Optimization of Diesel and Crude Oil Degradation in a Ghanaian Soil Using Organic Wastes as Amendment

Soil contamination by hydrocarbons poses numerous environmental, health and agricultural problems. The degradation of these pollutants can occur naturally but very slowly. It is therefore generally necessary to stimulate this degradation by different means. Thus, this study aimed to improve the bio-degradation of diesel and crude oil in a Ghanaian soil by biostimulation. For this, the sampled soil was characterized by standard methods and contaminated with diesel and crude oil at a proportion of 1% (w/w). Then, contaminated soil samples were supplemented with biochar-compost, poultry manure or cow dung at the proportion of 10% (w/w). Periodically, fractions of these samples were taken to evaluate the density of hydrocarbon utilizing bacteria (HUB) and the residual quantities of diesel or crude oil. The characteristics of the soil used show the need for supplementation for better degradation of hydrocarbons. The results of the study show that supplementing the soil with organic substrates increases HUB loads in soils contaminated by diesel and crude oil. They also show that the residual quantities of diesel and crude oil are generally significantly lower in supplemented soils (p = 0.048 and p < 0.0001 respectively). In addition, the study shows that degradation was generally greater in soils contaminated by diesel compared to those contaminated by crude oil, especially at the end of the study.

Infiltration characteristics of non-aqueous phase liquids in undisturbed loessal soil cores

The widespread contamination of soils and aquifers by non-aqueous phase liquids （NAPL）, such as crude oil, poses serious environmental and health hazards globally. Understanding the infiltration characteristics of NAPL in soil is crucial in mitigating or remediating soil contamination. The infiltration characteristics of crude and diesel oils into undisturbed loessal soil cores, collected in polymethyl methacrylate cylindrical columns, were investigated under a constant fluid head （3 era） of either crude oil or diesel oil. The infiltration rate of both crude and diesel oils decreased exponentially as wetting depth increased with time. Soil core size and bulk density both had significant effects on NAPL infiltration through the undisturbed soil cores; a smaller core size or a greater bulk density could reduce oil penetration to depth. Compacting soil in areas susceptible to oil spills may be an effective stratage to reduce contamination. The infiltration of NAPL into soil cores was spatially anisotropic and heterogeneous, thus recording the data at four points on the soil core is a good stratage to improve the accuracy of experimental results. Our results revealed that crude and diesel oils, rather than their components, have a practical value for remediation of contaminated loessal soils.

Degradation Kinetics of Petroleum Contaminants in Soil-Water Systems

On the basis of site investigation and sample collection of petroleum contaminants in the soil-water-crop system in the Shenyang-Fushun sewage irrigation area, the physical-chemical-biological compositions of the unsaturated zone is analyzed systematically in this paper. At the same time, the degradation kinetics of residual and aqueous oils is determined through biodegradation tests. The studies show that dominant microorganisms have been formed in the soils after long-term sewage irrigation. The microorganisms mainly include bacteria, and a few of fungus and actinomycetes. After a 110-days' biodegradation test, the degradation rate of residual oil is 9.74%-10.63%, while the degradation rate of aqueous oil reaches 62.43%. This indicates that the degradation rate of low-carbon aqueous oil is higher than that of high-carbon residual oil. In addition, although microbial degradation of petroleum contaminants in soils is suitable to the first-order kinetics equation, the half-lives of aqueous oil, No. 20 heavy diesel and residual oil in the surface soils (L2-1, S1-1 and X1-1) are 1732 h, 3465 h and 17325 h, respectively.

Ecological effects of crude oil residues on the functional diversity of soil microorganisms in three weed rhizospheres

Ecological effects of crude oil residues on weed rhizospheres are still vague. The quantitative and diversity changes and metabolic responses of soil-bacterial communities in common dandelion （Taraxacum officinale）, jerusalem artichoke （Silphiurn perfoliatum L.） and evening primrose （A colypha australis L.） rhizospheric soils were thus examined using the method of carbon source utilization. The results indicated that there were various toxic effects of crude oil residues on the growth and reproduction of soil bacteria, but the weed rhizospheres could mitigate the toxic effects. Total heterotrophic counting colony-forming units （CFUs） in the rhizospheric soils were significantly higher than those in the non-rhizospheric soils. The culturable soil-bacterial CFUs in the jerusalem artichoke （S. perfoliatum） rhizosphere polluted with 0.50 kg/pot of crude oil residues were almost twice as much as those with 0.25 kg/pot and without the addition of crude oil residues. The addition of crude oil residues increased the difference in substrate evenness, substrate richness, and substrate diversity between non-rhizospheric and rhizospheric soils of T. officinale and A. australis, but there was no significant （p〉0.05） difference in the Shannon＇s diversity index between non-rhizospheric and rhizospheric soils of S. perfoliatum. The rhizospheric response of weed species to crude oil residues suggested that S. perfoliatum may be a potential weed species for the effective plant-microorganism bioremediation of contaminated soils by crude oil residues.

