Degradation Rate Of Petroleum Hydrocarbons Research Articles

Interactions between plants and bacterial communities for phytoremediation of petroleum-contaminated soil.

Plants can stimulate the microbes to degrade ubiquitous petroleum hydrocarbons (PHCs), which has prompted a novel view on rhizoremediation. In the present study, the degradation rateof PHCs was investigated and 16S rRNA gene analysis was performed to investigate the PHC-degrading bacteria in petroleum-contaminated soil with different plants. Mirabilis jalapa (M. jalapa) has a higher PHC degradation rate than Lolium perenne (L. perenne) under petroleum contamination. The bacterial diversity in rhizospheric soil was decreased but the relative abundance of Actinobacteriota, Proteobacteria, and Candidatus Saccharibacteria were significant increased on 45days petroleum-contaminated rhizospheric soil. In addition, the relative expression of PHC degradation-related genes, the content ofmalic acid and citric acid of the root exudates in the two plants was significantly increased in response to petroleum stress. The content ofcitric acid increased 11.9 times in M. jalapa and 3.4 times in L. perenne, respectively, in response to petroleum stress. These results indicate that M. jalapa changes the hydrocarbon-degrading microbial community to enhance the degradation of PHCs by root exudates and phytostimulation.

Remediation of diesel contaminated soil by using activated persulfate with Fe3O4 magnetic nanoparticles: effect and mechanisms.

In this study, Fe3O4 magnetic nanoparticles (Fe3O4 MNPs) were assessed for their ability to enhance the activity of persulfate (PS). Various controlling factors including PS dosages, initial pH, water-soil ratio, ratio of Fe2+, and Fe3O4 MNPs to PS were considered in both the Fe2+/PS system and the Fe3O4 MNPs/PS system. Results showed that the Fe3O4 MNP-activated PS system exhibited high processing efficiency owing to the gradual release of Fe2+. This process occurred in a wide pH range (5-11), attributed to the synergistic action of sulfate radicals (SO4-·) and hydroxyl radicals (OH·) under alkaline conditions, effectively mitigating soil acidification. The ratio of Fe3O4 MNPs to PS and water-soil ratio significantly influenced the degradation rate with the highest petroleum hydrocarbon degradation rate exceeding 80% (82.31%). This rate was 3.1% higher than that achieved by the Fe2+/PS system under specific conditions: PS dosage of 0.05 mol/L, Fe3O4 MNPs to PS ratio of 1:10, water-soil ratio of 2:1, and initial pH of 11. Meanwhile, oxidant consumption in the Fe3O4 MNPs/PS system was halved compared to the Fe2+/PS system due to the slow release of Fe2+ and less ineffective consumption of SO4-·. Mechanistically, the possible degradation process was divided into three parts: the initial chain reaction, the proliferating chain reaction, and the terminating chain reaction. The introduction of Fe3O4 MNPs accelerated the degradation rate of pentadecane, heneicosane, eicosane, tritetracontane, and 9-methylnonadecane.

Root exudate glycine synergistically promotes phytoremediation of petroleum-contaminated soil

The exploitation of petroleum, the production and use of petroleum products causes pollution that is harmful to the ecology and environment. At present, petroleum hydrocarbon pollution has become a universal concern in the world. As one of the bioremediation methods, plant root exudate repair has the effect of eliminating toxic substances in the environment. To explore the role of root exudates glycine in phytoremediation of petroleum-contaminated soil, seed germination and pot experiments were carried out to study the effects of glycine on the degradation of petroleum hydrocarbons in different plants and soil types. The results showed that when the concentration of petroleum pollutants was constant, the order of seed germination rate of the eight plants was ryegrass > sudan grass > white clover > tall fescue > alfalfa > pennisetum > canine root > maize grass.1000 mg L−1 of glycine could effectively promote plant biomass and the petroleum hydrocarbons degradation rate. The degradation effect was ryegrass + glycine > ryegrass > sudan grass + glycine > sudan grass > white clover + glycine > white clover. The degradation rate of ryegrass + glycine in 18,000 mg kg−1 petroleum-contaminated soil reached 55.7%. All plants had the highest biomass and plant height in loamy soil, while the highest degradation rate of petroleum hydrocarbons was observed in sandy soil, ranging from 50.36% to 59.36%. Among them, ryegrass combined with 1000 mg L−1 of glycine reached the highest petroleum hydrocarbons degradation rate of 59.36% in sandy soil. Ryegrass, sudan grass and white clover had the potential to remediate petroleum-contaminated soils. In the three types of soil, ryegrass had a strong remediation efficiency, and the degradation effect to petroleum hydrocarbons was more significant after the addition of glycine. Therefore, ryegrass can be planted with glycine as a priority for remediation in oil field areas contaminated by petroleum hydrocarbons.

