Microplastics are choking our waters. Could a sponge made of squid bones help remove them?

Microplastics are everywhere. They have been found on the peak of Mount Everest and in creatures inhabiting the deepest trenches of the sea.

They’re in bottled water, human placentas and breast milk.

These tiny plastic particles choke wildlife, disrupt ecosystems, and threaten human health — and they are notoriously difficult to remove.

But scientists in China have come up with a possible solution: a biodegradable sponge made of squid bones and cotton.

A research team from Wuhan University used chitin from squid bones and cellulose from cotton — two organic compounds known for eliminating pollution from wastewater — to create a biodegradable sponge.

They then tested the sponge in four different water samples, taken from irrigation water, pond water, lake water and seawater, and found it removed up to 99.9 per cent of microplastics, according to a study published last month in Science Advances.

“The planet is under great threat from microplastics, and aquatic ecosystems are the first to suffer,” the authors wrote.

“Even under a variety of policies, including plastic product reduction, waste management, and environmental recycling, microplastic pollution is irreversible and escalating.”

The microplastics problem

Microplastics are tiny shards of plastic smaller than 5mm.

They come from everything from tyres, which are then broken down into smaller pieces, to microbeads, a plastic found in beauty products such as exfoliants.

One study from 2020 estimated there are 14 million metric tons of microplastics sitting on the ocean floor.

Scientists have called microplastics “one of this generation’s key environmental challenges” and the problem is an internationally recognised environmental issue.

Plastic is a persistent pollution that hurts wildlife, the ocean itself and there’s growing concern about the potential health risks it poses to humans.

The problem is only set to get worse with plastic production and pollution expected to increase.

Even if we embarked on an immediate and globally co-ordinated effort to reduce plastic consumption, an estimated 710 million metric tons of plastic would still pollute the environment by 2040, according to another study.

That makes finding solutions to get rid of the plastics contaminating our oceans all the more urgent.

The sponge created by the Wuhan researchers was able to absorb microplastics both by physically intercepting them and through electromagnetic attraction, the study said.

Previously studied methods for absorbing plastics tend to be expensive and difficult to make, limiting their scalability.

Last year, researchers in Qingdao, China developed a synthetic sponge made of starch and gelatin designed to remove microplastics from water, though its efficacy varied depending on water conditions.

The low cost and wide availability of both cotton and squid bones mean the sponge created in Wuhan “has great potential to be used in the extraction of microplastic from complex water bodies,” according to the study.

Shima Ziajahromi, a lecturer at Australia’s Griffith University who studies microplastics, called the squid-cotton-sponge method “promising” and said it could be an effective way to “clean up the high risk and vulnerable aquatic ecosystem.”.

However, the study’s authors did not address whether the sponge can remove microplastics that sink to the sediment, which is the majority of microplastics in our waters, said Ziajahromi, who was not involved in the study.

Another “critical issue” is the proper disposal of the sponges, Ziajahromi said.

“Although the material is biodegradable, the microplastics it absorbs need to be disposed of properly,” she said.

“Without careful management, this process risks transferring microplastics from one ecosystem to another.”

Ultimately, Ziajahromi added, minimising plastic pollution is in the first place should remain a “top priority”.