Remediation Of Oil-contaminated Soil Research Articles

Feasibility of microwave remediation of simulative crude oil-contaminated soil assisted by bluecoke-based modifiers

Microwave (MW) remediation of organics-contaminated soil technology offers the advantages of high efficiency and minimal damage, representing a new approach of soil thermal remediation. However, soil, being a weak MW-absorbing medium, struggles to convert MW energy into thermal energy, thus failing to attain the necessary temperature for thermal remediation. This paper prepared two new bluecoke (BC)-based modifiers (KHCO3@BC and KHCO3/MnO2@BC) to address temperature problem of MW remediation, as well as enhance soil quality. Their composition, structure and electromagnetic properties were analyzed to investigate their role in assisting with the MW remediation of an artificially crude oil-contaminated soil were investigated. Additionally, the industrial feasibility of MW remediation was addressed for the first time. The results showed that the KHCO3 and MnO2 particles in the two modifiers were covered on the BC surface and exhibited local agglomeration. Their carbon crystalline grain size increased, and the electromagnetic properties were weaker than those of the BC. Following 10 min of MW remediation assisted by KBC or KMnBC, the remediation temperatures exceeded 300 °C, with the removal rates of PHs reaching 76.16% and 88.31%, respectively. The organic matter content, soil potassium and mechanical fraction of the remediated soil were improved, but soil acidification still needed to be further addressed. The industrial application analysis indicated that the technical process and techno-economics of MW remediation of crude oil-contaminated soil were feasible, suggesting significant potential for the large-scale industrial application.

Synthesis of iron-manganese bimetallic materials supported by activated carbon and application of activated persulfate in the degradation of soil contaminated by crude oil

Heterogeneous catalytic processes based on zero-valent iron (ZVI) have been developed to treat soil and wastewater pollutants. However, the agglomeration of ZVI reduces its ability to activate persulfate (PS). In this study, a new Fe-Mn@AC activated material was prepared to activated PS to treat oil-contaminated soil, and using the microscopic characterization of Fe-Mn@AC materials, the electron transfer mode during the Fe-Mn@AC activation of PS was clarified. Firstly, the petroluem degradation rate was optimized. When the PS addition amount was 8%, Fe-Mn@AC addition amount was 3% and the water to soil ratio was 3:1, the petroluem degradation rate in the soil reached to the maximum of 85.69% after 96 hours of reaction. Then it was illustrated that sulfate and hydroxyl radicals played major roles in crude oil degradation, while singlet oxygen contributed slightly. Finally, the indigenous microbial community structures remaining after restoring the Fe-Mn@AC/PS systems were analyzed. The proportion of petroleum degrading bacteria in soil increased by 23% after oxidation by Fe-Mn@AC/PS system. Similarly, the germination rate of wheat seeds revealed that soil toxicity was greatly reduced after applying the Fe-Mn@AC/PS system. After the treatment with Fe-Mn@AC/PS system, the germination rate, root length and bud length of wheat seed were increased by 54.05%, 7.98 mm and 6.84 mm, respectively, compared with the polluted soil group. These results showed that the advanced oxidation system of Fe-Mn@AC activates PS and can be used in crude oil-contaminated soil remediation.

Biochar-bacteria-plant combined potential for remediation of oil-contaminated soil.

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.

Study of Bacterization of Medicago sativa L. and Cynodon dactylon (L.) Pers. During the Process of Phytoremediation of Oil-contaminated Soils

Recultivation of oil-contaminated soils on the Absheron Peninsula is one of the most important environmental and social problems for this region. One of the promising ways to solve the problem of soil pollution with petroleum hydrocarbons is the development of methods and approaches for their purification and detoxification in situ, and above all, biodetoxification and bioremediation. In a model vegetation experiment using complex systems of a mixture of plants and microorganisms, phytoremediation of soil contaminated with crude oil at a concentration of 15 g/kg was investigated. It has been established that the inoculation of plants with the modified Fermi-Start biological product affects the number of rhizosphere microorganisms that stimulate plant growth, as well as the degree of purification of gray-brown soil from oil. Cynodon dactylon is an effective biosystem for the remediation of oil-contaminated gray-brown soils as it is modified by a culture of an oil-oxidizing microorganism of the Pseudomonas aeruginosa, isolated from oil-contaminated gray-brown soil, the Fermi-Start biological product and belongs to the group of “effective microorganisms”, associated with plants — Medicago sativa. The joint introduction of the Fermi-Start biological product and the culture of P. aeruginosa had the greatest protective effect on seedlings from exposure to crude oil. The height of the shoots increased by 71% compared with the negative control, in parallel, the degree of oil degradation increased to 24%. A significant role of alfalfa in stimulating the number of rhizosphere microorganisms capable of hydrocarbon degradation has been revealed. This is confirmed by data showing that the number of microorganisms in the plant rhizoplane was 1–2 orders of magnitude higher (about 1.1×107 on average) than in the rhizosphere (about 1.4×105 on average), which may be due to secretion of plant root exudates. The results of the research allow us to recommend the use of a plant-microbial biosystem consisting of Medicago sativa and Cynodon dactylon, together with a Fermi-Start modified biological product for phytoremediation of gray-brown soil contaminated with crude oil.

