Total Petroleum Hydrocarbon Reduction Research Articles

Enhancing the Phytoremediation of Hydrocarbon-Contaminated Soils in the Sudd Wetlands, South Sudan, Using Organic Manure

Phytoremediation of hydrocarbon-contaminated soils is a challenging process. In an effort to enhance phytoremediation, soil was artificially contaminated with known concentration of light crude oil containing Total petroleum hydrocarbon (TPH) at a concentration of 75 gkg−1 soil. The contaminated soil was subjected to phytoremediation trial using four plant species (Oryza longistaminata, Sorghum arundinaceum, Tithonia diversifolia, and Hyparrhenia rufa) plus no plant used as control for natural attenuation. These phytoremediators were amended with concentrations (0, 5 and 10 gkg−1 soil) of organic manure (cow dung). Results at 120 days after planting, showed that application of manure at concentrations of 5 and 10 gkg−1 soil combined with an efficient phytoremediator can significantly enhance reduction of TPH compared to natural attenuation or use of either manure or a phytoremediator alone (p<0.05). The study also showed that a treatment combination of manure 5 gkg−1 soil, with a phytoremediator gives a similar mean percentage reduction of TPH as manure 10 gkg−1 soil (p>0.05). Therefore, the study concludes that use of phytoremediators and manure 5 gkg−1 soil could promote the restoration of TPH contaminated-soils in the Sudd region of South Sudan.

Phytoremediation Enhancement of Kenaf Plant (Hibiscus cannabinus L.) Grown on Spent Oil Polluted Soil

Oil pollution especially Spent Lubricating Oil is a wide environmental problem in Nigeria. It constitutes potential toxic effects on soil, flora, fauna and humans and also making the environment unsightly. This study assessed the potential of kenaf plant as a phytoremediator grown in spent oil polluted soil for a period of 84 days (12 weeks). Pot experiment was conducted in the Nursery site of the Moist Forest Research Station, Forestry Research Institute of Nigeria (FRIN), Ibadan, Oyo State, Nigeria. The treatments: amended (with organic manure) and unamended (without organic manure) soils and three pollution levels (0, 3 and 6%) of spent engine oil, each filled in eight-liter plastic pots with 6 kg soil. Growth parameters: plant height, stem diameter and number of leaves were collected and Total Petroleum Hydrocarbon (TPH) in soil was determined. Data were analyzed using descriptive statistics and ANOVA. Results at 12 weeks (84 days) showed amended (control 0%) treatment having highest plant height (112.17 cm), stem diameter (8.92 cm) and number of leaves (178.43), while 6% unamended level of pollution had the lowest plant height (26.78 cm), stem height (1.62 cm) and number of leaves (8.06). Amended soil had the highest total percentage reduction of TPH (75.90, 90.05 and 90.30%), when compared with unamended soil with lowest values (76.88, 85.18 and 82.36%) at 0, 3 and 6 pollution levels, respectively. Reduction of TPH in the phytoremediation process was in this order of pollution levels 6%> 3%> 0%. This study revealed effectiveness of kenaf with organic amendment in remediating Total Petroleum Hydrocarbon in oil polluted soil, hence a good potential phytoremediator.

BIOREMEDIATION OF IN-SITU CRUDE OIL CONTAMINATED SOIL USING SELECTED ORGANIC DUNG

The potential of cow, pig and poultry dung for the bioremediation of in-situ crude oil contaminated soil for a period of 3-15 days at different soil and dung ratios were the objectives of this investigation. Using simulated soil, 200 g were measured into polyethylene bags labelled A,B,C,D,E, F and G. Soil physicochemical parameters such as particle size distribution, pH, organic carbon, organic matter, nitrogen and phosphorus were analysed using standard methods. Total Petroleum Hydrocarbon (TPH) concentrations were analyzed using spectrophotometry method at 420 nm. The concentrations of TPH decreased progressively with an increase in dung and time in the order cow dung > pig dung > poultry dung except the control soil that showed slight TPH reduction. Results also show that biostimulant efficiency (BE) increases with increase in dung and reduces with time. Results also reveal that dung with high bioremediation constant recorded a corresponding short half-life. Results show that there is a significant difference (P 0.05) in amended soil and time for poultry dung except for cow and pig dung. This study has shown that cow dung is more effective in bioremediation of TPH in crude oil contaminated soil.