Application of bioremediation in oil contaminated soil

The long-term oil exploitation in oil fields has led to pollution of surrounding soil, creating a serious ecological problem. In order to promote and improve the application of microbial remediation in oil contaminated soil, experiment is carried out in polluted area in Zhongyuan Oilfield. In the experiment, indigenous microorganisms and other physical and chemical methods are employed, ryegrass is grown, and environmental factors in soil are regulated to degrade the oil and treat the polluted soil. Results show that when the average oil content in the soil is about 523.08 mg/kg, 65 days' remediation through plants and microorganisms could help bring the oil content down to 74.61 mg/kg, achieving a degradation rate of 85.74%; through salinity treatment, salt content in soil is reduced by 62.93-82.03% to 399-823 mg/kg from previous 2.22 g/kg. Through this experiment, the bioremediation method is improved and its effectiveness and feasibility are testified. The result has been applied in Zhongyuan Oilfield and has brought fair ecological and economic benefits, providing technical support to the treatment of contaminated soil of the same kind, and offering some insights to the treatment of soil contaminated by other organic pollutants.

Rapid Detection of Oil Pollution in Soil by Using Laser-Induced Breakdown Spectroscopy

Detection of oil pollution in soil has been carried out using laser-induced breakdown spectroscopy（LIBS）. A pulsed neodymium-doped yttrium aluminum garnet（Nd：YAG） laser（1,064 nm, 8 ns, 200 mJ） was focused onto pelletized soil samples. Emission spectra were obtained from oil-contaminated soil and clean soil. The contaminated soil had almost the same spectrum profile as the clean soil and contained the same major and minor elements. However, a C–H molecular band was clearly detected in the oil-contaminated soil, while no C–H band was detected in the clean soil. Linear calibration curve of the C–H molecular band was successfully made by using a soil sample containing various concentrations of oil. The limit of detection of the C–H band in the soil sample was 0.001 mL/g. Furthermore, the emission spectrum of the contaminated soil clearly displayed titanium（Ti） lines, which were not detected in the clean soil. The existence of the C–H band and Ti lines in oil-contaminated soil can be used to clearly distinguish contaminated soil from clean soil. For comparison, the emission spectra of contaminated and clean soil were also obtained using scanning electron microscope-energy dispersive X-ray（SEM/EDX） spectroscopy,showing that the spectra obtained using LIBS are much better than using SEM/EDX, as indicated by the signal to noise ratio（S/N ratio）.

Application of bacteria-plant association in bio-degradation of diesel oil pollutants in soil

The bacteria and plants were associated to remove diesel oil pollutants from soil.Three efficiently degrading bacteria(named strains Q10,Q14 and Q18,respectively) were isolated.Two plants(alfalfa and Indian mustard) were selected to form the association.Biodegradation of diesel oil pollutants in soil was accelerated by bacteria-plants association.The main results are summarized as follows.The plants-bacteria association was more effective in biodegradation of diesel oil pollutants in soil than in respective experiments carried out with plants or bacteria alone.Strain Q18-Indian mustard association resulted in the maximum diesel oil reduction(69.18%).The activities of catalase and polyphenol oxidase in soil were enhanced and microbial populations in soil,especially in rhizosphere,were also stimulated in the treatment of bacteria-plant association.Overall,the soil conditions might be improved by alfalfa or Indian mustard to benefit the growth of bacteria,which resulted in degradation of diesel oil pollutants more effective by the bacteria-plant association.The bacteria-plants association may be a better approach to the removal of diesel oil pollutants from soil.

