TPH Concentration Research Articles

Analyzing the Presence and Dispersion of Hydrocarbons at Mechanic Workshop Dumpsites, Port Harcourt, Rivers State, Nigeria

The study aimed to analyze the presence and dispersion of hydrocarbons in dumpsites at mechanic workshops in Port Harcourt, Rivers State, Nigeria. Soil samples were collected from within 15-25 cm soil depth from three mechanic workshops in Port Harcourt, situated at Elekahia, Rumeme and Eleme Local Governments. The total petroleum (TPH) and Polycyclic aromatic hydrocarbons (PAHs) concentrations in the soil samples were determined using standard methods. Total TPH concentration in mechanic workshop dumpsites ranged from 9508.18 ppm to 10342.41 ppm, while in the control the concentration was 424.41 ppm. Total PAH concentration in mechanic workshop dumpsites ranged from 312.45 ppm to 1654.08 ppm, while in the control the concentration was 157.89 ppm. All the dumpsites had high levels of PAHs, which was several folds more than in the control. Results revealed that soil at mechanic workshop dumpsites was highly contaminated with hydrocarbons, exceeding the allowable limit 50 mg/kg by the Department oof Petroleum Resources (DPR). Remediation of the soil is recommended, as well as proper management of waste, where relocation of the dumpsite is not possible.

Remediation of Petroleum-Contaminated Gas Station Soil Using High-Pressure Soil Washing Technology

Objectives : In this study, high-pressure soil washing was performed on in-situ gas station soils for the remediation of petroleum-contaminated gas station sites.Methods : On-site gas station soils (GSS) collected from four different locations were subjected to high-pressure soil washing to analyze the amount of fine soil removal and TPH concentration after washing according to the cut-off size (0.075, 0.105 mm). In addition, the four GSS were evaluated for the relationship between the organic matter content of each soil and TPH removal efficiency. Furthermore, to evaluate the disintegration force of high-pressure soil washing technology to disperse soil aggregates, the particle size distribution of the soil before and after washing was evaluated and XRD analysis was performed.Results and Discussion : As the cut-off size increased (0.075 mm → 0.105 mm), the removal rate of fine soil in the GSS increased, and the TPH concentration tended to decrease. With respect to the TPH Soil Contamination Warning Standard for Region 2 (800 mg/kg), only the GSS 3 was in compliance with the standard (630 mg/kg). There were no significant differences in fine soil removal rates among the soils, which was expected since all the soils tested represented the same sandy loam. Washing efficiencies by soil were relatively low for soils with relatively high organic matter content. The particle size distribution showed the largest particle reduction was in the 2-0.850 mm range after remediation, while soil particles increased in the 0.105-0.075 mm and <0.075 mm range. In addition, XRD analysis showed an increase in the peak intensity of Quartz and the removal of clay mineral after washing, confirming the effective breakdown of soil aggregates and removal of fine soil by cavitation.Conclusion : If an optimal cut-off size is established, considering the soil texture and economics of the contaminated site after identifying the initial organic content level in the soil prior to washing, it is anticipated that high-pressure soil washing technology will be effectively applied for the remediation of petroleum-contaminated gas station sites.

APPLICATION OF THE ELECTROCHEMICAL TREATMENT METHOD FOR THE REMEDIATION OF PETROLEUM HYDROCARBONS FROM CONTAMINATED SOILS

Contaminated soils with toxic and persistent pollutants pose significant potential hazards to the environment and human health. The problem of polluted soils and choosing the most appropriate remediation strategy is a current concern throughout the world. As a result of the industrial activities related to the energy sector (mainly from the extractive industry), the contaminants of interest at the national and international level in terms of the remediation of contaminated sites are petroleum hydrocarbons. In this context, the main aim of the present research was to evaluate the degree of remediation of these contaminants during the application of the electrochemical remediation method. The soil contaminated with crude oil, subject to remediation, is from Teleorman county, Siliștea commune, an area where oil and natural gas extraction wells are located. Following the application of the electrochemical process, a decrease in the TPH concentration level was observed from an initial concentration of 5000 mg/kg s.u. to 2228 mg/kg s.u., thus obtaining a 55% remediation percentage, after a period of 14 days. Consequently, it can be appreciated that the electrochemical process applied in order to remediate a soil contaminated with petroleum products is advantageous in terms of the short duration of time, but the method also presents some disadvantages such as energy consumption and implicitly significant related costs.

