Could natural decay be a solution to plastic pollution after all?

The site Nature Communications ran a remarkable article about wax worms that break down polyethylene. We read it through The Guardian and the Dutch site change.inc. But, we asked ourselves: isn’t polyethylene completely inert? At most to be dispersed in the form of microscopically small particles that will stay in the biosphere forever? No, so it appears. An investigation into a more optimistic view on plastic pollution.

plastic pollution
Plastic Pollution in Santa Luzia, Cape Verde. Photo: CaptainDarwin, Wikimedia Commons.

Chance

Researchers accidentally discovered that wax worms can digest polyethylene. One of the researchers, Federica Bertocchini of the Biological Research Centre in Madrid, is a beekeeper. Her beehives were infected with wax worms. ‘I started to clean the hives and collected the worms in a plastic bag,’ she told The Guardian. ‘After a while I saw holes in the bag. We discovered that this wasn’t just the result of chewing. It was chemical degradation.’ The worms’ saliva contains enzymes that can dissolve plastic bags and packaging.

These enzymes are the first known substances able to break down this plastic within a few hours. The key to a form of decay that could be cheap enough. And that would be good news. Thirty percent of all plastics in the world consist of polyethylene. The main applications of the material are in everyday commodities like bags and packaging. So far, there were just two ways to treat these plastic products when discarded. Incineration or downcycling – and in the latter application, polyethylene still stays intact.

Useful chemicals

A lot needs to be researched before this form of decay might be ready for commercial application. ‘We will have to do a lot of research, and think about how we can develop this new strategy to cope with plastic pollution,’ says Clemente Arias, researcher at the Spanish research centre, to Nature Communications. ‘Commercial application’ could mean: in large factories, where we might make useful chemicals from the plastic. But the researchers also have the idea that this process might be a home-based product. In the form of a recycle kit, that could recycle plastics to useful products.

Plastic pollution is all over the world. It has been found on Mount Everest’s summit and in the deepest trench in the oceans, the Mariana trench. On the other hand: we also discover processes that cause plastic to disappear in nature – some of it may be digested after all. Change.inc reported on German researchers who found an enzyme capable of downgrading plastics in a manure heap at a cemetery. And on Australian researchers who found a worm that can downgrade polystyrene (two links in Dutch).

plastic pollution
Plastic Trash in Raja Ampat, Bird’s Head Seascape. Photo: Jones/Shimlock / Secret Sea Visions, Wikimedia Commons.

Sunlight

At NIOZ, the Netherlands Institute for Sea Research, researchers even proved that plastics can be broken down by sunlight. The miniscule particles into which plastics degrade in the sea aren’t perfectly inert. Solar radiation will break down 2% of all plastics floating in the sea annually. ‘That may seem too little,’ says PhD student Annalisa Delre in a message, ‘but as this will happen each year, this phenomenon does explain why we lost a major part of the plastic soup in the oceans since the fifties.’

This explains why we find just part of the plastic that we dumped into the oceans. NIOZ says that this breakdown by sunlight explains about one fifth of this phenomenon. In the lab, researchers exposed plastic in sea water to UV light, mimicking sunlight. This caused plastic particles to shrink. Part of them dissolved in the form of nano particles, and even in the form of molecules not unlike those found in crude oil. Itself difficult to decompose, but not quite inert. Yet, just a small part of the plastic soup ended up as the entirely harmless breakdown product CO2.

Less plastic pollution is the best solution

The researchers don’t judge that we should solve the problem of plastic pollution though this mechanism. As if we should just discard plastic in the seas. It is in our advantage that the problem of plastic pollution is less permanent than we once thought. And yet, the most effective solution is to cap the volume of plastics production. The researchers who made a plea for this recently, hold that all other measures will not be able to keep pace with the growth of plastics production and plastic pollution.

Therefore, we should also take on the elephant in the room: that plastic cannot be a once-through commodity. We should start reflecting on the question which products should necessarily be made of plastic. And keep in sight the three Rs: reduce, reuse, recycle. Even taking into account all kinds of help from nature, we should find solutions of our own.

Interesting? Then also read:
Plastic recycling: urgent, but a major problem
New Plastics Economy: circular, not yet biobased
Closing the plastic loop

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