Biodegradation Of Crude Oil Research Articles

Effects of Dispersants and Biosurfactants on Crude-Oil Biodegradation and Bacterial Community Succession.

This study evaluated the effects of three commercial dispersants (Finasol OSR 52, Slickgone NS, Superdispersant 25) and three biosurfactants (rhamnolipid, trehalolipid, sophorolipid) in crude-oil seawater microcosms. We analysed the crucial early bacterial response (1 and 3 days). In contrast, most analyses miss this key period and instead focus on later time points after oil and dispersant addition. By focusing on the early stage, we show that dispersants and biosurfactants, which reduce the interfacial surface tension of oil and water, significantly increase the abundance of hydrocarbon-degrading bacteria, and the rate of hydrocarbon biodegradation, within 24 h. A succession of obligate hydrocarbonoclastic bacteria (OHCB), driven by metabolite niche partitioning, is demonstrated. Importantly, this succession has revealed how the OHCB Oleispira, hitherto considered to be a psychrophile, can dominate in the early stages of oil-spill response (1 and 3 days), outcompeting all other OHCB, at the relatively high temperature of 16 °C. Additionally, we demonstrate how some dispersants or biosurfactants can select for specific bacterial genera, especially the biosurfactant rhamnolipid, which appears to provide an advantageous compatibility with Pseudomonas, a genus in which some species synthesize rhamnolipid in the presence of hydrocarbons.

Characterization of Dietzia maris AURCCBT01 from oil-contaminated soil for biodegradation of crude oil.

The online version contains supplementary material available at 10.1007/s13205-021-02807-7.

Enhanced biodegradation of light crude oil by immobilized Bacillus licheniformis in fabricated alginate beads through electrospray technique.

Petroleum contamination of marine environments due to exploitation and accidental spills causes serious harm to ecosystems. Bioremediation with immobilized microorganisms is an environmentally friendly and cost-effective emerging technology for treating oil-polluted environments. In this study, Bacillus licheniformis was entrapped in Ca alginate beads using the electrospray technique for light crude oil biodegradation. Three important process variables, including inoculum size (5-15% v/v), initial oil concentration (1500-3500ppm), and NaCl concentration (0-30g/L), were optimized to obtain the best response of crude oil removal using response surface methodology (RSM) and Box-Behnken design (BBD). The highest crude oil removal of 79.58% was obtained for 1500ppm of crude oil after 14days using immobilized cells, and it was lower for freely suspended cells (64.77%). Our result showed similar trends in the effect of variables on the oil biodegradation rate in both free cell (FC) and immobilized cell (IC) systems. However, according to the analysis of variance (ANOVA) results, the extent of the variables' effectiveness was different in FC and IC systems. In the immobilized cell system, all variables had a greater effect on the rate of light crude oil degradation. Moreover, to evaluate the effectiveness of free and immobilized B. licheniformis in bioremediation of an actual polluted site, the crude oil spill in natural seawater was investigated. The results suggested the stability of beads in the seawater, as well as high degradation of petroleum hydrocarbons by free and immobilized cells in the presence of indigenous microorganisms.

Crude oil biodegradation in upper and supratidal seashores

The salinity of the upper parts of seashores can become higher than seawater due to evaporation between tidal inundations. Such hypersaline ecosystems, where the salinity can reach up to eight-fold higher than that of seawater (30–35 g/L), can be contaminated by oil spills. Here we investigate whether such an increase has inhibitory effects on oil biodegradation. Seawater was evaporated to a concentrated brine and added to fresh seawater to generate high salinity microcosms. Artificially weathered Hibernia crude oil was added, and biodegradation was followed for 76 days. First-order rate constants (k) for the biodegradation of GC-detectable hydrocarbons showed that the hydrocarbonoclastic activity was substantially inhibited at high salt – k decreased by ~75% at 90 g/L salts and ~90% at 160 g/L salts. This inhibition was greatest for the alkanes, although it extended to all classes of compounds measured, with the smallest effect on four-ring aromatics (e.g., chrysenes). Genera of well-known aerobic hydrocarbonoclastic bacteria were only identified at 30 g/L salts in the presence of oil, and only a few halophilic Archaea showed a slight enrichment at higher salt concentrations. These results indicate that biodegradation of spilled oil will likely be slowed in supratidal ecosystems and suggest that occasional irrigation of oiled supratidal zones could be a useful supporting strategy to remediation processes.