Coupling biostimulation and phytoremediation for the restoration of petroleum hydrocarbon-contaminated soil

Total petroleum hydrocarbons (TPH) continue to be among the most common pollutants in soil worldwide. Bioremediation and phytoremediation have become sustainable ways of dealing with TPH contamination and biostimulation-assisted phytoremediation is considered as a potential approach for the treatment of pollutants. In this study, the response surface was used to optimize the single-factor biological stimulation experiment of moisture content, leavening agent content and compound fertilizer content and got the best experimental plan of biological stimulation. It was found that TPH degradation rate was 28.6% by biostimulation after 70 days. Further, from 20 kinds of plant seeds, 5 kinds of suitable or growth and high germination rate were selected for petroleum hydrocarbon degradation experiment. In the phytoremediation, peanut was selected as the best plant species by measuring the TPH degradation rate, bacteria count, growth of test plants, germination rate and amount of catalase in the soil and it could achieved 31.1% degradation rate of petroleum hydrocarbons after 70 days. Finally, the artificial biostimulation and phytoremediation combined degradation experiment of petroleum hydrocarbons-contaminated soil was designed and it achieved 38.9% TPH degradation rate after 70 days.

Cleaning up oil pollution in the ocean with photocatalytic concrete marine structures

Treating petroleum pollution in the ocean by use of photocatalytic techniques has become a hot topic in recent years, but the existing methods that degrade petroleum by photocatalytic techniques are still limited. This paper proposed an approach to clean up oil pollution in the ocean with marine structures constructed of photocatalytic concrete. The photocatalytic concrete was prepared by using a photocatalyst (Na-g-C3N4) and ordinary concrete. The Na-g-C3N4 was created from waste melamine and NaCl and was then combined with the concrete surface. In this way, the surfaces of marine concrete structures would have the capability to degrade petroleum films on the sea surface under sunlight. To test the performance of photocatalytic concrete, we conducted degradation experiments, and seven influencing factors (e.g., irradiation time, irradiation intensity, irradiation angle, time of wave scouring, height of photocatalytic region, pH and seawater temperature) were also considered. The experimental results showed that the degradation rates of petroleum hydrocarbons by photocatalytic concrete could reach approximately 50%. Among the seven influencing factors, the first five factors could influence the degradation process significantly, while the pH and temperature of seawater do not play an important role in photocatalytic degradation. Based on the observations of the trials, it was found that the degradation rate was limited to about 50% due to the thickness of the petroleum film. When the film thickness is not sufficient to support the formation of petroleum film, the photocatalytic degradation process will stop. Our study represents a successful attempt to combine the fields of clean energy, photocatalysis, environmental pollution control and building materials, as well as to provide a new method to clean up petroleum pollution by photocatalytic techniques. We will demonstrate that photocatalytic concrete can effectively degrade oil films on the surface of the ocean in complex marine environments, so it is feasible to use marine photocatalytic concrete structures to eliminate petroleum pollution in the ocean.

Remediation potential of immobilized bacterial strain with biochar as carrier in petroleum hydrocarbon and Ni co-contaminated soil

