Phytoremediation Of Crude Oil Contaminated Soil Research Articles

Phytoremediation of crude oil-contaminated soil using Vigna Unguiculata and associated rhizosphere bacteria

Persistent crude oil contamination poses a significant environmental challenge. In this study, the efficacy of Vigna unguiculata (L.) and associated rhizospheric microorganisms in remediating crude oil-contaminated soil within a microcosm setting was investigated. A randomized block design was employed, and soil samples were subjected to varying degrees of contamination: 0% (UR), 2.5% (CR2), 5.0% (CR5), 7.5% (CR7), and 10.0% (CR10) w/w crude oil. The investigation aimed to assess the potential of Vigna unguiculata (L.) in mitigating crude oil contamination across these defined contamination gradients. The plant growth and crude oil removal were monitored concurrently post-emergence. Plant emergence and growth were significantly affected due to contamination, especially among plants in CR5 and CR10. The bacterial population was higher in the rhizosphere, and the treatments with lower hydrocarbon contamination. It was shown that plant density encouraged the growth of bacterial communities. Significant reduction in soil TPH was observed in CR2 (76.61%) and CR7 (65.88%). There was a strong correlation between plant growth and oil-utilizing bacterial population (r2 = 0.966) and plant growth and hydrocarbon reduction (r2 = 0.956), signifying the role of plant-bacterial synergy. Saturate fractions (C30 – C32) were significantly degraded to lower molecular weight compounds (C11 – C14). Except in CR5 and CR10, the remediation within the cowpea rhizosphere was effective even at regulatory standards. Understanding the rhizosphere ecological dynamics would further highlight the role the bacteria played; hence, it is recommended.

Enhanced Phytoremediation and Physicochemical Parameters of Crude Oil Polluted Soil Using Pseudomonas fluorescens and Bacillus substilis

There have been worry over the Niger Delta's environmental contamination. Bacteria and other microorganisms have shown to be very helpful in the breakdown of hydrocarbons generated from petroleum. The goal of this research is to use elbow bufallow grass and sedge plants for phytoremediation of soil affected by crude oil. Standard microbiological techniques were applied to the contaminated soil once it was gathered. Using a hand auger, contaminated soil samples were taken twice a month for three months from two separate locations in Rivers State at two distinct depths: 0–15 cm and 15–30 cm. The following physicochemical parameters of samples were analysed using Standard Laboratory Procedures: pH, Temperature, Nitrogen, Phosphorus, Potassium available in the polluted soil and the total hydrocarbon content (THC). Two plant species common in the Ogoni region of Rivers state, i.e. Sedge plant (Schoenoplectus), Elbow buffalo grass (Panicum subalbidum) were used for phytoremediation monitoring. A combination of treatment consisting of the application of Pseudomonas fluorescens Bacillus substilis, Panicum subalbidum and Schoenoplectus senegalensis was evaluated during 28 days of remediation. Each pot contained crude oil mixture in the soil as a sole source of carbon and energy. THB counts ranged from 2.35 to 4.15 cfu/g. The statistical analysis revealed that there was no significant difference (p>0.05) in the total heterotrophic bacteria counts between the samples. HUB counts range from 0.7 to 1.45cfu/g. The total bacterial population counts obtained from soil sample during bioremediation monitoring ranged from 17+1.41 (CS+PAN) to 40+1.412cfu/g (CS+PSE+BAC+PAN) in Day 1. Results of Day 14 range from 13+1.41 (CS+PAN) to 35.5+3.542cfu/g (CS+BAC+SCH). Results of Day 28 ranged from 8.5+0.71 (CS+PAN) to 27+1.412cfu/g (CS+PSE+BAC+PAN). The presence of microbial activity was determined by the enumeration and isolation of total heterotrophic and hydrocarbon utilizing bacteria. The results of physicochemical parameters before bioremediation is as follows: pH (5.43), Temperature (27oC), Electrical conductivity (9), Moisture content (7.80%), Total organic carbon (0.93%), Soil organic matter (1.60%), Nitrogen (56.695mg/kg), Phosphorus (0.621mg/kg), Potassium (7.125mg/kg) and Total Hydrocarbon content (700mg/kg). Results revealed amount of soil hydrocarbon removed and percentage (%) Bioremediation remediated after 28 days of monitoring to be higher in set up with CS+PSE+SCH (3454mg/kg; 85.28%) and lowest in set up with US+SCH (434mg/kg: 62%) and the amount of root hydrocarbon content removed and percentage (%) Bioremediation remediated after 28 days of monitoring to be higher in set up with CS+BAC+SCH (632Mg/kg; 15.6%) and lowest in set up with US+SCH (12.2mg/kg; 1.74%).
 Three (3) most occurring hydrocarbon utilizing bacterial isolates were isolated and identified culturally and phenotypically from the soil samples these bacteria isolates were confirmed to be Peudomonas, Priestia megaterium and Bacillus spp molecularly via sequencing of the 16SrRNA gene. The most common bacteria isolated were Bacillus spp at a dilution of 104. This research revealed and recommend that Panicum subalbidum as a suitable plant species for phytoremediation of crude oil-contaminated soil.