Advanced materials for immobilization of purple phototrophic bacteria in bioremediation of oil-polluted wastewater

Oil pollution which results from industrial activities, especially oil and gas industry, has become a serious issue. Cinder beats (CB), coconut fiber (CF) and polyurethane foam (PUF) are promising immobilization carriers for crude oil biodegradation because they are inexpensive, nontoxic, and non-polluting. The present investigation was aimed to evaluate this advanced technology and compare the efficiency of these immobilization carriers on supporting purple phototrophic bacterial (PPB) strains in hydrocarbon biodegradation of crude oil contaminated seawater. The surface of these biocarriers was supplemented with crude oil polluted seawater and immobilized by PPB strains, Rhodopseudomonas sp. DD4, DQ41 and FO2. Through scanning electron microscopy (SEM), the bacterial cells were shown to colonize and attach strongly to these biocarriers. The bacteria-driven carrier systems degraded over 84.2% supplemented single polycyclic aromatic hydrocarbons (PAHs). The aliphatic and aromatic components in crude oil that treated with carrier-immobilized consortia were degraded remarkably after 14 day-incubation. Among the three biocarriers, removal of the crude oil by CF-bacteria system was the highest (nearly 100%), followed by PUF-bacteria (89.5%) and CB-bacteria (86.3%) with the initial crude oil concentration was 20 g/L. Efficiency of crude oil removal by CB-bacteria and PUF-bacteria were 86.3 and 89.5%, respectively. Till now, the studies on crude oil degradation by mixture species biofilms formed by PPB on different carriers are limited. The present study showed that the biocarriers of an oil-degrading consortium could be made up of waste materials that are cheap and eco-friendly as well as augment the biodegradation of oil-contaminated seawater.

Optimization of Crude Oil Biodegradation by Brevibacterium sp. Isolated from the Native Sponges of the Persian Gulf.

Background: The native sponges of Persian Gulf are unique species facing difficult climate conditions and environmental contamination. It is necessary to investigate these native sponges because global warming most probably destroyed many of these creatures. Therefore, the study of the microorganisms associated with sponges will introduce new bacterial strains with various industrial and environmental applications and, in this way, a part of the Persian Gulf biodiversity will be preserved for posterity.Objective: The aim of this study was the isolation and molecular identification of bacteria associated with the ability of biodegrading crude oil from the native sponges of the Persian Gulf. Also, optimization of crude oil biodegradation was done for one of the most efficient bacterial strains.Materials and Methods: Isolated species were compared in terms of E24 index and growth rate in a culture medium containing at least 2% of oil as the sole carbon source. Molecular identification was done for five bacterial strains. Using the Taguchi experimental design, the effects of 4 factors, namely, carbon source auxiliary, organic and inorganic nitrogen sources, salinity and pH, were evaluated at 3 levels. GC-Mass analysis was performed on the remaining oil in the culture medium.Results: In the initial screening of two native species of sponges, 22 bacterial strains were isolated which were capable of decomposing oil. Five bacterial strains showed the best results and were recorded in NCBI with access numbers KY283126, KY283128, KY285290, KY285289, and KY285288. Brevibacterium sp. (KY283128) showed the highest level of oil degradation (about 97%) and growth rate. The results showed that the optimal oil degradation occurs in the absence of carbon source auxiliary, at 0.5% of salinity, with NH4Cl as the nitrogen source and at a pH of 6.5.Conclusions: This bacterial strain can be used for biodegradation in oil-contaminated areas and oil refineries. By isolating the oil degrading gene in this bacterial strain and cloning it in other bacterial strains, the efficiency of eliminating oil contamination can be increased.

