Development of Waste Based Bio-stimulant for the Remediation of Crude Oil Contaminated Soil

Development of Waste Based Bio-stimulant for the Remediation of Crude Oil Contaminated Soil

Chapter One

Aim and Objectives

The aim of this study is to develop a waste based biostimulant for the remediation of crude oil contaminated soil; thereby providing a solution for waste management as well as mitigation of soil pollution resulting from the contamination.

In other to achieve this, the following objectives were undertaken:

Determination of the physiochemical properties of soil and plant waste.
Determination of the effect of nutrient on the rate of crude oil degradation
Determination of the rate of degradation and degradation efficiency of plant waste (plantain peels) on the soil sample.
Evaluation of the optimum values of factors that affects crude oil degradation and the possible responses using design expert simulation software.

CHAPTER TWO

LITERATURE REVIEW

Principle of Bioremediation

Crude oil is a composite mixture of thousands of different chemical compounds. As the composition of each type of oil is unique, there are different ways to deal with them through microbes and flora. Bioremediation can occur naturally or can be encourage with addition of microbes and fertilizers. The microbes present in the soil first recognize the oil and its constituent by biosurfactants and bio emulsifiers, and then they attach themselves and use the hydrocarbon present in the petroleum as a source of energy and carbon. The low solubility and adsorption of high molecular weight hydrocarbons limit their availability to microorganisms. The addition of biosurfactants enhances the solubility and removal of these contaminants, improving oil biodegradations rates.

Bioremediation of contaminated soils has beeninvestigated since the late 1940s, but interest in the field did not become widespread until the Exxon Valdez oil spill in 1989(Margesin & Schinner, 1997). Consequently, there have been a large number ofstudies conducted, and bioremediation has almost always been found to be aneffective treatment of hydrocarbon-contaminated sites ((Huesemann & Moore, 1993); (Li, Zhang, & Xu, 1995); (Zhou & Crawford, 1995).

In the field of biostimulation, nutrient supplementation forhydrocarbon degradation has traditionally focused on addition of N and P,either organically or inorganically. Because Cabon is a major constituent ofpetroleum fuels, its traditional role in bioremediation research has typicallybeen as an index to determine the amount of N and P that need to be added toreach the optimal C:N:P ratio (Riser-Robert, 1998). Moreover, the role of Carbon supplementation in hydrocarbon bioremediation in low organic matter orotherwise Carbon-poor soils has never been investigated. Various nutrient sourcessuch as, inorganic fertilizer, urea, sawdust, compost, manure, and biosolidshave been used in biostimulation (walworth & Reynolds, 1995);(Cho et al, 1997);(williams et al, 1999); (Namkoong, Hwang, Park, & Choi, 2002).

The constituents of oil differ distinctly in volatility, volubility, and susceptibility to biodegradation. Some compounds are easily degraded, some resist degradation and some are non-biodegradable. The biodegradation of different petroleum compounds occurs simultaneously but at different rates because different species of microbes preferentially attack different compounds. This leads to the successive disappearance of individual components of petroleum over time. Microorganisms produce enzymes in the presence of carbon sources which are responsible for attacking the hydrocarbon molecules. Many different enzymes and metabolic pathways are involved to degrade a hydrocarbons contained in petroleum. But lack of an appropriate enzyme will either prevents attack or will act as a barrier to complete hydrocarbon degradation.

Bacteria

Although, many microorganisms are capable of degrading the crude oil present in the soil, it has been found beneficial to employ mix culture opposed to pure cultures in bioremediation as it shows the synergistic interactions. Bacteria for hydrocarbon decomposition are commercially available as freeze dried bacteria, which can be used for bioremediation after propagation to a minimum of 2×108 CFU/ml. Bacterias that can degrade petroleum products are-Pseudomonas, Aeromonas, Moraxella, Beijerinckia, F lavobacteria, chrobacteria, Nocardia ,Corynebacteria,Atinetobacter, Mycobactena, ,Modococci , Streptomyces, Bacilli, Arthrobacter,Aeromonas, Cyanobacteria etc.