ABSTRACT The remediation of organic pollutant-heavy metal co-contaminated soil is a great challenge. Immobilized microorganism technology (IMT) is a potential approach to remediate co-contaminated soil. In this study, we evaluated the feasibility of IMT for the remediation of petroleum hydrocarbon-heavy metal nickel (Ni) co-contaminated soil. The Ni resistant and hydrocarbon-degrading bacteria strain Citrobacter sp. was added to co-contaminated soil by immobilizing on corncob biochar. The potential performance in biodegradation of petroleum hydrocarbon and changing the mobility and speciation of nickel (Ni) in soil were determined, with consideration of the influences of the soil properties and dehydrogenase activity. The results demonstrated that the degradation rate of petroleum hydrocarbons by immobilized microorganisms group (IM) was 45.52%, significantly higher than that of the free bacteria (30.15%), biochar (25.92%) and blank group (18.47%) (P<0.05). At the same time, IM was more effective in immobilizing Ni in the soil by transforming available Ni to a stable fraction with a maximum residual concentration increasing by 101.50 mg·kg−1, and the carcinogenic nickel sulfide was not detected after remediation in IM. IM exhibited a higher level of soil dehydrogenase activity (0.3956 μg·mL−1·h−1·g−1) than that of free bacteria (0.2878 μg·mL−1·h−1·g−1). A linear correlation was found between the petroleum pollutants degradation rate and dehydrogenase activity (P<0.05). This study indicates the effectiveness and potential of IMT application in degrading petroleum hydrocarbon and immobilizing heavy metals in co-contaminated soil.

On Optimal Condition of Plant–Microbial Remediation of Petroleum Hydrocarbon Polluted Soil

ABSTRACT At present, plant–microbial remediation of soil petroleum pollution has been widely used, but the study of using models to predict remediation effect and find optimal remediation conditions is still very lacking. In this paper, on the basis of the numerical model of previous research, the effects of Suaeda salsa–microbial remediation technique on soil petroleum hydrocarbon pollution were simulated under different soil initial pollutant concentration, soil moisture content and tillage depth. The spatial and temporal degradation of petroleum hydrocarbons and the corresponding degradation rate were studied. The results showed that under different remediation conditions, the degradation rate of microbes, plant and plant–microbial of petroleum hydrocarbon is in the range of 12.70%–24.70%, 4.14%–54.58% and 29.32%–67.28% in 180 days, respectively. It was found that the degradation rate of petroleum hydrocarbons was significantly affected by soil initial pollutant concentration, soil moisture content and tillage depth. The optimal application conditions of S. salsa–microbial remediation technology were found for the remediation of soil petroleum hydrocarbon pollution.

Laboratory-scale bioremediation potential of single and consortia fungal isolates from two natural hydrocarbon seepages in Trinidad, West Indies

A study was conducted to isolate and evaluate the hydrocarbon-degrading potential of indigenous fungi in consortia from natural petroleum seepages in Trinidad. Sixty-seven isolates were obtained from two seepages using medium containing four single hydrocarbon fractions: diesel, naphthalene, pyrene, and asphaltene. The majority of the isolates belonged to the genera Aspergillus (52%) and Fusarium (20%), while fewer belonged to the genera Penicillium and Curvularia, and the order Mucorales (2–14%). The isolates were initially screened for degradation of crude oil in BSM broth before the top 16 (4 per hydrocarbon) were evaluated in soil spiked with single hydrocarbons over 28 days. Three consortia comprising the best performing isolates from each hydrocarbon were then evaluated for their bioremediation potential using soil spiked with crude oil and the four hydrocarbons. Consortium 1, comprising of the top degraders (Aspergillus terreus-SRF-15 (diesel), Fusarium proliferatum-SRF-50 (naphthalene), Fusarium sp-SRF-58, (pyrene) and Aspergillus sp-SRF-67 (asphaltene)), was the most effective with a total petroleum hydrocarbon degradation rate of 92% as compared to the other consortia (64–76%) and the single isolates (10–65%) over a 28-day period. The results of this study show great potential for using indigenous fungi to develop consortia for bioremediation in tropical environments.

