The impact of sea trade

The global maritime transport is notably driven by globalization and the rising economic importance of Asia. It has recorded an annual long-term growth rate of about 3 to 4% (1997-2017, source: HIS Maritime). When in operation, ships produce fuel oil residue, which is called “slop”.

Previously, this residue was discharged into the sea.

For instance, a container ship which is powered by a 50 000 horsepower engine generates 1.6 tons of fuel oil residue in the form of sludge, in relation to a daily consumption of 180 tons of fuel.

Thanks to the MARPOL Convention, marine fuel oil residue has now to be collected and treated on land.

Slops include various hydrocarbon residues produced by maritime activity, such as sludges, bilge waters and ballast waters. They are composed, in variable proportions, of water, hydrocarbons, sediments and various pollutants.

They are produced in the engine rooms during the purification of fuels used by the ships. They contain 80% of hydrocarbons.


These polluted bilge waters contain a mixture of fuel oil, seawater, freshwater, cooling water, oil leaks and lube oils. They contain 10% of hydrocarbons.


Also called slops, ballast waters are used in older tankers to stabilize the ship by replacing the oil when they navigate with no payload. By extension ballast waters also include tank-cleaning waters. They contain 20% of hydrocarbons.


Categorized as industrial waste, slops are collected in ports and typically dealt with by ship owners. Their variable composition and the nature of the pollutants (sediments, heavy metals) make them particularly hard to treat and recycle. Therefore, more often than not, they are incinerated.

Thanks to its treatment process, which enables slops to be recycled, Ecoslops offers port infrastructures, waste collectors and ship-owners an economical and ecological solution, in accordance with regulation regarding the collection and the treatment of this kind of waste.