Total Petroleum Hydrocarbon Reduction Research Articles

Remediation of crude oil polluted soil using a combination of macerated cobs of <i>Zea mays</i> and <i>Pleurotus ostreatus</i>

This study evaluated the bio-absorptive potentials of Pleurotus ostreatus and macerated cobs of Zea mays in the remediation of crude oil polluted soil. Crude oil contaminated soil was collected from B-Dere community located in Gokana L.G.A, Rivers State and analyzed for physicochemical, Total petroleum hydrocarbon (TPH) Polycyclic aromatic hydrocarbons (PAHs) and heavy metal. The crude oil polluted soil sample was divided into five parts of 2,000 g each with the following quantity of macerated cobs of Zea mays, P. ostreatus and triton x- 00 added and labeled thus: a) Polluted soil without treatment – cell A (control sample), b) 20ml of triton x-100 - cell B, c) 150 g of macerated cob of Zea mays – cell C, d) 150 g of P. ostreatus – cell D and e) 100 g of macerated cobs of Zea mays and P. ostreatus(i.e. 50 g each) – cell E.Soil samples were collected six (6) weeks after treatment with macerated cobs of Zea mays and P. ostreatus and incubated in sterile plastic bags and transferred to the laboratory for physicochemical, TPH, PAHs and heavy metal analyses. There were significant changes in the mean physico-chemical parameters before remediation (i.e., week 0) and remediation. After 6 weeks of remediation, TPH and PAHs concentration across all the cells were significantly (p< 0.05) reduced. The remediation process led to a notable reduction in TPH, PAHs and heavy metal concentrations suggesting its effectiveness in removal of these toxicants. Thus, the combination method is more effective and can enhance bioremediation process as well as solve the problem of waste management and utilization.

Costus speciosus (Koen ex. Retz.) Sm.: a suitable plant species for remediation of crude oil and mercury-contaminated soil.

The aim of this study was to evaluate the efficiency of Costus speciosus (Koen ex. Retz.) Sm. in the degradation of crude oil and reduction of mercury (Hg) from the contaminated soil in pot experiments in the net house for 180days. C. speciosus was transplanted in soil containing 19150mgkg-1 crude oil and 3.2mgkg-1 Hg. The study includes the evaluation of plant biomass, height, root length, total petroleum hydrocarbon (TPH) degradation, and Hg reduction in soil, TPH, and Hg accumulation in plants grown in fertilized and unfertilized pots, chlorophyll production, and rhizospheric most probable number (MPN) at 60-day interval. The average biomass production and heights of C. speciosus in contaminated treatments were significantly (p < 0.05) lower compared to the unvegetated control. Plants grown in contaminated soil showed relatively reduced root surface area compared to the uncontaminated treatments. TPH degradation in planted fertilized, unplanted, and planted unfertilized pot was 63%, 0.8%, and 38%, respectively. However, compared to unvegetated treatments, TPH degradation was significantly higher (p < 0.05) in vegetated treatments. A comparison of fertilized and unfertilized soils showed that TPH accumulation in plant roots and shoots was relatively higher in fertilized soils. Hg degradation in soil was significantly (p < 0.05) more in planted treatment compared to unplanted treatments. The fertilized soil showed relatively more Hg degradation in soil and its accumulation in roots and shoots of plants in comparison to unfertilized soil. MPN in treatments with plants was significantly greater (p < 0.05) than without plants. The plant's ability to produce biomass, chlorophyll, break down crude oil, reduce Hg levels in soil, and accumulate TPH and Hg in roots and shoots of the plant all point to the possibility of using this plant to remove TPH and Hg from soil.