Toxic effects of crude-oil-contaminated soil in aquatic environment on Carassius auratus and their hepatic antioxidant defense system

Under the indoor simulant conditions, toxic effects of crude-oil-contaminated soil which was put into aquatic environment on the young fishes Carassius auratus and their hepatic antioxidant system after a 20-d exposure were investigated. Results showed that the relationship between the mortality of C. auratus and the exposed doses could be divided into 3 phases： fishes exposed to the low dose groups （0.5-5.0 g/L） were dead due to the ingestion of crude-oil-contaminated soils in aquatic environment; at the medium dose groups （5.0-25.0 g/L） fishes were dead due to the penetration of toxic substances; at the high dose groups （25.0-50.0 g/L） fishes were dead due to environmental stress. The highest mortality and death speed were found in the 1.0 g/L dose group, and the death speed was sharply increased in the 50.0 g/L dose group in the late phase of exposure. The activities of superoxide dismutase （SOD）, catalase （CAT） and glutathione S-transferase （GST） and the content of malaondialdehyde （MDA） in the hepatic tissues of C. auratus were induced significantly. The activity of SOD was increased and then decreased. It was significantly inhibited in the 50.0 g/L dose group. The activity of CAT was highly induced, and restored to a level which is little more than the control when the exposed doses exceeded 10.0 g/L. The activity of GST was the most sensitive, it was significantly induced in all dose groups, and the highest elevation was up to 6 times in the 0.5 g/L dose group comparing with the control. The MDA content was significantly elevated in the 50.0 g/L dose group, and the changes of the MDA content were opposite with the changes of GST activity.

Effects of vegetable oil residue after soil extraction on physical-chemical properties of sandy soil and plant growth

Vegetable oil has the ability to extract polycyclic aromatic hydrocarbons(PAHs)from contaminated sandy soil for a remediation purpose,with some of the oil remaining in the soil.Although most of the PAHs were removed,the risk of residue oil in the soil was not known.The objective of this study was to evaluate the effects of the vegetable oil residue on higher plant growth and sandy soil properties after soil extraction for a better understanding of the soil remediation.Addition of sunflower oil and column ex...

Surfactant-Enhanced Washing of Soils Contaminated with Wasted-Automotive Oils and the Quality of the Produced Wastewater

An old automotive industrial site located at Mexico City with many years of operation and contaminated with heavy oil hydrocarbons, particularly spent oils, was assessed for restoration using the surfactant enhanced soil washing (SESW) process. The main goal of this study was to characterize the contaminated soil in terms of TPHs, BTEX, PAHs, and metals contents as well as microbiologically (total heterotrophs and specific degrading microorganisms). We also aimed to determine the surfactant type and concentration to be used in the SESW process for the automotive waste oil contaminated soil. At the end, sixteen kg of contaminated soil were washed and the produced wastewater (approximately 40 L) was characterized in terms of COD, BOD;solids, and other physico-chemical parameters. The soil contained about 14,000 mg of TPH/kg soil (heavy fraction), 0.13 mg/kg of benzo (k) fluoranthene and 0.07 mg/kg of benzo (a) pyrene as well as traces of some metals. Metals concentrations were always under the maximum concentration levels suggested by Mexican regulations. 15 different surfactants were used to identify the one with the capability to achieve the highest TPH removal. Surfactants included 5 anionics, 2 zwitterionic, 5 nonionics and 3 natural gums. Sulfopon 30 at a concentration of 0.5% offered the best surfactant performance. The TPH removals employing the different surfactants were in the range from 38% to 68%, in comparison to the soil washing with water (10% of TPH removal). Once the surfactant was selected, 70 kg of soil were washed and the resulting water contained approximately 1300 mg/L of COD, 385 mg/L of BOD (BOD/COD = 0.29), 122 mg/L of MBAS, and 212 mg/L of oil and greases, among other contaminants.

Status quo of soil petroleum contamination and evolution of bioremediation

Along with the rapid development of oil industries internationally,petroleum prospecting and exploitation activities are growing intensively.Especially in China,with the fastest economic growth in the world and shortage of petroleum resources,we are leading the practices of petroleum deep exploitation.Obviously,the risk of damage to the natural environment from these activities is high.Oil contamination in soils and groundwater is becoming a big issue along with pesticide pollution,which makes organic pollution prevention and control （OPPC） much more complex.In this paper,based on recent research on oil-contaminated soil at home and abroad,we make comments on the remediation technologies for polluted soil,emphasizing bioremediation techniques and degradation mechanisms in order to push forward research into bound organic pollution prevention and control （OPPC）,especially in China.