Heavy fuel oil-contaminated soil remediation by individual and bioaugmentation-assisted phytoremediation with Medicago sativa and with cold plasma-treated M. sativa.

Developing an optimal environmentally friendly bioremediation strategy for petroleum products is of high interest. This study investigated heavy fuel oil (HFO)-contaminated soil (4 and 6gkg-1) remediation by individual and combined bioaugmentation-assisted phytoremediation with alfalfa (Medicago sativa L.) and with cold plasma (CP)-treated M. sativa. After 14weeks of remediation, HFO removal efficiency was in the range between 61 and 80% depending on HFO concentration and remediation technique. Natural attenuation had the lowest HFO removal rate. As demonstrated by growth rate and biomass acquisition, M. sativa showed good tolerance to HFO contamination. Cultivation of M. sativa enhanced HFO degradation and soil quality improvement. Bioaugmentation-assisted phytoremediation was up to 18% more efficient in HFO removal through alleviated HFO stress to plants, stimulated plant growth, and biomass acquisition. Cold plasma seed treatment enhanced HFO removal by M. sativa at low HFO contamination and in combination with bioaugmentation it resulted in up to 14% better HFO removal compared to remediation with CP non-treated and non-bioaugmented M. sativa. Our results show that the combination of different remediation techniques is an effective soil rehabilitation strategy to remove HFO and improve soil quality. CP plant seed treatment could be a promising option in soil clean-up and valorization.

Characteristic microbiome and synergistic mechanism by engineering agent MAB-1 to evaluate oil-contaminated soil biodegradation in different layer soil.

Bioremediation is a sustainable and pollution-free technology for crude oil-contaminated soil. However, most studies are limited to the remediation of shallow crude oil-contaminated soil, while ignoring the deeper soil. Here, a high-efficiency composite microbial agent MAB-1 was provided containing Bacillus (naphthalene and pyrene), Acinetobacter (cyclohexane), and Microbacterium (xylene) to be synergism degradation of crude oil components combined with other treatments. According to the crude oil degradation rate, the up-layer (63.64%), middle-layer (50.84%), and underlying-layer (54.21%) crude oil-contaminated soil are suitable for bioaugmentation (BA), biostimulation (BS), and biostimulation+bioventing (BS+BV), respectively. Combined with GC-MS and carbon number distribution analysis, under the optimal biotreatment, the degradation rates of 2-ring and 3-ring PAHs in layers soil were about 70% and 45%, respectively, and the medium and long-chain alkanes were reduced during the remediation. More importantly, the relative abundance of bacteria associated with crude oil degradation increased in each layer after the optimal treatment, such as Microbacterium (2.10-14%), Bacillus (2.56-12.1%), and Acinetobacter (0.95-12.15%) in the up-layer soil; Rhodococcus (1.5-6.9%) in the middle-layer soil; and Pseudomonas (3-5.4%) and Rhodococcus (1.3-13.2%) in the underlying-layer soil. Our evaluation results demonstrated that crude oil removal can be accelerated by adopting appropriate bioremediation approach for different depths of soil, providing a new perspective for the remediation of actual crude oil-contaminated sites.

