Table 2
Physicochemical and microbiological characteristics of soil used for the study
PARAMETERS OFSAMPLES ANALYZED/ UNITS | FOSSIL OIL CONTAMINATED SAMPLE | NATURAL CONTROL | SOIL | FOSSIL OIL |
---|
C% | 2.44 | 0.669 | | 2.969 |
N03ppm | 0.091 | 1.335 | | NIL |
Phosphate | 0.244 | 0.287 | | NIL |
Ca% | 0.863545 | 0.441133 | | 0.23786 |
Mg% | 0.020542 | 0.012565 | | 0.002699 |
K% | 0.269008 | 0.357037 | | 0.123716 |
Na% | 0.005853 | 0.004552 | | 0.008581 |
Cr% | 0.000086 | 0.000132 | | 0.000086 |
Co% | 0.000106 | 0.000072 | | 0.000072 |
Cd% | 0.000054 | 0.000043 | | 0.000031 |
Se% | 0.000403 | 0.000297 | | 0.000197 |
Pb% | 0.00056 | 0.00323 | | 0.000273 |
Mn% | 0.001103 | 0.001924 | | 0.000288 |
Cu% | 0.000369 | 0.000862 | | 0.000271 |
Zn% | 0.00072 | 0.000343 | | 0.000199 |
Fe% | 0.008012 | 0.022919 | | 0.001233 |
Ni% | 0.000228 | 0.000164 | | 0.000114 |
Ph | 5.75 | 7.84 | | |
Elect.Cond.(EC) | 56.90 | 102.80 | | |
Temperature | 28.00 | 28.00 | | |
CEC | 9.60 | 3.30 | | |
TPH | 7488 | 8.54 | | |
Keys:
Carbon (C) Potassium (K) Selenium (Se) Iron (Fe)
Nitrate (NO3) Sodium (Na) Lead (Pb) Nickel (Ni)
Phosphate (P) Chromium (Cr) Manganese (Mn) Potential of Hydrogen (pH)
Calcium (Ca) Cobalt (Co) Copper (Cu) Electrical Conductivity (EC) Magnesium (Mg) Cadmium (Cd) Zinc (Zn) Cation Exchange Capacity (CEC).
In Table 2, the pH of the impacted soil was 5.75 ± 1 (acidic), while the pH of the unaffected soil was 7.84 ± 1 (alkaline). Following the American Public Health Association’s recommended methodology [40], the following soil properties were examined: texture, electrical conductivity, moisture content, nitrogen, total organic carbon, and phosphate. Heavy metal analysis revealed that the polluted and the natural soil had a lead
Table 3: Organic Compost and its composition
PARAMETERS | RESULTS |
---|
Ph | 8.00 |
Conductivity (µs/m) | 13830 |
Temperature (◦C) | 27.90 |
Nitrate (mg/kg) | 309.93 |
Total organic carbon (%) | 118.08 |
Moisture content (%) | 1.70 |
Table 4 Characterization of the Biomass
Nano Particles | Characterization Techniques |
---|
| Scanning electron microscopy analysis (SEM) Transmission Electron Microscope (TEM) |
Nano Particles | CharacterizationTechniques | Results |
| UV-Vis spectroscopy | Green fluorescence of carbon dot under ultraviolet light |
| EDX (Energy dispersive X- Ray) | Displayed the various elements present in the carbon dot |
Carbon dot (C-dot) | X-ray diffraction analysis | It indicates the graphite crystal structure of the carbon dot |
concentration of (0.00056 and 0.00323) compared to nickel (0.000228 and 0.000164) and cadmium (0.000054 and 0.000043). Inductively coupled plasma (ICP-OES) was used to analyze some of the heavy metals present in the sample. Nitrate and phosphate concentrations in the soil were 0.091 and 1.335 ppm, 0.244 and 0.287 mg/kg, respectively. The soil exhibited CEC values of 9.60 and 3.30. The concentrations of calcium (Ca), magnesium (mg), potassium (K), and sodium (Na) in the various soil samples are 0.863545% and 0.441133%; 0.020542% and 0.012565; 0.269008% and 0.357037; 0.005853% and 0.004552%.
Table 5 shows that identification was accomplished by removing the samples’ geneomic DNA using the ZymoBIOMICS DNA Microprep Kit (Zymo Research, Catalogue No. D4031). Five of the isolates were gram positive rod formers and two were gram negative using the culture dependent and culture independent (molecular) methods. Bacillus thuringiensis,Bacillusvelezensis, and Lysinibacillus fusiformis are the isolates. Using the nutrient broth, consortia of the used organisms were scaled up. Both the culture dependent and culture independent methods were used to identify them based on their macroscopic, microscopic, and biochemical traits [8]. Utilizing microorganisms that consume hydrocarbons has been shown to have an antagonistic effect on the harmful effects of petroleum. These bacteria are screened and used as environmental remediation agents, which speeds up the removal of these contaminants from the environment. By altering their exterior mechanism and secreting bioemulsifiers to improve their contact to aim the hydrocarbon substrates, these bacteria increase the holding capacity of cells according to [23, 25].