Fenton Pre-Oxidation Followed by Microbial Degradation for Removing Crude Oil from Contaminated Soil

Through the Fenton pre-oxidation followed by microbial degradation,this study gave full play to its advantages while avoiding its shortcomings for the remediation of crude oil contaminated soil.The Fenton reagent coupled with different volumes of H2O2 was applied to the oil contaminated soil and then the microbial agents were introduced to biodegrade the residual oil for 15 days.The correlation between the characteristics of residual oil in soil,the changes in soil physical-chemical property after the Fenton pre-oxidation,and the biodegradation were analyzed in this paper.The results show that the above factors are strongly correlated with the subsequent biodegradation rate,and the order of correlation is as follows:the ratio of TOC to NH4+-N(R^2=0.9513)>the ratio of light oil components to the heavy oil components(R^2=0.9095)>the proportion of hydrocarbons with carbon chain number of less than C23(R^2=0.8259)>the crude oil content(R^2=0.7603)>the soil pH(R^2=0.7492)>the number of microorganisms(R^2=0.6506).During the biodegradation and pre-oxidation reactions of heavy oil components,an appropriate C:N ratio turns out to be the most critical factor in this study.

Uptake of B,Co and Ni by Plants from Oil Contaminated Soil Capped with Peat

Plant uptake of contaminants provides vital information for the reclamation of large area of contaminated soils.A field experiment was conducted using four plant species growing in four kinds of oil contaminated soils to estimate the uptake of organic and inorganic contaminants by plants from the oil contaminated soils.The experiment showed that the concentrations of some selected elements,such as B,Co and Ni in plants growing in the oil contaminated soils were significantly higher than those in plants growing in the uncontaminated control soil.The accumulation of metals in plants increased with plant biomass;however,the removal of metals by plants from the oil contaminated soils was not practical.

Achieving High Soil Fertility, Efficient Fruit Harvesting and Low Carbon Footprint Palm Oil Production in Malaysia

The current palm oil harvesting process removes the whole fruit bunch from the palm with most of the fruit unripe, and takes the whole fruit bunch from the plantation to a processing mill. There are two consequences. This robs the symbiotic palm/soil eco-system of important nutrients and steadily reduces soil fertility. Poor soil fertility is now the limit to palm oil production in peninsular Malaysia despite much use of expensive fertiliser, and weak palms in unhealthy soil are prone to the fungus Ganoderma. Secondly, it takes much energy to remove the fruit from the bunch and the quantity and quality of the oil is less than that of ripe fruit. All this is because ripe fruit—which naturally becomes loose—has been defined as “a problem” in harvesting. This paper proposes covering the fruit bunch in a mesh sack whilst ripening, which prevents ripe fruit naturally from becoming loose being a problem and transforms the whole harvesting process. This allows efficient fruit separation and fruit pressing to be done at the foot of the palm tree with only the oil being removed from the plantation, both simplifying and improving the harvesting process and maintaining the organic fertility cycle, adding value in every respect.

Germination Tolerance of Four Mutant Lines of Barley （Hordium vulgare L.）, Wheat （Triticum aestivum L.） and Garden Cress （Lipidium sativum L.） to Crude Oil Contaminated Soil

Phytoremediation shows promise as an alternative low-cost to most remediation methods. This study evaluated the germination of six crops, including four mutant lines of barley （Hordium vulgate L.） （1-9-3, 150-2-3, 1-1-200 and 150-1-5）, wheat （Triticum aestivum L.） and garden cress （Lipidium sativum L.）. This experiment was conducted in laboratory at room temperature. Oil extracted from crude oil contaminated soil was added to sand used in different concentrations （0%, 2%, 4%, 6%, 8% and 10%）. 10 seeds of each crop were sown in ptri-dishes with different treatments separately. For Each treatment four replicates were used in completely randomized design, germination percent was calculated, after one week, shoot and root length were measured. Data were statistically analyzed using MINTAB version 12. The results show that barley mutant line （150-2-3） was significantly different from other entries in germination percent, shoot and root length except mutant line 150-1-5 in germination percent. Results demonstrated that the mutant line 150-2-3 was promising to remediate crude oil contaminated soil.

Profile of Polycyclic Aromatic Hydrocarbons in Soil Environment around Selected Auto-Technicians’ Workshop in ObioAkpor, Rivers State Nigeria

A study on the storage and disposal practices of spent oil from Automobile workshops in ObioAkpor Local Government Area of Rivers state was conducted to determine the levels of polycyclic aromatic hydrocarbons (PAHs) in soil samples. Questionnaire was administered and a total of 150 autotechnicians were sampled. Taro Yamani formula was used to determine the sample size. Soil samples were collected at depths of 0 - 15 cm from 8 randomly selected sites and analyzed for PAH. Control consisted of a similar soil with no history of spent oil-contamination. Results showed that autotechnicians had little or no formal education. Only 51% of respondents had secondary/technical education. 94% of the study population disposed of their generated spent oil in various types of containers before disposal. 94% disposed of their spent oil by selling. 60% of the autotechnicians were not aware that spent oil was hazardous. More so, 76% were not aware that spent oil could be recycled. Analysis of soil samples showed that mean concentration of PAH was lower than the DPR standard in all locations. Control values did not show any consistent pattern when compared with the test values in all locations. Soil contamination by PAH in the study area ranged from minor to severe. The automobile workshops pose potential sources of PAH pollution. The study recommends enactment and enforcement of legislations to control the management of spent oil.

