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Oily Sand Bioaugmentation Study

Oily SandOn June 24, 2010, EBS acquired five sand samples from the Louisiana coast. The purpose of the study was to test the extent of oil degradation in the sand with bioaugmentation. Three of the sand samples were contaminated with oil and the remaining two samples were clean. Each of the sand samples was initially tested for oil & grease by direct n-hexane extraction. The three oil contaminated samples were then combined as a composite sample, as were the two clean sand samples. Both composites were tested for initial oil and grease content before bioaugmentation studies began. Samples were split into eight trays and each treated with different amounts of nutrients, bioaugmentation, and surfactants over a period of six weeks. Once a week during the six-week study, each sample was tested for oil and grease composition and nutrient content.

Results

The results of the study found that all samples showed some oil degradation over the six week period. This suggests that all samples began with some natural bacteria present which was able to degrade oil over time. However, the trays treated with bioaugmentation had the highest rate of oil degradation. Enhancing the natural bacterial concentration in the samples via bioaugmentation helped increase the rate of oil degradation. Supplementing the samples with nutrients alone did not demonstrate an increase in oil degradation, nor did the addition of nutrients and surfactants without bioaugmentation. The treatment that demonstrated the highest rate of oil degradation was the combination of nutrient and surfactant addition and bioaugmentation. In this treatment combination, the surfactant acted as a dispersing agent making it easier for the bacteria to metabolize the oil. The study concluded that the use of bioaugmentation supplemented by a nutrient blend and a surfactant can significantly help in reducing or degrading oil contamination in soil by at least 87%.