Microstructure-dependent CO2-responsive microemulsions for deep-cleaning of oil-contaminated soils

CO2-responsive microemulsion (ME) is considered a promising candidate for deep-cleaning and oil recovery from oil-contaminated soils. Understanding the responsive nature of different microstructures (i.e., oil-in-water (O/W), bicontinuous (B.C.) and water-in-oil (W/O)) is essential for unlocking the potential and mechanisms of CO2-responsive emulsions in complex multiphase systems and providing comprehensive guidance for remediation of oil-contaminated soils. Herein, the responsiveness of microstructures of ME to CO2 trigger was investigated using experimental designs and coarse-grained molecular dynamic simulations. MEs were formed for the first time by a weakly associated pseudo-Gemini surfactant of indigenous organic acids (naphthenic acids, NAs are a class of natural surface-active molecules in crude oil) and tetraethylenepentamine (TEPA) through fine tuning of co-solvent of dodecyl benzene sulfonic acid (DBSA) and butanol. The O/W ME exhibited an optimal CO2-responsive character due to easier proton migration in the continuous aqueous phase and more pronounced dependence of configuration on deprotonated NA ions. Conversely, the ME with W/O microstructure exhibited a weak to none responsive characteristic, most likely attributed to its high viscosity and strong oil-NA interactions. The O/W ME also showed superior cleaning efficiency and oil recovery from oil-contaminated soils. The results from this study provide insights for the design of CO2-responsive MEs with desired performance and guidance for choosing the favorable operating conditions in various industrial applications, such as oily solid waste treatment, enhanced oil recovery (EOR), and pipeline transportation. The insights from this work allow more efficient and tailored design of switchable MEs for manufacturing advanced responsive materials in various industrial sectors and formulation of household products.

Complex Restoration of Oil-Contaminated Soils with New Organomineral Reagents

Among pollutants, petroleum hydrocarbons are recognized as the priority pollutants of the environment. Petroleum hydrocarbons can cause changes in the physical and chemical properties of soils, leading to a decrease in the functional activity of the microbiota of soil biocenoses. The aim of the study was to develop ways and methods of oil-contaminated soil remediation with the new generation sorbents based on organomineral biofertilizer “Kazuglegumus” and aluminum alloys activated by indium, gallium, and tin. The structure and composition of the organomineral reagents, as well as soils with different degrees of contamination were proved by Fourier transform infrared spectroscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy, differential scanning calorimetry, and thermogravimetry. As a working hypothesis, it was accepted that the aluminum alloy activated by gallium, indium, and tin forms complex compounds with humic or fulvic acids, which are low-toxic or non-toxic for plants. The efficiency of cleaning oil-contaminated soils with organomineral sorbents was evaluated. The reduction of oil concentration in soil samples by 12–22% depending on the concentration of reagents and oil content in soil was revealed. The character of oil pollution impact on plants of legume families alfalfa, melilot, and sainfoin, which are characterized by the ability to accumulate and then give nitrogen to the soil, was studied. The phytotoxicity of uncontaminated and non-oil-contaminated soils was studied in laboratory and field conditions. Significantly accelerated plant growth was observed in samples of oil-contaminated soil after treatment with sorbent based on activated aluminum alloy Rau-85 and fertilizer “Kazuglegumus”. The plants had stronger root systems. These experiments are explained by the effect of Rau-85 alloys in favor of reducing the oil concentration to the normalized limits, as well as the transformation of natural humic substances and additionally applied fertilizer “Kazuglegumus” (potassium humates), which increased their biological activity.

Oil-Contaminated Soil Remediation with Biodegradation by Autochthonous Microorganisms and Phytoremediation by Maize (Zea mays).

Biological methods are currently the most commonly used methods for removing hazardous substances from land. This research work focuses on the remediation of oil-contaminated land. The biodegradation of aliphatic hydrocarbons and PAHs as a result of inoculation with biopreparations B1 and B2 was investigated. Biopreparation B1 was developed on the basis of autochthonous bacteria, consisting of strains Dietzia sp. IN118, Gordonia sp. IN101, Mycolicibacterium frederiksbergense IN53, Rhodococcus erythropolis IN119, Rhodococcus globerulus IN113 and Raoultella sp. IN109, whereas biopreparation B2 was enriched with fungi, such as Aspergillus sydowii, Aspergillus versicolor, Candida sp., Cladosporium halotolerans, Penicillium chrysogenum. As a result of biodegradation tests conducted under ex situ conditions for soil inoculated with biopreparation B1, the concentrations of TPH and PAH were reduced by 31.85% and 27.41%, respectively. Soil inoculation with biopreparation B2 turned out to be more effective, as a result of which the concentration of TPH was reduced by 41.67% and PAH by 34.73%. Another issue was the phytoremediation of the pre-treated G6-3B2 soil with the use of Zea mays. The tests were carried out in three systems (system 1-soil G6-3B2 + Zea mays; system 2-soil G6-3B2 + biopreparation B2 + Zea mays; system 3-soil G6-3B2 + biopreparation B2 with γ-PGA + Zea mays) for 6 months. The highest degree of TPH and PAH reduction was obtained in system 3, amounting to 65.35% and 60.80%, respectively. The lowest phytoremediation efficiency was recorded in the non-inoculated system 1, where the concentration of TPH was reduced by 22.80% and PAH by 18.48%. Toxicological tests carried out using PhytotoxkitTM, OstracodtoxkitTM and Microtox® Solid Phase tests confirmed the effectiveness of remediation procedures and showed a correlation between the concentration of petroleum hydrocarbons in the soil and its toxicity. The results obtained during the research indicate the great potential of bioremediation practices with the use of microbial biopreparations and Zea mays in the treatment of soils contaminated with petroleum hydrocarbons.

