How mussels can reduce the impact of microplastics

Microplastics are everywhere – from the deep sea of the Arctic to the snow-capped peaks of Everest. It is spread by winds and ocean currents and caused by the breakdown of the litter of 360 million tons of plastic produced annually. The long-term impact of microplastics on human and animal life is not entirely understood but its effects are there to see. It’s ingested by fish, birds and zooplankton, the tiny animals that make up the base of the food chain in most marine ecosystems.

However, whilst the impact of plastic pollution has the world’s attention, plastic is still a hugely valuable material – and it is predicted that plastic manufacturing could almost double by 2050. Society is thus left with the question, how best do you limit the harmful impact of microplastics?

Plastic is practical, lightweight, inexpensive, waterproof and incredibly versatile, which is why it’s used in everything from food packaging, cosmetics and medical equipment to bridges, buildings and homes. For those of us in the automotive industry, it has contributed to safety, performance and fuel efficiency innovations. For example, switching from selling grapes in bunches to sealed plastic trays in retail stores has reduced waste typically by over 20%, whilst modern medicine has greatly benefited from the disposable plastic syringe invented in 1955.

But the scourge of plastic waste on the environment is clear to see, from large items of debris on our shorelines and in our seas and at landfills, where more than 50% of plastic waste ends up. And then there are microplastics – tiny particles less than 5mm in size, most often smaller than 1mm – that end up in our seas, contaminating beach sediments and being ingested by birds and sea creatures. And the impact of these microplastics is now becoming more widely understood, thanks to this year’s winners of the Volvo Environment Prize – Professor Richard Thompson, Professor Tamara Galloway and Professor Penelope Lindeque. Their work has been instrumental in raising societal awareness of plastic pollution, particularly microplastics, and triggering policy action.

In 1950, the world only produced two million tons of plastic. Since then, annual production has skyrocketed nearly 230-fold and is set to reach 590 million metric tons by 2050. So how do you handle this exponential growth in plastics and their blight on the environment? Turning the clock back to a pre-plastic age is not an option; after all, plastic has the potential for good. Twenty-two percent of an Airbus A380 double-decker aircraft is built with lightweight carbon fibre-reinforced plastics, saving fuel and lowering operating costs by 15%. Renewable energies, meanwhile, rely on plastics for pipes, solar panels, wind turbines and rotors.

But we need to move beyond this “throw away” society and reduce our use of single-use plastic, with its short life in service and long persistence in waste. Moreover, action needs to be considered to avoid unintended consequences, like a rise in food waste, if we suddenly switch from plastic packaging without a viable alternative. Our challenge is to mitigate the worst effects of its proliferation and find ways of reducing the pollution it causes.

The scientific community offers our greatest hope, where exciting nature-based solutions to help remove microplastics from our oceans are being explored. At the Plymouth Marine Laboratory, Professor Penelope Lindeque and her team are looking into the ability of mussels to filter microplastics from water. Voracious filter-feeders can remove bacteria and excess algae from water and in lab-based experiments, five kilograms of mussels have been shown to release a quarter of a million pieces of plastics per hour.

Plastics at the concentrations found in the marine environment are not thought to be harmful to the mussel. Clusters of mussels could be sited near the mouths of rivers and estuaries, in marinas, harbours and near wastewater treatment works in large submersible baskets. Net-like receptacles can be used to collect their waste matter along with microplastics, which can then be hauled in and removed from the water. Harnessing this natural filtration could provide an environmentally safe and cost-effective solution and one that could be rolled out at scale.

Clearing up plastic waste cannot be the only solution we pursue; our relationship with plastic must also change. For example, in some applications, it is the right material, so we need to use it more sustainably and look for greater circularity.

Currently, we take oil and gas from the earth to make plastic, much of which is only used once. We can reduce the amount of plastic that goes to waste but this begins in the design phase, where we must shed our traditional linear “take-make-waste” model. Instead, we should adopt a more holistic, circular approach that considers the source of our primary materials and the longer-term impact our products have both now and in their second and third lives. A prime example is micro-beads in cosmetics and personal care products. It was decades after their creation before anyone understood their harmful environmental effect, leading to their ban in many countries worldwide.

We must design products that can deliver life in service and ensure maximum use at every stage. And we must ensure the plastic we use can be effectively recycled after its useful life. That means ensuring we do not mix recyclable and non-recyclable plastic parts in products. A more circular approach is better for the environment, sure, but it also offers economic and societal benefits too.

There is no doubt as to the value of plastic, so it doesn’t serve us to demonize it completely. At the same time, the environmental effect of plastic pollution must be addressed with swift and considered action. We must allow science to lead us so that we, as industry leaders and policymakers, can make evidence-based decisions. The health of humans and the planet depends upon a healthy ocean and we cannot afford to let them down.