Diesel Contamination Research Articles

Small Scale In-Situ Bioremediation of Diesel Contaminated Soil – Screeing Life Cycle Assessment of Environmental Performance

Spillage of diesel oil and other petroleum products is a commonly creating need for site remediation of contaminated soils. In Sweden the most common remediation action is excavation of the contaminated soil and off site biological treatment by composting. However, a number of small sites spread out in rural areas end up low on priority lists, and will not be attended to within foreseeable future if ever. For such areas a low cost, easy to apply remediation techniques would be of interest. Enhanced bioremediation of diesel contaminants in soil by whey addition has been demonstrated in lab scale. Whey is a by-product from cheese production. A first pilot remediation trial on an actual site in Gäddede, County of Jämtland, was started the summer of 2010. Using this site as a case study a screening life cycle assessment model has been set up. The goal of the study was to investigate the environmental performance of the whey method, to benchmark the whey method toward the excavation and composting practice and to identify environmental hot spots in the whey treatment life cycle. The study aims at establishing if further work should be put into developing the method, or if the environmental performance is such that the whey method should be abandoned. It should be noted that even with a slightly worse environmental performance compared to other remediation alternatives whey treatment could still be of interest, since the small scale sites in rural areas we talk about here otherwise most often would not be attended to. Results from the screening life cycle assessment indicate a rather good environmental performance of the whey method, partly depending on impact category considered. For the whey method, impacts from farming activities in the milk production chain allocated to the whey give significant contributions. Transportation gives important impacts from both the whey method and the excavation and off site composting, thus logistics should always be considered and optimized. The whey onsite treatment could be an interesting alternative for bioremediation especially at sites that would not otherwise be treated, due to small size or remote location.

Optimization, kinetics, physicochemical and ecotoxicity studies of Fenton oxidative remediation of hydrocarbons contaminated groundwater

Fenton oxidation remediation of hydrocarbons contaminated groundwater was investigated for efficiency and effectiveness. 10% pollution was simulated in the laboratory by contaminating groundwater samples with diesel and domestic purpose kerosene (DPK) in two different experimental set ups. Optimum conditions of concentrations of the treatment solutions and pH were established: 300mg/L (FeSO4), 150,000mg/L (H2O2) and pH = 3 for the kerosene contaminant; 100mg/L (FeSO4), 300,000mg/L (H2O2) and pH = 3 for the diesel contaminant. The results from kinetics study show that the remediation process is pseudo-first order reaction with a rate constant of 8.07×104mgL−1hr−1 and 3.13×104mgL−1hr−1 for the diesel and kerosene contaminants in that order with 95.32% and 79.25% reduction in chemical oxygen demand (COD) for diesel and kerosene contaminated samples at the end of the remediation process respectively indicated that remediation have occurred significantly. Percent reduction in Total Petroleum Hydrocarbon (TPH) as kerosene was 89.84% and that of the diesel contaminant as 91.87% after 6hours of remediation. The general pollution index (GPI) for the hydrocarbons contaminated samples was in the range of 6.70–7.52 against the background value of 4.39 for the control groundwater sample. After treatment the GPI had dropped to 4.13–4.43 which depicts remarkable remediation although the samples remained impaired. Therefore there is the need of post-treatments to make the groundwater fit for domestic and agricultural uses. The application of the Fenton oxidative process is found to be very efficient, effective and rapid in reducing total petroleum hydrocarbon as kerosene and diesel as target contaminants.

The effect of soot and diesel contamination on wear and friction of engine oil pump

The effect of oil contamination and oil degradation on friction and wear of engine oil pump are addressed in this paper. It provides a summary of an experimental study on the effects of oil contamination and oil degradation on tribological performance of a Variable Displacement Vane Pump (VDVP); a particular focus is on the vane-rotor contact. Firstly, a lab-based artificial ageing of fully-formulated engine oil (FFO) with the addition of contaminants such as carbon black (CB) and diesel is conducted. Secondly, the impact of these contaminants on the bulk property of the oil during the ageing process is investigated, using rheometry and Attenuated Total Reflectance/Fourier Transform Infrared Spectroscopy (ATR/FTIR). Thirdly, the performance of these oils on friction and wear of the vane-rotor contact under boundary lubrication regime is evaluated. The wear mechanism and chemical nature of tribofilms formed in tribological tests are addressed using Scanning Electron Microscopy/Energy Dispersive X-ray analysis (SEM/EDX) and Raman spectroscopy. It is found that the consumption of the additives by soot (additive adsorption) in the engine oil during the ageing process has a significant effect on wear of the components. This mechanism has a higher impact on producing high wear than abrasion by soot particles.