Biodegradation of crude oil using symbiont crude‐oil degrading bacteria isolated from corals collected at the Persian Gulf

AbstractBACKGROUNDAbout 25,000 oil tankers are transported annually through the Persian Gulf in Iran. Therefore, oil pollution in this region is very high. Research on the use of marine bacteria to degrade crude oil has yielded good results in recent years. The present study investigates bacteria that are symbiotic with marine corals and their ability to degrade crude oil. Corals were collected from five regions in the Persian Gulf and enriched with decomposing bacteria in ONR7a culture. After biochemical and molecular identification of bacterial isolates, the ability of the strains to degrade crude oil by spectrophotometric, gravimetric, and Gas Chromatography‐ Mass Spectroscopy (GC‐MS) methods was investigated.RESULTSFinally, 26 bacterial strains were identified from 5 coral samples. The efficient strains that had the highest crude‐oil degradation belonged to genera Cobetia, Shewanella, Alcanivorax, and Cellulosimicrobium. Strains IAUK3568, IAUK3568, IAUK3502, IAUK3531, and IAUK3552 exhibited a maximum degradation of crude oil of 93.5%, 88.13%, 87.24%, 85.17%, and 77.3%, respectively.CONCLUSIONThe results showed that all bacterial isolates degrade medium‐chain alkanes better than long‐ and short‐chain alkanes. The data obtained in this study confirm that the corals of the Persian Gulf have the necessary bacterial diversity to decompose crude oil and, consequently, reduce pollution in this region. © 2021 Society of Chemical Industry (SCI).

Optimization of Crude Oil Biodegradation of Fungi Isolated from Refinery Effluent Site using Response Surface Methodology

The activities involved in the production and exploration of crude oil has constantly polluted the environment. This study investigated the ability of an indigenous fungus to utilize petroleum hydrocarbon. Response Surface Methodology was used to optimize the effects of pH, microbial concentration (spores/ml), and contact time (days) on the crude oil removal efficiency in refinery effluent. Monocillium sp. was isolated and used for the treatment of refinery effluent due to its predominance in the contaminated soil. Twenty experimental runs were analyzed to determine the effect of pH, microbial concentration and contact time on the oil removal efficiency. From theexperimental results obtained, a maximum oil removal efficiency of 98.42 % was achieved at a pH of 6.5, contact time of 14 days, and a microbial concentration of 3 spores/ml. The results obtained showed the percentage of crude oil removal in the effluent sample increased with an increase in time. Optimization of the experimental result was achieved at a removal efficiency of 98.59 %, a contact time of 13.96 days, a pH of 6.85, and a microbial concentration of 3.01 spores/ml. The findings of this study revealed that Monocillium sp. is a viable hydrocarbon degrader, and can be used in the bioremediation of petroleum contaminated environments.
 Keywords: Response surface, optimization, bioremediation, hydrocarbon, removal efficiency, Monocillium sp.

The effects of biostimulation and bioaugmentation on crude oil biodegradation in two adjacent terrestrial oil spills of different age, in a hyper-arid region