小黑麦对石油污染盐碱土壤细菌群落与石油烃降解的影响

PDF HTML阅读 XML下载 导出引用 引用提醒 小黑麦对石油污染盐碱土壤细菌群落与石油烃降解的影响 DOI: 10.5846/stxb201809272101 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目（31470571，31170575）；哈尔滨师范大学研究生创新基金项目（HSDSSCX2018-50） Effect of triticale (Triticale hexaploide L.) growth on the bacterial community and petroleum hydrocarbon degradation in petroleum-contaminated saline-alkali soil Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:为了研究小黑麦对石油污染盐碱土壤中的细菌群落与石油烃降解率的影响，采用高通量测序技术，设置0 g/kg，1 g/kg和5 g/kg三个石油浓度，以未种植小黑麦的土壤作为对照，对6组不同处理的盐碱土壤样品的细菌群落结构及其多样性进行测定，并分析土壤中的石油烃降解率。结果表明：在土壤石油浓度为1 g/kg和5 g/kg时，小黑麦根际土壤中的石油烃降解率相较对照组分别提高了36.67%和33.20%。从6个土壤样品中分别获得21398-27899条测序序列。在石油污染土壤中，小黑麦根际土壤的细菌群落多样性和丰度均大于对照组的土壤。同时，在"门"，"纲"，"属"的分类水平上，小黑麦根际土壤细菌群落中的一些根际细菌的相对丰度增加了，主要包括变形菌门（Proteobacteria）、酸杆菌门（Acidobacteria）、γ-变形菌纲（Gamma-proteobacteria）、烷烃降解菌科-未命名菌属（Alcanivoracaceae_norank）、黄单胞菌属（Xanthomonas）、亚硝化单胞菌-不可培养菌属（Nitrosomonadaceae_unculture）等。有一些相对丰度增加的根际细菌是以石油及石油分解物为碳源的微生物。本研究证明种植小黑麦改变了石油污染盐碱土壤根际土壤细菌群落结构组成和多样性，促进了降解石油微生物群落的构建，显著提高了盐碱土壤石油污染的降解效果。研究结果为石油污染盐碱土壤的植物修复奠定了理论基础。 Abstract:In order to study the effect of triticale on the bacterial community and petroleum hydrocarbon degradation rate in petroleum-contaminated saline-alkali soil, three concentrations of petroleum with 0 g/kg, 1 g/kg and 5 g/kg were introduced into the research and non-triticale-planted soil was set as control group for corresponding concentration of petroleum which formed six different experiment groups. The high-throughput sequencing technology was utilized to study the structure and diversity of the microbial community of six soil samples and to analyze the petroleum hydrocarbon degradation rate. The results showed that the cultivation of triticale increased the degradation of petroleum hydrocarbon by 36.67% and 33.20% in the condition of 1 g/kg and 5 g/kg petroleum, respectively. 21398 to 27899 sequencing sequences were obtained from 6 soil samples. The diversity and abundance of the bacterial communities in the rhizosphere of triticale were higher than those of the soil without plant in the petroleum-contaminated soil. Moreover, the abundance of some rhizosphere bacteria increased in the classification level of "phylum", "class", "genus", such as Proteobacteria, Acidobacteria, Gamma-proteobacteriaria, Alcanivoracaceae_norank, Xanthomonas, Nitrosomonadaceae_unculture, etc. Some rhizosphere bacteria with the increased relative abundance are microorganisms that use petroleum and petroleum decomposition as carbon sources. This study proved that planting triticale changed the composition and diversity of bacterial community in rhizosphere soil of petroleum-contaminated saline-alkali soil, promoted the construction of petroleum-degrading microbial community, and significantly improved the degradation effect of petroleum-contaminated saline-alkali soil. The results laid a theoretical foundation for phytoremediation of petroleum-contaminated saline-alkali soils. 参考文献 相似文献 引证文献

Phytoremediation of a petroleum-polluted soil by native plant species in Lorestan Province, Iran.

Petroleum hydrocarbons are potentially toxic for organisms due to the inherent properties, such as solubility, volatility, and biodegradability. The petroleum materials released from corroded old pipelines would pollute soils, shallow groundwater and air as a consequence, and threat the health of human and environment. Therefore, the removal of these compounds from environment is vital. The stability of these pollutants at the soil and their gradual accumulation over time would disrupt the normal function of the soil, such as reduced agricultural capability. In this research, the influence of two plant species (Bromus tectorum L. and Festuca arundinacea) with different amendments including arbuscular mycorrhizal fungi, alfalfa residues, and nutrient solution on the degradation rate of petroleum hydrocarbons in soil was studied. The results showed that the most effective treatment for petroleum remediation was related to B. tectorum L. plant when treated with mycorrhizal fungi and nutrient solution. The degradation rate during 40days was about 83.27% when compared to the control. Arbuscular mycorrhizal associations are important in the restoration of degraded ecosystems because of the benefits to their symbiotic partners. This fungal phytotechnological mechanism is still in its infancy and there has been little research on aged-contaminated soils.