Comparative Bioremediation of Diesel Oil Bearing Soil by <i>Pseudomonas aeruginosa</i> and <i>Pseudomonas fluorescence</i>

The quality of life on earth is directly linked to the overall quality of the environment. The natural ecosystem encompasses all living and non-living things existing on earth naturally. It is an environment that interacts with all living species, but which may be contaminated with diesel a derivative of hydrocarbons. Diesel spills contaminate both aquatic and terrestrial environments. To prevent the environmental and health risks of this, remediation needs to be advanced. Bioremediation, degradation by microbes, is one of the suitable methods for cleaning diesel contamination. In the present work, the biodegradation of diesel oil contaminated soil has been investigated comparatively with Pseudomonas aeruginosa and Pseudomonas fluorescence coupled with fertilizer as essential nutrients. Based on observations carried out in 18 days, Pseudomonas aeruginosa alone as well as in the presence of essential inorganic nutrients was found to exhibit higher remediation potential in degrading soil contaminated with diesel oil than Pseudomonas fluorescence.

Study Potential of Indigenous Pseudomonas aeruginosa and Bacillus subtilis in Bioremediation of Diesel-Contaminated Water

Petroleum products which are used in a wide variety of industries as energy sources and raw materials have become a major concern in pollution of terrestrial and marine environments. The purpose of this study was to assess the potential of indigenous microbial isolates for degradation of diesel fuel. Two most proficient bacterial strains among five isolated strains from polluted soil of an industrial refinery were studied. The isolates then were identified as Pseudomonas aeruginosa and Bacillus subtilis using biochemical tests and 16S rRNA gene sequence analyses. P. aeruginosa showed higher biodegradation efficiency than B. subtilis in shaking flask containing diesel-contaminated water. P. aeruginosa and B. subtilis degraded about 87 and 75% of total hydrocarbons, respectively, in flasks containing 2% diesel and 98% water. The biodegradation efficiency of the isolates decreased as diesel contamination increased from 2 to 5%. The isolates showed significantly higher efficiency on degradation of short-chain hydrocarbons in 20 days, i.e., by using P. aeruginosa, removal efficiency of C10 hydrocarbons was near 90%, while about 69% of C20+ hydrocarbons and 47% of aromatic hydrocarbons were removed. Therefore, the isolates showed high capability in biodegradation of diesel contamination of the refinery.

Citrate and malonate increase microbial activity and alter microbial community composition in uncontaminated and diesel-contaminated soil microcosms

Abstract. Petroleum hydrocarbons (PHCs) are among the most prevalent sources of environmental contamination. It has been hypothesized that plant root exudation of low molecular weight organic acid anions (carboxylates) may aid degradation of PHCs by stimulating heterotrophic microbial activity. To test their potential implication for bioremediation, we applied two commonly exuded carboxylates (citrate and malonate) to uncontaminated and diesel-contaminated microcosms (10 000 mg kg−1; aged 40 days) and determined their impact on the microbial community and PHC degradation. Every 48 h for 18 days, soil received 5 µmol g−1 of (i) citrate, (ii) malonate, (iii) citrate + malonate or (iv) water. Microbial activity was measured daily as the flux of CO2. After 18 days, changes in the microbial community were assessed by a community-level physiological profile (CLPP) and 16S rRNA bacterial community profiles determined by denaturing gradient gel electrophoresis (DGGE). Saturated PHCs remaining in the soil were assessed by gas chromatography–mass spectrometry (GC-MS). Cumulative soil respiration increased 4- to 6-fold with the addition of carboxylates, while diesel contamination resulted in a small, but similar, increase across all carboxylate treatments. The addition of carboxylates resulted in distinct changes to the microbial community in both contaminated and uncontaminated soils but only a small increase in the biodegradation of saturated PHCs as measured by the n-C17 : pristane biomarker. We conclude that while the addition of citrate and malonate had little direct effect on the biodegradation of saturated hydrocarbons present in diesel, their effect on the microbial community leads us to suggest further studies using a variety of soils and organic acids, and linked to in situ studies of plants, to investigate the role of carboxylates in microbial community dynamics.

