Fig. 5 compares the GC chromatograms for the extracted TPH
from the sandy soil on days 0 and 270. The chromatogram for the
extracted oil on day 270 has lower number of peaks indicating near
complete degradation of some components. Other peaks appeared
smaller than the corresponding peaks in the chromatogram
obtained for the extracted residual oil on day 0 indicating the
biodegradability of most components of the gasoil. Another point
form comparing the chromatograms is that the total area of the
peaks for the chromatogram of the sample on day 270 is 76.5%
smaller than the total area of the peaks for the chromatogram of the
sample extracted on day 0. This figure is reasonably close to the
removal percentage of TPH (70%) obtained by the gravimetric
method (EPA Method 9071B). The reduction in total area of peaks,
therefore, can be considered as an approximate measure for the
reduction in TPH content of the soils.
The FTIR spectra of the extracted hydrocarbons from the sandy
soil on days 0 and 270 have been presented in Fig. 6. Inspection of
the spectra shows considerable change in the extracted sample
after bioremediation. All spectra show strong absorptions in the
wavelength range of 3000e2840 cm1. The absorptions arise from
CeH stretching in the alkanes. This indicates that the remaining
hydrocarbons after bioremediation are mainly alkanes. Many of
absorption peaks at lower wavelengths have been weakened or
disappeared