With IMO 2020 fast approaching, a new problem regarding potential wash water pollution from ships installed with scrubbers has arisen.

Many shipowners decided to install scrubbers to clean the exhaust gases from ships to comply with the new regulations. Owners with scrubbers installed can continue to use cheaper Heavy Fuel Oil (HFO) rather than switch to the new, more expensive Low-Sulphur Fuels (LSF). Some newer vessels are compliant through complex water management systems.

What is IMO 2020?

On 1 January 2020, the International Maritime Organization (IMO) will implement a new regulation for a 0.50% global sulphur cap for marine fuels. Under the new global cap, ships will have to use marine fuels with a sulphur content of no more than 0.50% against the current limit of 3.50% in an effort to reduce the amount of sulphur oxide. The Emission Control Areas (ECAs) will remain at the 2015 standard of 0.1% content.

However, the wash water used to clean the scrubbers contains pollutants that may be harmful to ocean flora and fauna.

In recent months, local and regional maritime authorities around the world have introduced their own regulations related to scrubber wash water pollutants to protect their marine environment. The different rules have increased the complexity for ship owners and other stakeholders, who need to comply or face penalties.

This patchwork of different regulations will not be resolved until 2021 when the IMO hopes to have harmonised rules and guidance on the discharge of liquid effluents from Exhaust Gas Cleaning Systems or scrubbers in place.

The availability of two scrubber types – open loop and closed loop – add to the complexity of the situation.

Stian Aakre, General Manager Business Development, Exhaust Gas Cleaning for Wärtsilä explains. “One must make a distinction between open and closed-loop systems when addressing this. A closed-loop system, from Wärtsilä or any other supplier, must have a wash water treatment system as the scrubbing water turns ‘dirtier’ when being recirculated in the system. Upon discharge, it must always low-sulphur in order to comply with IMO discharge requirements. (IMO makes no distinction between open and closed-loop wash water discharge.)

“An open-loop system might discharge the wash water directly and still be compliant with the IMO regulations as the water passes through the system only once and is less impacted by impurities. Wärtsilä offers and recommends water treatment system also for open-loop systems. However, this adds to the complexity and cost of the system and customers typically reject this option.”

However, sympathetic to the shipowners, there are now signs that local and regional port authorities will not be so aggressive in implementing new restrictions. This may be due to more information being circulated in the shipping industry, that the potential environmental impact of scrubber wash water discharge may not be as harmful as first thought, according to Aakre.