Evaluation of accelerated biodegradation of oil-SPM aggregates (OSAs)

The studies of the formation of oil-Suspended Particulate Matter (SPM) aggregates (OSAs) have advanced significantly in the scientific community, however there is a need to accelerate oil biodegradation that was dispersed by the formation of OSAs. The present research presents a pioneering character regarding the addition of nutrients as biostimulus for autochthonous hydrocarboclastic bacteria in the biodegradation of Total Petroleum Hydrocarbons (TPH) dispersed by the formation of OSAs. Water aliquots were taken over 60 days from eight bioreactors to perform ionic species analysis, pH, salinity and temperature monitoring, liquid/liquid extraction, serial dilution methodology and filter membrane. TPH quantification was performed on the gas chromatograph with a flame ionisation detector (GC-FID). The addition of nutrients contributed positively to the rate and extent of biodegradation of TPH in association with field-collected SPM. The best result found was with the lowest nutrient concentration (Bio 1) with an average of 98.65% of TPH reduction.

Bio-stimulation Approach in Bioremediation of Crude Oil Contaminated Soil Using Fish Waste and Goat Manure

Aim: This study aimed to evaluate the ability of Fish waste and Goat manure to bio-stimulate the degradation process during bioremediation of crude oil-contaminated soil.
 Study Design: Research was designed to evaluate and compare the strength of the organic nutrients (Goat manure and fish waste) to stimulate the biodegradation of crude oil contaminated soil within 56 days.
 Place and Duration of Study: Study was carried out in Rivers State University Farm, Rivers state, Nigeria for 56 days from July to September 2018. Analyses were carried out weekly (per 7 days interval).
 Methodology: Eight (8) experimental set-up were employed, each having 5kg farm soil, all were left fallow for 6 days before contamination with crude oil on the 7th day in the respective percentages. Four of the set-ups were contaminated with 5% Crude oil while the other four were contaminated with 10% Crude oil. The contaminated plots were further allowed for 21 days for proper contamination and exposure to natural environmental factors to mimic a crude oil spill site before the application of bio stimulating agents (fish waste and goat manure). The set-ups of 5% Crude Oil Contaminated Soil (5% COCS) and 10% Crude Oil Contaminated Soil (10% COCS) were then stimulated with nutrient organics; Goat Manure (GM) and Fish Waste (FW) except two setups (one 5% COCS and the other 10% COCS) which were used as controls. The treatments (setups) were as follows: 5% COCS (control 1), 5% COCS + GM, 5% COCS + FW, 5% COCS + GM + FW and 10% COCS (Control 2), 10% COCS +GM, 10% COCS + FW, 10% COCS + GM + FW. Physiochemical and microbiological status of the soil before and after contamination was evaluated while parameters including Nitrate, Sulphate, Phosphate and Total Petroleum Hydrocarbon (TPH), as well as Microbial analyses, were monitored throughout the experimental period. Bioremediation efficiency was estimated from percentage (%) reduction of Total Petroleum Hydrocarbon (TPH) from day 1 to the residual concentration at day 56 of bio-stimulation setups with the control. The bio-stimulating potentials of goat manure and fish waste were compared using statistical tools.
 Results: The results revealed decrease in TPH with increasing time. The Amount (mg/kg) and Percentage (%) of Total Petroleum Hydrocarbon (TPH) remediated within the period of this study for 5% Crude Oil Contaminated Soil were as follows: 5% COCS-Ctrl 1 (563.52 mg/kg; 8.60%) < 5% COCS + GM (3608.84 mg/kg; 55.11%) < 5% COCS + FW (4156.49 mg/kg; 63.47%) < 5% COCS + GM + FW (4350.69 mg/kg; 66.44%) while 10% crude oil contaminated soil were: 10% COCS-Ctrl 2 (125.71 mg/kg; 1.21%) < 10% COCS + GM (4422.75 mg/kg; 42.82%) < 10%COCS + FW (5542.16 mg/kg; 53.66%) < 10% COCS + GM + FW (6168.66 mg/kg; 59.72%). This result shows that combination treatment with goat manure and fish wasteis more effective and has more bio-stimulating potentials than the single treatments. With respect to individual bio-stimulating agent, fish waste proves more effective and had a higher bioremediation efficiency than goat manure. The results of colonial counts obtained revealed that the total heterotrophic bacterial and total fungal counts generally increased during the study across the trend. The counts obtained from day 7 to 56 in the respective experimental set ups were as follows: Total Heterotrophic Bacteria counts increased from 6.32 to 8.20 Log10CFU/g (Control) < 6.32 to 9.05 Log10CFU/g (COCS+FW) < 6.41 to 9.13 Log10CFU/g (COCS+GM) < 6.32 to 9.58 Log10CFU/g (COCS+FW+GM). Similar progression was observed for total fungi, hydrocarbon utilizing bacteria and hydrocarbon utilizing fungi in all the experimental set ups although irregular differences were observed in the control set ups.
 Conclusion: The combination of organic nutrient such as goat manure and fish waste as bio-stimulating agents have shown to have higher percentage (%) bioremediation efficiency than when applied singly. It was also observed that the microbial biomass increased with time; moreover the nutrient monitoring analysis revealed a continuous gradual increase of the soil nutrient as bioremediation increases with time. The nutrient inherent in the bio-stimulating agents’ fish waste and goat manure resulted in increased soil nutrient (from day 7 to 56) as bioremediation period increase thereby enhancing soil nutrients at end of experiment. It is therefore recommended that bio-stimulating agents such as fish waste and goat manure should be employed in bioremediation of crude oil-contaminated soil especially due to its soil nutrient enhancement after bioremediation exercise. It’s a very good nutrient amendment option.

