Polluting discharge from scrubbers is a potential threat to marine life. Photo: Flickr.com / Hans Hillewaert CC BY-NC-ND

Global scrubber washwater discharges

A new report from the International Council for Clean Transportation (ICCT) provides the first global assessment of the mass of washwater discharges expected from ships using scrubbers to remove sulphur dioxide (SO2) from ship exhausts. The scrubber washwater is more acidic than the surrounding seawater and contains polycyclic aromatic hydrocarbons, particulate matter, nitrates, nitrites, and heavy metals including nickel, lead, copper, and mercury. It is toxic to some marine organisms, harms others, and can reduce water quality.

The authors calculate that, absent additional regulations, ships with scrubbers will emit at least 10 gigatonnes (Gt) of scrubber washwater each year. For context, the entire shipping sector carries about 11 Gt of cargo each year.

Approximately 80 per cent of scrubber discharges occur within 200 nautical miles of shore, and there are hot spots in heavily trafficked regions, including the Baltic Sea, North Sea, Mediterranean Sea, the Strait of Malacca, and the Caribbean Sea. Scrubber discharges also occur in IMO-designated Particularly Sensitive Sea Areas (PSSAs), including the Great Barrier Reef and the Baltic Sea.

Source: ICCT, 29 April 2021. The report: https://theicct.org/publications/global-scrubber-discharges-Apr2021


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