Laboratory Effectiveness Testing of Oil Spill Dispersants

Abstract

Dispersant effectiveness tests are reviewed. Studies have been conducted of the variances among several standard regulatory tests. Three main causes of differences have been identified, oil-to-water ratio, settling time and energy. Energy can be partially compensated for in high energy tests by correcting for natural dispersion. With this correction and with high oil-to-water ratios and a settling time of at least 10 minutes, five apparatuses yield very similar results for a variety of oils and dispersants. Recent studies into the energy variation of dispersant tests show that the energy level varies in many apparatuses. The repeatability of energy levels in apparatus is largely responsible for the variation in dispersant effectiveness values in certain apparatus. Studies of analytical procedures show that traditional extraction and analysis methods cause a bias to results. Methods to overcome these difficulties are presented.

A Review of Research and Practice on the Application of Chemical Dispersant in Oil Spills

“…With the advantages of well controlled and repeatability, and the well reflection of the actual conditions, the tank test of the dispersant effectiveness has been used more universal. Generally, dispersant effectiveness was measured in two ways: by accumulating the concentrations of oil in the water column by fluorometric measurements and by removing and weighing oil on the surface [18]. As the measurements of the oil concentration are hard to make, the mass balance are difficult to achieve.…”

Where Has All the Oil Gone? Dispersed Oil Detection in a Wave Basin and at Sea

“…However, dispersants rarely appear to work as well in sea spills as would be expected from these tests. A recent article 4 that reviews a number of sea trials concludes that the observed dispersant effectiveness is too low to justify extensive use. Why do dispersants appear to work poorly in spills at sea?…”