Differential Impacts of Willow and Mineral Fertilizer on Bacterial Communities and Biodegradation in Diesel Fuel Oil-Contaminated Soil.

Despite decades of research there is limited understanding of how vegetation impacts the ability of microbial communities to process organic contaminants in soil. Using a combination of traditional and molecular assays, we examined how phytoremediation with willow and/or fertilization affected the microbial community present and active in the transformation of diesel contaminants. In a pot study, willow had a significant role in structuring the total bacterial community and resulted in significant decreases in diesel range organics (DRO). However, stable isotope probing (SIP) indicated that fertilizer drove the differences seen in community structure and function. Finally, analysis of the total variance in both pot and SIP experiments indicated an interactive effect between willow and fertilizer on the bacterial communities. This study clearly demonstrates that a willow native to Alaska accelerates DRO degradation, and together with fertilizer, increases aromatic degradation by shifting microbial community structure and the identity of active naphthalene degraders.

Diesel Adsorption to Polyvinyl Chloride and Iron During Contaminated Water Flow and Flushing Tests.

This paper presents an experimental and theoretical study of aqueous diesel contamination and decontamination of a polyvinyl chloride (PVC) surface and an iron (Fe) surface. A test apparatus designed for the purpose of studying adsorption of diesel from a flowing dilute diesel/water mixture was used to measure the mass of diesel adsorbed per unit surface area (the excess surface density) and the bulk concentration of the diesel in the flow using a fluorescence based measurement technique. Both bulk composition and the excess surface density measurements were achieved via a traverse of the fluorescent measurement probe perpendicular to the test surface. The diesel adsorption to each test surface was examined for three different Reynolds numbers between zero and 7000. Measurements for a given condition were made over a period of approximately 200 h for a diesel mass fraction of approximately 0.15 % in tap water. For a Reynolds number of approximately 7000, the largest excess layer thickness was approximately 4.4 μm, which was measured on a PVC surface. Averaging over all contaminating flow rates and exposure times, the excess layer thickness on the PVC surface was approximately 2.0 μm. Reynolds number had little or no effect on the accumulation of diesel on an iron surface, which was approximately 0.71 μm. The adsorbed diesel on the PVC and iron surfaces was removed by flushing with tap water. Models to predict excess layer thickness during flushing and contamination were developed. The models predict flushing times to within 7 h and predict the influence of pipe surface on contamination level.

Enhanced Degradation of Diesel in the Rhizosphere of Lupinus luteus after Inoculation with Diesel-Degrading and Plant Growth-Promoting Bacterial Strains

The association of plants and rhizospheric bacteria provides a successful strategy to clean up contaminated soils. The purpose of this work was to enhance diesel degradation in rhizosphere by inoculation with selected bacterial strains: a diesel degrader (D), plant growth-promoting (PGP) strains, or a combination (D+PGP). Plants were set up in pots with the A or B horizon of an umbric Cambisol (A and B) spiked with diesel (1.25%, w/w). After 1 mo, the dissipation of diesel range organics (DRO) with respect to = 0 (i.e., 1 wk after preparing the pots with the seedlings) concentration was significantly higher in inoculated than in noninoculated (NI) pots: The highest DRO losses were found in A D+PGP pots (close to 15-20% higher than NI) and in B D pots (close to 10% higher). The water-extractable DRO fraction was significantly higher at = 30 d (15-25%) compared with = 0 (<5%), probably due to the effects of plant root exudates and biosurfactants produced by the degrader strain. The results of this experiment reflect the importance of the partnerships between plants and bacterial inoculants and demonstrate the relevance of the effect of bacterial biosurfactants and plant root exudates on contaminant bioavailability, a key factor for enhancing diesel rhizodegradation. The association of lupine with D and PGP strains resulted in a promising combination for application in the rhizoremediation of soils with moderate diesel contamination.