Remediation of Petroleum-contaminated Soil by Highly Efficient Oil-degrading Bacteria and Analysis of Its Enhancement Mechanism

A 120-day in situ remediation of oil-contaminated soil was carried out by using highly efficient oil-degrading bacteria. The effects of bio-enhanced remediation and changes in soil physicochemical properties and enzyme activities were investigated. Combined with metagenomic sequencing and bioinformatics analysis, the strengthening mechanism was revealed. The results showed that compared with the blank control group (Ctrl), the degradation rate of total petroleum hydrocarbons in the bioremediation group (Exp-BT) was significantly increased, reaching 81.23%. During enhanced bioremediation by highly efficient oil-degrading bacteria, the pH of the soil was stable, the oxidation capacity of the system was improved, and the electrical conductivity was in the range suitable for agricultural activities. Lipase and dehydrogenase maintained high activity during repair. In addition, the analysis of the initial contaminated soil (B0), the highly efficient oil-degrading bacteria obtained from domestication (GZ), and the soil samples after bioremediation (BT) in the obtained samples showed that, at the phylum level, the total proportion of Proteobacteria and Actinobacteria increased by 17.1%. At the genus level, the abundance of Nocardioides, Achromobacter, Gordonia, and Rhodococcus increased significantly. The species and function contribution analysis of COG and KEGG proved that the above bacterial genera had important contributions to the degradation of petroleum hydrocarbons. A high abundance of petroleum hydrocarbon-related metabolic enzymes and five petroleum hydrocarbon-related degradation genes was found in the soil after remediation:alkM, tamA, rubB, ladA, and alkB. The analysis showed that the introduction of the exogenous petroleum hydrocarbon-degrading bacteria group enhanced the metabolic activity of microorganism-related enzymes and the expression of corresponding functional genes.

Effect of oil and surfactants on changes in some physical properties of soils

The paper shows that oil pollution of gray forest and soddy-podzolic soils led to a decrease in capillary water capacity, plasticity and solid phase of soils. As a result of the introduction of the nonionic surfactant tween-80 into the oil-contaminated soil, these indicators were partially restored, but their values remained lower than in soil samples subjected to oil treatment. The obtained materials allow us to speak about the fundamental possibility of using surfactants for the remediation of oil-contaminated soils.

Strategies for cost-effective remediation of widespread oil-contaminated soils in Kuwait, an environmental legacy of the first Gulf War

The Kuwaiti oil fire during the first Gulf War resulted in the formation of approximately 300 “oil lakes” of varying sizes that covered over 110 km2 of the desert land. This threatens the fragile desert ecosystems and human health. Following the award of over US$2 billion to the State of Kuwait by the United Nations, large-scale remediation of the oil-contaminated soils has now been on the agenda. However, how to implement the remediation program in a cost-effective way represents a major challenge. In this study, cost-effective remediation strategies were developed based on field and laboratory investigations in a typical oil lake area. Overall, most of the lighter petroleum hydrocarbons (PHCs) were lost due to evaporation. Long-chain aliphatic PHCs dominated the PHCs in the investigated oil lake area. This has implications for developing remediation strategies. Toxicity assessment results showed that the majority of soils pose a low environmental risk with a hazard index <1. Therefore, intensive treatment of these PHCs may not be necessary for these soils. Although active treatment methods are needed to remove the contaminants as soon as practical for the relatively small areas of high contamination, more cost-effective passive methods should be considered to minimize the remedial costs for the larger area of the non-hotspot areas. Given the extremely low risk in terms of groundwater contamination by the contaminated soils, it may not be necessary to remove the soils from the contaminated sites. A low-cost capping method should be sufficient to minimize human exposure to the PHC-contaminated soils.

Experimental Study on Repairing the Mechanical Characteristics of Oil-Contaminated Silty Clay in Ancient Dike with Modified Lime Mortar.