Impacts of crude oil on Arctic sea-ice diatoms modified by irradiance

Anthropogenic climate change is reducing ice and snow thickness in the Arctic. The loss of summer sea ice has led to increased access to Arctic waters and the development of marine resources, which raises the risk of oil spills. Thinning ice and snow also increases irradiance in the upper ocean which is predicted to increase primary productivity, disfavoring shade-adapted sea-ice algae while benefitting phytoplankton and cryopelagic taxa. Studies have confirmed the lethality of crude oil and its distillates to Arctic phytoplankton; less well-constrained are the sublethal impacts to sea-ice algae in combination with other drivers. This study investigates the combination of two drivers, crude oil exposure and irradiance, on the growth rate and maximum cell concentration of four sea-ice diatoms (Attheya septentrionalis, Fragilariopsis cylindrus, and two strains of Synedropsis hyperborea) isolated from landfast sea ice near Utqiaġvik, Alaska. Crude oil inhibition of growth was complex and dependent on species and irradiance level. A. septentrionalis was generally tolerant to crude oil exposure, but toxicity was enhanced at the highest irradiance. The cryopelagic taxon, F. cylindrus, exhibited strong growth inhibition at TPH concentrations greater than approximately 6 mg L−1. Growth rates of S. hyperborea strains were stimulated at low concentrations of oil at all light levels. A simple numerical model was used to simulate an oil spill under varying snow depths to follow composition of a mock community comprised of these four isolates across a spring season. Results highlight that the reduction of algal biomass accumulation and the community composition change following a crude oil spill are more severe in a simulated low-snow spring, due to the relative sensitivity of F. cylindrus. We show that a brighter Arctic, which is predicted to increase the relative importance of cryopelagic taxa like F. cylindrus, may render the Arctic ecosystem more vulnerable to crude oil spills.

Effect of different diesel treatments on growth of single and mixed plant communities and petroleum hydrocarbon dissipation during rhizoremediation

The use of mixed plant communities has been proposed to address phytotoxicity while improving plant stress tolerance and contaminant degradation. However, there has been conflicting findings on the use of mixed plant community. This study assessed the impact of three diesel treatments on plant growth and TPH dissipation in single and mixed plant communities. This involved greenhouse experiment with Medicago sativa, Festuca arundinacea, and Lolium perenne and Medicago sativa + Lolium perenne with the diesel-spiked soils at 102,000, 151,000 and 320,000 µg kg-1 TPH represented as Treatments 1, 2 and 3 respectively. Plant growth was inhibited with root biomass yield was greater compared to plant shoots especially for F. arundinacea and L. perenne. There was a significant decrease in the root biomass yield of M. sativa, L. perenne, F. arundinacea and M. sativa + L. perenne. The highest TPH dissipation of 81, 69 and 72 % was displayed by L. perenne in the Treatments 1, 2 and 3 respectively. However, TPH dissipation was generally comparable for the vegetated and unvegetated soil and were not significantly different (p>0.05) for the different plants and treatments. The impact of plant communities on the rhizoremediation of TPH-contaminated soils may dependent on factors such as plant species, TPH concentration stress tolerance and benefits of individual plant if mixed plants are to be employed.

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

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

PHYTOREMEDIATION CAPACITY OF MAIZE (ZEA MAYS) ON DIESEL OIL POLLUTED SOIL

The potential of maize plants in the remediation of diesel oil-polluted soil was evaluated. Soil samples were polluted with diesel oil in concentrations of 100ml, 200ml, 300ml, and 400ml and amendedseparately with poultry droppings. Samples wereanalyzed at two weeks intervals for 9 weeks. Results show a significant reduction of diesel oil in polluted soil.The effect was concentration dependent. Agromorphological parameters that were observed were Petiole Length, Plant Height, Leaf Length, Leaf Width, and Number of Leaves. Results obtained showed that as the concentration increased the more it reduced the growth of the plant. TPH content of diesel oil showed a significant reduction through the growth period, reducing from a baseline data of 8502mg/kg to 2843mg/kg. Hence, theplants have a higher potential for phytoremediation of diesel-contaminated soils.