Comparison of in-plane and out-of-plane piezoelectric microresonators for real-time monitoring of engine oil contamination with diesel

Real-time monitoring of the physical properties of liquids, such as lubricants, is a very important issue for the automotive industry. For example, contamination of lubricating oil by diesel soot has a significant impact on engine wear. Resonant microstructures are regarded as a precise and compact solution for tracking the viscosity and density of lubricant oils. In this work, we report two different resonators for the monitoring of oil dilution with diesel fuel; one device was designed to vibrate in out-of-plane modes (12-mode or 14-mode), while the other micro-plate was actuated in the first extensional in-plane mode. To determine from the measurements the resonance parameters of interest (resonance frequency and quality factor), an interface circuit was implemented and included within a closed-loop scheme. Two types of oscillator circuits were tested, a Phase-Locked Loop based on instrumentation and a more compact version based on discrete electronics, showing similar resolution. A model with fitting parameters was validated allowing for the determination of the viscosity and density of the fluids under test, for which only a small amount of test liquid, in the range of 0.5 ml, was required. Our results demonstrate the performance of the resonators in oils with viscosity up to 90 mPa s. For such viscosity, the quality factor measured at 25 °C was 7 for the 12-mode, 19 for the 14-mode and 16 for the extensional mode. The best resolution for both fluid material parameters was obtained in the 14-mode, showing 3.92 × 10ź5 g/ml for the density and 1.27 × 10ź1 mPa s for the viscosity, in pure lubricant oil SAE 0W30. Finally, the resonator with the best result (14-mode) was also tested in continuous-flow measurements, showing a resolution of 0.5 ppm of diesel contamination in a pure lubricant oil SAE 2.5 W.

Bioremediation of diesel contamination at an underground storage tank site: a spatial analysis of the microbial community.

The present study reports on a real case of contamination due to the chronic leakage of diesel fuel from an underground tank at a dismissed service station. Speciation of the microbial community according to both lateral and vertical gradients from the origin of the contaminant release was analyzed by means of the PCR-DGGE technique. Moreover, the effects of a landfarming treatment on both the microbial community structure and the abatement of contamination were analyzed. The concentration of total petrol hydrocarbons (TPHs) decreased along the horizontal gradient (from 7042.2 ± 521.9 to 112.2 ± 24.3 mg kg(-1)), while increased downwards from the position of the tank (from 502.6 ± 43.7 to 4972.5 ± 275.3 mg kg(-1)). PCR-DGGE analyses and further statistical treatment of the data indicated a correlation between structure of the bacterial communities and amount of diesel fuel contamination. On the other hand, level of contamination, soil texture and depth were shown to affect the fungal community. Chloroflexi and Ascomycota were the most abundant microbes ascertained through culture-independent procedures. Landfarming promoted 91.6 % reduction of TPHs in 75 days. Furthermore, PCR-DGGE analyses evidenced that both bacterial and fungal communities of the treated soil were restored to the pristine conditions of uncontaminated topsoil. The present study demonstrated that bacterial and fungal communities were affected differently by soil factors such as level of hydrocarbon contamination as well as soil depth and texture. This report shows that a well-planned landfarming treatment can drive the restoration of the soil in terms of both abatement of the contaminants and resilience of the microbial community structure.

Optimisation of solid-state urea clathrate formation as a chemical separation method coupled to compound-specific stable carbon isotope analysis

ABSTRACTSolid-state urea clathrate formation (SSUCF) as a chemical separation method prior to stable carbon isotope fingerprinting of diesel fuel contaminations was studied. The stable carbon isotope ratios (δ13C) of n-alkanes in diesel fuel can be used to trace the origin of a contamination. The accurate measurement of the stable isotopic composition of individual compounds requires baseline separation from any other co-eluting compounds. For this purpose silica gel column chromatography (SGCC) and SSUCF were applied. Detailed optimisation of SSUCF was performed: different activators, clathrate formation temperatures, activator volumes, clathrate formation times and sample capacity were investigated. The main benefits of the developed method are reduced clathrate formation time and increased recoveries for lower molecular weight n-alkanes. The recoveries of the developed SSUCF method ranged between 63 and 100% for C10–C24 n-alkanes with relative standard deviation no more than 7%. The precision of the gas chromatography-isotope ratio mass spectrometry measurement was acceptable with a standard deviation of the δ13C values ranging between 0.08 and 0.15‰. The absence of isotopic fractionation was also investigated.The robustness of the method was tested within a model experiment. Nine different water samples including distilled water, tap water, river water, industrial wastewaters and groundwater samples were spiked with the same diesel fuel. The water samples were extracted with n-hexane and after purification with both SGCC and SSUCF n-alkanes were measured. The δ13C values of n-alkanes were found to be similar for all samples. The importance of sample purification prior to compound-specific isotope analysis (CSIA) was also demonstrated within this model experiment by analysing samples from different stages of the sample preparation.Our results show that the proposed method can remarkably improve the precision of compound-specific stable carbon isotope analysis of n-alkanes originating from diesel contamination of the aquatic environment.