As shown in Fig. 2, the biosynthesis of carbon dot materials using plant materials is known as phyto nanotechnology. This method is highly encouraged to reduce the use of toxic chemicals during synthesis and to produce eco-friendly, straightforward, and economically viable nanomaterials that are scalable, biocompatible, and simple to synthesize using water as the universal solvent. These nanomaterials have longer half-lives, improved uniformity, and finer particle sizes [20, 38]. Significant levels of potassium and minor concentrations of magnesium, calcium, copper, zinc, and iron were found in carbondot (CD), which may boost the fertilizer’s value. With few adjustments, the hydrothermal process was used to create the biomass (coconut shaft [39, 42]. Figure 3’s EDX findings showed 69.10% for C, 7.20% for O, 2.22% for Na, 3.20 for Fe, 0.23 for Ca, and 0.33 for Si. This simply demonstrated that the plant extract did more than just act as a bioreductant; it also stabilized and capped the nanopa, which may be attributed to the biomolecules of the plant extract. Soil carbon provides nutrients through mineralization, helps to aggregate soil particles (structure), and provides resilience to physical degradation. It also increases microbial activity, water storage, and availability to plants, and protects the soil from erosion. By using a scanning electron microscope (SEM), it was possible to analyze the morphological properties of the carbon dot recovered from the coconut shaft. The micrograph in Fig. 4 shows that the nanoparticles are consistently sized and oblong in shape.However, a few pores were also seen in the micrographs, which will facilitate the nanoparticles’ surface mobility. The presence of apparent and visible holes in the coconut shaft, as revealed by SEM morphology, indicates that the chemical activation activities of the carbon were effective. According to this study, chemically activated carbon adsorbents derived from biomass are a great alternative to synthetic adsorbents like silica gel for removing contaminants.
Figure 5 depicts cocci-shaped, separated, and spherically packed nanoparticles from transmission electron microscopy (TEM). Along with validating growth direction and crystal quality in agreement with the results of [4], the image also showed cocci appearance of the nanoparticles. Figure 7 illustrates how the uncovered eye of the UV-visible spectroscopy depicts the biomass synthesis, demonstrating its color change from brown to greenish. With an absorption peak at 342 nm, UV-visible spectroscopy was used to confirm the nanoparticles’ production. The measured absorbance value indicates a high biomass concentration, and the wavelength of absorption is consistent with previous studies [1]. In the study by [16, 18]. As shown in Fig. 6, the X-ray detects the structural layers based on the d-spacing of the clay minerals. The d-spacing is the precise distance between the crystal lattices that are staked, and it represents how the atoms in a material are visible. When the X-ray passes through the clay samples, it produces peaks that are typical of each type of diffracted along a combination of planes, and the way they are diffracted is what makes the presentation of the atoms within the mineral distinctive.
In Table 5, the research’s findings showed that the bacterial consortia, when used in conjunction with other organic amendments (compost, carbon dot, and composite microbial culture), has a significant catalytic effect on hydrocarbon in any form. Tables 8, 9, 10 and 11 from the study’s findings show that the following biomass were used both separately and in combination to design the setup. As a result, compost from food waste and carbon dots from coconut husk were sourced locally, and for the composite microbial culture in consortium, they were isolated from the affected soil.(Bacillus thuringiensis, Bacillus velezensis, and Lysinibacillus fusiformis). The setup was created in three identical copies, and it was observed in the lab at room temperature (25?270 ) for a duration of 0–84 days, [5]. During this period some parameters were analysed and result realized using the Gas chromatography flame induction detector (GC-FID) revealed that the control (Natural attenuation) were in the range of 1071.62 ± 0.54 and 84.27 ± 0.01, for the 1.0% whereas the 10% recorded 12504.50 ± 0.71 and 200.08 ± 0.16 within the period of exposure, drastic reduction of TPH was observed within the early and the final stage of the laboratory experiment. For the biostimulation set up, Composite microbial culture (CMC) with three concentrations, A were within the range of 948.46 ± 0.07 and 29.7 ± 0.01, while B was within 110.07 ± 0.10 and 21.95 ± 0.08, C was within 99.99 ± 0.01 and 13.88 ± 0.04, the reduction of the TPH was so drastic that it was almost within detectable limit especially with concentration A as this is a true fact that microbes has catalytic effect on hydrocarbons, for Carbon dot, concentration A were within 1026.52 ± 0.01 and53.88 ± 0.00, while for the B they are 455.71 ± 0.15 and 11.54 ± 0.01, for C 182.38 ± .011 and 1.37 ± 0.01, whereas for the Compost concentration A recorded 1506.21 ± 0.01 and 55.00 ± 00.71, for B they were within the range of 455.81 ± 0.01 and 12.56 ± 0.01 and for concentration C they were: within the range of 46.00 ± 0.00 and 1.77 ± 0.01,for the Biostimulation and Bioaugumentation, concentration A were within the range of 1006.76 ± 0.06 and 45.10 ± 0.01, for B it recorded 553.67 ± 0.22 and 15.63 ± 0.04, for C it was 214.77 ± 0.15 and 4.13 ± 0.01 respectively, Fossil fuels are complex mixtures of aliphatic and aromatic compounds that require diverse bacterial genus with dissimilar catabolic genes to completely mineralize them. This is due to the fact that various bacterial species have various catalytic enzymes, which causes a wide range in their contributions to fossil fuel-contaminated locations [13, 46].
