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

Author(s):  
V. G. Awari ◽  
D. N. Ogbonna ◽  
R. R. Nrior

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

Author(s):  
D. N. Ogbonna ◽  
S. A. Ngah ◽  
R. N. Okparanma ◽  
O. Ule ◽  
R. R. Nrior

Aim: The aim of the study was to assess Percentage Bioremediation of Spent Mushroom Substrate (SMS) and Mucor racemosus in hydrocarbon contaminated soil Place and Duration of Study: A portion of Rivers State University demonstration farmland in Nkpolu-Oroworukwo, Mile 3 Diobu area of Port Harcourt, Rivers State was used for this study. The piece of land is situated at Longitude 4°48’18.50’’N and Latitude 6o58’39.12’’E measuring 5.4864 m x 5.1816 m with a total area of 28.4283 m2. Bioremediation monitoring lasted for 56 days, analysis carried out weekly (per 7 days’ interval). Methodology: Five (5) experimental plots employing the Randomized Block Design were used each having dimensions of 100 x 50 x 30 cm (Length x Breadth x Height) = 150,000cm3. Baseline study of the uncontaminated and the deliberately contaminated agricultural soil was investigated for its microbiota and physico-chemical properties. Two of these plots were designated as pristine (Unpolluted soil) (CTRL 1) and crude oil contaminated soil without nutrient organics and bioaugmenting microbes (CTRL 2); these two serve as controls. Each of the experimental plots, except the control (CTRL 1), was contaminated with 2500 cm3 (2122.25 g) of crude oil giving initial Total Petroleum Hydrocarbon (TPH) value of 8729.00 mg/kg. The crude oil polluted soil in Plot 3 was further treated with 750 ml of Mucor racemosus broth (CS+Muc), Plot 4 was treated with 3000 g of Spent Mushroom Substrate (CS+SMS) while plot 5 was treated with the combination of both (CS+Muc+SMS). The plots were left for 7 days to ensure even distribution and soil-oil bonding. Sampling was done at seven-day interval (Day 1, 7, 14, 21, 28, 35, 42, 49, 56).  Physicochemical parameters monitored were pH, Temperature, Nitrogen, Phosphorus, Potassium, and Total Petroleum Hydrocarbon (TPH) throughout the experimental period. Microbial parameters monitored were Total Heterotrophic Bacteria (THB), Total Heterotrophic Fungi (THF), Hydrocarbon Utilizing Bacteria (HUB) and Hydrocarbon Utilizing Fungi (HUF). Percentage (%) Bioremediation was estimated from percentage (%) reduction of Total Petroleum Hydrocarbon (TPH) from day 1 to day 56 in relation to control plots.  Net % Bioremediation were also assessed to ascertain the actual potential of treatment agents singly or combined. Results: Total Heterotrophic Bacteria (THB) (CFU/g) recorded on day 7 and day 56 of the bioremediation were; day 7; CTRL 1 – US (1.07 x109), CTRL- CS (5.4 x108), CS+Muc (3.0 x108), CS+SMS (4.6 x108) and CS+Muc+SMS (5.0 x108). On day 56, data obtained were CTRL 1 –US (9.4 x108), CTRL 2 –CS (7.2 x109), CS+Muc (3.7 x108), CS+SMS (8.1x108) and CS+Muc+SMS (6.8 x108). The increase in number in the treated plots is a depiction of an increase in activity of the organism and the stimulating effect of bio-organics SMS while the untreated plot CTRL 1-US showed decrease in population at day 56. Similar trend showed for Total Heterotrophic Fungi. Generally, it was observed that the highest growth/ count was recorded at the 7th and 8th week (day 42 or day 49), at the 9th week there was an observable decrease; probably due to depletion of nutrients and other factors such as rainfall and seepage. The Net Percentage Hydrocarbon Utilizing Bacteria and Fungi (Net %HUB and Net %HUF) were highest in Crude Oil contaminated plot treated with Spent Mushroom Substrate (SMS) singly; that is (CS+SMS) (11.02% and 12.07%) and lowest in the uncontaminated soil – Control (CTRL 1 –US) (5.41% and 9.26%) respectively. The trend in decreasing order of Net % Hydrocarbon Utilizing Bacteria were as follows: CS+SMS (11.02%) > CS+Muc+SMS (10.14%) > CS+Muc (9.43%) > CTRL 2 –CS (8.1%) > CTRL 1 –US (5.41%) while Net % Hydrocarbon Utilizing Fungi followed similar trend and were: CS+SMS (12.07%) > CS+Muc+SMS (11.76%) = CS+Muc (11.76%) > CTRL 2 –CS (11.05%) > CTRL 1 –US (9.26%). Evaluation of Amount of Crude Oil or Hydrocarbon remediated and Net %Bioremediation revealed Crude Oil contaminated plot augmented with Mucor racemosus broth singly (CS+Muc) as having the highest bioremediation potential while the least is the untreated soil. The trend is as follows:  CS+Muc (8599.19 mg/kg; 33.93%) > CS+Muc+SMS (8298.95 mg/kg; 32.74%) > CS+SMS (8197.03 mg/kg; 32.34%) > CTRL 2 –CS (166.54 mg/kg; 0.66%) > CTRL 1 –US (85.48 mg/kg; 0.34%) Conclusion: This shows that a single nutrient substrate or augmenting microorganism applied appropriately may have a more positive result, that is; higher bioremediation potential than combined or multiple mixed treatments. It was further observed that microbial counts decreased with time in treatments with augmenting organisms alone but increased considerably in treatments supplement with organics having its peak on the 49th day.   It is therefore recommended that bioremediation of crude oil-polluted soil using bio-augmenting microorganism should be applied appropriately noting the volume: area ratio and be supplemented with efficient nutrient organics after every 49-day interval.


