Petroleum Degradation Research Articles

Synergistic bioremediation of petroleum-contaminated soil using immobilized consortium of Rhodococcus rhodochrous and Bacillus subtilis laccase

Petroleum-contaminated soil represents a significant environmental and public health challenge on a global scale. Microbial bioremediation has shown potential, yet the role of enzymes in enhancing petroleum degradation remains underexplored. In this study, the synergistic effects of Rhodococcus rhodochrous (R.rh) and Bacillus subtilis-derived laccase (BsLac) was investigated in the remediation of petroleum-contaminated soil. Immobilized R.rh (PSIMRH) and BsLac (ADIMLac) exhibited higher petroleum degradation rates than their free state, achieving 78.3% and 56.3% degradation in liquid systems, respectively. The combined treatment of PSIMRH and ADIMLac demonstrated a synergistic effect on petroleum degradation, achieving 43.6% with a maximum degradation constant of 0.0335 d−1, representing a 202.7% improvement over untreated soil. PSIMRH enhanced petroleum degradation through microbial metabolism, while ADIMLac accelerated the initial breakdown of complex hydrocarbons into simpler, more bioavailable ones via enzymatic oxidation, providing growth substrates for microbes and significantly improving petroleum degradation rates. The microbial analysis revealed an increase abundance of known petroleum-degrading bacterial genera, including Rhodococcus, Lysobacter, Micromonospora, and Streptomyces. However, the presence of BsLac appeared to reduce the competitive advantage of Rhodococcus, promoting the proliferation of indigenous strains like Lysobacter and Streptomyces. These results suggest that enzyme-microbe synergy can enhance the bioremediation process by altering microbial community dynamics and accelerating petroleum degradation. This study attempts to remediate petroleum-contaminated pollution with the combined use of strains and enzymes, providing a new approach for the remediation of other pollution problems.

Bioremediation of petroleum-contaminated soil based on both toxicity risk control and hydrocarbon removal-progress and prospect.

Petroleum contamination remains a worldwide issue requiring cost-effective bioremediation techniques. However, establishing a universal bioremediation strategy for all types of oil-polluted sites is challenging. This difficulty arises from the heterogeneity of soil textures, the complexity of oil products, and the variations in local climate and environment across different oil-contaminated regions. Several factors can impede bioremediation efficacy: (i) differences in bioavailability and biodegradability between aliphatic and aromatic fractions of crude oil; (ii) inconsistencies between hydrocarbon removal efficiency and toxicity attenuation during remediation; (iii) varying adverse effect of aliphatic and aromatic fractions on soil microorganisms. This review examines the ecotoxicity risk of petroleum contamination to soil fauna and flora. It also discusses three primary bioremediation strategies: biostimulation with nutrients, bioaugmentation with petroleum degraders, and phytoremediation with plants. Based on current research and state-of-the-art challenges, we highlighted future research scopes should focus on (i) exploring the ecotoxicity differentiation of aliphatic and aromatic fractions of crude oil, (ii) establishing unified risk factors and indicators for evaluating oil pollution toxicity, (iii) determining the fate and transformation of aliphatic and aromatic fractions of crude oil using advanced analytical techniques, and (iv) developing combined bioremediation techniques that improve petroleum removal and ecotoxicity attenuation.

The influence of benzene on the composition, diversity and performance of the anodic bacterial community in glucose-fed microbial fuel cells.

Bioelectrochemical systems offer unique opportunities to remove recalcitrant environmental pollutants in a net positive energy process, although it remains challenging because of the toxic character of such compounds. In this study, microbial fuel cell (MFC) technology was applied to investigate the benzene degradation process for more than 160 days, where glucose was used as a co-metabolite and a control. We have applied an inoculation strategy that led to the development of 10 individual microbial communities. The electrochemical dynamics of MFC efficiency was observed, along with their 1H NMR metabolic fingerprints and analysis of the microbial community. The highest power density of 120 mW/m2 was recorded in the final period of the experiment when benzene/glucose was used as fuel. This is the highest value reported in a benzene/co-substrate system. Metabolite analysis confirmed the full removal of benzene, while the dominance of fermentation products indicated the strong occurrence of non-electrogenic reactions. Based on 16S rRNA gene amplicon sequencing, bacterial community analysis revealed several petroleum-degrading microorganisms, electroactive species and biosurfactant producers. The dominant species were recognised as Citrobacter freundii and Arcobacter faecis. Strong, positive impact of the presence of benzene on the alpha diversity was recorded, underlining the high complexity of the bioelectrochemically supported degradation of petroleum compounds. This study reveals the importance of supporting the bioelectrochemical degradation process with auxiliary substrates and inoculation strategies that allow the communities to reach sufficient diversity to improve the power output and degradation efficiency in MFCs beyond the previously known limits. This study, for the first time, provides an outlook on the syntrophic activity of biosurfactant producers and petroleum degraders towards the efficient removal and conversion of recalcitrant hydrophobic compounds into electricity in MFCs.