Laccase-mediated degradation of petroleum hydrocarbons in historically contaminated soil

Laccases (EC1.10.3.2) have attracted growing attention in bioremediation research due to their high reactivity and substrate versatility. In this study, three genes for potential novel laccases were identified in an enrichment culture from contaminated field soil and recombinantly expressed in E. coli. Two of them, designated as PlL and BaL, were biochemically characterized regarding their optimal pH and temperature, kinetic parameters, and substrate versatility. In addition, lacasse PlL from Parvibaculum lavamentivorans was tested on historically contaminated soil. Treatment with PlL led to a significantly higher reduction of total petroleum hydrocarbons (83% w/w) compared to the microbial control (74% w/w). Hereby, PlL was especially effective in degrading hydrocarbons > C17. Their residual concentration was by 43% w/w lower than in the microbial treatment. In comparison to the laccase from Myceliophthora thermophila (MtL), PlL treatment was not significantly different for the fraction > C17 but resulted in a 30% (w/w) lower residual concentration for hydrocarbons < C18. In general, PlL can promote the degradation of petroleum hydrocarbons. As a consequence, it can be applied to reduce remediation time by duly achieving remediation target concentrations needed for site closure.

Demonstration of a scalable process for remediation of petroleum-impacted soil using electron beam irradiation

Petroleum-impacted soils pose several hazards and require fast, effective, and versatile remediation techniques. Electron beam irradiation provides a novel means of heating soil and inducing non-equilibrium chemical reactions and has previously been applied to environmental remediation. In this work a scalable process for remediation of petroleum-impacted soils using a 100 kW, 3 MeV industrial electron beam is investigated. The process involves conveying impacted soil through a beam at a controllable rate to achieve a desired dose of approximately 1000 kGy. Reductions to less than 1% Total Petroleum Hydrocarbon (TPH) content from an initial TPH of 3.3% were demonstrated for doses of 710–1370 kGy. These reductions were achieved in in conditions equivalent to 4 m3 per hour, demonstrating the applicability of this technique to remediation sites. TPH reduction appeared to be temperature-dependent but not heavily dependent on dose rate, with reductions of 96% achieved for a dose of 1370 kGy and peak temperature of 540 °C. The performance of the process at high dose rates suggests that it can be incorporated into remediation of sites for which a high rate of material processing is required with a relatively small device footprint.

The effect of temperature curing on total petroleum hydrocarbon (TPH) values of slag-based polluted sample leachate

Alkaline activation is noteworthy in manufacturing due to its environmental implications since it enables the use of waste materials containing amorphous SiO2 and Al2O3 as initial components. Herein, stabilization/solidification (S/S) using the alkaline activation of granulated blast furnace slag (GBFS) was used to reduce the total petroleum hydrocarbon (TPH) of the crude oil-polluted sample leachate. By producing cementitious products and reducing the pore spaces of the oil-contaminated soil, the alkaline activation of slag created a dense structure and significantly lowered TPH. By raising the curing temperature, the TPH reduction intensity increased and reached > 60 %. Besides helping the circular economy by extracting high-quality resources from waste, this method controls oil pollution spread and decreases environmental pollution as it replaces cement and lime.

Reduction of hydrocarbon pollutants by hyacinth plants (Eichhornia crassipes)

Background: The application of phytoremediation by utilizing plants has been used to control oil pollution in waters. One of the plants that can act as a phytoremediator is the hyacinth because this plant can reduce various pollutants including petroleum hydrocarbons. This study aims to study the reduction ability of petroleum hydrocarbons at different concentrations including improving water quality. Methods: This research used an experimental method implementing a Completely Randomized Design (CRD) with one factor, namely TPH concentration with five treatment levels and three replications. The treatments were as follows E1 (10 mg/L), E2 (30 mg/L), E3 (50 mg/L), E4 (70 mg/L), and E5 (90 mg/L), and E0 (control) was carried out only at the highest concentration (90 mg/L), aiming to see whether there was a TPH reduction process without plants. Maintenance of water hyacinth was carried out in media with salinity (3 ppt). Observations were made for 14 days, with measurements of TPH and leaf chlorophyll content observed at D-1, D-7 and D-14. While water quality parameters such as temperature, pH and dissolved oxygen were observed every 2 days Results: The results showed that the hyacinth plant was able to reduce hydrocarbon in terms of total petroleum hydrocarbon (TPH) by 79% while it was only between 17–27% naturally without the hyacinth. The reduction of TPH in the water was in line with the decrease of chlorophyll in the leaves of hyacinths, and it was followed by the increase of dissolved oxygen in the water media. Conclusions: In conclusion, hyacinths can reduce petroleum hydrocarbons and they can improve the water quality as well. Futhermore, water hyacinth which are commonly found in freshwater can be used as phytoremediatiors in coastal area; its application in coastal areas requires futher study