Optimization of reed-specific degrading bacteria by response surfaces for remediation of crude oil-polluted soil in Xinjiang,China

This paper discussed the optimization of conditions for remediation of crude oil-polluted soil based on pot experiment by applying reed-specific degrading bacteria, and using response surfaces methodology. We took the initial crude oil concentration, the amount of inoculation, the ratio of nitrogen and phosphorus, and the use of surfactant （Tween-80） as independent variables （factors）, and the degrading ratio of crude oil as the dependent variable （response） after a 90-day experiment. The experiment explored the impacts of each independent variable and their interactions on the bioremediation of crude oil-polluted soil using the Box-Behnken design. Working with a simulated forecasting model the study obtained optimization va reed＋specific degrading bacteria, a nitrogen to phosphorus ues for the treatment parameters of 200 g/kg of the ratio of about 6.0. and 0.2% surfactant. Under experimental conditions, for crude oil concentrations of 10, 30 and 50 g/kg, the optimal effects of the treatments achieved 71.87%, 66.61% and 54.52% degradation of the crude oil, respectively. The results can provide a basis for the technical development of plant-microorganism combined bioremediation of crude oil-polluted soil.

Towards Sustainable Oil Palm Plantation Management: Effects of Plantation Age and Soil Parent Material

This study was conducted to generate information required to guide plantation management in relation to replanting on soils derived from different parent materials. Six oil palm estates in coastal lowlands of southwest Cameroon were considered. Oil palm yield data (in t&#8901;ha&#8722;1 of fresh fruit bunch, FFB) and corresponding age of palms (in years after planting, YAP) were obtained for the various estates. In all the estates, average yields were &#8901;FFB&#8901;ha&#8722;1 and highly variable. Plantation age, solely, explained between 20% - 58% of the variation in yield. The highest average yields (11.5 t&#8901;FFB&#8901;ha&#8722;1) were obtained in plantations aged between 9 and 18 YAP and the lowest (4.66 t&#8901;FFB&#8901;ha&#8722;1) were obtained in old plantations (>23 YAP). Plantations located on volcanic parent materials generally had higher yields compared to those established on sedimentary parent materials. In order to intensify production and increase yields while conserving the environment, one important measure to consider is the replacement of aged palms, and the recommended optimal replanting age in coastal plains of southwest Cameroon should be at most 23 YAP. Estimated mean yields, if aged palms are replanted on time, can increase by 43% - 65%. Additionally, site-specific nutrient management options should be considered in plantation intensification programs.

Management of Petroleum Impacted Soil with Phytoremediation and Soil Amendments in Ekpan Delta State, Nigeria

The study is aimed at evaluating the effectiveness of phytoremediation in the management of oil impacted soil in Ekpan communities of Delta state, Nigeria. To do this, the study adopted an experimental research design that involve the use of phytoremediation (carpet grass Axonopus compressus) and nutsedge Cyperus rotundus) in the management of petroleum impacted soil site in Ekpan, This experiment spans for three months periods (one planting season). It involves the treatment of the oil impacted site with different plant species and soil amendments. Laboratory analysis of the soil samples was conducted to determine the effect of phytoremediation and soil amendments on hydrocarbon loss in oil impacted sites. The study revealed that the combined effect of Axonopus sp., Cyperus sp. and oil amendments accounted for 59% reduction in hydrocarbon. However Axonopus sp. and Cyperus sp. accounted for 47% and 48% reduction in hydrocarbon respectively. This shows that though, both plant species can be used successfully as a phytoremediation technique for the reclamation of oil impacted soils, but Axonopus sp. and Cyperus sp. was the most effective when applied with soil amendment (organic and inorganic manure). It is therefore recommended that iindigenous plant species (particularly Axonopus sp. and Cyperus sp.) should be used together with soil amendments in phytoremediation rather than the traditional bioremediation involving the use of microorganism. Oil companies operating in the Niger Delta region of Nigeria are encouraged not only to carry out physical clean-up of oil spills but should also carry out bioremediation to restore the environment back to its natural or near natural state. The methodology adopted in this study could be followed by oil companies to manage oil impacted soils in the Niger-Delta environment in Nigeria and indeed everywhere in the world.