Innovative process for total petroleum hydrocarbons reduction on oil refinery sludge through microbubble ozonation

Oil refinery sludge is a complex mixture of hydrocarbons, water and sediments produced in the refining process, which is classified as a hazardous waste. The source reduction of sludge is inhibited by the combination of total petroleum hydrocarbons (TPH) and solid particles, and the decomposition of TPH is a critical step for oily sludge (OS) disposal. Microbubble ozonation was introduced to improve the efficiency for TPH removal in this work. 70.9% of TPH was found to be decomposed from OS with the initial pH of 3, ozone dosage of 0.27 gO3/gTS and total solid of 2% in 120 min. The corresponding reaction rate constant k for the rapid stage reached 0.0269 min−1, two times higher than the control system of macrobubble ozonation. The synergistic effect of oxidation and flotation was observed in the microbubble system by destroying the chemical bonds between petroleum hydrocarbons and particle surface and improving the adhesion probability between microbubbles and oily flocs. A broad-spectrum removal rate of 71.7–79.5% was observed for the middle or long chain hydrocarbons fractions (nC7-C10, nC11-C20, nC21-C30 and nC31-C40) in TPH. Most of heavy hydrocarbons (nC21-C40) in OS were oxidized and decomposed to the low boiling point hydrocarbons according to thermogravimetric results. The principal intermediates included 42.6% carboxylic acids, 18.8% phenolics and 13.9% alcohols and other gaseous byproducts. Microbubble ozonation is expected to be the first step for detoxification and decomposition of OS, thus reducing the generation of hazardous wastes.

Biological removal of crude oil with the use of native bacterial consortia isolated from the shorelines of the Caspian Sea

This study was aimed at investigating the possibility of biological removal of crude oil with the use of native bacterial strains, isolated from the shorelines of the Caspian Sea. For this purpose, based on the growth rate, hemolytic and emulsification activity, oil spreading assay and liquid surface tension reduction, 115 bacterial strains were isolated from seven selected stations across the shorelines of the Caspian Sea. Among them, 15 isolates were selected for further analyses. Three isolates (J3, J5 and J12) showed the highest efficiency for crude oil removal. Based on the sequence of 16S rRNA gene, the isolates were identified as Bacillus cereus (J3), Staphylococcus haemolyticus (J5) and Pseudomonas aeruginosa (J12). The results showed that isolate J3 had a better ability to degrade short (C9–C13) and medium length (C13–C25) in comparison with the long length (C32–C35) of n-alkanes in the crude oil residues. The total petroleum hydrocarbon (TPH) reduction by the B. cereus (J3) isolate was about 88.8 (mg g−1). It can be concluded that about 60% of n-alkanes in crude oil residues were removed. Also, the TPH reduction for S. haemolyticus (J5) and P. aeruginosa (J12) isolates were about 123.6 and 113.2 (mg g−1), respectively, so these strains could reduce the TPH about 55% and 50%, respectively. The TPH reduction in consortia containing B. cereus, S. haemolyticus and P. aeruginosa was about 18.3 (mg g −1), 83% of crude oil residues (1%, v/v) in 22 days.