Electron beam remediation of soils impacted with heavy hydrocarbons

During electron beam (EBeam) irradiation, high-energy electrons can generate physical and chemical changes in a substance such as chain scission and cross-linking. Irradiation of soil is shown to be an effective technology for rapid reduction of Total Petroleum Hydrocarbons (TPH) in crude oil impacted soils. An experimental apparatus for batch treatment of 100 g soil samples was built and tested using a 10 MeV, 15 kW electron beam. The samples were a variety of crude oil impacted soil samples with TPH contents ranging between 1.6 and 32% by mass. Soils of initial TPH up to 9.1% (dry weight basis) TPH levels were reduced to below a target cleanup level of 1% with irradiation doses ranging from 700 kJ/kg to 1100 kJ/kg and treatment times less than 200 s, with maximum soil temperatures less than 450 °C. Soils with elevated moisture content required higher dosages or preliminary drying. EBeam treatments resulted in 1) reduction for both light and heavy hydrocarbon, 2) generation of new light hydrocarbons, and 3) generation of fixed carbon, indicating that the mechanisms of electron beam remediation include radical induced reactions at relatively low temperature and relatively short time scales and not simply thermal desorption effects.

Reduction of hydrocarbon pollutants by hyacinth plants (Eichhornia crassipes)

Background: The application of phytoremediation by utilizing plants has been used to control oil pollution in waters. One of the plants that can act as a phytoremediator is the hyacinth because this plant can reduce various pollutants including petroleum hydrocarbons. This study aims to study the reduction ability of petroleum hydrocarbons at different concentrations including improving water quality. Methods: This study consisted of one treatment (petroleum hydrocarbon) consisting of five factors with three replicates. The treatments consisted of 10 ppm (E1), 30 ppm (E2), 50 ppm (E3), 70 ppm (E4), 90 ppm (E5), and (E0) without aquatic plants as controls. The treatments were observed daily and measured from the first day (D-1), the seventh day (D-7), and the 14th day (D-14). The water quality in each treatment was also measured, such as water temperature, pH, and dissolved oxygen. Results: The results showed that the hyacinth plant was able to reduce hydrocarbon in terms of total petroleum hydrocarbon (TPH) by 79% while it was only between 17–27% naturally without the hyacinth. The reduction of TPH in the water was in line with the decrease of chlorophyll in the leaves of hyacinths, and it was followed by the increase of dissolved oxygen in the water media. Conclusions: In conclusion, hyacinths can reduce petroleum hydrocarbons and they can improve the water quality as well.

Biostimulation of Petroleum-Contaminated Soils with Synthetic and Natural Sources of NPK Fertilizer