A metagenome-derived artificial intelligence modeling framework advances the predictive diagnosis and interpretation of petroleum-polluted groundwater

Groundwater (GW) quality monitoring is vital for sustainable water resource management. The present study introduced a metagenome-derived machine learning (ML) model aimed at enhancing the predictive understanding and diagnostic interpretation of GW pollution associated with petroleum. In this framework, taxonomic and metabolic profiles derived from GW metagenomes were combined for use as the input dataset. By employing strategies that optimized data integration, model selection, and parameter tuning, we achieved a significant increase in diagnostic accuracy for petroleum-polluted GW. Explanatory artificial intelligence techniques identified petroleum degradation pathways and Rhodocyclaceae as strong predictors of a pollution diagnosis. Metagenomic analysis corroborated the presence of gene operons encoding aminobenzoate and xylene biodegradation within the de novo assembled genome of Rhodocyclaceae. Our genome-centric metagenomic analysis thus clarified the ecological interactions associated with microbiomes in breaking down petroleum contaminants, validating the ML-based diagnostic results. This metagenome-derived ML framework not only enhances the predictive diagnosis of petroleum pollution but also offers interpretable insights into the interaction between microbiomes and petroleum. The proposed ML framework demonstrates great promise for use as a science-based strategy for the on-site monitoring and remediation of GW pollution

Petroleum-contaminated soil bioremediation and microbial community succession induced by application of co-pyrolysis biochar amendment: An investigation of performances and mechanisms

This study aimed to remediate petroleum-contaminated soil using co-pyrolysis biochar derived from rice husk and cellulose. Rice husk and cellulose were mixed in various weight ratios (0:1, 1:0, 1:1, 1:3 and 3:1) and pyrolyzed under 500 °C. These biochar variants were labeled as R0C1, R1C0, R1C1, R1C3 and R3C1, respectively. Notably, the specific surface area and carbon content of the co- pyrolysis biochar increased, potentially promoting the growth and colonization of soil microorganisms. On the 60th day, the microbial control group achieved a 46.69% removal of pollutants, while the addition of R0C1, R1C0, R1C3, R1C1 and R3C1 resulted in removals of 70.56%, 67.01%, 67.62%, 68.74% and 67.30%, respectively. In contrast, the highest efficiency observed in the abiotic treatment group was only 24.12%. This suggested that the removal of petroleum pollutants was an outcome of the collaborative influence of co-pyrolysis biochar and soil microorganisms. Furthermore, the abundance of Proteobacteria, renowned for its petroleum degradation capability, obviously increased in the treatment group with the addition of co-pyrolysis biochar. This demonstrated that co-pyrolysis biochar could notably stimulate the growth of functionally associated microorganisms. This research confirmed the promising application of co-pyrolysis biochar in the remediation of petroleum-contaminated soil.

Contrasting Distribution of Microbial Communities, Functional Genes, and Antibiotic Resistance Genes in Produced Water Treatment Plants with Different Treatment Technologies

A massive volume of produced water (PW) generated in the process of oil extraction must be treated effectively due to its threat to the ecosystems and human health. Different biological treatment technologies have been used in wastewater treatment plant (WWTP) systems to treat PW. However, their influence on treatment performance has not been investigated. In this study, three PW treatment plants (PWTPs) with different treatment technologies were compared in the following aspects: microbial community structure and assembly, functional genes, and the spread of antibiotic resistance genes (ARGs). The results indicated that different biological treatment technologies led to the variations in the diversity and composition of the microbial community. Phylogenetic bin-based null model analysis (iCAMP) revealed that different treatment technologies deterministically drove the assembly of microbial communities, especially the genera associated with the removal of petroleum hydrocarbons. The results of the metagenomic analysis showed that the genes related to the degradation of alkanes and aromatic hydrocarbons were the most abundant in PWTP3, suggesting it had the highest petroleum degradation potential. In addition, the highest abundance of ARGs in PWTP1 indicated the potential facilitation of ARG dissemination in activated sludge systems. Network analysis indicated that the dissemination of ARGs in the PWTPs might be mediated by transposases.

