Center for Environment and Energy Research and Studies (CEERS)
Abstract
Bioremediation is an effective measure in dealing with such
contamination, particularly those from petroleum hydrocarbon sources.
The effect of soil amendments on diesel fuel degradation in soil was
studied. Diesel fuel was introduced into the soil at the concentration
of 5 % (w/w) and mixed with three different organic wastes tea leaf,
soy cake, and potato skin, for a period of 3 months. Within 84 days, 35
% oil loss was recorded in the unamended polluted soil while 88, 81 and
75 % oil loss were recorded in the soil amended with soy cake, potato
skin and tea leaf, respectively. Diesel fuel utilizing bacteria counts
were significantly high in all organic wastes amended treatments,
ranging from 111 × 106 to 152 × 106 colony forming unit/gram
of soil, as compared to the unamended control soil which gave 31 ×
106 CFU/g. The diesel fuel utilizing bacteria isolated from the
oil-contaminated soil belongs to Bacillus licheniformis , Ochrobactrum
tritici and Staphylococcus sp. Oil-polluted soil amended with soy
cake recorded the highest oil biodegradation with a net loss of 53 %,
as compared to the other treatments. Dehydrogenase enzyme activity,
which was assessed by 2,3,5-triphenyltetrazolium chloride technique,
correlated significantly with the total petroleum hydrocarbons
degradation and accumulation of CO2. First-order kinetic model revealed
that soy cake was the best of the three organic wastes used, with
biodegradation rate constant of 0.148 day-1 and half life of 4.68 days.
The results showed there is potential for soy cake, potato skin and tea
leaf to enhance biodegradation of diesel in oil-contaminated soil