دراسة مقارنة لمستويات الهيدروكربونات النفطية الكلية في محافظة البصرة / العراق

As the document of national strategy for Iraqi environment protection from(2013-2017) shows that the environmental awareness concepts is new in the Iraqi society and so limited due to the economic and security priorities under the current conditions, especially aqua environmental awareness side, for verifying this important variable an investigation was carried out to measure the amount of Total Petroleum Hydrocarbon for six water channels in Basrah, which polluted from different sources, these are Al Garmah River, Shatt Al Arab(Corniesh street location), (Abu Floos, Khor Al Zubair, Umm Qasr, and Al Fao ) Ports. The highest concentration of TPH was found inUmm Qasr Port, 22.10 µg/L and the lowest concentration of TPH was found in Al Garmah River, 5.35 µg/L.

The use of locally formulated green de-oiler in oil field effluent water treatment

The purpose of this research was to examine the feasibility of treating refining wastewater with activated carbon made from plantain peels. Physiochemical analysis was conducted on the activated carbon to determine its properties, and the results showed that it was suitable for use in water treatment. The effluent water was also analyzed for its TDS, TSS, metals, phenols, oil and grease, and TPH content, which were found to be above the maximum recommended levels. The efficacy of activated carbon at various doses for wastewater treatment was then investigated. Results showed that as the dosage of activated carbon increased, the absorption of metallic ions such as lead, nickel, zinc, iron, cadmium, and copper increased. As the amount was increased, both the total dissolved solids and the total dispersed solids were found to have diminished. Furthermore, the study found that the pH level of the treated water fluctuated at different levels of adsorbent dosage, but the 30g dosage gave the standard level of the treated water. In conclusion, this study demonstrates that activated carbon produced from plantain peels can be effectively used for the purification of refinery effluent water. The use of activated carbon can significantly reduce the levels of TDS, TSS, metals, phenols, oil and grease, and TPH in the effluent water. Based on the findings, treating industrial effluent with activated carbon may be a viable long-term option.

Influence of Spent Lubricating Oil Spiked Compost on Microbial Counts and Hydrocarbon Degradation Rate in Soils

This study evaluated the influence of organic fertilizers produced from spent lubricating oil (SLO) spiked aerobic composting technique on hydrocarbon degradation rate in soils. The compost windrows (Ft2 and Ft4), consisting of kitchen and agricultural wastes, were spiked with varying concentrations (2% and 4%) of SLO. The resultant organic fertilizers were employed as amendment in pollution simulated potted soils laid out in a complete randomized block design with three replications for 90 days. Results revealed higher counts of hydrocarbon utilizing microbes (HUB: 4.2±0.02×104cfu/g in Ft2, 3.0±0.02×104cfu/g in Ft4; HUF: 3.9±0.2×104cfu/g in Ft2, 2.5±0.02×104cfu/g in Ft4) in spiked compost compared to the control, Ft0 (HUB: 7.9±0.02×103cfu/g; HUF: 6.0±0.2×103cfu/g). Mean count in amended soils reflected a dose-dependent increase which followed the trend: Ft2 ˃ Ft0 ˃ Ft4 for the 5% (3.7×108 cfu/g), 10% (9.2×107 cfu/g) and 15% (6.9×107 cfu/g) levels of fertilizer treatments respectively. There was a significant (P<0.05) reduction in the TPH content of soils after 90days treatment with organic fertilizers. Generally, remediation efficiency followed the order: Ft2 ˃ Ft0 ˃ Ft4, with the highest (11.51%) achieved at 5% Ft2 application. Spiking technique was responsible for the higher counts of hydrocarbon utilizing microbes and enhanced bioremediation associated with the use of fertilizers Ft2.

Potentially Toxic Substances in Singed and Unsinged Cow Skin from Selected Abattoirs Consumed in Port Harcourt Metropolis

Singed and unsinged cow skin (pelts), from four slaughter houses (Ishiodu, Eliozu, Rumuosi, and Rumuodumaya); sold and consumed in Portharcourt, Rivers State city - were evaluated for the concentration of PAHs, TPH and heavy-metals, using GC/FID and atomic absorption spectrophotometer respectively and the outcomes were then exposed to statistical examination (Spearman connection coefficient framework and One-Way ANOVA) to decide critical distinction between the singed and unsinged samples utilizing SPSS programming bundle (form 20.0). The total PAHs and TPH of singed cattle pelts were 0.023, 0.031, 0.035, and 0.035 mg/kg; 1.63, 2.16, 2.52, and 2.62 mg/kg for Ishiodu, Eliozu, Rumuosi, and Rumuodumaya slaughter houses respectively, of which the unsinged pelts and edible-flesh were pointedly (p<0.05) higher than the singed samples. The Fe, Cu, Cd, Zn, Cr, Pb contents were pointedly beyond the passable boundary while Aluminum, Arsenic, and BTEX were not detected. Mercury (Hg) was essentially not identified in singed samples purchased from the slaughter houses with the exclusion of Rumuodumaya (at 0.01mg/kg). The processing procedures aided with certain environmental activities impact negatively on the nutritional content of foods, thus placing consumers at potential wellbeing hazard.

