well established and those still in their infancy. Such techniques include bioremediation such as phytoremediation and landfarming, where percent removal of contaminated soils was reported from 68% to 89 % in 40 days to 1 year, respectively; physical methods such as excavation and incineration (75-86% removal); chemical methods such as oxidation (48 % by Fenton process); and photocatalysis (67% using titanium dioxide). The choice of remediation in mining, transportation and petroleum industries depends on the urgency and hazardous effects of the pollutant. In Zambia, Mopani Copper Mines uses landfarming as a means to mitigate large amounts of soil contaminated with oil wastes, but the process is slow. In the proposed research, photocatalysis coupled with adsorption of oil on clay will be used to assess the effectiveness of this emerging technology to quicken the degradation of oil in soils. Clay will be incorporated with metal ions and with hydrophobic groups to enhance light absorption and oil-clay interaction, respectively. Photochemical remediation techniques for remediation of soils polluted with oil have attracted considerable interest as the processes are reported to enhance the degradation of oils in soil compared to the biological and physical methods. The extent of photo-degradation of oil waste will be evaluated using the Soxhlet technique by determining the percent residual oil. The importance of remediating contaminated soil in any nation cannot be overemphasized as consequences of not remediating this precious resource might be devastating. Since economic development through industrialization will continue, there is need to constantly improve on methods of mitigating the impact of wastes on the environment, especially in developing countries, where engineering of cheap, nontoxic materials for soil remediation is paramount. [ABSTRACT FROM AUTHOR]

The U.S. Environmental Protection Agency’s (EPA) Superfund—the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) database—has collected and built an open-source database based on nearly 2000 US soil remediation cases since 1980, providing detailed information and references for researchers worldwide to carry out remediation work. However, the cases were relatively independent to each other, so the whole database lacks systematicness and instructiveness to some extent. In this study, the basic features of all 144 soil remediation projects in four major oil-producing states (California, Texas, Oklahoma and Alaska) were extracted from the CERCLA database and the correlations among the pollutant species, pollutant site characteristics and selection of remediation methods were analyzed using traditional and machine learning techniques. The Decision Tree Classifier was selected as the machine learning model. The results showed that the growth of new contaminated sites has slowed down in recent years; physical remediation was the most commonly used method, and the probability of its application is more than 80%. The presence of benzene, toluene, ethylbenzene and xylene (BTEX) substances and the geographical location of the site were the two most influential factors in the choice of remediation method for a specific site; the maximum weights of these two features reaches 0.304 and 0.288.

Soil microbial community structure is altered by petroleum contamination in response to compound toxicity and degradation. Understanding the relation between petroleum contamination and soil microbial community structure is crucial to determine the amenability of contaminated soils to bacterial- and fungal-aided remediation. To understand how petroleum contamination and soil physicochemical properties jointly shaped the microbial structure of soils from different oilfields, high-throughput sequencing of 16S and ITS amplicons were used to evaluate the shifts of microbial communities in the petroleum-contaminated soils in Ughelli East (UE), Utorogu (UT), and Ughelli West (UW) oilfields located in Delta State, Nigeria. The results showed 1515 bacteria and 919 fungal average OTU number, and community richness and diversity, trending as AL > UT > UW > UE and AL > UW > UT > UE for bacteria, and AL > UW > UT > UE and UW > UT > AL > UE for fungi, respectively. The bacterial taxa KCM-B-112, unclassified Saccharibacteria, unclassified Rhizobiales, Desulfurellaceae, and Acidobacteriaceae and fungal Trichocomaceae, unclassified Ascomycota, unclassified Sporidiobolales, and unclassified Fungi were found to be the dominant families in petroleum-contaminated soils. Redundancy analysis (RDA) and Spearman's correlation analysis revealed that total carbon (TC), electric conductivity (EC), pH, and moisture content (MO) were the major drivers of bacterial and fungal communities, respectively. Gas chromatography-mass spectrophotometer (GC-MS) analysis exhibited that the differences in C7–C10, C11–C16, and C12–C29 compounds in the crude oil composition and soil MO content jointly constituted the microbial community variance among the contaminated soils. This study revealed the bacterial and fungal communities responsible for the biodegradation of petroleum contamination from these oilfields, which could serve as biomarkers to monitor oil spill site restoration within these areas. Further studies on these contaminated sites could offer useful insights into other contributing factors such as heavy metals. [ABSTRACT FROM AUTHOR]

At present, the development and optimization of methods to eliminate the consequences of soil contamination with hydrocarbons is gaining increasing economic and social importance; it is the basis for sustainable development of the oil industry. Within the frames of the scientific research, a review of literature was carried out in the sphere of utilization of organic wastes from the food industry in reclamation of oil-contaminated soils; an experimental study of efficiency of the use of wastes from the brewing industry in the process of bioremediation of oil-contaminated soils was conducted and phytotoxicity of these wastes was determined. Experimental research was conducted at different initial concentrations of oil in the soil, which allowed to establish the optimal range of oil pollution level at which the efficiency of brewing waste use is the highest. Thus, at low concentrations (1000-2000 mg/kg), the dynamics of oil concentration decrease in the soil remained preserved throughout the whole duration of the experiment, and the efficiency of oil destruction in the soil exceeded 98%, which confirmed the overall efficiency of application of brewing waste for reclamation of oil-contaminated soils. [ABSTRACT FROM AUTHOR]