Role of Bacterial Consortium and Synthetic Surfactants in Promoting the Phytoremediation of Crude Oil-Contaminated Soil Using Brachiaria mutica

Crude oil is causing widespread pollution in both aquatic and terrestrial environments. Phytoremediation, which is an emerging technology, involves the efficient use of plant species to remove, detoxify, and/or immobilize contaminants in the soil through natural processes. For this study, Para grass (Brachiaria mutica) inoculated with a previously isolated and characterized bacterial consortium was grown in a pot containing crude oil-contaminated soil. The effects of different concentrations (0.01, 0.1, and 1% of 10% detergent solution in ultrapure water) of nonionic surfactant (Triton X-100) on the degradation of crude oil in contaminated soil were observed. After 4-month experimentation, the maximum growth of the plant root length (28.57 cm), shoot length (65.73 cm), and dry biomass of root and shoot (92.42 g) in the pot having an application of surfactants of 0.1% augmented with the bacterial consortium (T7) was observed. Increasing the concentration of Triton X-100 from 0.01 to 1% augmented with a bacterial consortium led to the maximum removal of total petroleum hydrocarbons ranging between 6 and 40%. This is an indication of the inhibiting effect of Triton X-100 above 0.1% on the growth of plants. Furthermore, the hydrocarbon degradation was confirmed by the FTIR study that can be attributed to the adopted plant species' ability to degrade crude oil contamination, and it is evident through the FTIR results after 120 days of experimentation that the different functional groups are responsible for petroleum hydrocarbons present in soil samples. The current study concludes that the application of integrated treatment of crude oil-contaminated soil by using Triton X-100 and augmented with microbes can help to restore polluted soils for agricultural use. Future strategies such as bioaugmentation of contaminated soil with PGPR and the use of genetically modified (GMO) plants may result in amplifying plant tolerance and ultimately lower the level of soil pollutants for better soil health and boost plant yield.

Biochar and compost-based phytoremediation of crude oil contaminated soil

Objectives: To study the effect of compost and biochar on phytoremediation of crude oil-contaminated soil. Methods: An attempt was made to remediate crude oil contaminated soil, using the phytoremediation method. The soil was amended with biochar and compost. Initially, the pH, moisture content and C/N ratio of the soil and amendments were determined. A pot culture experiment was conducted to study the effect of the amendments on the degradation of the Total Petroleum Hydrocarbons (TPH) in the crude oil contaminated soil using the plant species nutgrass (Cyperus rotundus). To avoid seepage of water from the pots plastic pots were used. The initial concentration of TPH was found to be 17mg/kg soil. The experiment was conducted from January to March 2019. No microorganism was inoculated either to enhance the growth of the plant or degrade the hydrocarbon. The study was conducted with natural microflora. The pots were kept (open) under direct sunlight with 8 hours of photoperiodism. The plants were watered daily with tap water to maintain optimum moisture content. Once in 15 days, the soil samples collected from each treatment were analysed for pH, moisture content and C/N ratio. The TPH removal rate was determined for the 45th day and 60th day. Findings: The soil amended with compost (200 kg/soil) and biochar (50 kg/soil) enhanced the degradation of TPH by the plant species. The highest degradation percent of 62.2 and 77.1% was achieved on 45th and 60th day respectively in the treatment T5 (amended with biochar and compost). Further, there was an increase in shoot length (54.52 cm/plant), root biomass (0.74 g/plant) and shoot biomass (5.08g/plant) of the plants in the biochar and compost amended soil which was comparable with the results of the treatment T2 (Plants were grown in soil without crude oil contamination). Applications: Biochar and compost amendment improves the water holding capacity and nutrient status of the soil, thereby enhancing the growth of TPH degraders in soil. Hence, from the study, it is understood that biochar and compost could be used for phytoremediation of crude oil contaminated soils. Keywords: Amendments; degradation of TPH; nutgrass

The Effect of Fertilizer on Epipremnum Aureum in Phytoremediating Soil Contaminated with Crude Oil

Epipremnum aureum is a common ornamental foliage which is used mainly for indoor decoration. It demonstrates tolerance to low light environment and the ability to remove atmospheric chemicals such as gasoline and formaldehyde. A previous screening study showed the ability of Epipremnum aureum to remove crude oil from soil. Further to the screening study, this study examined the effect of fertilization on phytoremediation of crude oil-contaminated soil by Epipremnum aureum Epipremnum aureum was grown in pots with soil contaminated with 5%, 10% and 15% of crude oil by weight respectively, with and without the addition of fertilizer. In line with previous study, Epipremnum aureum showed the ability to remove crude oil contaminants. The plant demonstrated highest crude oil removal rate in pots with 15% contamination. Application of fertilizer enhanced the removal of crude oil in all experimental pots by Week 6, hence increasing the rate of crude oil decline over the experimental duration. It is deemed that application of fertilizer provides nutrients to promote plant growth and proliferation of roots which enhance rhizodegradation of crude oil in soil. This study extends on the existing knowledge that Epipremnum aureum can phytoremediate crude-oil contaminated soil by characterizing its tolerance to crude oil and its response to fertilization, which is crucial to its practical application in phytoremediation. Phytoremediation presents a promising yet cost-effective measure in treating contaminated land. Further study can examine the optimum fertilizer concentration for phytoremediation and the tolerance level of Epipremnum aureum to crude oil contamination.