Crude-oil Degrading Bacteria and Stimulants

Micro organisms like bacteria, fungi has gained impetus in the remediation of crude oil contaminated soil since its discovery in oil degradation and mineralization. Studies has reported different oil degrading bacteria belongs to the genus bacillus, Bravillus, Achromobacter, Psaudomonas etc. ((Lal & Khanna, 1996), (Roy, 2016)). Many heterotrophic bacteria are able to utilize hydrocarbons as a source of carbon and energy (Nichols et al., 1996) as cited in(Yenn R, 2015). The most commonly used heterotrophic soil bacteria are Pseudomonas and Arthrobacter. They are capable of breaking down hydrocarbons through various metabolic pathways (Morelli et al., 2005) as cited in (Yenn R, 2015) and breakdown of the hydrocarbon compounds depends on solubility and concentration of hydrocarbons.

At low concentrations of hydrocarbon, all fractions are to be expected of being attacked by bacteria. However, at high concentrations, only those fractions most susceptible to degradation will be broken down. Also the concentration of contaminants will affect the number of organisms present. Although numerous bacteria are able to metabolize organic contaminants; it should be noted that no single bacterium have the metabolic potential to degrade all or even most of the organic compounds in a polluted soil. The genetic information of more than one organism is necessary to degrade the complete mixtures of crude oil compounds present in the contaminated region, for this reason mixed microbial community have the most influential degradation potential than pure culture(fritsche & Hofrichter, 2008).

Hence, this study shall seek to utilize biostimulant from plant waste in the remediation of soil with different proportion of crude oil contamination. As reported by (Bouchez et al, 1995) mixed culture of microorganisms may possibly enhance PAH utilization since the intermediatory biotransformation products of one microorganism may serve as substrate for catabolism and growth for other bacteria.

As mentioned above degradation of crude oil seems to involve a consortium of microorganisms, including both eukaryotic and prokaryotic such as Acinetobacter, Actinobacter, Arthrobacter, Bravibacillins, Berijerinckia, Cellulosimicrobium,Flavobacterium ,Microbacterium, Mycobacterium, Mycococcus, Nocardia, Pseudomonas etc. Among the crude oil mineralizing organisms usually the gram negative bacteria, most of them belong to the genus Peudomonas are common in degradation of polycyclic aromatic hydrocarbon like Naphthalene. Besides these, studies have also been reported the bacteria from the genera Corynbacterium, Aeromonas, Rhodococcus and Bacillus (Neilson & Allard, 2008);(Annweiler & et al, 2000). On the other hand, a few organisms are capable of degrading fluoranthene which includes mainly bacteria from the genera Mycobacterium and Alcaligenes. Studies have also been conducted on strains from Pseudomonas, Aeromonas, Arthrobacter,Sphingomonas, Mycobacterium and Nocardia on phenanthrene degradation (Cerniglia, 1984;Pinyakong et al., 2000) as cited in (Riser-Robert, 1998).

CHAPTER THREE

MATERIALS AND METHOD

Materials

The materials used for this research work includes:

Plant waste(plantain peels).
Soil sample: Sandy soil
Crude oil
Distilled water
Micro organisms
N-Hexane, Acetone and Dichloromethane (DCM)

Source of Materials:

Plant waste (plantain peels) was obtained from food canteens (Bole joints) in FUPRE.
Sandy soil was obtained from FUPRE campus.
Distilled Water was sourced from chemical engineering laboratory FUPRE.
Crude oil used for contamination was sourced from oml 30 field (Afiesereflowstation)
Micro-organisms used for the degradation process was sourced from Environmental Management and Toxicology laboratory FUPRE and from biological laboratory in Warri.
N-Hexane/Acetone/DCM was gotten from TUDAKA environmental consultants in Ekpan Warri Effurun.

