Abstract

Uncontrolled releases of free-phase petroleum to open-water surfaces, e.g. oil spills, can be contained using existing products and techniques, such as booms, sorbents etc. Biotic and abiotic remedial approaches (such as use of dispersants, formation of oil-mineral aggregates [OMA] and bioremediation "products") also exist for managing or treating spilled oil in the water or in shoreline areas, although varying effectiveness in this regard has been reported.

A two-year project (2008-2010) targeting laboratory scale development and optimization of nutrient-bearing treatment products was recently completed. The designed products, when applied to spilled oil occurring in open-water marine areas, were intended to accomplish the following objectives:

  1. promote formation of OMA with desired buoyancy characteristics, that

  2. facilitate increased activity of indigenous, aerobic microbial populations and thus

  3. increased degradation rates of the bound petroleum constituents.

When successfully optimized, such treatment products potentially provide a cost-effective alternative to existing approaches for treating oil spills (e.g. dispersants or clays only), possibly also with a wider time-window for use.

Selected combinations of clay minerals, nutrients and dispersants partly capable of meeting the objectives in laboratory scale experiments were identified through the project. A range of material combinations was screened in small scale laboratory experiments, and - based on a set of criteria of which initial biodegradation of oil was the most important - some combinations were selected for further examination. Testing was primarily done using a single crude oil topped to 150°C, and incubated at 10°C. Further examination of microbial population responses and better quantification of OMA formation and increased degradation of oil in OMA formed is warranted, including product effectiveness on emulsified oil. Large-scale laboratory and field pilot testing is also recommended to document results observed at small lab scale.

The petroleum industry is moving into increasingly remote and complex locations, such as deeper waters and the Arctic. In Norway at least, this calls for improved spill contingency, and there is currently a strong focus from the authorities to improve and expand the available "toolbox" of effective treatment approaches, as has been the focus internationally for some time. The Deepwater Horizon accident and the resulting moratorium on deep-sea drilling also support the needs in this regard.

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