Monoaromatic Hydrocarbon Bioremediation of Hydrocarbon-contaminated Soil Using HBB5 Biosurfactant Produced by Pseudomonas xiamenensis

Abstract

Biodegradation of benzene toluene ethylbenzene and xylenes (BTEX) is a slow and complex process. However, many microbial organisms have been shown to possess the capacity to biodegrade various components of a hydrocarbon. This study was aimed at investigating the role of biosurfactant on soil polluted with these monoaromatics. Samples were collected and analyzed using standard techniques. The biodegradation set up was carried out using five earthen pots; each containing unpolluted soil, polluted soil alone, polluted soil + poultry wastes, polluted soil + HBB5 biosurfactant and polluted soil + poultry wastes + HBB5 biosurfactant. The biodegradation of BTEX were periodically monitored every seven days for 28 days using gas chromatograph-mass spectrometer coupled with head space (GC-MS-HS). The respective initial and final concentrations of BTEX (ppm) were as follows; 0.7936 and 0.2063, 0.9733 and 0.0231, 0.9526 and <0.0001, 0.9241 and <0.0001 with degradation efficiencies of 74.0%, 97.6%, 100% and 100% for polluted soil alone, polluted soil + poultry wastes, polluted soil + HBB5 biosurfactant and polluted soil + poultry wastes + HBB5 biosurfactant respectively. The microbial counts increased greatly, and the concentrations of the limiting nutrients reduced during the experimental period. The effective treatments for bioremediation increased in the following order: polluted soil alone < polluted soil + poultry waste < polluted soil + HBB5 biosurfactant < polluted soil + poultry waste + HBB5 biosurfactant. Results clearly showed that application of HBB5 biosurfactant only or in combination with poultry wastes has the ability to degrade ethylbenzene and xylenes (BTEX) and thus, can be employed in the clean-up of crude oil contaminated soil.