Large-scale bioventing degradation rates of petroleum hydrocarbons and determination of scale-up factors

ABSTRACTBioventing is a cutting edge, nondestructive treatment method that uses indigenous soil microorganisms in situ to remediate petroleum hydrocarbons in the unsaturated soil zone. Transferring the application of this technology to a field environment still has some uncertainties due to scale-up challenges. In order to identify the scale-up factor, a 80-kg soil reactor system was developed, consisting of a custom-made reactor, climate chamber, low-flow venting system, and an off-gas capture device. Sandy and clayey soils were tested with known concentrations of spiked synthetic gasoline. Various environmental conditions were monitored, which included moisture levels, pH, microbial levels, and nutrient and oxygen levels. Results show a second-stage degradation rate similar to the degradation rate obtained from research conducted with a 4-kg reactor, giving an average scale-up factor of 2.3 ± 0.4. The completed research shows that working with a 80-kg laboratory reactor is feasible, yet not always necessary for the development of scale-up factors. A complimentary study with aged soil contaminants was performed and yielded degradation rates that were significantly reduced.

Degradation of n-alkanes and PAHs from the heavy crude oil using salt-tolerant bacterial consortia and analysis of their catabolic genes.

In the present study, salt-tolerant strains, Dietzia sp. HRJ2, Corynebacterium variabile HRJ4, Dietzia cinnamea HRJ5 and Bacillus tequilensis HRJ6 were isolated from the Dagang oil field, China. These strains degraded n-alkanes and polycyclic aromatic hydrocarbons (PAHs) aerobically from heavy crude oil (HCO) in an experiment at 37°C and 140rpm. The GC/MS investigation for degradation of different chain lengths of n-alkanes (C8-C40) by individual strains showed the highest degradation of C8-C19 (HRJ5), C20-C30 (HRJ4) and C31-C40 (HRJ5), respectively. Moreover, degradation of 16 PAHs with individual strains demonstrated that the bicyclic and pentacyclic aromatic hydrocarbons (AHs) were mostly degraded by HRJ5, tricyclic and tetracyclic AHs by HRJ6 and hexacyclic AHs by HRJ2. However, the highest degradation of total petroleum hydrocarbons (TPHs), total saturated hydrocarbons (TSH), total aromatic hydrocarbons (TAH), n-alkanes (C8-C40) and 16 PAHs was achieved by a four-membered consortium (HRJ2+4+5+6) within 12days, with the predominance of HRJ4 and HRJ6 strains which was confirmed by denaturing gradient gel electrophoresis. The abundance of alkB and nah genes responsible for catabolism of n-alkanes and PAHs was quantified using the qPCR. Maximum copy numbers of genes were observed in HRJ2+4+5+6 consortium (gene copies l-1) 2.53×104 (alkB) and 3.47×103 (nah) at 12days, which corresponded to higher degradation rates of petroleum hydrocarbons. The superoxide dismutase (SOD) (total SOD (T-SOD), Cu2+Zn2+-SOD), catalase (CAT) and ascorbate peroxidase (APX) activities in Allium sativum and Triticum aestivum were lower in the HRJ2+4+5+6-treated HCO as compared to the plantlets exposed directly to HCO. The present results revealed the effective degradation of HCO-contaminated saline medium using the microbial consortium having greater metabolic diversity.

Sand amendment enhances bioelectrochemical remediation of petroleum hydrocarbon contaminated soil

Bioelectrochemical system is an emerging technology for the remediation of soils contaminated by petroleum hydrocarbons. However, performance of such systems can be limited by the inefficient mass transport in soil. Here we report a new method of sand amendment, which significantly increases both oxygen and proton transports, resulting to increased soil porosity (from 44.5% to 51.3%), decreased Ohmic resistance (by 46%), and increased charge output (from 2.5 to 3.5Cg−1soil). The degradation rates of petroleum hydrocarbons increased by up to 268% in 135d. The degradation of n-alkanes and polycyclic aromatic hydrocarbons with high molecular weight was accelerated, and denaturing gradient gel electrophoresis showed that the microbial community close to the air-cathode was substantially stimulated by the induced current, especially the hydrocarbon degrading bacteria Alcanivorax. The bioelectrochemical stimulation imposed a selective pressure on the microbial community of anodes, including that far from the cathode. These results suggested that sand amendment can be an effective approach for soil conditioning that will enhances the bioelectrochemical removal of hydrocarbons in contaminated soils.