Phytoremediation of crude oil-contaminated soil with local plant species

Contamination of soil by crude oil is prevailing due to increasing petroleum-related activities. Soil contaminated by crude oil is often rendered unfit for habitation and agriculture due to health concerns. Phytoremediation has emerged as a cost-effective and uncomplicated method of remediating crude oil-contaminated soil. This study examines the potential of four local plant species in phytoremediation of crude oil-contaminated soil, i.e. Pteris vittata, Epipremnum aureum, Mucuna bracteata and Imperata cylindrica. Changes in the crude oil concentrations, pH and moisture of potted soil planted with the aforementioned species were tracked over six weeks. The results were compared against an un-vegetated pot of soil serving as control. The results showed that all vegetated pots had higher crude oil removal compared to the control. Epipremmum aureum demonstrated the highest ability of crude oil removal with 50.4% of crude oil removed, followed by Imperata cylindrica (39.5%), Pteris vittata (36%) and Mucuna bracteata (30.9%). The sequence of plant species in terms of increasing rate of crude oil removal is Pteris vittata, Imperata cylindrica, Mucuna bracteata and Epipremmum aureum. Soil moisture and pH fluctuated over small ranges. This study contributes to identification of local, readily-available plant species and their effectiveness for cost-effective phytoremediation of crude oil-contaminated soil.

Phytoremediation of crude oil-contaminated soil employing Crotalaria pallida Aiton.

The purpose of the study was to evaluate the phytoremediation potentiality of a herb named Crotalaria pallida which are abundantly grown on crude oil-contaminated soil of oil field situated at upper Assam, India, so that this plant could be used to remediate hydrocarbon from contaminated soil. To evaluate the potentiality of the plant, a pot culture experiment was conducted taking 3kg of rice field soil mixed with crude oil at a concentration of 10,000 (10g/kg), 20,000 (20g/kg), 30,000 (30g/kg), 40,000 (40g/kg), 50,000 (50g/kg), 60,000 (60g/kg), 70,000 (70g/kg), 80,000 (80g/kg), 90,000 (90g/kg), and 100,000 (100g/kg) ppm. Ten numbers of healthy seeds of C. pallida were sown in three pots of each concentration for germination, and after 15days of germination, single healthy seedling in each pot was kept for the study. A control setup was also maintained without adding crude oil. The duration of the experiment was fixed for 6months. The results showed that uptake of hydrocarbon by the plants was increased with increasing the concentration of crude oil in the soil up to 60,000ppm. After that, uptake of hydrocarbon by the plants was found to be lower with increasing doses of crude oil concentration. Uptake of hydrocarbon by the shoot was found to be maximum, i.e., 35,018ppm in 60,000ppm concentration. Dissipation of total petroleum hydrocarbon (TPH) from the soil was also gradually increased with increasing concentration of crude oil in the soil up to 60,000ppm. Maximum dissipation, i.e., 78.66%, occurred in 60,000ppm concentration of crude oil-mixed soil. The plant could not survive in 100,000ppm concentration of crude oil-mixed soil. The results also demonstrated that there was a reduction in plant shoot and root biomass with an increase of crude oil concentration. Furthermore, results revealed that the shoot biomass was higher than root biomass in all the treatments.

Plant species affect colonization patterns and metabolic activity of associated endophytes during phytoremediation of crude oil-contaminated soil.

Plants coupled with endophytic bacteria hold great potential for the remediation of polluted environment. The colonization patterns and activity of inoculated endophytes in rhizosphere and endosphere of host plant are among the primary factors that may influence the phytoremediation process. However, these colonization patterns and metabolic activity of the inoculated endophytes are in turn controlled by none other than the host plant itself. The present study aims to determine such an interaction specifically for plant-endophyte systems remediating crude oil-contaminated soil. A consortium (AP) of two oil-degrading endophytic bacteria (Acinetobacter sp. strain BRSI56 and Pseudomonas aeruginosa strain BRRI54) was inoculated to two grasses, Brachiaria mutica and Leptochloa fusca, vegetated in crude oil-contaminated soil. Colonization patterns and metabolic activity of the endophytes were monitored in the rhizosphere and endosphere of the plants. Bacterial augmentation enhanced plant growth and crude oil degradation. Maximum crude oil degradation (78%) was achieved with B. mutica plants inoculated with AP consortium. This degradation was significantly higher than those treatments, where plants and bacteria were used individually or L. fusca and endophytes were used in combination. Moreover, colonization and metabolic activity of the endophytes were higher in the rhizosphere and endosphere of B. mutica than L. fusca. The plant species affected not only colonization pattern and biofilm formation of the inoculated bacteria in the rhizosphere and endosphere of the host plant but also affected the expression of alkane hydroxylase gene, alkB. Hence, the investigation revealed that plant species can affect colonization patterns and metabolic activity of inoculated endophytic bacteria and ultimately the phytoremediation process.