Flood-controlled ancient dikes play a significant role in flood control and have received widespread attention as historical and cultural symbols. Flood-controlled ancient dikes often undergo disasters, and research on their repair is receiving increasing attention from experts and scholars. This article studies the control of seepage and bank slope instability in flood-controlled ancient dikes. Starting from the repair of ancient dike materials, three types of work are carried out: a test of soil's mechanical properties, finite element numerical simulation, and repair technology research. The research results show that the soil of the ancient dike site has hardened after being contaminated with waste oil from catering. The strength index of the ancient dike soil decreases and shows brittleness when the water content is 15% and the oil content exceeds 6%. The strength index and permeability coefficient of oil-contaminated soil improved using modified lime mortar (MLM), which was achieved using the method of MLM to repair oil contaminated soil. When the MLM content was 10% and the oil content was 6%, the friction angle of the soil sample reached its maximum value. When the MLM content was the same, the higher the density of the soil sample, the greater the friction angle and cohesion and the smaller the permeability coefficient. Establishing a finite element numerical model, through comparative analysis, it was found that after MLM remediation of oil-contaminated soil, the extreme hydraulic gradient of the ancient dike decreased by 31.3%, and the extreme safety factor of the bank slope stability increased by 31.2%. MLM pressure grouting technology was used to improve the soil during the remediation of contaminated soil at the ancient dike site. Through on-site drilling inspection, the effective diffusion radius of MLM grouting was obtained, and the plane layout and grouting depth of MLM pressure grouting were determined. The on-site water injection permeability test showed that using MLM pressure grouting technology can effectively repair oil-contaminated soil in the ancient dike while reducing the permeability coefficient by 8-15%.

Microbiological remediation of oil-contaminated soils

Microbiological remediation is a promising technology for the elimination of environmental contamination by oil and petroleum products, based on the use of the metabolic potential of microorganisms. The issue of environmental contamination by crude oil and its refined products is relevant in the Russian Federation since the oil industry is one of the leading sectors of the country. Mechanical and physico-chemical methods of treatment are widely used to clean oil-contaminated soils. However, the methods belonging to these groups have a number of significant drawbacks, which actualizes the development of new methods (mainly biological), since they are more environmentally friendly, cost-effective, less labor-intensive, and do not require the use of technical capacities. Various bio-based products based on strains and consortia of microorganisms have been developed that have proven effectiveness. They include certain genera of bacteria, microscopic fungi, and microalgae, substances or materials acting as sorbents of biological agents and designed to retain them in the soil and increase the efficiency of bioremediation, as well as some nutrients. Statistical data, the most effective methods, and technologies, as well as cases of using microorganisms to restore oil-contaminated soils in various climatic conditions are presented.

Microwave Heating Remediation of Light and Heavy Crude Oil-Contaminated Soil

Microwave Heating Remediation of Light and Heavy Crude Oil-Contaminated Soil

Enhanced crude oil degradation and reshaped microbial community structure using straw-sludge biochar-persulfate oxidative system in oil-contaminated soil

The straw-sludge biochar is an environmentally friendly and novel alternative activator. In this study, a novel biochar (SSBC), co-pyrolyzed by waste rice straw and municipal sludge using ZnCl2 activation method, was applied in persulfate (PS)-based remediation for crude oil in soil, which has a high efficiency up to 69.11% in 35 days. Compared with sludge-BC, SSBC had a higher surface area of 667.81 m2‧g−1, pore volume of 0.47 cm3‧g−1, and pore surface area of 233.22 m2‧g−1, FT-IR showed that SSBC is in richer surface functional groups, e.g., -COOH with a content of 1.03 mM‧g−1 and -OH with a content of 2.77 mM‧g−1, which were responsible for its good PS activation performance. Besides, the EPR results showed that SSBC activated PS to generate SO4−• and •OH, which certainly supported the construction of the system. In SSBC-PS oxidative system, the SSBC dosage (0.03 g), the PS dosage (1 mM) and the initial pH value (7) of the system were optimized, and it were applied in oil-contaminated soil. Owing to the SSBC-PS oxidative system, the crude oil degradation rate reached to 34.17% in first week. And these long-chain alkanes were oxidized to short-chains, or cyclane and aromatics were oxidized into short-chain alkanes. Besides, the relative abundance of potential crude oil degraders greatly increased finally, including Alcanivorax (12.52% ∼ 12.86%), Marinobacter (10.78% ∼ 12.54%), Aliifodinibius (7.01% ∼ 7.09%) and Salinisphaera (6.55% ∼ 7.16%), which changed organic pollutions to CO2 and H2O via TCA cycle in crude oil degradation process. Consequently, the combination of SSBC-PS oxidative system and indigenous microbes would be a potential application in crude oil-contaminated soil remediation.