This study deals with two adjacent terrestrial oil spills, with similar properties, located in a hyper-arid region in Israel, one from 1975 and the other from 2014. It tests the effect of biostimulation on crude oil degradation in both spills and whether biostimulated sediments from the 1975 spill can bioaugment crude oil degradation in the 2014 spill. Soil hydrophobicity, expressed as Water Drop Penetration Time (WDPT), and Gasoline Range Organics (GRO) and Diesel Range Organics (DRO) content in sediments were measured in one-month ex-situ experiments. No significant reduction in hydrophobicity and GRO + DRO content was observed in non-biostimulated controls. A combined treatment of mineral fertilization at t0 and maintaining 50% water saturation, significantly accelerated the decrease in hydrophobicity and GRO + DRO content in sediments of both spills. The addition of biostimulated sediments from the 1975 spill failed to accelerate the reduction of GRO + DRO content and hydrophobicity in the 2014 spill. Surprisingly, the GRO + DRO degradation rate in biostimulated sediments from the 2014 spill was 36% higher than in biostimulated sediments from the 1975 spill. Crude oil composition in both spills changes during its degradation and is characterized by an increase in the GRO fraction. To a certain range, WDPT was found to serve as a reliable indicator for oil content in the soil. We conclude that even in a hyper-arid region, oil bio-degradation capabilities develop in a relatively short time. Moreover, while biostimulation was effective in accelerating biodegradation, bioaugmentation with biostimulated sediments from a nearby older spill was found ineffective.

Biodegradation of Crude Oil Under Low Temperature by Mixed Culture Isolated from Alpine Meadow Soil

Petroleum hydrocarbons have been worldwide concern contaminants because of their mutagenicity and carcinogenicity. The potential biodegradation of petroleum hydrocarbons at low temperatures is important for petroleum contamination remediation in cold region. In this study, a mixed cold-adapted bacteria flora JY, including seven petroleum-degrading strains (B1, H1, H2, H3, R1, R2, and S), was isolated from Alpine Meadow soil. Based on their 16S rRNA sequence analysis, B1, R1, and H3 were identified as Arthrobacter sp.; R2, S, H1, and H2 were identified as Rhodococcus sp., Pseudomonas sp., Stenotrophomonas sp., and Sphingobacterium sp., respectively. The mixed flora demonstrated 53.68% of total petroleum hydrocarbons (TPH) removal of the contaminated water (1 g oil L-1) after 30 days of incubation under 10 °C. In the degradation process, alkanes were more preferred to be degraded by JY than polycyclic aromatic hydrocarbons (PAHs) and other polar component. During this period, the abundant bacteria in the flora were transformed from alkane degraders of Rhodococcus sp. and Sphingobacterium sp. to PAH degraders of Pseudomonas sp. and sheltered Arthrobacter sp. This study verified that a cold-adapted mixed culture JY isolated from alpines meadow soil was capable in degrading TPH under low temperature through flora cooperation.

Re-biodegradation of all alkanes after chemical oxidation in soils

This study aimed to investigate the rapid restoration of indigenous hydrocarbon degraders after chemical oxidation, in order to enhance the subsequent biodegradation of crude oil in soils. The Fe-SOM (2231 mg kg−1) and H2O2 were added into the oil-contaminated soil (total petroleum hydrocarbon (TPH): 16064 mg kg−1) for chemical oxidation. Then, the all and partial alkane re-biodegradation reagents were added for re-biodegradation experiments. Calculated and analyzed C-source (DOC and TPH) and N-source ( $$ {\mathrm{NH}}_4^{+}-\mathrm{N} $$ , $$ {\mathrm{NO}}_3^{-}-\mathrm{N} $$ , $$ {\mathrm{NO}}_2^{-}-\mathrm{N} $$ ) consumption and the population of hydrocarbon degraders in each period. After chemical oxidation, the total biodegradation of all alkanes (re-biodegradation degree: 100%) with reagent for all alkane re-biodegradation in the late stage was higher than that in the early stage. Further study found that DOC was the main C-source and $$ {\mathrm{NH}}_4^{+}-\mathrm{N} $$ was the main N-source in the early stage, while TPH and nitrate were the main C&N-sources in the late stage of re-biodegradation. In other words, the C&N-sources changed over to TPH and nitrate in the late stage. After re-biodegradation stage, increasing biodegradation (from 644 mg kg−1 in the 1st stage to 842 mg kg−1 in the 3rd stage) was observed. The results showed that re-biodegradation of all alkanes could recover growth of indigenous hydrocarbon degraders and continuously increase biodegradation of all alkanes after chemical oxidation. The C&N-sources changed from DOC and $$ {\mathrm{NH}}_4^{+}-\mathrm{N} $$ to all alkanes and $$ {\mathrm{NO}}_3^{-}-\mathrm{N} $$ during re-biodegradation stage was the key factor.