Biodegradation of Total Petroleum Hydrocarbon by Molecularly Identified Bacteria Isolated From an Oilfield Wastewater in Nigeria

Biodegradation of petroleum hydrocarbon is a complex process that depends on the nature and on the amount of the hydrocarbon present. Many microbial organisms have been shown to possess the capacity to biodegrade various components of hydrocarbon. Hence this study was aimed at assessing the potential of bacterial species isolated from oilfield wastewater to biodegrade total petroleum hydrocarbon in crude oil. Oilfield wastewater was collected from an onshore oil production platform. Standard procedures were observed during collection and microbiological analysis of wastewater samples. Bacteria isolated were identified using conventional and molecular methods. The biodegradation set up was done using six conical flasks containing basal medium of mineral salt broth and crude oil as the source of energy for growth. Bacteria isolated were identified as Acinetobacter species, Enterobacter hormaechei, Myroides odaratimimus and Lysinibacillus species. Flasks of experimental set ups were inoculated with 1ml of individual isolate and mixed culture except the control. The biodegradation of TPH were periodically monitored for 35 days using Gas Chromatography (GC). Total viable counts (CFU/ML) obtained during the experiment ranged from 0-1.8×105, 1.65×105 - 3.2×106, 1.90×106 -1.28×107, 1.52×106 – 8.9×106, 1.13×106 – 1.48×107, 3.4×106 – 2.19×107 in control, Acinetobacter species, Enterobacter hormaechei, Myroides odaratimimus, Lysinibacillus species and the mixed culture treatment options respectively. The initial concentration of TPH at day 1 was 3241.47mg/l. At the end of the experiment (day 35), control, Acinetobacter species, Enterobacter hormaechei, Myroides odaratimimus, Lysinibacillus speccies and the mixed culture treatment options recorded final concentration of 2823.33, 363.72, 383.44, 284.55, 472.70 and 212.21mg/l respectively. Highest percentage removal of 93.5% was observed in the mixed culture while the least of 12.9% was observed in the control; individual species showed significant reduction in TPH with different capability. Results showed that bacteria isolated from oilfield wastewater have the ability to degrade total petroleum hydrocarbon (TPH) and can be used in the clean-up of crude oil contaminated area.

Self-Cleaning Nanoscale Coating for the Separation of Oil–Water Mixture

The current study pertains to the self-cleaning nanoscale coating of graphene/polymer nanohybrid system for the separation of oil–water mixture. Using a single nanohybrid system, we have developed a two-stage process for the selective removal of the hydrocarbons. Total petroleum hydrocarbons (TPHs) and separation efficiency are determined by gas chromatography-flame ionization detector (GC-FID). Analysis of the polycyclic aromatic hydrocarbons (PAHs) in the two stage samples is carried out by using gas chromatography coupled to mass spectrometry (GC-MS). The analysis shows the reduction in TPHs from 290 ppm to less than 1 ppm and more than 99.5% separation efficiency (oil removal from oil–water mixture) is achieved. No polycyclic aromatic hydrocarbons (PAHs) were detected in the treated water.

Bioremediation Efficiency of Bacillus amyloliquefaciens and Pseudomonas aeruginosa with the Nutrient Amendment on Crude Oil Polluted the Soil

