Telfaira Occidentalis Aided Rhizoremediation of Agricultural Soils Subjected to Different Crude Oil Contamination Levels

Abstract

Rhizoremediation process was undertaken to evaluate the effectiveness of Telfaira occidentalis in the cleanup of a crude oil contaminated soil. The microbial profile of the agricultural soil used in the study was determined before and after crude oil treatment to identify the indigenous flora present in the soil. Microbiological analysis of the soil sample revealed the presence of Aspergillus fumigatus, Aspergillus niger, Penicillium sp, Candida sp, Pseudomonas fluorescence, Acinetobacter baumanni, Bacillus mycoides, Klebsiella sp., Staphylococcus aureus and Escherichia coli.  Subsequent analysis revealed the disappearance of S. aureus and Escherichia coli and the persistence of other aforementioned microorganisms after treatment of the soil with crude oil. The Telfaira occidentalis seeds were planted in Green house and field test soils polluted with 100, 200, 400 and 800 ml of crude oil. Gas chromatographic (GC) analysis was carried out subsequently on the test soils to determine the total petroleum hydrocarbon (TPH) content of the samples by comparing them with the TPH value of 4157.04 and 3986.65 mg/kg for control sample of green house and field respectively. The TPH value obtained from rhizoremediation in the Green house were 55, 110, 325 and 667 mg/kg, while those of the field were 78, 126, 256 and 472 mg/kg for crude oil concentrations of 100, 200, 400 and 800 ml respectively. Results obtained from the gas chromatographic (GC) analysis also depict the different alkane groups that were removed from the interaction to be within the range of C₇ to C₁₂; and C₃₀ to C₄₀ alkanes. Nevertheless, both shorter and longer chain alkanes, with time were eliminated from contaminated soils.

Keywords: Rhizoremediation, agricultural soil, crude oil, alkanes, microbes, Telfaira occidentalis