Combined microbial degradation of crude oil under alkaline conditions by Acinetobacter baumannii and Talaromyces sp

The purpose of this work was to study the biodegradation of crude oil under alkaline condition by defined co-culture of Acinetobacter baumannii and Talaromyces sp. The n-alkanes in crude oil could be completely degraded by bacteria and fungi with the ratio of 1:1 at pH 9 in 14 d water simulation experiment. Meanwhile, the total degradation rate of crude oil could reach 80%. Fungi had stronger ability to degrade n-alkanes, while bacteria could better degrade other components such as aromatics and branched alkanes. The two strains were both capable of producing a small amount of biosurfactant. High cell viability was the main factor for strains to exert high degradation ability in alkaline environment. It was preliminarily verified that bacteria and fungi rely on the differences of enzyme systems to achieve synergy in the degradation process. These results indicated that the defined co-culture had great potential for bioremediation in alkaline soils.

Characterization of Severely Biodegraded Crude Oils Using Negative-Ion ESI Orbitrap MS, GC-NCD and GC-SCD: Insights into Heteroatomic Compounds Biodegradation

A slightly and two severely biodegraded crude oils with the same origin were analysed using negative-ion electrospray ionization Orbitrap mass spectrometry (ESI Orbitrap MS), gas chromatography-nitrogen chemiluminescence detector (GC-NCD), and GC-sulfur chemiluminescence detector (GC-SCD) to investigate the composition of heteroatomic compounds and their fate during severe biodegradation and to provide insights into biodegradation pathway of hopanes, nitrogen- and sulfur-containing compounds. Twelve heteroatomic compound classes, including O1–O5, N1, N2, N1O1–N1O3, N1S1 and O3S1, were detected and assigned unambiguous molecular formulae. The O1 species are likely phenols with additional naphthenic and/or aromatic rings. Carboxylic acids (O2 species) are originated from oxidation of hydrocarbons, and the tricyclic naphthenic acids are the most resistant, followed by bicyclics. Hopanes could be biodegraded by demethylation or by unstable hopanoic acids as intermediates to yield 25-norhopanes. The N1 species are pyrrolic compounds with naphthenic and/or aromatic rings and are dominated by carbazole analogues. Carbazoles with more aromatic rings are more resistant to biodegradation. The N1 species could be converted to N1O1 and N1O2 compounds via ring-opening and hydroxylation pathways. The N1S1 species contain a pyrrolic and cyclic sulfide structure, which are highly recalcitrant to biodegradation. Benzothiophenes and dibenzothiophenes might be biodegraded via the complete pathway or the sulfur-specific pathway rather than by other pathways to yield acidic oxygenated sulfur compounds.

Biodesalination and biodegradation of crude oil in aqueous solutions by Halobacillus halophilus

Biodesalination and biodegradation of crude oil in aqueous solutions by Halobacillus halophilus

Investigations on the characterizations, optimization and effectiveness of goat manure compost in crude oil biodegradation

This study investigates the potential of ready to use goat manure compost (GMC) in the biodegradation of crude oil (CO). Microbial respiration (CO₂ evolved), and heterotrophic bacteria count (HBC) in the CO contaminated soil treated with goat manure compost (COCS-GMC) were also investigated. The HBC demonstrated that the COCS-GMC contained valuable microbial populations while the CO₂ evolved in COCS-GMC and control samples were 500 ​mg ​g−1 and 230 ​mg ​g−1, respectively. The characterization of the CO showed that the dormant hydrocarbon compositions were saturates with traces of aromatic hydrocarbon, resins and asphaltene. The one-way analysis of variance (ANOVA) and Tukey's post-hoc analysis revealed that the CO₂ evolved within 30 days of incubation was significant (P ​< ​0.05) while the CO₂ evolved within 10, 20, 40, and 50 days were not. Instrumental analysis such as the XRD, FTIR and SEM were carried out on the GMC to give further information on the surface morphology and elemental compositions. The results obtained from the RSM indicated the satisfactory performance of the quadratic model with R2 (0.9779), adjusted R2 (0.9621), and predicted R2 (0.8951). The solution selected from the numerical optimization process was CO concentration of 63 ​g ​L−1 and pH 6 with the desirability of 1.