Aim: To assess the Bioremediation efficiency of Bacillus amyloliquefaciens and Pseudomonas aeruginosa strain CL 9 with nutrient amendment using bio-stimulating agents such as Fish waste and Goat manure on crude oil polluted soils in Rivers State, Nigeria.
 Study Design: The study employs experimental design, statistical analysis of the data and interpretation.
 Place and Duration of Study: A portion of Rivers State University demonstration farmland in Nkpolu-Oroworukwo, Mile 3 Diobu area of Port Harcourt, Rivers State was used for this study. The piece of land is situated at Longitude 4°48’18.50’’N and Latitude 6o58’39.12’’E measuring 5.4864 m x 5.1816 m with a total area of 28.4283 m2. Bioremediation monitoring lasted for 56 days, analysis carried out weekly (per 7 days interval).
 Methodology: Seven (7) experimental plots were employed using a Randomized Block Design each having dimensions of 100 x 50 x 20 cm (Length x Breadth x Height) were formed and mapped out on agricultural soil and left fallow for 6 days before contamination on the seventh day; after which it was allowed for 21 days for proper contamination and exposure to natural environmental factors to mimic crude oil spill site. Thereafter bio stimulating agents usually referred to as nutrient amendment organics in this study (fish waste and goat manure) and bio-augmenting microorganisms were applied. Soil profile before and after contamination was assayed while parameters like Nitrate, Sulphate, Phosphate, Total Organic Carbon (TOC) and Total Petroleum Hydrocarbon (TPH), were monitored throughout the experimental period. Microbial analyses such as Total Heterotrophic Bacteria (THB), Total Heterotrophic Fungi (THF), Hydrocarbon Utilizing Bacteria (HUB) and Hydrocarbon Utilizing Fungi (HUF) were recorded. Bioremediation efficiency was estimated from percentage (%) reduction of Total Petroleum Hydrocarbon (TPH) from day 1 to the residual hydrocarbon at day 56 of bio augmented/ biostimulation plots with the control.
 Results: Results revealed amount of remediated hydrocarbon and % Bioremediation efficiency at 56 days in the different treatment plots (initial TPH contamination value of 9296.83 mg/kg) in a decreasing order as follows: PS+Bac+Pse+GF+FW (8032.825 mg/kg; 86.40%) >PS+GF+FW (6867.825 mg/kg; 73.87%) >PS+Bac+Pse (6587.825mg/kg; 70.86%) >PS+FW (6441.825mg/kg; 69.29%) >PS+GF (5909.825 mg/kg; 63.57%) >CTRL 2 (Polluted soil without amendment) (3604.825mg/kg; 38.78%). Microbiological results showed increased colonial values with increase time exposure. The results observed on day 56 indicate that Polluted soil + Bacillus + Pseudomonas (10.11 Log10 CFU/g) > Polluted soil but un-amended soil (8.76 Log10 CFU/g) > unpolluted soil (8.68 Log10 CFU/g). Comparatively, Polluted soil +Bacillus + Pseudomonas expressed higher heterotrophic bacteria of 9.77 and 9.67 Log10 CFU/g while fungal counts recorded 6.04 and 6.82 Log10 CFU/g.
 Conclusion: Study showed that bioremediation of crude oil-polluted soils with bacteria singly is less effective but a combination with other organic nutrients is a better palliative measure. Therefore, amendment with organic nutrients like Goat manure and Fish wastes is recommended for crude oil polluted soils due to its high nutrient content as substrates for biostimulation of indigenous and augmenting biodegrading microbes. This process could be a source of enhanced natural attenuation of oil-contaminated environments in Nigeria.

Bioremediation of Refinery Effluent by Consortium of Bacteria Isolated from Abattoir Waste

Aim: This research was conducted to examine the efficacy of bioremediation of refinery effluent by a consortium of bacterial organisms from abattoir waste.
 Study Design: The experimental and analytical research designs were adopted for the study.
 Place and Duration of Study: The study was conducted in a laboratory in the Department of Environmental Management and toxicology, Federal University of Petroleum Resources, Effurun, Delta State, Nigeria. The research was conducted within three months.
 Methodology: Standard methods were adopted for sample collection, microbiological analysis and determination of physicochemical properties.
 Results: Out of eight bacterial species isolated from abattoir waste, Pseudomonas, Proteus and Bacillus species recorded high hydrocarbon utilization potential. There was a significant difference between the physicochemical property of the control and the refinery effluents. The effluents had a mean Biochemical Oxygen Demand (BOD) of 19 mg/l, Dissolved Oxygen (DO) of 3 mg/l, Total Dissolved Solids (TDS) of 35 ppm, pH of 6.67, Electrical Conductivity (EC) of 71 µs/cm and temperature of 29.5°C. Samples subjected to 0 – 10 days biodegradation test by Pseudomonas, Proteus and Bacillus species recorded a mean increment in EC, reduction in pH, increase of TDS and reduction in Total Petroleum Hydrocarbon (TPH) with Proteus species being the best. The percentage of degradation by Proteus was 69.7%, Bacillus 61.56% and Pseudomonas 53.19%.
 Conclusion: The use of abattoir waste bacteria for bioremediation purposes are very safe, cost-effective and aids the environment from accumulating more burdens of unsafe compounds that render it harmful for living organisms including man.