ABSTRACT Soil contamination with petroleum hydrocarbons has imposed drastic damages to plant, animal, and human life, leading to the development of various remediation technologies. However, the implementation of these methods is often difficult or requires a long time. In this study, the performance of synthetic (salts) and natural (sawdust, cow manure, and hen manure) sources of nitrogen:phosphorus:potassium (NPK) fertilizer was compared in the biostimulation of petroleum-contaminated soil, by measuring the total petroleum hydrocarbon (TPH) reduction after 28 days, via gas chromatography (GC). Four types of isolates with the potential for hydrocarbon degradation were identified and characterized based on morphological and biochemical tests. The results showed more efficiency of natural sources compared to synthetic sources, as a TPH reduction of 84.4, 81.9, and 79.7% was obtained by adding 4 wt.% of hen manure, cow manure, and sawdust, respectively. The analysis of variance (ANOVA) of the designed experiment for the synthetic sources showed the NPK of 1275:497:112 as the optimum ratio and the N and K as the most effective elements. The finding of this study can pave a way for proving the high efficiency of natural waste materials as a cost-effective and simple method, for bioremediation of petroleum hydrocarbon soils.

OPTIMIZATION OF BIOSTIMULANTS REQUIREMENTS FOR ENHANCED BIOREMEDIATION OF CRUDE OIL SLUDGE POLLUTED SOILS

The study was aimed at investigating the optimal requirement of biostimulants in the bioremediation of crude oil sludge polluted soils. The contaminated environment was simulatedwith 1.0kg crude oil sludge on 2.0kg soil and uniformly homogenized. The polluted soils were then simulated with NPK, Cowdung and Moringaleaf powder based on total biostimulant to soil ratio of 0:1 to 0.75:1. These biostimulants were applied individually and in varying combinations to the polluted soils in three distinct segments (1, 2, 3) corresponding to the total biostimulant to soil ratios 0.25:1, 0.50:1 and 0.75:1 respectively while the control experiment which proceeded on natural attenuation was 0:1. Results of the experiments which lasted for 92 days showed marked reduction in Total Petroleum Hydrocarbon (TPH) content in the biostimulated experiments, E1 to E30. The control experiment, E31, which was non-biostimulated showed minimal reduction in TPH throughout the experiment due to the absence of added nutrients. In the single biostimulant application, moringa leaf powder (MLP) was found to give the best degradative performance at an optimal biostimulant to soil ratio of 2.04:1corresponding to 99.9957% bioremediation of the polluted soil being investigated. This result justifies the introduction of MLP as a suitable biostimulant for bioremediation studies and a possible substitute for NPK which is very expensive and not readily available for use. In the double biostimulant combination category, NPK + mlp mixing resulted in the best degradation efficiency. The optimum extent of degradation was 100% at optimum biostimulant to soil ratio of 2.04:1. The optimum extent of remediation for combination of all three biostimulants (NPK + CD + MLP) were found to be 99.15% at optimal biostimulant to soil ratio of 2.04:1.

Assessing Earthworm Influence on Remediating Potentials of Soil Micro-Organisms, and Bioavailable Hydrocarbon Pollutant in the Niger Delta, Nigeria

In the Niger Delta region of Nigeria, oil explorations and exploitations abound, causing environmental pollution with serious consequences on soil ecosystem and its biodiversity. In spite of the relationship between microbes and fauna in soil ecosystem, such that both organisms can metabolize certain range of petroleum hydrocarbon substrates with the fauna influencing the remediation potentials of bacteria, yet soil fauna is still not fully considered in bioremediation. The influence of earthworm; Lumbricus terrestris on the remediating potentials of soil bacteria in petroleum hydrocarbon contaminated soils was investigated. Eighteen pots were filled with 700 g of soil each, with nine treated with mixture of 3 levels crude oil and remediated with earthworm, while the other nine had no earthworm. The total petroleum hydrocarbon (TPH), soil physical, nutrient compositions, and TPH degrading bacteria biodiversity were determined before contamination or commencement of study and thirty days after. The results showed a decrease in TPH concentration of 55.58%, 62.57% and 67.07% in 1 ml, 2 ml and 3 ml crude oil contaminated soil, respectively. Species richness and abundance of bacteria organisms increased with high relative abundance in soils remediated with earthworms, hydrocarbon utilizing bacteria increased from less than 0.1 cfu/g to 0.4 cfu/g, and total heterotrophic bacteria 1.6 cfu/g at the end of the study. Earthworms increased rate of remediation potentials of bacteria, such that within 30 days post remediation treatment, 34.14% of reduced concentration was achieved over soil samples without earthworms at 3 ml, and 25.14% at 2 ml concentration. Reduction in pH levels in remediated soils was between 6.39 to 6.17 and 6.74 to 6.72 in unremediated soils, while moisture content was 6.73% to 6.77% unremediated and 5.85% to 6.62% in earthworm remediated soils. Total organic carbon, nitrates in soils inoculated with earthworms were lower in concentration than those without earthworms. Reverse was the case with potassium, phosphate and phosphorous concentrations which were above those without earthworms. Results indicate statistically, significant difference between reduction in TPH in earthworm remediated soils and unremediated soils, pointing out that earthworm is a good candidate for facilitation of bacteria remediation-petroleum hydrocarbon contamination.

