Modern scrubber systems become more popular

The ship’s use of modern scrubber systems has become more popular in just the last year, despite the fact that the debate about their viability in mitigating sulfur emissions from ships does not stop. The thing is that open-loop scrubbers are considered to be more dangerous than closed-loop wet scrubbers because of the release of sulfur emissions that they treat in ships back into the sea.

According to the latest data, nowadays about 4.000 ships have installed scrubber systems, compared to only 800 in 2018. Herewith, out of these, just 65 wet scrubbers are closed-loop, while the rest are vessels with open-loop scrubbers. To be more precise, the International Maritime Organisation (IMO) adopted the International Convention for the prevention of air pollution from ships, according to which the air pollution control is required, and deliberate emissions of ozone-depleting substances, for example, sulfur oxides and nitrous oxides are forbidden.

Thus, exhaust scrubber systems are regarded as one of the most preferred ways to make the level of sulfur exhaust lower because they catch air pollutants out of emissions. Nevertheless, closed-loop wet air scrubbers are safer between the two types because they retain the sulfur emissions for safer disposal at the port, while open-loop wet scrubbers discharge pollutants back in the sea after the air treatment.

It should also be noted that it is permitted to apply open-loop scrubbers as “an equivalent – which is defined as ‘any fitting, appliance or apparatus to be fitted in a ship or other procedures, alternative fuel oils, or compliance methods used as an alternative”. But the shipowners have to follow strict rules for the discharge of wash water from exhaust gas air treatment systems.

At present, the uncertainty around the sustainability of open-loop wet scrubbers continues to increase in the shipping industry, especially, ahead of the IMO’s sulfur cap implementation in 2020. Therefore, the previous amount of sulfur in fuel oil  (3.5 percent m/m (mass/mass)) is required to be reduced to 0.5% m/m from January 1, 2020. Herewith, open-loop wet scrubber systems find more popularity among shipowners than closed systems.

Additionally, hybrid wet scrubbers are distinguished, their operating principle is based on the ability to switch between open and closed-loop scrubber systems depending on situations, for instance, local rules that permit or forbid the water discharge. Finally, the experts confirm that in hybrid wet air scrubbers the wash water has to follow strict criteria like the wash water for discharge must have a pH level of no less than 6.5. Moreover, a group of specialists on the scientific aspects of marine environmental protection has been created to assess the accessible data relating to the environmental impact of discharges of exhaust gas air treatment system effluent and to provide air pollution control.

If you search for the best air treatment device to improve air quality, you can buy a high-tech completely new type of wet scrubber – a Multi-Vortex wet air scrubber produced by Redwood Technology.

Redwood technology is a fast-growing vendor of wet air scrubbers. The multi-vortex scrubber can remove gas emissions, dust, vapors, and other pollutants from a gas stream. It is an innovative technology created to save water that makes it more cost-efficient and differs from other types of scrubbers.  If you have any questions or would like to purchase a multi-vortex wet air scrubber, please contact us at

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