Effect of immature and mature compost addition on petroleum contaminated soils composting: kinetics.

The kinetic studies and effect of amendment addition on the performance of the composting process in reduction of total petroleum hydrocarbons (TPH) from petroleum contaminated soils (PCS) were investigated in the present research. Seven composting experiments containing various mixing ratios of PCS to unfinished compost (UC) and finished compost (FC) were set up and operated for 14weeks. The mixing rations consisted of 1:0 (as control experiment), 1:0.3, 1:0.6, and 1:1. The initial C/N/P and moisture contents of the composting piles were adjusted to 100/5/1 and 50-55%, respectively. Results showed that 50.09-79.49% of TPH was removed in the composting experiments after 14weeks. The highest and lowest removal rates were achieved in the ratios of 1:1 and 1:0.3, respectively. Moreover, application of UC as amendments and bulking agent is more efficient than FC. The biodecomposition of TPH was fitted to the first-order kinetic with the half lives and rate constants of 5.63-11.55days and 0.060-0.123 d-1, respectively. The bacteria detected from the composting treatments were Staphylococcus sp., Bacillus sp., and Pseudomonas sp. The study confirmed the suitability of composting process for PCS bioremediation and superiority of UC than FC as bulking agent.

Bioremediation Protocols of Hydrocarbon Contamination: A Critical Appraisal of a Case Study of Soil Contamination

Soil contamination by petroleum hydrocarbons is a widespread and global environmental contamination concern that needs to be carefully treated and controlled. This research investigates, compares, and analyze the viability of bioremediation technologies for the ex situ remediation of hydrocarbon polluted soils. It also outlines the most appropriate bioremediation technique. Results showed one of the important advantages of necrophytoremediation as a remediation protocol. The degradation amount of oil in different treatments follows this sequence: pea straw (PS) > combination of pea straw and Bacillus consortium (BAPS) > Bacillus consortium (BA) > natural attenuation (NA). The same amount of “bacteria” was added into treatment BAPS and BA. Necrophytoremediation using pea straw has a positive effect on the degradation of TPH by 96% during 12 weeks of treatment; the same pattern was followed for the combination of necrophytoremediation and bioaugmentation (pea straw and Bacillus consortium) with 95% total petroleum hydrocarbons (TPH) reduction. Natural attenuation and bioaugmentation microcosms modified with Bacillus were the least practical with TPH reduction of 79% and 76% respectively. The findings from this study recommend researching the possibility of relying on in situ necrophytoremediation as a valuable, economical, and invulnerable method for enhancing the bioremediation efficiency of oil contaminated soils.

Assessment of plants for phytoremediation of hydrocarbon-contaminated soils in the Sudd Wetland of South Sudan

Hydrocarbon contaminants have become a global concern due to their long-term adverse effects on soil ecosystems and human health. Successful implementation of phytoremediation to clean up hydrocarbon contaminants requires the identification of the most effective remediation plant species. Twelve native plant species of the Sudd Wetland in South Sudan were evaluated for their potential application as phytoremediators. The treatments included six total petroleum hydrocarbon (TPH) concentrations of 0, 25, 50, 75, 100 and 125 g/kg soil. The twelve native plant species tested were: Sorghum arundinaceum Desv., Oryza longistaminata A. Chev. & Roehrich, Hyparrhenia rufa Nees, Abelmoschus ficulneus L., Gossypium barbadense L., Nicotiana tabacum L., Sorghum bicolour L. Moench, Eleusine coracana Gaertn., Capsicum frutescens L., Zea mays L., Tithonia diversifolia Hemsl. and Medicago sativa L. Significant differences in phytoremediation rates were observed amongst the treatments with exception of the 125 g/kg soil concentration of hydrocarbon that was lethal to all the plant species. Over 50% TPH reduction in the 75 g/kg soil concentration was observed in contaminated soil phytoremediation in H. rufa, G. barbadense, O. longistaminata, T. diversifolia and S. arundinaceum, making them potential phytoremediators of hydrocarbon-contaminated soil in the Sudd-Wetland of South-Sudan.