Table 5
Consortium of microorganisms used
SAMPLE IDENTITY | PERCENTAGE | GenBank ACCESSION NUMBER |
---|
Bacillus thuringiensis | 97.18% | CP044978.1 |
Lysinibacillus fusiformis | 94.84% | FJ418643.1 |
Bacillus velezensis | 84.83% | CP045835.1 |
Table 6
Naturalattenuation(Control) | Impacted soil and Natural soil | Polluted soil (1.0g) | |
---|
Bioaugumentation using (CMC) | Composite microbial culture | 60g(Consortium of organisms) | 6g (Consortium of organisms) |
---|
CS(Contaminated sample) | 40g (polluted sample) | 4g (polluted sample) | 0.4g (polluted sam- ple) |
NS (Natural sample) | 900g(unpolluted sample) | 990g(unpolluted sample) | 999g(unpolluted sample) |
TOTAL | 1000g | 1000g | 1000g |
Table 7
Experimental Design of GC-FID Result Presented in Mean Standard Deviation
Exposure Period (Days) | A (1%) | B (10%) |
---|
0 | 1071.62 ± 0.54 | 12504.50 ± 0.71 |
28 | 423.76 ± 0.03 | 756.39 ± 0.19 |
56 | 119.79 ± 0.26 | 267.41 ± 0.24 |
84 | 84.27 ± 0.01 | 200.08 ± 0.16 |
Natural attenuation (Natural and Contaminated soil) 1000g (100,000mg/l and 10,000mg/l)
Table 8
Experimental Design of GC-FID Result Presented in Mean Standard Deviation
Exposure Period (Days) | A | B | C |
---|
0 | 948.46 ± 0.07 | 110.07 ± 0.10 | 99.99 ± 0.01 |
28 | 600.13 ± 0.91 | 84.90 ± 0.01 | 60.25 ± 0.01 |
56 | 54.73 ± 0.01 | 47.76 ± 0.01 | 25.55 ± 0.01 |
84 | 29.7 ± 0.01 | 21.95 ± 0.08 | 13.88 ± 0.04 |
Biostimulation (Composite Microbial Culture) 1000g |
A = 60;40:900 = 100,000mg/kgB = 6:4:990 |
= 10,000mg/kgC = 0.6;0.4:999 = 1000mg/kg |
Table 9
Experimental Design of GC-FID Result Presented In Mean Standard Deviation
Exposure Period (Days) | A | B | C |
---|
0 | 1026.52 ± 0.01 | 455.71 ± 0.15 | 182.38 ± 0.011 |
28 | 859.97 ± 0.04 | 98.45 ± 0.07 | 55.81 ± 0.01 |
56 | 182.38 ± 0.11 | 32.80 ± 0.01 | 16.50 ± 0.71 |
84 | 53.88 ± 0.00 | 11.54 ± 0.01 | 1.37 ± 0.01 |
Biostimulation (Carbon dot) : 1000g |
A = 60;40:900 = 100,000mg/kgB = 6:4:990 |
= 10,000mg/kgC = 0.6;0.4:999 = 1000mg/kg |
Table 10
Experimental Design of GC-FID Result Presented In Mean Standard Deviation
Exposure Period (Days) | A | B | C |
---|
0 | 1506.21 ± 0.01 | 455.81 ± 0.01 | 46.00 ± 0.00 |
28 | 1089.73 ± 0.00 | 105.36 ± 0.01 | 27.96 ± 0.01 |
56 | 209.63 ± 0.52 | 49.26 ± 0.36 | 19.17 ± 0.01 |
84 | 55.00 ± 0.71 | 12.56 ± 0.01 | 1.77 ± 0.01 |
Biostimulation (Compost) 1000g A = 60;40:900 = 100,000mg/kgB = 6:4:990 = 10,000mg/kgC = 0.6;0.4:999 = 1000mg/kg |