Orimulsion is an oil-in-water emulsion of Venezuelan bitumen. Orimulsion was found to behave predictably in salt (33°/oo NaCl) and fresh water, driven by buoyancy to rise in salt water and sink in fresh water; but behaviour in brackish water (20°/oo NaCl) was difficult to predict. Temperature has also been indicated as having an influence on Orimulsion behaviour. The current study extended experimentation down to lower temperatures, and a variety of mixing energies.

This study resulted in new information on the behaviour of Orimulsion spills in salt, fresh, and brackish water with salinity values of 20 and 33 degrees at temperatures of 5 and 15 degrees Celsius. Energy was varied by adjusting the applied rotational field and measurement with thermal probes. Depletion rates and characteristics were determined by adding Orimulsion to a 300-L tank of water, taking a time series of samples, and determining the concentration of bitumen and the particle size distribution. Changes in bitumen concentration and particle size distribution as a function of time were also measured. Using these data, simple equations were developed to describe and predict the concentration of bitumen in the water column as a function of time. Similarly nomograms showing the amount of oil on the bottom and on the water surface are presented.

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