Naturally degrading sorbents in the cleanup of oil spills
Sorbent materials which absorb or adsorb liquids are a cleanup option for oil spills. There are three basic types:
- natural organic sorbents include peat moss, straw, hay, sawdust, ground corncobs, feathers, and other readily available carbon-based products
- natural inorganic sorbents consist of clay, perlite, vermiculite, glass wool, sand, or volcanic ash
- synthetic sorbents include man-made materials that are similar to plastics, such as polyurethane, polyethylene, and polypropylene, cross-linked polymers and rubber materials.
The decision to use sorbents must consider the net environmental benefit.
Logistics of retrieval may be difficult in a remote area, and some sensitive habitats may be damaged or have recovery reduced by disturbance during the retrieval process. In some circumstances though, this may be less damaging than allowing oil to spread uncontrollably.
The project aimed to review current literature and experience in the use of sorbents which naturally degrade in the environment. Such sorbents could potentially be deployed to contain the spread of oil but then left in place to degrade naturally over time. The Centre for Ecological Impacts of Coastal Cities (University of Sydney) undertook the project on behalf of the National Plan in 2000-2001.
The best types of sorbents were found to be those with great capacity for primary absorption of oil, particularly those formed from long fibres, such as wool, cotton and so forth. Wool-based sorbents have further merits. They are natural, available on a sustainable basis and handling, storage and transport of wool are routine in many parts of Australia. Other possible sorbents with useful properties were also identified using a diverse set of criteria.
It remains difficult to make recommendations given scarce data and lack of field assessments of any of the materials studied.