Indigenous microbial strains as bioresource for remediation of chronically polluted Niger Delta soils

An increase in artisanal crude oil refining within the Niger Delta Creeks has led to colossal environmental problems occasioned by spillages and subsequent ecosystem damage. Bacteria have been shown to play key role in biogeochemical cycling and degradation of pollutants from petroleum sources. The present study investigated the degradation efficiency of a bacterial consortia recovered from heavily inundated site in Bie-Ama community, having total petroleum hydrocarbons (TPH) concentration of 22,000 mg/kg, a value higher than Department of Petroleum Resources (DPR)’s 1000 mg/kg intervention limit. Soil samples were collected at 15 cm depth with soil auger while microbial isolation was done using enrichment and vapor phase transfer methods in Bushnell Haas medium. Colorimetric method using 2, 6-dichlorophenol indophenol (DCPIP) redox indicator was employed to determine biodegradation potentials of isolates. Bacterial isolates identified using 16S rRNA gene by Sanger sequencing were further screened for biosurfactant production and aromatic hydrocarbon degradation abilities. A consortium for efficient biodegradation of crude oil was constituted from individual isolates that totally decolorized DCPIP. Total culturable heterotrophic and hydrocarbon utilizing bacterial counts were 2.07 × 106 and 1.71 × 106 CFU/g soil respectively. Bacterial strains from the genera Pseudomonas, Bacillus, Klebsiella, Enterobacter produced biosurfactants while all strains utilized aromatics (benzene and naphthalene). A combination of Pseudomonas, Bacillus, Lysinibacillus and Enterobacter was the most efficient crude oil degrading consortium with significant mean difference (p = 0.05) as evidenced by GC-analysis confirming a more than 25% reduction in total petroleum hydrocarbon (TPH) concentration of 1% crude oil within 48 h. Conclusively, the extant indigenous bacterial community in the impacted site has the natural capability to degrade hydrocarbons and could be further enhanced through biostimulation for in situ remediation.

Biodegradation of buried crude oil in soil microcosm by fungal co-culture

Crude oil pollution in soil is a major environmental problem over the world. After long-term contamination, crude oil can be buried in the soil and leaving the toxic and persistence compounds. Treatment of buried crude oil in soil is a major challenge. In this study, buried crude oil in soil (20 cm-depth) was treated by the co-culture of three fungal strains (Pestalotiopsis sp. NG007/Polyporus sp. S133/Trametes hirsuta D7 with composition 1/1/1 and pre-grown in wood meal) placed on the top or bottom layer of the soil. Biodegradation behavior of crude oils were analyzed at different depth interval (0–5 cm, 5–15 cm, and 15–20 cm) with constant oxygen diffusion. The results showed that both position of fungal co-culture could degrade crude oil 63 – 92% after 30 days. Placing the co-culture in the bottom layer position of the soil demonstrated more effective degradation for all the depth interval than that of the top layer position. During the biodegradation, the co-culture produced oxidative enzymes such as catechol 1,2-dioxygenase, catechol 2,3-dioxygenase, laccase, manganese peroxidase, and lignin peroxidase with significant activities. This study offers an important strategy to remediate crude oil contaminated soil, specifically buried crude oil.