Nature-based solutions for contaminated site remediation: Key principles and a practical case

The article considers opportunities applying nature-based solutions to remediate oil-contaminated sites. It is suggested using such industrial wastes as brewer’s spent grain, beet pulp, and lignin as structurers. It is demonstrated that structurers bearing such genes as Bacillus, Arthrobacter, etc. perform as active petroleum degraders. It was found out that the hydrocarbon removal rate ranged from 90 to 99% for all structurers studied. It is recommended using 1% of the lignin-based degrader to reduce hydrocarbon content in soils preparing them to the future phytoremediation.

Exploring novel alkane-degradation pathways in uncultured bacteria from the North Atlantic Ocean.

Microbes play a significant role in the degradation of petroleum hydrocarbons in the oceans, yet little is known about the native bacteria that metabolize hydrocarbons before an oil spill. The Faroe-Shetland Channel (FSC) is a deepwater subarctic region of the North Atlantic with prominent oil production and a diverse microbial community associated with the degradation of petroleum. Here, we combine DNA-based stable-isotope probing (DNA-SIP) with metagenomics to elucidate the metabolic underpinnings of native alkane-degrading bacteria from the FSC. From two 13C n-hexadecane SIP experiments using seawater from 5 and 700 m depths in the FSC, we obtained 42 metagenome-assembled genomes (MAGs) belonging to 19 genera, including two previously overlooked hydrocarbon-degrading bacteria, Lentibacter (Alphaproteobacteria) and Dokdonia (Bacteroidetes). Diversity surveys indicated Lentibacter were dominant members of the FSC, constituting up to 17% of these communities. Many of the SIP-enriched MAGs (20/42) encoded a complete alkane oxidation pathway, including alkane monooxygenase (AlkB), rubredoxin reductase (AlkT), and rubredoxin-2 (AlkG). Fourteen Aphaproteobacteria MAGs lacked AlkG for electron transfer. Instead, they encoded novel disulfide isomerases with iron-binding cysteine motifs conserved across rubredoxins. Dokdonia lacked AlkT and AlkG, however, their central alkane-degradation catabolic pathways were complete. We describe previously unrecognized bacteria capable of hydrocarbon degradation, including the dominant genera Lentibacter, which may continuously purge hydrocarbons released from oil exploration activities in the FSC. This advances the understanding of the diversity and physiologies of alkane degradation in the North Atlantic and provides evidence of new mechanisms used to metabolize alkanes. IMPORTANCE Petroleum pollution in the ocean has increased because of rapid population growth and modernization, requiring urgent remediation. Our understanding of the metabolic response of native microbial communities to oil spills is not well understood. Here, we explored the baseline hydrocarbon-degrading communities of a subarctic Atlantic region to uncover the metabolic potential of the bacteria that inhabit the surface and subsurface water. We conducted enrichments with a 13C-labeled hydrocarbon to capture the fraction of the community actively using the hydrocarbon. We then combined this approach with metagenomics to identify the metabolic potential of this hydrocarbon-degrading community. This revealed previously undescribed uncultured bacteria with unique metabolic mechanisms involved in aerobic hydrocarbon degradation, indicating that temperature may be pivotal in structuring hydrocarbon-degrading baseline communities. Our findings highlight gaps in our understanding of the metabolic complexity of hydrocarbon degradation by native marine microbial communities.

