Conditioned sorbents

Conditioned sorbents exist in a variety of different forms, making them easier to use than bulk sorbents. However, these products are expensive and therefore cannot be used on a large scale. They can be used on very small amounts of pollution or to finish clean-up after recovering the oil using other means.

Sheets or pads (AFNOR type B)

Sorbent pads are flexible and thin (3 cm or less), and the length and breadth, although less than a metre, are far greater than the thickness (ratio of at least 10:1 between the breadth and the thickness, and between the length and the thickness). They are sufficiently resistant to be able to be easily handled.

Rolls (AFNOR type C)

Sorbent rolls can be several tens of metres long. They are often made of non-woven (felt-like) fabrics. They are easy to use and especially to recover manually. These products have a considerably higher impregnation potential than booms and pillows for low to average density oil (150 to 2,500 cSt), thanks to their large outer surface area, which allows extensive contact with the pollutant. However they are not well suited to viscous pollutants, which do not impregnate easily.

Certain manufacturers suggest using sheets and rolls several times in a row, wringing them out after each use to extract the trapped pollutant. In practice, it is often more convenient to think of them as single-use, disposable products. They can be used on small amounts of pollution, already contained to a greater or lesser extent, or, in the case of rolls, to recover a constant leak in weak currents (less than 0.20 m/s).

Pillows (AFNOR type D)

Sorbent pillows are flexible and the sorbent material is contained in a permeable envelope, which is resistant enough to be able to be manipulated. The length of this envelope is far greater than the other dimensions, but is less than a metre.

Booms (AFNOR type E)

Sorbent booms are flexible and the sorbent material is contained in a permeable envelope, which is resistant enough to be able to be manipulated. The length of this envelope is far greater than the other dimensions (in a ratio of at least 20:1 between the length and the diameter) and is greater than a metre. The boom parts should be designed to be joined together and overlap

Despite being called "booms", they are largely inefficient in terms of containment. Because of their small draught (lack of skirt), they are unable to efficiently contain an oil slick, except in particularly good conditions (no current and little wave action).

To improve containment performance, some manufacturers sell ballasted sorbent booms (increased draught) and/or booms with a skirt. They should therefore be considered more as large sponges capable of soaking up pollutant, which are much easier to use than bulk sorbents. They are however more expensive and, if the pollutant is very fluid, it is often difficult to fully saturate them.

Their use is therefore more suited to limited spills in ports or sheltered areas, to recover slicks contained by ordinary booms, or downstream from a recovery site to trap any potential leaks of pollutant.
 

Mops (AFNOR type F)

These types of sorbents are made of flexible, thread-like materials, forming light open structures able to trap viscous liquids. They are used manually like mops, mainly on thick pollutant on surfaces or in crevices.

With these sorbents the pollutant is not absorbed by the fibres but rather caught between the fibres, which explains why they are best suited to heavy hydrocarbons.

Special products (AFNOR type G)

Special products include all the sorbents which do not belong to the categories listed above.