Ammonium Cycling and Nitrification Stimulation during Oil Sludge Remediation by Gram-Positive Bacteria Lysinibacillus sphaericus Using Red Wiggler Earthworm Eisenia fetida

The performance of a mixture between L. sphaericus and E. fetida was evaluated for ammonium cycling and nitrifying bacteria stimulation during oil sludge remediation. The addition of E. fetida significantly increased ammonium concentration (p = 0.0218) and total Colony-forming units (CFU) count p = 0.02848). However, oil sludge with worms and L. sphaericus reached lower ammonium concentrations and CFU counts than sludge with worms alone. Sludge inoculated only with L. sphaericus presented higher ammonium concentration than sludge without inoculum, but the bacterial population reached a lower density during the final days. Final DNA and RNA extractions from all treatments amplified for L. sphaericus putative amoA and Gram-negative nitrifying bacteria amoA genes correlated with diminished ammonium concentrations during the final days of the experiment. Final RNA extractions for L. sphaericus amplified for Molybdenum transporter gene suggesting possible nitrogen fixation by L. sphaericus. The addition of Red Wiggler Earthworm to oil sludge remediation systems may provide better conditions for bacterial populations to carry out hydrocarbon degradation. The addition of E. fetida to a L. sphaericus crude oil biodegradation system may improve soil ammonium concentrations and nitrifying activity, and this could be crucial in oil sludge remediation because of bacterial inhibition due to high C:N ratios. The final product of this process may be used for soil enhancement due to its richness in nutrients and beneficial bacterial populations.

Origin and Biodegradation of Crude Oils from the Northernmost Fields in the Bolivar Coastal Complex (Zulia State, Venezuela)

The organic geochemical features of 30 sampled oils from the northern Bolivar Coastal Complex (Lake Maracaibo Basin, NW Venezuela) were examined by combining carbon isotope, classical biomarker, and extended diamondoid analyses to clarify source facies and to assess the thermal maturity and extent of biodegradation of the oils analyzed. In this work, oils are understood as a mixture of two episodes of petroleum generation from the La Luna Formation: a paleobiodegraded oil pulse during Paleogene times and a late pulse having a higher maturity in the post-Oligocene. For the oil samples analyzed, results revealed a mixing composed of different proportions of almost a terrestrially derived siliciclastic-sourced and a purely marine carbonate-sourced oil pulse. Moreover, two main groups of oils were identified by means of hierarchical cluster analysis. Finally, inter- and intrafield variations in the extent of biodegradation were also assessed using two classification schemes (Peters and Moldowan, and Manco scales).

Bioremediation of Crude Oil Contaminated Soil Using Pig Droppings and Bone Char

Oil extraction operations as well as equipment failure and infrastructure vandalism have caused serious environmental pollution with crude oil spills world-wide. The remediation of the polluted sites is an environmental problem beckoning for solution. In this study, the possibility of pig droppings and pig bone char mixture (biostimulant) to stimulate and optimize crude oil biodegradation in soil was investigated. Exactly 500g of loamy soil was spiked with 3% (w/w) of crude oil. The spiked soil was amended with varying percentage mixtures of the biostimulant and labelled A – E. The spiked soil without biostimulant served as the Control. Each experiment was setup in six (6) replicates, carried out for six weeks, and destructively sampled and analysed on a weekly basis. The removal efficiencies of the biostimulated and unbiostimulated soils were observed to range from 66.70 to 86.70% and 3.69%, respectively. The biodegradation first-order rate constants ranged from 0.1978 to 0.3391wk-1 and 0.0050wk-1 for the biostimulated and unbiostimulated soils, respectively. Optimum removal of total petroleum hydrocarbon (TPH) was observed for biostimulated soil C comprising 50% bone char and 50% pig droppings. Results from biostimulated soils A, B, D and E indicated that pig droppings is a more effective biostimulant than pig bone char. A first-order kinetic model adequately predicted the removal of TPH with the optimum biostimulant. It is concluded that using agro-organic waste materials such as pig droppings and pig bone char in a ratio of 1:1 can offer a simple, effective, inexpensive and environmentally friendly solution to the problem of soil contamination with crude oil.