Biomarker modulation associated with marine diesel contamination in the Iceland scallop (Chlamys islandica).

The decrease of ice cover in the Arctic will lead to an increase of ship traffic in the upcoming decades. Consequently, oil pollution is expected. In this context, the goals of this study were to evaluate the biological impact of marine diesel contamination and, on this basis, to determine analytical tools of interest (biomarkers) for future biomonitoring of diesel spills. Using a 7-day contamination protocol, this study investigated biochemical modulations in the digestive gland of the Iceland scallop (Chlamys islandica). Incorporation of contaminants was verified assessing haemolymph metabolites. Results showed a response of glutathione-S-transferase to contamination suggesting detoxification processes and the suitability of such a tool for diesel spill biomonitoring. The lack of modulation of superoxide dismutase activity and lipid peroxidation suggests no oxidative stress and the unsuitability of these molecular tools for biomonitoring.

Preliminary Test of Hydrocarbon Exposure on &lt;i&gt;Lepironia articulate &lt;/i&gt;in Phytoremediation Process

The preliminary tests is physically and visually observed to estimate the concentrations of contaminants that can give negative effects on plants growth and at which concentration the plants can tolerate and survive. In this study, bulrush of Lepironia articulate was subjected to diesel to assess its ability to survive when exposed to diesel contaminants with different concentrations (0, 5, 10, 20, 30, 35 and 40 mL diesel/L water). The investigation was conducted in 30 days with two flow systems, free surface (FSF) and sub-surface flow (SSF), were adopted to observe in which system the plant can tolerate to diesel better. These findings will be applied in future study of phytotoxicity test to assess its ability to phytoremediate polycyclic aromatic hydrocarbon (PAHs) contamination in wastewater. At the end of diesel exposure, the result indicated that the plant growth in SFS was better compared to FSF system. The plant had shown that it could only grow and survive in concentrations of 5, 10, 20, 30, 35 and 40 mL diesel/L water in SSF and in concentrations of 5, 10 and 20 mL/L in FSF system. The results of this study will be a basis for future study that aims to study PAHs removal from water using L. articulate plants.

Biodegradation of tetradecane using Acinetobacter venetianus immobilized on bagasse

Immobilized cells present advantages for degrading organic pollutants compared to free suspended cells. However, the immobilization of cells with reference to agricultural waste is still limited. This study investigated using bagasse as a carrier to immobilize Acinetobacter venetianus (A. venetianus) for the degradation of n-alkane. The degradation of alkane based on both adsorption and biodegradation by immobilized A. venetianus was observed, where 93.3%, 77.7% and 24.0% of tetradecane (400mgL−1) were removed by the immobilized cells, free cells and bagasse after 36h incubation, respectively. Additionally, alkane (C10–C25) in diesel was effectively degraded by the immobilized cells, of which 800mgL−1 of alkane was completely degraded after 60h. Furthermore, results showed: (1) tetradecane served as the optimal carbon source at the concentration of 100mgL−1; and (2) cells immobilization reached its peak efficiency with the cells-to-bagasse ratio of 0.5mgcellg−1bagasse. Cells strongly immobilized on bagasse retained a high degradation rate of 77.6% after shaking at 1500rpm. Bagasse protected the cells from pollution stress including cadmium (Cd(II)) and phenanthrene. After 8 reuse cycles, immobilized cells became more stable and efficient. Bagasse-A. venetianus has potential for future application in remediating diesel contaminants.

Development of an NDIR CO₂ sensor-based system for assessing soil toxicity using substrate-induced respiration.