Synergistic effects of rice husk biochar and aerobic composting for heavy oil-contaminated soil remediation and microbial community succession evaluation

Soil petroleum pollution is an urgent problem in modern society, which seriously threatens the ecological balance and environmental safety. Aerobic composting technology is considered economically acceptable and technologically feasible for the soil remediation. In this study, the combined experiment of aerobic composting with the addition of biochar materials was conducted for the remediation of heavy oil-contaminated soil, and treatments with 0, 5, 10 and 15 wt% biochar dosages were labeled as CK, C5, C10 and C15, respectively. Conventional parameters (temperature, pH, NH4+-N and NO3--N) and enzyme activities (urease, cellulase, dehydrogenase and polyphenol oxidase) during the composting process were systematically investigated. Remediation performance and functional microbial community abundance were also characterized. According to experimental consequences, removal efficiencies of CK, C5, C10 and C15 were 48.0%, 68.1%, 72.0% and 73.9%, respectively. The comparison with abiotic treatments corroborated that biostimulation rather than adsorption effect was the main removal mechanism during the biochar-assisted composting process. Noteworthy, the biochar addition regulated the succession process of microbial community and increased the abundance of microorganisms related to petroleum degradation at the genus level. This work demonstrated that aerobic composting with biochar amendment would be a fascinating technology for petroleum-contaminated soil remediation.

Biochar aerogel enhanced remediation performances for heavy oil-contaminated soil through biostimulation strategy.

Petroleum leakages can seriously damage the soil environment and cause a persistent harm to human health, due to the release of heavy oil pollutants with a high viscosity and high molecular weight. In this paper, biochar aerogel materials were successfully prepared under 600, 700 and 800℃ (accordingly labeled as 600-aerogel, 700-aerogel and 800-aerogel) with green, sustainable and abundant sisal leaves as raw materials for the remediation of heavy oil-contaminated soil. The remediation performances of biochar aerogel supplement for heavy oil-contaminated soil were investigated, while microbial abundance and community structure were characterized. The degradation efficiency of 600-aerogel, 700-aerogel and 800-aerogel treatments was accordingly 80.69%, 86.04% and 86.62% after 60 days. Apart from adsorption behavior, biostimulation strengthened the degradation efficiency, according to findings from first-order degradation kinetics. Biochar aerogel supplement basically increased genera microbial abundance for Sinomonas, Streptomyces, Sphingomonas and Massilia with petroleum degradation abilities through microorganisms' biostimulation. Sinomonas as the dominant genus with the highest abundance probably contributed much higher capacities to heavy oil degradation. This study can provide an inspiring reference for the development of green carbon-based materials to be applied in heavy oil-contaminated soils through biostimulation mechanisms.

Microbial Electrochemical-based Biofuel Cell System for Remediation of Oil Contaminated Soil

With the growing problem of oil seepage from gas stations around the world, remediation of oil-contaminated soils is receiving increased attention. Microbial electrochemical techniques have been shown to remove hydrocarbons from soil. Microbial fuel cells (MFC) show a strong potential to immobilize and dissipate contaminants using microorganisms. In this context, this review briefly introduces the conventional methods for remediation of petroleum soil contamination, focusing on the effects of different factors and configurations on the effectiveness of MFC remediation. Compared to traditional remediation methods, applying MFC to petroleum leaks in gas stations has better environmental and economic benefits. It does not require the application of chemicals or ex situ remediation of the soil, which largely reduces the cost and does not cause secondary pollution to the surrounding environment such as soil or atmosphere. In the long term, this technology has a good potential to enhance the remediation effect by changing the applied electric field, soil texture, and petroleum degrading bacteria. In addition, making soil MFC simultaneously achieve combined remediation of petroleum hydrocarbons and other contaminants remains to be studied. Finally, this paper emphasizes that there are few practical applications about MFC site remediation and there is a need to conduct site tests with large scale. If the pilot-scale tests are similar to the laboratory-scale treatment results, the technology will gain more popularity.

Electrochemical Remediation of Oil-Contaminated Soils Factoring in Terrain: Theoretical and Experimental Studies

Electrochemical Remediation of Oil-Contaminated Soils Factoring in Terrain: Theoretical and Experimental Studies