Biotreatment of Crude Oil Contaminated Soil

Biodegradation of hydrocarbons by microorganisms represents one of the primary mechanisms by
which petroleum and other hydrogen pollutants are eliminated from the environment. This work was
carried out on the effect of microorganisms on the biotreatment of oil in crude oil contaminated soil.
Microorganisms were isolated from two experimental soil samples contaminated with Bonny Crude
and normal uncontaminated soil as a control over a period of seven months. The microbial as well as
the physico-chemical parameters of the soil samples were all analyzed using standard methods.
Changes in total petroleum hydrocarbon level were measured appropriately. Treatments used were
the microbial isolates.
Forty-four microorganisms were isolated from the contaminated soils and identified as species of
Pseudomonas (7), Flavobacterium (6), Bacillus (8), Proteus (4), Klebsiella (1), Pencillium (5),
Aspergillus (7), Fusarium (3), Trichypton (2) and Neurospora (1). Ten of the forty-four isolates had
ability to degrade crude oil in the laboratory. On contamination a value of 1.0X105 cfu/g in microbial
counts were obtained followed by a subsequent increase in population levels after a period of
2months with a value of 1.0X106 cfu/g. Oil application to the soil resulted in an increase in total
petroleum hydrocarbon from 0.31 ppm to 5.53 ppm; organic matter from 0.41% to 7.34%; available
phosphorus from 1.75 ppm to 2.84 ppm. The treatment measures all showed progressive decrease in
oil concentration in the soil. Mixture of bacterial and fungal isolates as a treatment measure proved to
be more favourable above all others, it brought the concentration from 5.53 ppm to 0.31 ppm after a
period of 5 weeks of treatment, which is same value with the normal soil (uncontaminated).
Species of Pseudomonas, Bacillus, Flavobacterium, Proteus, Klebsiella, Penicillium, Aspergillus,
Fusarium, Trichyphyton and Neurospora had potential for the degradation of bonny crude oil. They
could therefore be employed in environmental cleanup of petroleum spill site.