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Evaluating Chemical Dispersant Efficacy In An Experimental Wave Tank: 1, Dispersant Effectiveness As A Function Of Energy Dissipation Rate
Citation:
Li, Z., K. Lee, T. King, P. Kepkay, M. C. Boufadel, AND A. D. VENOSA. Evaluating Chemical Dispersant Efficacy In An Experimental Wave Tank: 1, Dispersant Effectiveness As A Function Of Energy Dissipation Rate. D. Grasso (ed.), Submitted to: ENVIRONMENTAL ENGINEERING SCIENCE. Mary Ann Liebert, Inc., Larchmont, NY, 26(6):1139-1148, (2009).
Impact/Purpose:
To evaluate the effectiveness of chemical dispersants of different formulations on different crude oils under a variety of wave conditions, and to resolve the effects of breaking wave energy dissipation rate and dispersant application on oil dispersion.
Description:
Numerous laboratory test systems have been developed for the comparison of efficacy between various chemical oil dispersant formulations. However, for the assessment of chemical dispersant effectiveness under realistic sea state, test protocols are required to produce hydrodynamic conditions close to the mixing, transport, and dilution effects found in the natural environment. To this end, we have designed and constructed an experimental wave tank system capable of generating waves of different energy levels, ranging from regular non-breaking waves to pluging breakers. The hydrodynamics of these wave conditions were characterized using an autocorrelation function method applied to in situ velocity measurements. We report here an investigation of the effectiveness of two chemical dispersants (Corexit 9500 and SPC 1000) on two crude oils (weathered MESA and fresh ANS) under three different wave conditions in the wave tank operated in batch mode. Corexit 9500 dispersed approximately 75% of the weathered MESA and more than 90% of the fresh ANS crude, and SPC 1000 dispersed about 53 and 64%, respectively. Under control conditions (absence of chemical dispersant), only 10 to 20% of the crude oils were dispersed. Quantitative relationships were established between dispersant effectiveness and energy dissipation rate under the different simulated wave conditions. These relationships are essential for the development of accurate predictive models on dispersant effectiveness and operational guidelines for dispersant use.
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Abstract
EVALUATING CHEMICAL DISPERSANT EFFICACY IN AN EXPERIMENTAL WAVE TANK: 1, DISPERSANT EFFECTIVENESS AS A FUNCTION OF ENERGY DISSIPATION RATE