IMO mulling restrictions on scrubber wastewater

Shipping classification society DNV GL believes the International Maritime Organisation (IMO) is planning to target the discharge of wastewater from scrubbers.

Exhaust gas cleaning systems, known as scrubbers, allow vessels to keep burning 3.5pc sulphur marine fuel oil despite the IMO's 0.5pc sulphur cap, which came into force on 1 January.

Wastewater from open-loop scrubbers can be released into the sea and some environmental groups have criticised the IMO for allowing scrubbers after the 0.5pc sulphur cap.

DNV environment director Eirik Nyhus said the IMO is probably content with the new 0.5pc sulphur cap and is not planning any further fuel sulphur-content restrictions.

"The IMO sees itself in practical terms done with the 0.5pc regulation that came into force at the beginning of this year, with a very limited number of issues," Nyhus said.

But he said wastewater from scrubbers is the IMO's next target, adding: "The key challenge here is that scrubber discharge restrictions do remain under discussion at the IMO, and we do see local regulations popping up around the world on this, so operators with scrubbers may face some future challenges in this context.

"It can probably be dealt with, but there are some issues," he said.

The IMO had planned to meet at the end of March to approve a draft scope to look into scrubber wastewater and any potential restrictions, but this was delayed by the Covid-19 pandemic.

An outright ban on open-loop scrubbers across the world is considered unlikely, but potential measures include discharge limits, which would apply both in port areas and the open sea, or a framework for geographical restrictions.

A number of jurisdictions already ban either the discharge of scrubber wastewater in ports and inland waterways, or even the use of open-loop scrubbers themselves. Discharging scrubber wastewater is prohibited in the port area of Singapore, the world's largest bunkering destination, while Fujairah in the UAE bans the use of open-loop scrubbers in the port area.

According to DNV, 4,267 vessels will either have a scrubber installed or have one on order in 2020 out of a global fleet of around 60,000 ships. The majority of these are open-loop.

By George Collard