Enhanced microbial hydrocarbon biodegradation as stimulated during field-scale landfarming of crude oil-impacted soil

The study investigated microbial population dynamics and petroleum hydrocarbon degradation during 56-day landfarming bioremediation of crude oil-polluted soil at a Community in Niger Delta Nigeria. Landfarming involved the addition of fresh top soil from unpolluted soil to the polluted soil followed by periodic ploughing. Active oleophilic bacteria identified by 16S rRNA sequencing were screened with 2,6-dichlorophenol indophenol (DCPIP) redox indicator for their degradation profile. Physicochemical parameters monitored during landfarming included the extractable Total Petroleum Hydrocarbons (TPH), Polycyclic Aromatic Hydrocarbons (PAHs), pH and heavy metals. TPH was more than 9000 mg/kg which exceeded the Department of Petroleum Resources’ (DPR's) intervention value of 5000 mg/kg. Total viable counts of culturable heterotrophic and hydrocarbon utilizing bacteria in the polluted soil pre-landfarming were between 0.2 and 0.5 × 103 cfu/g. Monitoring of microbial population dynamics on days 0, 9, 18, 36 and 56 revealed an increase in hydrocarbon utilizing bacterial population from 104 up to 107 cfu/g which correlated significantly (R = 0.88; p = 0.05) with TPH reduction to below 700 mg/kg by day 56 when bioremediation experiment ended. Pseudomonas aeruginosa was the most efficient diesel degrader which showed 100% DCPIP decolourization. Acinetobacter, Myroides, Pseudomonas and Bacillus were central in the degradation of the long chain hydrocarbon fraction in the spill site. The fungal classes recovered included Eurotiomycetes, Saccharomycetes and Sordariomycetes. The findings from this study showed that the addition of virgin top soil to a compromised and chemically stressed soil is a green and eco-friendly strategy for enriching microbial degradative activities without addition of chemical fertilizers.

Metagenomic Insights into the Bacterial Functions of a Diesel-Degrading Consortium for the Rhizoremediation of Diesel-Polluted Soil.

Diesel is a complex pollutant composed of a mixture of aliphatic and aromatic hydrocarbons. Because of this complexity, diesel bioremediation requires multiple microorganisms, which harbor the catabolic pathways to degrade the mixture. By enrichment cultivation of rhizospheric soil from a diesel-polluted site, we have isolated a bacterial consortium that can grow aerobically with diesel and different alkanes and polycyclic aromatic hydrocarbons (PAHs) as the sole carbon and energy source. Microbiome diversity analyses based on 16S rRNA gene showed that the diesel-degrading consortium consists of 76 amplicon sequence variants (ASVs) and it is dominated by Pseudomonas, Aquabacterium, Chryseobacterium, and Sphingomonadaceae. Changes in microbiome composition were observed when growing on specific hydrocarbons, reflecting that different populations degrade different hydrocarbons. Shotgun metagenome sequence analysis of the consortium growing on diesel has identified redundant genes encoding enzymes implicated in the initial oxidation of alkanes (AlkB, LadA, CYP450) and a variety of hydroxylating and ring-cleavage dioxygenases involved in aromatic and polyaromatic hydrocarbon degradation. The phylogenetic assignment of these enzymes to specific genera allowed us to model the role of specific populations in the diesel-degrading consortium. Rhizoremediation of diesel-polluted soil microcosms using the consortium, resulted in an important enhancement in the reduction of total petroleum hydrocarbons (TPHs), making it suited for rhizoremediation applications.

Suspended particles enhance biodegradation of oil in sea

Biodegradation patterns of oil in four distinct phases were compared over a 14-day series of exposures. The dispersibility and stability of oil droplets in the water column were important factors affecting oil biodegradation. Due to the stability of oil droplets with particle interactions, oil-suspended particulate matter aggregates (OSA) showed a five-fold enhancement in biodegradation compared to non-dispersed oil. The reduction of total petroleum hydrocarbons was highest in OSA (51.45%), followed by chemically dispersed oil (33.5%), oil film (21.6%), and water-accommodated fractions (WAF, 14.3%). Polycyclic aromatic hydrocarbon (PAH) profiles and percentage weathering plots showed that reductions in PAHs in WAF, oil film, and chemically dispersed oil were mainly due to evaporation (41.5–69.5%) and only partially due to biodegradation (7.4–16.3%). However, the reduction of PAHs in OSA was driven more by biodegradation (36.8%) than evaporation (29.7%). The strong PAH–particle interactions in OSA inhibited evaporation of PAHs and enhanced microorganism biodegradation in the water column.