An integrated investigation of hydrocarbon pollution in Ahoada area, Niger Delta Region, Nigeria.

This study investigates hydrocarbon pollution in the Ahoada community of the Niger Delta region of Nigeria. The study uses a geographic information system (GIS) for mapping oil spill hotspots in the region. The resistivity method was used to delineate the extent of hydrocarbon pollution to a depth of 19.7m in the Ahoada area of the region. Three categories of soil samples, impacted soil (IMS), remediated soil (RS), and control soil (CS), were collected and analyzed for the presence of BTEX, PAH, TPH, TOC, and TOG. The concentrations of the samples from the IMS and RS were compared to that of the CS to determine the extent of pollution. The GIS mapping shows that the most polluted areas in the Niger Delta Region are Rivers, Bayelsa, and Delta states. Results of the geophysical images revealed contaminants' presence to depths beyond 20m at some locations in the study area. The highest depth of contaminant travel was at Ukperede. Soil samples' analysis showed that the range of concentrations of TPH in IMS at Oshie was 17.27-58.36mg/kg; RS was 11.73-50.78mg/kg which were higher than the concentrations of 0.68mg/kg in the CS. PAHs are more prevalent in Ukperede, ranging from 54.56 to 77.54mg/kg. BTEX concentrations ranged from 0.02 to 0.38mg/kg for IMP and 0.01-2.7mg/kg for RS against a CS value of 0.01mg/kg. The study revealed that there are characteristically high resistivity values in the samples which were corroborated by the findings from the resistivity survey. TOC was found to be higher in the IMS and RS than in the CS, demonstrating that a significant quantity of the hydrocarbon has undergone appreciable decomposition.

Bio-evaluation of the Ecological Health Status of Petroleum Effluent Receiving Water from Eleme River, Nigeria

The ecological Health Status of Eleme River receiving treated petroleum effluent wastes from Eleme Petroleum Refinery Company was evaluated using a combined approach of biological methods; petroleum effluent bioindicators, functional diversity and community assemblage metrics, and physicochemical methods; TPH, nutrients, turbidity, DO, pH, Heavy metals, and total dissolved solids analysis. This was carried out, knowing that effluent discharges change the biodiversity of aquatic macro invertebrates, particularly insects, reduce their functional roles, and change their physicochemical requirements. The River was divided into 3 stations; upstream (receiving point), midstream, and downstream, with each station further divided into 3 sampling points. The collection of macro invertebrates was done, using handnets and Eckman’s grab from floating vegetation, logs, and sediments. The samples were placed in a 4-L bucket containing 70% ethanol and 5% glycerin and transported to the Entomology Research Laboratory, Department of Animal and Environmental Biology, the University of Port Harcourt for sorting and identification. Composite water samples were taken for analyses of physicochemical properties using standard devices and methods. Results obtained indicated that out of 18 species encountered, 12 were monitor indicators, 5 were facultative tolerant indicators and none were sensitive indicators. Five species (taxa) occurred at both up and mid-streams and seven occurred downstream. Daphnia barbata and macrobranchium sp., occurred commonly in the three stations. The insect indicators encountered were seven, all of the downstream, and were dominated by insects belonging to the order: Hemiptera. Three functional groups; Detritivorous, collector-herbivorous, and predators were encountered with detritivorous being dominant. The TPH, nitrate, phosphate, copper, and nickel concentrations in all sampling stations were above the intervention limits of the World Health Organization (WHO). Concentrations of physicochemical properties except DO and pH were higher downstream. Shannon-Weiner index showed that the absence of species belonging to Ephemeroptera, Plecoptera, and Trichoptera in all stations indicated that Eleme River has a poor ecological health status.