Effects of soil organic carbon metabolism on electro-bioremediation of petroleum-contaminated soil

Soil organic carbon (SOC) potentially interacts with microbial metabolism and may affect the degradation of petroleum-derived carbon (PDC) in the electro-bioremediation of petroleum-contaminated soil. This study evaluated the interactions among organic carbon, soil properties, and microbial communities to explore the role of SOC during the electro-bioremediation process. The results showed that petroleum degradation exerted superposition and synergistic electrokinetic and bioremediation effects, as exemplified by the EB and EB-PR tests, owing to the maintenance and enhancement of SOC utilization (P/S value), respectively. The highest P/S value (2.0–2.4) was found in the electrochemical oxidation zone due to low SOC consumption. In the biological oxidation zones, electric stimulation enhanced the degradation of PDC and SOC, with higher average P/S values than those of the Bio test. Soil pH, Eh, inorganic ions, and bioavailable petroleum fractions were the main factors reshaping the microbial communities. SOC metabolism effectively buffered the stress of environmental factors and pollutants while maintaining functional bacterial abundance, microbial alpha diversity, and community similarity, thus saving the weakened PDC biodegradation efficiency in the EB and EB-PR tests. The study of the effect of SOC metabolism on petroleum biodegradation contributes to the development of sustainable low-carbon electro-bioremediation technology.

Enhanced degradation of petroleum in saline soil by nitrogen stimulation and halophilic emulsifying bacteria Bacillus sp. Z-13

Remediation of petroleum-contaminated soil is a widely concerned challenge. As an ecofriendly method, the performance improvement of indigenous microbial degradation is facing the bottleneck. In this study, a strain with high efficiency of petroleum degradation was isolated from the petroleum-contaminated soil and identified and named as Bacillus sp. Z-13. The strain showed the ability to produce lipopeptide surfactant which could improve 66% more petroleum hydrocarbons eluted. Strain Z-13 and its biosurfactant exhibited broad environmental adaptability to salinity (0–8%), pH (6−9) and temperature (15–45 °C). With the addition of strain Z-13 and the stimulation of NH4Cl, up to 59% of the petroleum in the contaminated soil was removed at the carbon to nitrogen ratio of 10. Microbial community analysis showed that petroleum-degrading bacteria, represented by Bacillus, became the dominant species at genus level and played an important role in the remediation. Additionally, ammonium stimulation facilitated both pathways of ammonium assimilation and nitrification in native microorganisms to achieve efficient degradation of petroleum hydrocarbons. This study could provide a promising approach for stable, environmental-friendly and efficient remediation of petroleum-contaminated soil.

Metagenomic insight on consortium degradation of soil weathered petroleum and its supplement based on gene abundance change

Petroleum biodegradation is of importance for the mitigation of secondary pollutants from soil chemical remediation. Describing the gene abundance change of the petroleum degradation emerged as an important practice for success. In this study, an indigenous consortium with targeting-enzyme was utilized to develop a degradative system that was later subjected to metagenomic analysis on the soil microbial community. Centering on ko00625 pathway, abundance change of dehydrogenase gene was firstly found increasing from groups D, DS to DC in turn, just in an opposite direction with that of oxygenase. In addition, gene abundance of responsive mechanism went rising with degradative process as well. This finding sufficiently promoted that equal attention should be paid to both degradative and responsive processes. Hydrogen donor system was innovatively built on the consortium-used soil to satisfy the demand of dehydrogenase gene tendency and to sustain further petroleum degradation. Anaerobic pine-needle soil was supplemented to this system, bi-functionally serving as dehydrogenase substrate with nutrients and hydrogen donor. In doing so, two successive degradations optimally achieved the total removal rate 75.6–78.7% for petroleum hydrocarbon. The conception on the gene abundance changes and its corresponding supplement helps industries of concern to develop geno-tag guided framework.

Assessment of the Microbial Communities in Soil Contaminated with Petroleum Using Next-Generation Sequencing Tools

Microbial communities are known to play a principal role in petroleum degradation. This study tries to determine the composition of bacteria in selected crude oil-contaminated soil from Tabasco and Tamaulipas states, Mexico. We determined the microbial populations living under these conditions. We evaluated the structure and diversity of bacterial communities in the contaminated soil samples. The most abundant phylum is proteobacteria. Next Generation Sequencing (NGS) analysis of the sampled soils from both states revealed that this phylum has the most relative abundance among the identified bacteria phyla. The heatmap represented the relative percentage of each genus within each sample and clustered the four samples into two groups. Moreover, this allowed us to identify many genera in alkaline soil from Tamaulipas, such as Skermanella sp., Azospirillum sp. and Unclassified species from the Rhodospirillaceae family in higher abundance. Meanwhile, in acidic soil from Tabasco, we identified Thalassospira, Unclassified members of the Sphingomonadaceae family and Unclassified members of the Alphaproteobacteria class with higher abundance. Alpha diversity analysis showed a low diversity (Shannon and Simpson index); Chao observed species in both Regions. These results suggest that the bacteria identified in these genera may possess the ability to degrade petroleum, and further studies in the future should elucidate their role in petroleum degradation.