Isolation of Petroleum Hydrocarbon Degrading Bacteria from the Liaohe Estuary at Cold Climate

Two cold-tolerant petroleum hydrocarbon degrading bacteria strain named CHD1 and CHD2 were isolated from oil-contaminated soil at cold climate. The isolated strains were able use diesel oil as sole carbon. The petroleum hydrocarbon degradation rate was analyzed using UV-spectrometry-based methods. The results showed that the diesel oil degradation rate of CHD1 and CHD2 were 22% and 25%, respectively.

Enhanced biodegradation of aged petroleum hydrocarbons in soils by glucose addition in microbial fuel cells

AbstractBACKGROUNDBioelectrochemical remediation of soils contaminated by petroleum hydrocarbons has received increasing attention as an effective approach to remove pollution with simultaneous electricity generation.RESULTSHere, glucose was added as a co‐substrate in this system. The charge output of soil microbial fuel cells (MFCs) was enhanced by 262%, and the total petroleum hydrocarbon degradation rate increased by 200%. According to the increased dehydrogenase and polyphenol oxidase activities, the exogenetic glucose substantially activated hydrocarbon degradation bacteria (such as Alcanivorax). The Shannon–Wiener Index and richness of soil microbial community decreased after glucose addition, indicating that a selective enrichment of specific communities was imposed by glucose. Correlation analysis showed the biodiversity in soil far from the cathode was mainly determined by the concentration of petroleum hydrocarbons, while that in soil close to the cathode was dominated by the current.CONCLUSIONThis study demonstrated that an exogenetic carbon source enhanced the bioelectrochemically assisted degradation of aged petroleum hydrocarbons in saline soils, providing an effective approach to remove contaminations from soil in barren areas or extreme environments. © 2015 Society of Chemical Industry

Phytoremediation of soils polluted with crude petroleum oil using Bassia scoparia and its associated rhizosphere microorganisms

The ability of Bassia scoparia (L.) A. J. Scott to remediate petroleum-contaminated arid land sandy soil was studied with natural and sterilized soils, and with supplemental nutrients and water. The species showed good tolerance of petroleum hydrocarbons (PHs) in soils reaching 2–3% (oil:soil by mass) pollution levels. After five months of phytoremediation, the average degradation rate of petroleum hydrocarbons ranged between 31.2 ± 1.15–57.7 ± 1.29% for natural soil and 28.7 ± 1.04–51.1 ± 1.53% for pre-sterilized soil. The highest breakdown of PHs for both saturated and poly-aromatic fractions was achieved when plants were present. Changes in saturated and aromatic fractions were monitored and measured using gas chromatography and high performance liquid chromatography. Moderate concentrations of PHs activated specialized oil-degrading microorganisms which in turn promoted the efficiency of phytoremediation. Polluted soils planted with B. scoparia also showed a significant reduction in sulfur levels. The potential demonstrated for remediation of petroleum hydrocarbons and sulfur by B. scoparia suggests it may be a useful tool for remediation of arid land soils contaminated with crude oil.

Effects of Aquifer Heterogeneity and Geochemical Variation on Petroleum-Hydrocarbon Biodegradation at a Gasoline Spill Site

In subsurface environment, small-scale heterogeneities usually cause the reduction of the applicability of in situ remedial techniques. Biogeochemical heterogeneities and preferential groundwater flow paths create complex hydrogeologic conditions at most contaminated sites. A thorough understanding of the resulting three-dimensional distribution of contaminants is a necessity prior to determining a need for remediation. In this study, a gasoline spill site was selected to examine the effects of aquifer heterogeneities and geochemical variations on petroleum hydrocarbon biodegradation via different oxidation-reduction process. At this site, two multilevel sampling wells were installed to delineate the lateral (5 m) and vertical (0.5 m) distribution of contaminant concentrations and different biogeochemical parameters. Two 5-cm (I.D.) continuous soil cores [from 4 to 8 m below land surface (bls)] were collected within the gasoline plume to evaluate the distribution of the microbial population in soils. Results show that high microbial activities were observed in soil samples based on the following evidences: (1) high petroleum hydrocarbon degradation rate, and (2) high microbial biomass. Each soil section was used for chemical extraction, microbial enumeration, and grain size distribution. Results show that the soil sections with more permeable sediment materials corresponded with higher biomass (total anaerobes &gt; 2 x 106cells/g) and significant contaminant degradation. However, those sections with less permeable sediments contained lower microbial population. Results indicate that the subsurface microorganisms were distributed unevenly in the aquifer, and some regions were devoid of microorganisms and biodegradation activities. Spatial distribution of microorganisms, soil materials, and biogeochemical characteristics in the subsurface soils control the extent and kinetics of contaminant biodegradation. Thus, using blended aquifer materials for measurement of in situ biodegradation rates may not achieve representative results.