Soil treatment using a biosurfactant producing bacterial consortium in rice fields contaminated with oily sludge— a sustainable approach

A consortium of two biosurfactant-producing bacteria (Bacillus pumilus KS2 and Bacillus cereus R2) was developed to remediate petroleum hydrocarbon-contaminated paddy soil. Soil samples from a heavily contaminated rice field near Assam's Lakwa oilfield were collected and placed in earthen pots for treatment. After each month of incubation, 50 g of soil from each earthen pot was collected, and the soil TPH (ppm) in each sample was determined. The extracted TPH samples were analysed by Gas chromatography-mass spectrometry (GC-MS) to confirm microbial degradation. The soil samples were examined for changes in pH, conductivity, total organic content (TOC), water holding capacity, and total nitrogen content in addition to TPH degradation. An increasing trend in TPH degradation was observed with each passing month. After six months of treatment, the sample with the lowest initial TPH concentration (1735 ppm) had the highest degradation (91.24%), while the soil with the highest amount of TPH (5780 ppm) had the lowest degradation (74.35%). A wide range of aliphatic hydrocarbons found in soil samples was degraded by the bacterial consortium. The soil samples contained eight different low- and high-molecular-weight PAHs. Some were fully mineralized, while others were significantly reduced. With the decrease in the TPH level in the polluted soil, a significant improvement in the soil's physicochemical qualities (such as pH, electrical conductivity, total organic content, and water-holding capacity) was observed.

Evaluation of the soluble fraction of B100 biodiesel and S500 diesel in seawater using Experimental Design

Biodiesel is considered a clean and renewable energy source, however it is important to know the environmental impacts caused by the water-soluble fraction (WSF) of this fuel, in the event of a spill. The objective of this research was to evaluate the seawater-soluble fraction of biodiesel (B100) compared to diesel (S500). A factorial design was used to carry out the experiments and evaluate the WSF's, varying the type of fuel and the contact time between oil and water (O/W) from 1h to 24h. The mortality rate (%) of Mysidopsis juniae and the concentration of total hydrocarbons (TPH) were used as response variables. The results obtained demonstrate that diesel showed greater toxicity, with an average mortality rate of 98.4 % and TPH concentration of 475.8 µg/L in the water-soluble fraction. On the other hand, biodiesel did not present significant toxicity in the exposure of organisms, even after 24 hours of contact, but it can still cause risks in cases of spillage (average mortality rate of 15.0%). The empirical models obtained using the experimental design methodology were able to satisfactorily estimate the TPH concentrations and the mortality rate in the WSF, with precision above 99%, with correlation coefficients (R²) of 0.9963 and 0.9970. Pure biodiesel, due to its low lethality of organisms, biodegradable and from a renewable source, is an ecologically favorable proposal as a fuel, causing less impacts in cases of spillage in seawater.

Biosolids-derived biochar enhances the bioremediation of diesel-contaminated soil

Biochar, a low-cost carbonaceous product, is gaining relevance in the remediation of hydrocarbon-contaminated soil. Current literature has shown that biochar studies have been carried out under different conditions. Although some attempts have been made to assess the effect of varying conditions in biochar-based remdediation studies, no work has assessed the effect of biochar pyrolysis temperature, biochar dose, and fertiliser dose altogether on the efficacy of biosolids-derived biochar in the remediation of diesel-contaminated soil, despite the fact that the influence of these parameters on the efficacy of the remediation process are likely to be significant. This study aimed to investigate the effect of biosolids-derived biochar on the remediation and ecotoxicity of diesel-contaminated soil, as well as to assess the influence of biochar pyrolysis temperature, biochar dose, and fertiliser addition on soil remediation. After 12 weeks, the contaminated soil amended with biochar produced at 900 °C and applied at 10% together with 1% fertiliser had a TPH concentration lower than the EPA Victoria maximum threshold for Category D waste (5000 mg/kg); in contrast, the TPH concentration in the control exceeded this threshold. Further, soil ecotoxicity at week 12 was lower in most of the biochar treatments. The alkB gene copy numbers increased at week 12 in almost all treatments. Hydrocarbon removal and soil ecotoxicity was affected by the studied factors. This study demonstrated the potential of biosolids biochar as a low-cost treatment to enhance the bioremediation of diesel-contaminated soils, while showing the importance of the treatment conditions on the biochar efficacy in remediation.