Author(s):  
David N. Ogbonna ◽  
Renner R. Nrior ◽  
Festus E. Ezinwo

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


Author(s):  
Barisiale Baranu ◽  
Chimezie Ogugbue ◽  
Gideon Okpokwasilli

This study identified the efficacy of different amendments as biostimulants in bioremediation. This experiment was carried out for 4 weeks in the laboratory. One kilogram of pristine soil was spiked with one liter of crude oil in earthen pots, to each pot 10 grams of amendments were added and mixed thoroughly. The amendments used were poultry dropping (C-PD), cow dung (D-CD), N.P.K (E), and a control (A and B) setup undergoing natural attenuation. The microcosms’ initial physicochemical characteristics such as total organic nitrogen, pH, temperature, total organic carbon, total petroleum hydrocarbon (TPH), and polyaromatic hydrocarbon (PAH). The microbial enumeration was done for total heterotrophic bacteria (THB) and hydrocarbon utilizing bacteria (HUB). The molecular characterization of the pristine soil (A) and contaminated soil (B) was also done using the shotgun analysis. The THB of A and B was 1.3 x 107 and 2.1 x 102 while the HUB was 1.63 x 105 and 1.1 x 101on day 1 respectively. The THB of treatments during bioremediation at week 2 was 1.75 x 108, 1.89 x 108, 1.5 x 108 and 2.2 x 108 while at week 4, the THB was 1.90 x 108, 2.1 x 108, 2.20 x 108 and 2.25 x 108 while the HUB at week 2 was 1.20 x 105, 3.0 x 105, 2.5 x 105 and 1.98 x 105 while at week 4, the HUB was 2.0 x 106, 2.19 x 106, 2.46 x 106 and 2.1 x 106 for B, PD, CD ,and N.P.K respectively. The molecular characterization of A and B showed there was a higher microbial diversity in the contaminated soil than in the pristine soil. This study has shown that cow dung is more effective in the bioremediation of total petroleum hydrocarbon, and polyaromatic hydrocarbon in crude oil-contaminated soil.


Author(s):  
Mariana MARINESCU ◽  
Anca LACATUSU ◽  
Eugenia GAMENT ◽  
Georgiana PLOPEANU ◽  
Vera CARABULEA

Bioremediation of crude oil contaminated soil is an effective process to clean petroleum pollutants from the environment. Crude oil bioremediation of soils is limited by the bacteria activity in degrading the spills hydrocarbons. Native crude oil degrading bacteria were isolated from different crude oil polluted soils. The isolated bacteria belong to the genera Pseudomonas, Mycobacterium, Arthrobacter and Bacillus. A natural biodegradable product and bacterial inoculum were used for total petroleum hydrocarbon (TPH) removal from an artificial polluted soil. For soil polluted with 5% crude oil, the bacterial top, including those placed in the soil by inoculation was 30 days after impact, respectively 7 days after inoculum application, while in soil polluted with 10% crude oil,  multiplication top of bacteria was observed in the determination made at 45 days after impact and 21 days after inoculum application, showing once again how necessary is for microorganisms habituation and adaptation to environment being a function of pollutant concentration. The microorganisms inoculated showed a slight adaptability in soil polluted with 5% crude oil, but complete inhibition in the first 30 days of experiment at 10% crude oil.