Emergence of hydrocarbon-degrading bacteria in crude oil-contaminated soil in a hyperarid ecosystem: Effect of phosphate addition and augmentation with nitrogen-fixing cyanobacteria on oil bioremediation

Hyperarid hot deserts impose limiting conditions for microbial activity, thus delaying crude oil biodegradation resulting from accidental spills. This study examined the emergence of oil-degrading bacterial species in the soil of a hyperarid area in the southern Negev desert, Israel, which was exposed to a major oil spill. Amplicon sequencing of the 16S rRNA gene showed dominance of the phyla Proteobacteria and Actinobacteria in both contaminated and control soils. Significant differences were seen in the abundance of the phylum Firmicutes. Classes Actinobacteria, Gammaproteobacteria and Bacilli dominated the oil-contaminated soil. Bacterial species capable of degrading aromatic and aliphatic oil constituents were isolated from the contaminated soil. Contaminated soil microcosms were amended separately with nitrogen, phosphorus, or nitrogen-fixing cyanobacteria (NFC) biomass; the highest reduction in total petroleum hydrocarbons was observed in the phosphorus-supplemented soil. The abundance of alkB gene, encoding alkane monooxygenase, increased significantly in the control, NFC and phosphate treatments, but not in the nitrogen treatment. However, nahA abundance (coding for naphthalene dioxygenase) was only considerably increased with the phosphorus amendment. While nitrogen amendment via NFC bioaugmentation is a sustainable and novel biostimulation method, phosphorus amendment significantly accelerates the biodegradation of crude oil under extremely arid conditions.

Predicting selected kinetic parameters of hydrocarbon interactions with alum-based water treatment residuals

Kinetic parameters of hydrocarbon interactions with alum-based water treatment residuals (WTR) in the biostimulation of crude oil-polluted soil are very important because they reveal how long the WTR bind with the hydrocarbon to control its fate and transport in the soil. In this study, we used Michaelis-Menten biokinetic model to determine two important kinetic parameters, the maximum specific rate constant (μmax) and Michaelis-Menten constant (Km), as well as total petroleum hydrocarbon (TPH) degradation rate equation in the biostimulation of crude oil-polluted Niger Delta Oxisols using WTR synthesized from local fishpond effluents. Using the completely randomized design, the experimental setup consisted of 6-duplicate reactors including the control (labelled A to F) containing mixtures of soil, crude oil, and WTR in the ratios of 4:1:0, 4:1:1, 4:1:1.5, 4:1:2, 4:1:2.5, and 4:1:3, respectively. Treatment lasted for 70 days and TPH concentration was determined by gas chromatography-mass spectrometry (GC-MS). Results showed that a rounded average of 51% TPH reduction was achieved after 70 days of treatment. The rounded average of μmax was 0.5 mg/kg-day and Km was 270 mg/kg, while the TPH degradation rate equation was deduced as r=−0.5S/(270+S) at any TPH concentration, S. With an average root-mean-square error of 4.998 mg/kg, residual prediction deviation of 18.08, and corresponding validation r2 of over 99%, the model prediction was categorized as excellent with an error of only 1%. This shows the potential of the model to predict TPH in the biostimulation of crude oil-polluted Niger Delta Oxisols with alum-based WTR.

