Ships’ scrubbers used to remove ocean microplastics

A filter fitted to the sulphur scrubbers used on large ships has proven successful at removing microplastics from seawater

Spotted: Microplastics, defined as plastic fragments less than 5 millimetres in length, have now been found everywhere scientists have looked – in freshly fallen snow and rain, shellfish, table salt, drinking water, beer, and, of course, in the ocean. In 2021, a team from Kyushu University in Japan estimated that there are at least 24.4 trillion pieces of microplastic in the world’s seas. Now, technology group Wärtsilä and shipping company Grimaldi Group, have developed a microplastics filtration system for ships.

The new filter makes use of the open-loop scrubber system installed in most ocean-going vessels. Scrubbers use seawater to lower the sulphur content of the ship’s exhaust. This is necessary, as sulphur is a major pollutant. The new filter traps plastic particles in the water used in this system, removing them before the water is returned to the ocean.

Scrubbers powered by a 10-megawatt marine engine can process approximately 450 cubic metres of water per hour, potentially resulting in the capture of a large amount of microplastics. According to Wärtsilä, the filtration system can capture around 76 particles per cubic metre of water. Pilot testing on a voyage between Civitavecchia and Barcelona collected 64,680 microplastic particles.

Emanuele Grimaldi, Managing Director of the Grimaldi Group, explains that, “Reducing microplastic pollution in our world’s oceans is an important challenge, and we are pleased to provide a solution for the shipping industry. The idea for this innovative technology originated from recognising that open-loop exhaust gas cleaning systems can draw seawater for exhaust scrubbing and simultaneously collect micro-plastic present in the oceans as part of their normal operation.”

There are a growing number of innovations aimed at removing microplastics from the environment. Springwise has covered many of these, such as the use of okra to capture micro-plastics already in the environment and a tyre made from soy that could prevent the shedding of micro-plastics in the first place.