The eco-toxicological indicators used to evaluate soil quality complement the physico-chemical criteria employed in contaminated site remediation, but their cost, time, sophisticated analytical methods and in-situ inapplicability pose a major challenge to rapidly detect and map the extent of soil contamination. This paper describes a sensor-based approach for measuring potential (substrate-induced) microbial respiration in diesel-contaminated and non-contaminated soil and hence, indirectly evaluates their microbial activity. A simple CO2 sensing system was developed using an inexpensive non-dispersive infrared (NDIR) CO2 sensor and was successfully deployed to differentiate the control and diesel-contaminated soils in terms of CO2 emission after glucose addition. Also, the sensor system distinguished glucose-induced CO2 emission from sterile and control soil samples (p ≤ 0.0001). Significant effects of diesel contamination (p ≤ 0.0001) and soil type (p ≤ 0.0001) on glucose-induced CO2 emission were also found. The developed sensing system can provide in-situ evaluation of soil microbial activity, an indicator of soil quality. The system can be a promising tool for the initial screening of contaminated environmental sites to create high spatial density maps at a relatively low cost.

Clogging of vertical-flow constructed wetlands treating urban wastewater contaminated with a diesel spill

Clogging often leads to a decrease of the treatment performance of wetlands. The aims of this study were to compare the impact of different design and operational variables on the treatment efficiency and clogging processes and to model suspended solid (SS) accumulation within the saturated wetland zone using the Wang-Scholz model. Different vertical-flow constructed wetlands were operated from June 2011 until April 2014. Four treatment periods were assessed: set-up, first year after set-up period, second year after set-up period and diesel spill (for selected filters only). The filter with the highest chemical oxygen demand (COD) loading but no diesel contamination performed the best in terms of COD and biochemical oxygen demand (BOD) removal for the fourth and final treatment period. Filters contaminated by diesel performed worse in terms of COD and BOD but considerably better regarding nitrate-nitrogen removal. Serious clogging phenomena impacting negatively on the treatment performance and the hydraulic conductivity were not observed. Modelling results were generally poor for the set-up period, adequate for the first 2years after the set-up period and variable after the diesel spill. The Wang-Scholz model performed well for less complex operations.

Characterization of diesel degrading bacterial species from contaminated tropical ecosystem

The bacterial diversity in a diesel contaminated tropical soil was investigated using diesel oxidation in gradient cultures dynamics (pH and OD) of the pure cultures. The diesel dependent growths of these isolates were assessed for 15 days by monitoring the gradient fluxes in the pH and Optical density OD of the media. Results showed an increase in OD as well as fluctuations in pH values. The mean OD data obtained was 0.515- 1.187 with pH of 6.95-7.2. From the morphological and biochemical characterization and comparison with respect to the standard references, the isolates S1P1, S3P3, S2P2, S2P1,and S3P2 were presumably the members of the genera Bacillus, Pseudomonas and Mycobacterium species. From the study, it was apparent that the tropical ecosystems contained unique organisms with the ability to deal with diesel contamination.

Dynamic Resistivity Changes of Diesel Contamination Plume in Simulated Aquifer

Hydrocarbon contamination to subsurface from petroleum spills and underground tank leaking has become more and more concerned. In this study, the vertical migration processes of diesel was simulated in a scaled beach sand aquifer model using a cylinder Plexiglas tank and monitored by self-made automatic resistivity monitoring system. It was shown that the resistivity change curves were dissimilar among unsaturated zone, capillary fringe and saturated zone. Through the measurements of the soil samples, the water content and oil content variability were consistent with the resistivity changes. From the sharp point of resistivity change curves, the thickness of the accumulated oil zone could be estimated. It provides an effective method to dynamically monitor the light oil plume migration in ground aquifer after leaking and determine the location of the oil lens.

Bioaugmentation efficiency investigation on soil organic matters and microbial community shift of diesel-contaminated soils

This study investigated effects of microbial community shift, soil organic matter (SOM), and diesel contamination approaches with three independent batches. The SOM levels ranged from 2% to 55%. Diesel oil was artificially contaminated to soils with different approaches to achieve the highest level of 10000 TPH mg/kg. The three batches provided the same results regarding the negative influence of SOM on the TPH degradation rate (k). The results of Nonmetric multidimensional scaling indicated that (1) the bacterial community shift significantly associated with the TPH degradation stages; (2) when SOM levels were close to each other, their degradation performance and bacterial communities were similar to each other, and (3) dynamics of bacterial communities could influence the TPH degradability. In addition, the Intergenic spacer (ITS) microarray results emphasized the advantages of determining an effective bioaugmentation, confirming the successfulness of the inoculation, and identifying the survivors. Microbial community shift and SOM levels indeed influenced the TPH degradation.