Unraveling the Positive Effect of Soil Moisture on the Bioaugmentation of Petroleum-Contaminated Soil Using Bioinformatics.

Petroleum contamination is a severe threat to the soil environment. Previous studies have demonstrated that petroleum degradation efficiency is promoted by enhancing soil moisture content (MC). However, the effects of MC on soil microbial ecological functions during bioremediation remain unclear. Here, we investigated the impacts of 5% and 15% of moisture contents on petroleum degradation, soil microbial structures and functions, and the related genes using high-throughput sequencing and gene function prediction. Results indicated that petroleum biodegradation efficiency was increased by 8.06% in the soils with 15% MC when compared to that with 5% of MC. The complexity and stability of soil microbial community structures with 15% MC were higher than those in the soils with 5% MC when hydrocarbon-degrading bacterial flora (HDBF) were inoculated into the soils. Fifteen percent of moisture content strengthened the interaction of the bacterial community network and reduced the loss of some key bacteria species including Mycobacterium, Sphingomonas, and Gemmatimonas. Some downregulated gene pathways relating to bioaugmentation were enhanced in the soils with 15% MC. The results suggested that the dynamic balances of microbial communities and the metabolic interactions by 15% MC treatment are the driving forces for the enhancement of bioremediation in petroleum-contaminated soil.

Candidatus Alkanophaga archaea from Guaymas Basin hydrothermal vent sediment oxidize petroleum alkanes

Methanogenic and methanotrophic archaea produce and consume the greenhouse gas methane, respectively, using the reversible enzyme methyl-coenzyme M reductase (Mcr). Recently, Mcr variants that can activate multicarbon alkanes have been recovered from archaeal enrichment cultures. These enzymes, called alkyl-coenzyme M reductase (Acrs), are widespread in the environment but remain poorly understood. Here we produced anoxic cultures degrading mid-chain petroleum n-alkanes between pentane (C5) and tetradecane (C14) at 70 °C using oil-rich Guaymas Basin sediments. In these cultures, archaea of the genus Candidatus Alkanophaga activate the alkanes with Acrs and completely oxidize the alkyl groups to CO2. Ca. Alkanophaga form a deep-branching sister clade to the methanotrophs ANME-1 and are closely related to the short-chain alkane oxidizers Ca. Syntrophoarchaeum. Incapable of sulfate reduction, Ca. Alkanophaga shuttle electrons released from alkane oxidation to the sulfate-reducing Ca. Thermodesulfobacterium syntrophicum. These syntrophic consortia are potential key players in petroleum degradation in heated oil reservoirs.

Enhanced remediation of oil-contaminated intertidal sediment by bacterial consortium of petroleum degraders and biosurfactant producers

Oil pollution in intertidal zones is an important environmental issue that has serious adverse effects on coastal ecosystems. This study investigated the efficacy of a bacterial consortium constructed from petroleum degraders and biosurfactant producers in the bioremediation of oil-polluted sediment. Inoculation of the constructed consortium significantly enhanced the removal of C8–C40n-alkanes (80.2 ± 2.8% removal efficiency) and aromatic compounds (34.4 ± 10.8% removal efficiency) within 10 weeks. The consortium played dual functions of petroleum degradation and biosurfactant production, greatly improving microbial growth and metabolic activities. Real-time quantitative polymerase chain reaction (PCR) showed that the consortium markedly increased the proportions of indigenous alkane-degrading populations (up to 3.88-times higher than that of the control treatment). Microbial community analysis demonstrated that the exogenous consortium activated the degradation functions of indigenous microflora and promoted synergistic cooperation among microorganisms. Our findings indicated that supplementation of a bacterial consortium of petroleum degraders and biosurfactant producers is a promising bioremediation strategy for oil-polluted sediments.