Remediation of hydrocarbons contaminated groundwater by silica encapsulation technique

Silica encapsulation technique was investigated for effectiveness as a green remediation technology for the cleanup and restoration of hydrocarbons contaminated groundwater. Optimum conditions of pH, contact time, and the concentration of the treatment solution for each of the contaminants were known. After testing different kinetics models, the pseudo-first-order kinetics gave the best result in each case with the regression coefficient in the range of 0.9964–0.9988. Rate constants of 2.56 × 102, 2.70 × 102 and 1.23 × 102 mg−1 L h−1 were obtained from the kinetics plots for crude oil, diesel and domestic purpose kerosene in that order. The 82.34%, 86.24% and 97.58% reduction in chemical oxygen demand (COD) for crude oil, diesel and domestic purpose kerosene contaminated samples respectively at the end of the residence time of 144 h depicts that remediation occurs significantly. Percentage reduction in total petroleum hydrocarbon was in the range of 51.97–90.68%. The material data sheet of the reagents used indicates low toxicity. The encapsulated hydrocarbon in the silica coating is stable even in extreme acidic and basic states. At the end of the remediation only dissolved oxygen, biochemical oxygen demand, nitrates and ammonia as physicochemical parameters were within the safe permissible levels set by the Federal Minstry of Environment, Guideline and Standards for Environmental Pollution Control in Nigeria while others were not and therefore the need for post-treatment in order to make the treated contaminated groundwater safe for drinking and agricultural use.

Optimization of nutrients requirements for bioremediation of spent-engine oil contaminated soils

This paper presents a preliminary investigation of the optimum nutrients combination required for bioremediation of spent-engine oil contaminated soil using Box-Behnken-Design. Three levels of cow-manure, poultry-manure and inorganic nitrogen-phosphorus-potassium (NPK) fertilizer were used as independent biostimulants variables; while reduction in total petroleum hydrocarbon (TPH) and total soil porosity (TSP) response as dependent variables were monitored under 6-week incubation. Ex-situ data generated in assessing the degree of biodegradation in the soil were used to develop second-order quadratic regression models for both TPH and TSP. The two models were found to be highly significant and good predictors of the response fate of TPH-removal and TSP-improvement, as indicated by their coefficients of determination: R2= 0.9982 and R2= 1.000 at p≤ 0.05, respectively. Validation of the models showed that there was no significant difference between the predicted and observed values of TPH-removal and TSP-improvement. Using numerical technique, the optimum values of the biostimulants required to achieve a predicted maximum TPH-removal and TSP-improvement of 67.20 and 53.42%-dry-weight per kg of the contaminated soil were as follows: cow-manure–125.0 g, poultry-manure–100.0 g and NPK-fertilizer–10.5 g. The observed values at this optimum point were 66.92 and 52.65%-dry-weight as TPH-removal and TSP-improvement, respectively

Potential of Alfalfa for Use in Phytoremediation of Soil Polluted with Total Petroleum Hydrocarbons

Remediation technology is a promising technique decrease pollutant like hydrocarbons from the environment. An experimental work was made at green house of University of Technology in order to study the effect of crude oil on the vegetate growth and to measure the decrement which happened on shoot height, germination rate and the reduction of total petroleum hydrocarbon (TPH), which result, by this phytoremediation technique. The samples of soil were measured for TPH reduction and removal by Horiba model (oil content analyzer) OCMA–350. Five doses were used in this experiment (0 control, 10x103, 30 x103, 50 x103, 75 x103) (mg crude oil / kg soil). The polluted soil used in this study appeared to be a harmful environment for alfalfa plants, leading to serious adverse effects on alfalfa germination and growth. Seed germination is known to be a sensitive process affected by environmental factors like the presence of soil pollutants.