Effect of bacterial co-culture and organic amendments on the bioremediation of hydrocarbons in a soil contaminated with spent engine oil

Bioenhancement of hydrocarbonoclastic microorganisms with suitable nutrients has a huge impact in achieving positive bioremediation of polluted environments. This study was conducted to assess the bio-enhancing effect of some organic amendments on Streptococcus pyogenes and Enterococcus faecalis co-culture with a view to remediating spent engine oil (SEO) contaminated soil. Top soil (1.5 kg) was autoclaved and thereafter contaminated with SEO at three levels. The contaminated soil was inoculated with bacterial co-culture (150 mL) and subsequently bioenhanced with compost, processed cocoa pod husk (CPH) and cow dung. The factorial experiment was laid out in completely randomized design. Concentrations of total petroleum hydrocarbon (TPH) and selected polycyclic aromatic hydrocarbons (PAH) were estimated on the first day, 5th week and 10th week of incubation. Results obtained show that bacterial co-culture bioenhanced with compost produced the most significant TPH reductions (1318 and 261 mg kg-1) on 10% SEO contaminated soil at the 5th and 10th week respectively (p&lt;0.05). Again, bacterial co-culture bioenhanced with compost produced the most significant PAH reductions (65.9 and 55.8 mg kg-1) on 10% SEO contaminated soil at the 5th and 10th week respectively (p&lt;0.05). The significant bioremediation capabilities exhibited by the bacterial co-culture bioenhanced with organic amendments in this study has made these bioremediation agents potential candidates in remediating soils impacted with petroleum hydrocarbons.

Porcellio scaber Latr. and Lumbricus terrestris L.—PAHs Content and Remediation of Long-Term Aging Soil Contamination with Petroleum Products during a Single- and Two-Species Experiment

The presence of earthworms in soil contaminated with petroleum products (PPs) increase the rate of decomposition. The use of more than one animal species simultaneously in soil remediation could accelerate the process. However, the effects may be different when long-term aging soil contamination exists during which toxic by-products can be formed. This study evaluated the effect of soil contamination with PPs (petrol, diesel fuel, and used engine oil) carried out 12 and 24 months earlier on the life parameters of Lumbricus terrestris L. during single- and dual-species breeding with Porcellio scaber Latr. The changes in the content of total petroleum hydrocarbons (TPH) in the soil were also measured, as were the levels of polycyclic aromatic hydrocarbon (PAH) accumulation in the bodies of the test animals. Survival of earthworms cultivated separately (single-species experiment) in soil contaminated with diesel fuel 12 months earlier significantly decreased, while body mass gain was not significantly changed under the influence of tested PPs. Breeding of L. terrestris together with P. scaber contributed to significant mortality of earthworms regardless of treatments, while woodlice showed much greater resistance to PPs. Occurrence of both animals in soil contaminated with engine oil 24 months earlier resulted in a significant reduction in TPH after 4 weeks (by 29% compared to the initial soil). The content of PAHs in the tissues of L. terrestris was higher than in P. scaber, and the highest amounts of PAHs were found when earthworms were exposed to engine oil. Use of L. terrestris together with P. scaber can be considered a promising scenario for increasing the effectiveness of remediation of soils contaminated with petroleum products, however, further research is needed to establish conditions preventing excessive mortality of earthworms in such a layout.