Author(s):  
B. M. Popoola ◽  
A. A. Olanbiwonninu

Biodegradation of hydrocarbons by microorganisms represents one of the primary mechanisms by which petroleum and other hydrogen pollutants are eliminated from the environment. This work was carried out on the effect of microorganisms on the biotreatment of oil in crude oil contaminated soil. Microorganisms were isolated from two experimental soil samples contaminated with Bonny Crude and normal uncontaminated soil as a control over a period of seven months. The microbial as well as the physico-chemical parameters of the soil samples were all analyzed using standard methods. Changes in total petroleum hydrocarbon level were measured appropriately. Treatments used were the microbial isolates. Forty-four microorganisms were isolated from the contaminated soils and identified as species of Pseudomonas (7), Flavobacterium (6), Bacillus (8), Proteus (4), Klebsiella (1), Pencillium (5), Aspergillus (7), Fusarium (3), Trichypton (2) and Neurospora (1). Ten of the forty-four isolates had ability to degrade crude oil in the laboratory. On contamination a value of 1.0X105 cfu/g in microbial counts were obtained followed by a subsequent increase in population levels after a period of 2months with a value of 1.0X106 cfu/g. Oil application to the soil resulted in an increase in total petroleum hydrocarbon from 0.31 ppm to 5.53 ppm; organic matter from 0.41% to 7.34%; available phosphorus from 1.75 ppm to 2.84 ppm. The treatment measures all showed progressive decrease in oil concentration in the soil. Mixture of bacterial and fungal isolates as a treatment measure proved to be more favourable above all others, it brought the concentration from 5.53 ppm to 0.31 ppm after a period of 5 weeks of treatment, which is same value with the normal soil (uncontaminated). Species of Pseudomonas, Bacillus, Flavobacterium, Proteus, Klebsiella, Penicillium, Aspergillus, Fusarium, Trichyphyton and Neurospora had potential for the degradation of bonny crude oil. They could therefore be employed in environmental cleanup of petroleum spill site.


Author(s):  
David N. Ogbonna ◽  
I. K. E. Ekweozor ◽  
Renner R. Nrior ◽  
Festus E. Ezinwo

Aim: The aim of the study was to evaluate the impact of organic nutrient supplements and bioaugmenting microorganisms on crude oil polluted soils. Place and Duration of Study: Faculty of Agriculture Demonstration Farm, Rivers State University, Port Harcourt Nigeria. Methodology: Baseline study of a deliberately polluted agricultural soil was investigated for its microbiota from which selected fungal and bacterial isolates were obtained. Microbial analyses of goat manure, fish wastes and crude oil polluted soil were investigated. Using the Randomized Complete Block Design (RCBD) the land was partitioned into nine (9) blocks of 100 cm x 50 cm x 20 cm (Length x Breath x Height) giving 100,000 cm3 each. Two of these plots were designated as pristine (Unpolluted soil) and crude oil polluted soil without nutrient organics and bioaugmenting microbes to serve as controls respectively. Each of the experimental plots, except the control, was contaminated with 1,700 g of crude oil giving initial Total Petroleum Hydrocarbon (TPH) value of 9.296.825 mg/kg. The plots were left for 21 days to ensure even distribution and soil-oil bonding. All plots except Control 1 (plot 1) were separately and deliberately contaminated with 1,700 g of crude oil given Total Petroleum Hydrocarbon (TPH) value of 9.296.825 mg/kg. Sampling was done at seven day interval (Day 1, 7, 14, 21, 28, 35, 42, 49, 56).  Parameters monitored were Nitrate, Sulphate, Phosphate, Total Organic Carbon (TOC) and Total Petroleum Hydrocarbon (TPH), were monitored throughout the experimental period. Microbial analyses such as Total Heterotrophic Bacteria (THB), Total Heterotrophic Fungi (THF), Hydrocarbon Utilizing Bacteria (HUB) and Hydrocarbon Utilizing Fungi (HUF). Percentage (%) Bioremediation was estimated from percentage (%) reduction of Total Petroleum Hydrocarbon (TPH) from day 1 to day 56 in relation to control plots. Results: Two fungal; Aspergillus niger (Asp), Mucor racemosus (Muc); and two bacterial species – Bacillus armyloliqquefaciens strain FJAT-45825 (Bac) and Pseudomonas aeruginosa strain CL 9 (Pse) isolated from a baseline study showed biodegradability potentials. The physicochemical characteristics of organic nutrient supplement - goat manure (GM) and fish wastes (FW) employed in the study showed that it contained valuable sources of organic nutrients which enhanced the bioremediation process of the Crude oil polluted soil (PS). Mean counts of Hydrocarbon Utilizing Bacteria (HUB) and Hydrocarbon Utilizing Fungi {HUF} (Log10 CFU/g) respectively were: Control 2 which is crude oil Polluted soil (PS) (5.52±0.47, 4.92±0.29); PS+GM (5.832±0.68, 5.33±0.54); PS+FW (5.76±0.40, 5.10±0.40); PS+GM+FW (5.706±0.61, 5.17±0.27); PS+Asp+Muc (5.722±0.48, 5.08±0.49); PS+Bac+Pse (5.34±0.69, 5.01±0.52}; PS+Asp+Muc+Bac+Pse (5.652±0.48, 5.10±0.52}; PS+Asp+Muc+Bac+Pse+GM+FW (5.212±0.40, 4.76±0.53}. Evaluation of Bioremediation revealed the actual amount of crude oil (hydrocarbon) reduction and its percentage value from the initial contamination value of 9296.83 mg/kg during the period of 56days as PS+Asp+Muc+Bac+ Pse+GF+FW (9152.315 mg/kg; 98.45%) > PS+Bac+Pse+GF+FW (8032.825 mg/kg; 86.40%) > PS+GF+FW (6867.825mg/kg; 73.87%) > PS+Asp+Muc+GF+FW (6599.825 mg/kg; 70.99%) > PS+Bac+Pse (6587.825mg/kg; 70.86%) > PS+FW (6441.825 mg/kg; 69.29%) > PS+GM (5909.825 mg/kg; 63.57%) > PS+Asp+Muc+Bac+Pse (5081.825 mg/kg; 54.66%) > CTRL 2 (Polluted soil without amendment) (3604.825 mg/kg; 38.78%). Conclusion: Results obtained from this study has shown that goat manure and fish wastes due to their high moisture and nutrient content properties makes them appropriate agents for enhanced bioremediation. It further revealed that a combination of biostimulating and bioaugmentating agents creates more favorable conditions for biological activity to thrive and has shown to be effective, economical, eco-friendly and sustainable in remediating organic pollutants from polluted soils.