Joint Application of Biological Techniques for the Remediation of Waste Contaminated with Hydrocarbons

Cleaning the oil industry's fuel storage and management facilities generates high levels of hazardous waste. This research aims to assess the use of biological bioremediation treatments, most commonly used for decontaminating soil, by applying them to hydrocarbon-contaminated waste. Turned pile composting using food-derived sludge as a co-substrate and the necessary proportion of bulking agent enabled the bioremediation of the initial mixture via the succession of microbial populations (PLFAs), with a 70% lower TPH concentration obtained 6 months after the start of the process. Subsequent bioassays using the composted material showed survival rates of over 80% with earthworms (Eisenia andrei) and a larger decrease in TPH in the joint treatment with earthworms and plants (Pennisetum clandestinum). The composting process reduces the concentration of hazardous organic compounds, allowing for the proper development of fauna and flora in the compost by improving the biodegradation rate.Graphical

Field studies on monitoring the marine oil spill bioremediation site in Chennai

Oil spills have become a threat to the ecosystem by releasing the petroleum hydrocarbons and gained substantial public concern in the Chennai coast. This study assesses the effectiveness of bioremediation and its impact on the environment due to remedial operations in the site. Soil and water samples were collected from the bio remediation site at regular intervals of the pit from the topsoil and 20 cm below the ground level from June 2017 to Nov 2019. The average TPH concentration present in the bottom and top soil of bioremediation pit were vary in the range of 21,238.4–46,600 mg/kg and 17577–26910 mg/kg. Central Pollution Control Board (CPCB) allowable limit for TPH concentration present in the soil should be 5000 mg/kg. We have also observed that the mixing was not uniform in the pit and major amount of oil has been penetrated deep inside the soil. Results on gravimetric analysis showed that there was still a large amount of untreated long-chain hydrocarbons are there in the pit. From the results, we can conclude that nC30-nC40 and lower carbon range alkane intermediates have to be treated with additional treatment like thermal smoldering and pyrolysis.

Treatment of petroleum hydrocarbon contaminated soil by basic oxygen furnace slag activated persulfate oxidation in presence of electromagnetic induction heating

This work introduced a novel methodology for remediation of petroleum hydrocarbons (PHs) contaminated soil via basic oxygen furnace slag (BOFs) and persulfate in presence of electromagnetic induction heating. Results showed larger particle size of BOFs leaded to increase TPH removal rate when heated by electromagnetic induction. Higher TPH removal rate yielded when fine particle size of BOFs used for activation of persulfate due to Fe2+ easily released and reacted with persulfate for generation of more sulfate radical (SO4·－). Increasing the dosage of BOFs, the removal rate firstly increased then decreased due to high pH value for consumption of SO4·－. TPH removal rate increased as increasing dosage of persulfate and solution to soil ratio and decreases. Lower pH and initial TPH concentration resulted in higher removal rate, while prolonging reaction time and increasing temperature facilitated to increase TPH removal rate. In thermal/oxidation group, more SO4·－ was generated when BOFs reacted with persulfate under electromagnetic induction. Electromagnetic induction enhanced TPH removal efficiency and made oxidation and degradation reaction fast. Besides, after addition of BOFs, soil properties such as chemical and mineral composition, mechanical characteristics were improved.

The dominant microbial metabolic pathway of the petroleum hydrocarbons in the soil of shale gas field: Carbon fixation instead of CO2 emissions

In shale gas mining areas, indigenous microorganisms degrade organic pollutants such as petroleum hydrocarbons into carbon dioxide (CO2) and water (H2O) through aerobic metabolism. A large quantity of CO2 emissions will exacerbate the “Greenhouse effect”. Based on the clean sieved soil and oil-based drilling fluid in the shale gas mining area, this experiment set three concentration gradients (3523 ± 159 mg/kg, 8715 ± 820 mg/kg and 22,031 ± 1533 mg/kg) to treat the soil, and each group was disposed for the same amount of time (63 days). By analyzing the dynamic changes of microbial diversity and the abundance of key functional genes for carbon fixation, the impact of petroleum hydrocarbons on carbon fixation potential was discovered, and the natural attenuation law of petroleum hydrocarbons in contaminated soil was explored. It provided the scientific research basis of ecology for the carbon cycle, carbon allocation, and carbon fixation in microbial remediation of petroleum hydrocarbon contaminated soil. The results obtained indicated the following: i) The removal rate of petroleum hydrocarbons under high-concentration pollution (45.33 ± 3.90%) was significantly lower than low and medium-concentration pollution. The TPH concentration removal rate of each group was the largest in the early stage of culture (1-5d), and there was no significant correlation between the TPH content and the community composition (R2 = 0.0736, P > 0.05). ii) Composition and function of Carbon Fixation associated microbiota were assessed by 16S rRNA sequencing and PICRUSt (phylogenetic investigation of communities by reconstruction of unobserved states) analysis. The main carbon fixation pathway in this study is the reductive citric acid cycle, because there was no shortage of enzymes that can affect subsequent reactions.