Ex-situ bioremediation of petroleum hydrocarbon contaminated soil using mixed stimulants: Response and dynamics of bacterial community and phytotoxicity

Pollution of agricultural soils by excessive petroleum hydrocarbons (PHs) has recently become a severe worldwide environmental issue. Various approaches have been recently employed to biodegrade PHs and detoxify soils. In the present study, an experimental mesocosm was developed in a bioslurry reactor. Six treatments were applied to degrade PHs-and detoxify contaminated soil by adding external stimulants such as nutrients, activated sludge, synthetic surfactant, and long-chain rhamnolipids. The comparative analysis revealed that the combination of activated sludge, nutrients, and biosurfactant showed a 79.4% reduction in TPHs after 10 days in the mesocosm experiment. The lowest reduction in total PHs (48.5 %) was attained in the nutrient-supplied mesocosms. The consortia’s kinetic analyses of PHs revealed the lowest half-life time (t1/2 = 4.1 days), the highest biodegradation rate constants (k = 0.17 day1), and the reaction rate data from each bioremediation method was fitted with a first-order reaction rate model. The 16S rRNA gene amplicon and sequencing revealed that Streptomyces, Nocardioides, Arthrobacter, Pseudomonas, and Bacillus were the main oxidative species as PHs degraders. The highest relative abundances were in Arthrobacter, Pseudomonas, and Bacillus. The phytotoxicity studies proved that there was a significant decrease in the toxicity of soil after the biotreatment. According to the findings of this study, adding external stimulants such as activated sludge, nutrients, and biosurfactants enhanced the degradation of PHs in the soil in bioslurry enhancement as a promising approach to pilot scale.

Petroleum hydrocarbons reduction by selected tropical grass species in oil-based drill cuttings contaminated soil

The potential of phytoremediation of oil-based drill cuttings (OBDCs) contaminated soil was assessed by measuring the level of petroleum hydrocarbons reduction. The contamination experiment was simulated in a randomized complete block design by factorial of 6 × 3 × 2 × 2 for grass species (Pennisitum purpureum, Panicum maximum, Andropogon gayanus, Heteropogon contortus, Axonopus compressus, and Chloris virgata), drill cuttings treatments (0%, 25%, and 50% OBDCs contamination), time (0 day of planting and 105 days of harvesting), and growth stage (young and mature). The parameters assessed were total petroleum hydrocarbons (TPHs) in soils, roots, and shoots; bioconcentration factor in roots and shoots; and translocation factor. The TPH reductions achieved in 25% treatment level were young A. compressus (58.01%), mature P. purpureum, young A. gayanus and C. virgata (44.24%), young P. purpureum (27.67%), mature A. compressus (25.29%), mature H. contortus (2.56%), mature P. maximum (4.01%), and unplanted soils (2.10%). Thus young A. compressus, A. gayanus, C. virgata, and mature P. purpureum are recommended for TPH reduction in 25% OBDCs contaminated soils. Young P. purpureum and mature A. compressus can be used to achieve 25% − 27% TPH reduction.

REVITALIZING GROUNDWATER AND HYDROCARBON IMPACTED SOIL USING INSITU/EXSITU REMEDIATION TECHNIQUES IN OMKPOBU, RIVERS STATE, NIGERIA

With all the numerous spills all across Niger Delta ranging from various sources it become imperative for the remediation of the impacted areas. Remediation is means or a process by which an impacted area contaminated by crude oil is restored. Bioremediation could be view from two perspectives which includes Insitu and Exsitu strategies. Both strategies are primarily aimed at removing the contaminants from soil and ground water. While the Insitu strategy address contamination issues in the subsurface the Exsitu strategy address contamination at the surface. Typical examples of the insitu strategies includes Biosparging, Bioventing while that exsitu includes the deployment of landfarming strategies and Biopiling. This research deployed both insitu and exsitu remediation strategy. Specifically, Landfarming as an exsitu remediation techniques was used to address the soil component of the research work. While biosparging remediation strategy was deployed to address contamination within the groundwater. Biosparging and land farming techniques have shown that remediation, especially in terms of groundwater, can be done faster when there are used together. The Exhumed impacted soil was made to undergo steps associated with landfarming techniques. Contaminated soil were exhumed and spread over a prepared bed area for aeration or oxygenation. The spread soil was frequently tilled before there were used to construct windrows to aid the aeration process. The total petroleum hydrocarbons of land farmed soil were drastically reduced before they were returned. These is in line with the view of International Centre for Soil and Contaminated Sites (2006) that ‘’Effective remediation through landfarming will increase microbial activities that will eventually address contamination on soil. Similarly, the impacted ground water also felt the impact of this action and with addition of the sparging operations there were also reduction in the Total Petroleum Hydrocarbon level in the groundwater over the period of the project. The operations of biosparging do not only influence the reduction of Total Petroleum Hydrocarbon (TPH) in the groundwater but also other contaminants of concerns such as benzene.