REAKTOR ◽  
2019 ◽  
Vol 19 (2) ◽  
pp. 84-88
Author(s):  
Lely Fitriyani ◽  
Edwan Karadena ◽  
Sukandar Sukandar

Solvent extraction has been used as a method to wash oil content of oily contaminated soil in industry for years. Some solvents and temperature ranges has been chosen to increase the oil recovery rate of extraction process, however only few studies reported that it has been able to reach remaining Total Petroleum Hydrocarbon (TPH) less than 0.5% in less than 30 minutes. During the experiments, acetone and toluene chosen to extract oil content from contaminated soil by using solvent extraction process. Temperature selected were between 24°C up to 70°C. Mixing apparatus which has been utilized was centrifugation machine with 1000 rpm (1570 g) operational speed. Duration of treatment process was 10 minutes with some variations of solid to solvent ratio. During the experiments, it was observed that by using toluene and acetone as solvents, the optimum Total Petroleum Hydrocarbon (TPH) removal obtained at temperature 50°C. In the other hand, optimum solid to solvent ratio toluene ratio was 1:6. As a solvent acetone observed capable to reduce TPH content until below 0.5% as threshold limit for TPH of contaminated soil regulated by environmental regulation in Indonesia. During the experiments it was also observed the dependency of solid concentration (Cs) with dissociation coefficient (KD). In the other hand, heavy metal at the remaining extracted soil after soil washing was observed available in safe concentration to be discharged to the environment base on regulation in Indonesia. Keywords: solvent extraction, soil washing, contaminated soil, TPH, centrifugation, oil sludge, acetone, toluene, solid treatment.


Author(s):  
F. B. G. Tanee ◽  
K. Jude

Investigation on the use of urea in stimulating the phytoremediation of Chromolaena odorata in a crude oil contaminated soil was carried out at a crude oil spilled site at Botem-Tai, Ogoni, Nigeria. Three phytoremediation treatments labeled A – C in addition to the control (D) were used. The treatments were: A (Chromolaena odorata only), B (Chromolaena odorata + 20 g/m2 urea), C (Chromolaena odorata + 40 g/m2 urea), D (polluted soil without phytoremediation) arranged using Latin Square Design (LSD). Total petroleum hydrocarbon (TPH) and Total hydrocarbon content (THC) in soil and plant samples from the different treatment plots in addition to other soil nutrients were analyzed. The percentage reduction in TPH and THC in soil were as follows: Treatment B, {TPH (92.08%) and THC (95.37%)} > treatment A {TPH (88.95%) and THC (93.37%)}> C {TPH (78.78%) and THC (83.29%)} > Control {TPH (14.76%) and THC (32.90%)}. Treatment C had the highest TPH (2.67 mg/kg) and THC (20.57 mg/kg) accumulation in test   plant. Combining stimulant (urea) with phytoremediation also improved soil properties such  as pH, Nitrogen and Potassium. With the highest reduction of TPH and THC in treatment B (phytoremediation with 20 g/m2 urea) than other treatments is an indication that low   concentration of urea has a stimulatory effect on phytoremediation of crude oil by Chromolaena odorata.


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