Equipment/Apparatus Used

Equipment’s used for this research work includes:

Volumetric flasks and beakers
Measuring cylinders
Separating funnel
Weighing balance
Mechanical shaker
Mechanical sieve
Oven
Incubator
Gas chromatograph, etc.

Methodology

Collection and Processing of Samples

The Sandy soil sample used was collected randomly with a metal soil auger at a depth of 15 to 30 cm from FUPRE compound. It was bulked to form a composite sample and transported in a black polythene bag to the laboratory, air dried and sieved through a 2 mm mesh. Crude oil was collected from (OML 30) Afriesereflowstation. The organic waste (plantain peels) were collected from different food canteens on FUPRE campus. The organic wastes were sun-dried for 14 days and ground into fine powder to obtain a uniform particle size and stored in a sterilized airtight plastic container.

CHAPTER FOUR

RESULTS AND DISCUSSION

Physiochemical Properties of Soil and Biostimulant (Plantain Peels)

Table 4.1 Physiochemical Properties of Soil Sample

CHAPTER FIVE

CONCLUSION AND RECOMMENDATION

Conclusion

This research work focused on the development of a waste based biostimulant for the remediation of crude oil contaminated soil. The biostimulant so developed is of Plantain peels(PP). The physiochemical analysis performed on the agro waste revealed that PP is very rich in NPK(nitrogen Phosphorus and potassium) with values 0.81, 0.29 and 0.49(%) respectively; Which in turn serve as nutrient base for the hydrocarbon degraders (bacterial and fungi) identified from the soil sample. Hence there was no need for nutrient supplementation in the remediation process. eroth order kinetic model was used to describe the biodegradation process instead of 1^st order kinetics model because it best fits the model. From the results obtained in Table 4.7, the rate of biodegradation (K) was 2902.9, 3131.7, 3477.1, 3778.4 and 4131.9(day^-1) at 100,150, 200, 250 and 300(g) treatment respectively. Also, the percentage biodegradation increased as the treatment level increases. Hence, %D increased from 39.21984>42.07881>46.47457>50.7433>55.98218(%) as biostimulant treatment increased from 100>150>200>250>300(g) with biodegradation efficiency of 93.89>94.31>94.85>95.28>95.72(%). Percentage Biodegration of over 50% and Bioremediation efficiency of 95% revealed that the biostimulant (Plantain peel) is an effective agro waste for bio-remediation processes considering a remediation period of 28days and the results obtained may likely improve if the remediation period is extended.

The experimental results obtained were optimized using Box-Behnken model in response surface methodology (RSM) of Design Expert statistical software (Version 10.0.7). It was discovered that the optimum value of TPH and HUB were 14190.9mgKg and 2.34162cfug at mass A=282.312g, time B= 3.38379wks and temperature C= 21.3207^oC. A polynomial model of a quadratic order was used to arrive at the result so obtained. R² value for the optimized model was 0.9987 and that of the kinetic model was between 0.9828 to 0.9846; hence there is a correlation between both models.

The remediation technique employed in this study was a simple, cheap, effective and environmentally friendly approach to remediating crude oil contaminated soil samples and the biostimulant is readily available and compatible with the environment.

Recommendation

From the obtained results, it is clear that plantain peels is an effective waste based biostimulant for the remediation of crude oil contaminate soils and both kinetic and optimization models can be used to represent the behavior of process factors and prediction of performance (response). The design generated can be used for the design of a treatment plant for the remediation of crude oil contaminated sites where percentage degradation can be achieved on a large scale.

The results obtained from this study may not be 100% accurate. Hence there is a need for futher research in the following areas:

Analysis of physiochemical factors affecting remediation of contaminated soil.
Comparative studies of crude oil contaminated soils using different biostimulant
The use of a different optimization model other than Box-Behnken in the optimization of the process e.g factorial model.

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