Bioremediation of heavy metals from artisanal crude oil refinery (Kpo-Fire) impacted soil using Bacillus flexus and Pseudomonas aeruginosa in Ngie Community, Degema Local Government Area, Rivers State, Nigeria

Abstract

The existence of heavy metals in “kpo-fire” impacted soil creates significant risks to human health and the ecosystem. In this study, the efficacy of the elimination of heavy metal from “kpo-fire” impacted soil was evaluated using bacterial treatments. The organisms (Bacillus flexus and Pseudomonas aeruginosa) used in the bioremediation setup were isolated from the impacted soil. Heavy metal analysis was carried out using an Atomic Absorption Spectrophotometer. The experimental setup involved the recreation of the contaminated soil sample in three (3) vessels labeled as: Flask A containing 300g of un-amended sample (control) to monitor natural process; Flask B containing 300g of sterilized sample; Flask C containing 300g of sample with Pseudomonas aeruginosa and Bacillus flexus. Soil baseline physicochemical composition was determined to have a pH of 6.18, Temperature of 29.2oC, Total Organic Carbon 7.58 mg/kg and Phosphate concentration 37.56 mg/kg. At the end of the investigation, experimental setup C, containing bacterial inocula was observed to possess the best bio-removal rates for Mercury (99.32%), Cadmium (77.59%), Boron (72.84%) and Arsenic (93.43%) after a 42-day period of study. Also, the concentrations declined from 1.05264mg/kg to 0.00621mg/kg for Mercury; Cadmium declined from 5.93mg/kg to 1.16mg/kg; Boron declined from 3.61mg/kg to 0.82mmg/kg and Arsenic declined from 2.78mg/kg to 0.16mg/kg. Molecular characterization revealed the contaminated soil had predominance of isolates with genomic molecular weight of 1,500 bp and the phylogenetic construct showed the bacterial isolates were Pseudomonas aeruginosa (MT023359), Bacillus flexus (MT023375) and Lysinibacillus macroides (MT023377). Statistical analysis revealed a strong positive correlation between the bacterial biomass and heavy metal removal. The synergistic parts played by bacterial consortia in the bio-removal of heavy metals from the polluted soil have been established and these potentials can be harnessed as a roadmap for eco-recovery of impacted environment in the Niger Delta. Bacillus flexus and Pseudomonas aeruginosa in consortium are efficient in remediation of kpo-fire contaminated soil.

Pig (Sus scrofa domesticus) dung and their associated fungi: Potential candidates for bio-remediation and nutrients improvement of crude oil contaminated soils

“…High presence of nutrients especially carbon, vitamins, fibers (cellulose, hemicelluloses and lignin) and minerals coupled with adequate pH and water tension in dungs, may be the reason for this association. Heterotrophic fungi belonging to the genera Aspergillus, Penicillium, Mucor, Rhizopus, Alternaria, Beauveria, Paeclomyces, and Candida have been found to be dung-loving and to tolerate oilcontaminated environments (Dawodi et al 2015;Ughamba et al 2019). Findings from this work corroborate the report of several workers who found Candida sp., C. tropicalis, Rhizopus sp., Mucor sp., Aspergillus spp., A. niger to be strongly associated with cow and pig dung (Obire et al 2008;Zhou et al 2016;Samuel et al 2017) A wide variety of members of fungal divisions are found on dung; the Mucoromyceta (Zygomyceta) usually appear first, followed by Ascomycota and then the Basidiomycota.…”

“…However, chemical reclamation approaches though effective, have been reported to be attended by anthropogenic eutrophication among other shortfalls. Bio-remediation is a technology whereby environmental pollutants are degraded and cleaned up through microbial activity (Akhtar et al 2020;Ugboma et al 2020;Zhang et al 2020). This kind of approach to oil clean-up has the advantages of being non-invasive, rapidacting, cost-effective, eco-friendly and supportive to soil fauna and flora by increasing nutrient availability and uptake by plants (Erdogan et al 2011;Udeani et al 2012;Nwaogu et al 2015).…”

Toxicity of Soot Against Microorganisms Isolated from Artisanal Crude Oil Refining Sites in the Niger Delta

“…Holman 32 reported that bacteria failed to grow at low soot concentrations but grew at higher concentrations of the same soot. In agreement with the present study, Ugboma et al 33 reported that microorganisms isolated from soil impacted by artisanal crude oil refining grew well in the presence of heavy metals and were efficient in the elimination of heavy metals from the soil. Soot contains hydrocarbons in low amounts relative to crude oil.…”

Assessment of Heavy Metal Exposure in Soils of Ihwrekreka Communities, Delta State, Nigeria

“…Natural geological process, such as ore formation, weathering of rocks, leaching or degassing could introduce heavy metals as contaminant in soil (Gautam et al, 2014;Ali et al, 2019). However, human activities such as illegal refining of fossil fuels, petroleum prospecting, mining, and crude oil pollution can contribute to excessive release of these metals into soils or agricultural lands, resulting in increased concentrations of heavy metals in soil (Okoye et al, 2022;Njoku et al, 2016;Aigberua et al, 2017a;Moslen & Aigberua, 2019;Gwary et al, 2019;Ugboma et al, 2020). In the Ihwrekreka community, identified causes of pollution include illegal refining of crude oil and oil bunkering from pipelines carrying crude oil products (Nwaichi et al, 2016;Ogunkeyede et al, 2022).…”