Dispersant effectiveness seminar, Oslo, Norway, May 1985

An experimental program assessed which mechanisms control the rapid biodegradation of used lubricating oil which contaminates soils. The ultimate goal is to effect a rapid biodegradation before the contaminants in the oil are leached into the groundwater or carried into surface waters with runoff. Large amounts of lubricating-oil-degrading bacteria could be grown in liquid culture, as long as a dispersant was applied to form and maintain an oil-in-water emulsion. Application of the oil-degrading bacteria (up to 4.9 × 108/g soil) significantly increased the initial rate of oil degradation in soil plots. However, the long-term rate of degradation slowed as the more available or more biodegradable components of the oil were removed. The fastest removal rates were obtained when the oil-contaminated soil was put into a water-soil slurry and was inoculated with microorganisms and dispersant. Improved microorganism contact and dispersant effectiveness apparently were responsible for the rapid rates in slurry reactors. The increased rates demonstrated the potential value of adding a large, acclimated inoculum and providing good mixing and dispersion to make the oil more available to the microorganisms.

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LABORATORY STUDIES ON THE CHEMICAL AND NATURAL DISPERSABILITY OF OIL

International Oil Spill Conference Proceedings ◽

10.7901/2169-3358-1987-1-241 ◽

1987 ◽

Vol 1987 (1) ◽

pp. 241-246 ◽

Cited By ~ 5

Author(s):

Mervin F. Fingas ◽

Mark A. Bobra ◽

Ronald K. Velicogna

Keyword(s):

Laboratory Test ◽

Laboratory Testing ◽

Physical Property ◽

Test Results ◽

Laboratory Studies ◽

Oil Viscosity ◽

Property Data ◽

Dispersant Effectiveness ◽

Physical Property Data

ABSTRACT We have reviewed the laboratory testing of the chemical and natural dispersion of oil, noting the weaknesses of the Mackay test and comparing it to other methods. Results of both chemical and natural dispersion tests show that anomalous test results are produced in the Mackay apparatus at 0° C. This is attributed to preferential viscous shearing when the oil viscosity is 30 to 200 centistokes (cs). A new test uses a small swirling flask. Dispersant effectiveness results for ten oils from the Mackay, Labofina, and swirling flask tests were compared and the correlation found to be low. Results from the new swirling flask test correlate well with physical property data, especially viscosity. Each laboratory test produces somewhat unique results, and no way has yet been found to determine which test most accurately represents reality.

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