Why have plastic-eating bacteria not solved the problem of plastic pollution in the sea?

Why have plastic-eating bacteria not solved the problem of plastic pollution in the sea?

Researcher from the University of Texas announced that they have created an enzyme that eats plastic which could keep billions of pounds of plastic away from landfills.

Now, if that sentence gives you déjà vu, you are not alone.

Followers of science news may have seen similar exciting headlines over the years, from the 2008s The Science Fair project insulates plastic-eating microbes– about a 17-year-old science fair winner who caused bacteria to break down plastic bags by 43% – to last month’s New Enzyme Discovery is a new step towards plastic wastewhere British researchers developed an enzyme that could break down PTA, an ingredient in plastic bottles.

You’ve seen many similar titles in between: “New superenzyme eats plastic bottles six times faster,“”Plastic-eating bacteria can help global recycling effortsetc., which gives the impression of a silver bullet (in itself undoubtedly recyclable) that will kill our monstrous plastic problem.

Why do these plastic-eating bacteria just turn their fingers? We have one crisis to handle!

So what takes so long? Why do these bacteria just twist their thumbs while we have one crisis to handle?

It turns out that there are some reasons why things are not so simple:

Plastic is not the same. Many enzymes or bacteria only work for a certain type of plastic, and much of our rubbish combines several types of plastic.

Most plastic recycling efforts focus on PET, the plastic used in plastic bottles. PET accounts for about 20% of global plastic waste. It is chemically easier to degrade than polyethylene or polypropylene, types used in plastic film and food packaging.

This is an important warning: most of these solutions would only put a dent in our plastic problem, rather than solve it completely.

Many solutions only work under special conditions. Often the reactions or bacteria only work at certain temperatures, in special environments or after long periods of time. The more difficult it is to create the conditions, the less practical it is to do it on a large scale. This also means that it is unlikely that bacteria will solve the problem of plastic contaminants that already exist in nature – more on that soon.

They cost too much. These processes can be expensive. Furthermore, most solutions simply break down plastic into their original monomers, which are really only useful for create more plastic.

This has two problems: one, it does not reduce the amount of plastic in the world, and two, making new plastic is already very cheap. Creating a costly factory, transporting lots of waste to it and letting bacteria slowly break out ingredients that are worth virtually nothing – and still are not biodegradable – is not a good business model or perhaps even an efficient use of taxpayers’ funds.

It is not necessarily safe or effective to release into the wild. There is often an assumption that this bacterium can be released to chew through the plastic mountains that we currently have buried in landfills, swirling in the oceans or scattered as debris.

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But even if bacteria or enzymes could function under completely unregulated conditions, they can have toxic by-products, destroying plastics that are still in use (such as the device you are using to read this right now, making you unable to complete this valuable article), or require you to place huge amounts into an area to make a difference.

So at the moment, these technologies can really only be used within our existing recycling systems, rather than being a fundamentally new alternative. We will still need to sort, collect and process all the plastic we want the bacteria to eat.

Fortunately, there is also some good news: researchers from Japan to Saudi Arabia to US National Renewable Energy Laboratory work on these problems, and things improve.

For example, recently discovered at UT-Austin identified an enzyme that reduces the time to degrade plastic to a few hours, and it can operate at the relatively achievable temperature of 50 ° C (122 ° F). And it was found with an AI algorithm that could continue to iterate and improve its performance.

Fortunately, there is also some good news: researchers from the United States to Saudi Arabia to Japan are working on these problems, and things are improving.

And the first demonstration facility dedicated to enzyme-based plastic recycling recently opened. The French company Carbios, which runs it, announced that they have successfully produced new plastic bottles from PET with a process that makes them infinitely recyclable.

It’s a breakthrough worth celebrating. Today, even if plastic is recycled (over 80% do not, including over 90% in the US), it can generally only be turned into lower quality plastic, for niche uses such as carpets.

Traditional mechanical recycling processes are expensive and inefficient, requiring waste sorted, shredded, cleaned, melted and pelletized And dispose of all batches contaminated with food or incompatible materials. Chemical recycling processes can often create their own toxic by-products.

Carbios plans to create a plant on a commercial scale by 2024, and although they do not expect their plastic to be as cheap as newly made variants, they hope that environmentally conscious companies and consumers will pay a little extra for it. In addition, its approach will allow plastics to be recycled from mixed waste more efficiently and with less waste.

We do not have to rely on miracle bacteria to do our dirty work.

Time will tell whether new processes will help tear down our plastic problem. Meanwhile, other researchers and companies are creating biodegradable materials that can completely replace plastic, from MIT’s cellulose-based solution to companies that use bacteria to grow durable materials. European governments are taking a different approach and prohibits more difficult to recycle plastic.

And of course, you do not have to wait for any of them – individuals around the world find creative ways to reduce their own plastic use. No matter how exciting they are, we do not have to rely on miracle bacteria to do our dirty work.

This article was originally published by our sister site, Freethink.

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