Evaluation of the Effectiveness of the Biopreparation in Combination with the Polymer γ-PGA for the Biodegradation of Petroleum Contaminants in Soil.

Biodegradation is a method of effectively removing petroleum hydrocarbons from the natural environment. This research focuses on the biodegradation of aliphatic hydrocarbons, monoaromatic hydrocarbons such as benzene, toluene, ethylbenzene, and all three xylene isomers (BTEX) and polycyclic aromatic hydrocarbons (PAHs) as a result of soil inoculation with a biopreparation A1 based on autochthonous microorganisms and a biopreparation A1 with the addition of γ-PGA. The research used biopreparation A1 made of the following strains: Dietzia sp. IN133, Gordonia sp. IN138 Mycolicibacterium frederiksbergense IN53, Rhodococcus erythropolis IN119, Rhodococcus sp. IN136 and Pseudomonas sp. IN132. The experiments were carried out in laboratory conditions (microbiological tests, respirometric tests, and in semi-technical conditions (ex-situ prism method). The biodegradation efficiency was assessed on the basis of respirometric tests, chromatographic analyses and toxicological tests. As a result of inoculation of AB soil with the biopreparation A1 within 6 months, a reduction of total petroleum hydrocarbons (TPH) (66.03%), BTEX (80.08%) and PAHs (38.86%) was achieved and its toxicity was reduced. Inoculation of AB soil with the biopreparation A1 with the addition of γ-PGA reduced the concentration of TPH, BTEX and PAHs by 79.21%, 90.19%, and 51.18%, respectively, and reduced its toxicity. The conducted research has shown that the addition of γ-PGA affects the efficiency of the biodegradation process of petroleum pollutants, increasing the degree of TPH biodegradation by 13.18%, BTEX by 10.11% and PAHs by 12.32% compared to pure biopreparation A1.

Enhanced degradation of hydrocarbons in constructed wetlands aided with nutrients, surfactant, and aeration

The use of constructed wetlands (CWs) is a promising approach for the remediation of hydrocarbon-polluted wastewater. The amendments of CWs with nutrients, surfactants, and aeration enhances the removal of pollutants from wastewater. The objective of the present study was to explore the effect of external stimulants, i.e., nutrients, surfactant, and aeration on hydrocarbons degradation potential of CWs. The CWs mesocosms were developed by the vegetation of Phragmites australis and amendments with nutrients (20 mg l−1 N, 2.6 mg l−1 P, and 16.4 mg l−1 K), surfactant Tween 20 (0.2%, v/v), and aeration (7 mg l−1) for the remediation of diesel-spiked water (2%, w/v). The comparative analysis showed that the addition of nutrients, surfactant, and aeration individually enhanced total petroleum hydrocarbons (TPHs) reduction, and maximum TPHs reduction (88.4%) was achieved after 60 days in the mesocosms amended with the combination of nutrients, surfactant, and aeration. Among different individual treatments, the aeration (alone) also played a pivotal role in TPHs reduction (61%). The least (12%) reduction in TPHs was achieved in the mesocosms supplied with surfactant only. This study revealed that the combined application of nutrients, surfactant, and aeration in CWs enhanced its hydrocarbons degradation performance.