The effect of petroleum levels on some soil biological properties under phytoremediation and bioaugmentation

With the development of industries and excessive use of petroleum compounds, petroleum pollution has become a serious threat to the environment. The aim of this study was to the effect of petroleum levels on the biological activities of soil affected by phytoremediation and bioaugmentation. A surface soil sample was collected from the polluted areas around Bandar Abbas Oil Refinery Company, and the petroleum-degrading bacteria were isolated.M. yunnanensis(native) was selected among the isolated colonies for further experiment. The used soil in this study was a surface soil collected from Baghu region of Bandar Abbas, Sothern Iran, and treatments were added to soil samples. To evaluate removal of petroleum levels (0, 4, and 8%) from the soil by phytoremediation (control, sorghum, barley, and bermudagrass) and bioaugmentation (control, A. brasilense (non-native) and M. yunnanensis) and bioaugmented phytoremediation, a factorial pot experiment with completely randomized design and three replications was performed. The results demonstrated that sorghum and bermudagrass were more resistant than barley to the toxic effects of petroleum. Positive effect of bacteria on dry weight in polluted soil was greater than in the non-polluted soil. The degradation of petroleum reaches 77% in sorghum + M. yunanesis + 4% petroleum. Plants had stronger ability to degrade total petroleum hydrocarbon (TPH), while bacteria could better degrade polyaromatic hydrocarbons (PAHs). Application of bacteria and plants stimulated soil biological characteristics (dehydrogenase, arylsulfatase, lipase, bacterial population, and respiration) in polluted soil. Among measured enzymes, dehydrogenase exhibited a stronger response to petroleum levels. Four-percent level had greater irritating effect on soil biological properties. Plants and bacteria rely on differences in biological properties to attain synergy in petroleum degradation. Results indicated that M. yunnanensis has a high ability to remove petroleum from soil, and plants enhance the efficiency of this bacterium.

Enhanced Petroleum Removal by Potent Biosurfactant Producer Bacillus Subtilis CC9 Strain Isolated from an Oil Field

This study aimed to enhance the removal of petroleum with potent biosurfactant producing bacterial strains (Bacillius subtilis CC9, Enterobacter asburiae WMB1, Klebsiella oxytoca Rizhao 536-1, and Acinetobacter pittii PgBE252) isolated from an oil field. The biosurfactant production was determined by different screening methods such as hemolytic activity, drop-collapse, oil spreading, BATH, emulsification index and surface tension. While the presence of biosurfactant was detected with individual bacterial strain, B. subtilis CC9 strain was found to be quite effective on petroleum degradation (92%) with a high yield of biosurfactant production (0.95 ±0.05 g L-1). The degradation rate constant and half-life period of B. subtilis CC9 strain were calculated as K = 2.533 day−1, t1/2 = 0.273. It has been clearly shown with GC/MS analysis that B. subtilis CC9 strain was effective on the removal of long chain n-alkanes (C31 - C35) as well as short and medium chains. The FT-IR analysis also approved the presence of aliphatic and peptide moieties of biosurfactant extracted from B. subtilis CC9 strain. It is remarkably pointed out with this study that high yield of biosurfactant producing B. subtilis CC9 strain can be used in advanced petroleum bioremediation studies as an alternative to chemical surfactants.

Raman spectroscopic and microscopic monitoring of on-site and in-situ remediation dynamics in petroleum contaminated soil and groundwater

The mechanistic study of soil and groundwater remediation in petroleum contaminated lands significantly demands rapid qualitative and quantitative identification of petroleum substances. However, most traditional detection methods cannot provide the on-site or in-situ information of petroleum compositions and contents simultaneously even with multi-spot sampling and complex sample preparation. In this work, we developed a strategy for the on-site detection of petroleum compositions and in-situ monitoring of petroleum contents in soil and groundwater using dual-excitation Raman spectroscopy and microscopy. The detection time was 0.5 h for the Extraction-Raman spectroscopy method and one minute for the Fiber-Raman spectroscopy method. The limit of detection was 94 ppm for the soil samples and 0.46 ppm for the groundwater samples. Meanwhile, the petroleum changes at the soil-groundwater interface were successfully observed by Raman microscopy during the in-situ chemical oxidation remediation processes. The results revealed that hydrogen peroxide oxidation released petroleum from the interior to the surface of soil particles and then to groundwater during the remediation process, while persulfate oxidation only degraded petroleum on the soil surface and in groundwater. This Raman spectroscopic and microscopic method can shed light on the petroleum degradation mechanism in contaminated lands, and facilitate the selection of suitable soil and groundwater remediation plans.

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.