Effect of salinity on the bioremediation of petroleum hydrocarbons in a saline-alkaline soil

The aim of this paper is to check the effect of salinity on the bioremediation process of petroleum hydrocarbons in the saline-alkaline soil. In this study, soil salinity was adjusted to different levels by water leaching method and the bioremediation process was conducted for 28 days. Soil pH increased after leaching and decreased during bioremediation process. At initial time, moderate salinity enhanced the biodegradation and addition of microbial consortium was not effective in enhancing degradation rate of petroleum hydrocarbons. At day of 28 days, higher degradation rate was found in treatments with more leaching times with a maximum value of 42·36%. Dehydrogenase activity increased with the progress of bioremediation and positive correlation was found between dehydrogenase activity and degradation rate of petroleum hydrocarbons. Denaturing gradient gel electrophoresis analysis result showed decreased microbial community diversity with increased salt content. The result suggested that salinity had great impact on bioremediation, and leaching and addition of inoculated consortium were effective in enhancing biodegradation of petroleum hydrocarbons in the saline-alkaline soil. The result of this study is important for understanding the bioremediation process of petroleum in contaminated soil. New remediation method of petroleum contaminated soil can be developed based on this study.

Effect of biochar on the fate of volatile petroleum hydrocarbons in an aerobic sandy soil

Biochar addition to soil is currently being investigated as a novel technology to remediate polluted sites. A critical consideration is the impact of biochar on the intrinsic microbial pollutant degradation, in particular at sites polluted with a mixture of readily biodegradable and more persistent organic pollutants. We therefore studied the impact of biochar (2% on dry weight basis) on the fate of volatile petroleum hydrocarbons in an aerobic sandy soil with batch and column studies. The soil–water partitioning coefficient, K d, was enhanced in the biochar-amended soil up to a factor 36, and petroleum hydrocarbon vapor migration was retarded accordingly. Despite increased sorption, in particular of monoaromatic hydrocarbons, the overall microbial respiration was comparable in the biochar-amended and unamended soil. This was due to more rapid biodegradation of linear, cyclic and branched alkanes in the biochar amended soil. We concluded that the total petroleum hydrocarbon degradation rate was controlled by a factor other than substrate availability and the reduced availability of monoaromatic hydrocarbons in the biochar amended soil led to greater biodegradation of the other petroleum compounds.

Experimental Study on Bioremediation of Petroleum Contaminated Soil in Puyang Oilfield

According to the previous experience on remediation experiment in laboratory and field, the study on microgial ecological remediation of petroleum contaminated soil in Puyang oilfield was carried out under 3 different conditions. Here the results from remediation show that the technology of microbe cooperated with alfalfa, single microbe technology and single alfalfa technology all possess remedial effect on petroleum contaminated soil through 99-day period remediation, and the technology of microbe cooperated with alfalfa creates the best remedial mission with petroleum hydrocarbon degradation rate of 65.27%, while the rest single technologies exerts degradation rate of about 40% on petroleum hydrocarbon, Moreover, the experiment results indicate that few nutriment such as soluble salt, NO3-, Cl-,etc can infiltrate into the lower soil layer(50cm). However, the distinct increase of NH4+ in the second and third remediation area may attribute to abundance fertilizer transportation into depth soil layer due to the nitrogen fixation of alfalfa’s roots. In addition, we also find that the remediation effect can be impacted by the factors containing tempertation, water, oxygen, nutriment and mini-geo-enviroment.