plastic – BIOLOGY, ENVIRONMENT & MORE

There’s a spat between tech companies trying to develop a new generation of plastics that biodegrade harmlessly without leaving a trace and skeptics worried that such novel substances won’t live up to their promise and will worsen the plastic waste problem.

The companies are calling for more time to perfect their inventions — which they say differ from earlier efforts to make cleaner plastics — while environmental campaigners demand even firmer regulatory action to get rid of plastic garbage. Firms are also battling against the image problem of an earlier generation of innovative biodegradable plastics that experts say haven’t lived up to the hype.

“The popular understanding of biodegradability is based on legacy solutions such as oxodegradable plastic, many of which unfortunately don’t work,” said Niall Dunne, the CEO of British firm Polymateria, adding that the “landscape has moved on significantly yet outdated perceptions remain.”

Polymateria has developed a process, called biotransformation, to produce plastic products it says decompose harmlessly when littered.

It involves mixing bio-transformation chemicals with normal plastics to create food and drink packaging, bubble wrap, fruit nets, plastic bags and the like. The technology helped to define a new British standard for biodegradability.

“The role of innovation is consistently underestimated when solving complex global issues, including climate change and plastic pollution,” Dunne said.

But potential innovations like that are facing headwinds.

An expert study, published last week, found that a lack of standards and reliable certification schemes for biodegradable plastics — and, in some cases, misleading labeling — confuses consumers and can “exacerbate” environmental pollution.

The biggest problem, according to the report from the Science Advice for Policy by European Academies, is that while biodegradables can break down under ideal conditions they have a much tougher time doing so in a natural environment like deep in a landfill or on a beach.

Polymateria is tackling those issues. Although it can be recycled in the normal way, its new plastic will decompose into a wax or grease-like substance in a matter of months when exposed to sunlight, air and water. Bacteria and fungi will digest the wax, breaking it down into carbon dioxide, water and more microbes. Most importantly, there are no microplastics left behind.

For now the additives only work when added to the most littered type of plastics — polyolefins, which include polyethylene (plastic bags and packaging) and polypropylene (plastic cups and cutlery, bottle caps and containers).

In lab tests that mimic ambient real-world conditions, “there’s nothing left of polyethylene waxes in 226 days and the polypropylene waxes disappear in 336 days,” said Dunne.

The plan is to stamp a “recycle by” date on each piece of plastic to show consumers that they have a deadline to dispose of them responsibly in the recycling system before they start breaking down.

The technology is currently being tested in a handful of countries, including the U.K. and India, but has already helped to define the first standard for measuring biodegradability, published by the U.K.’s national standards body BSI in October.

That European Commission is also busy developing its own policy framework for bio-based plastics and biodegradable or compostable plastics, which it expects to adopt next year.

Not everyone is lyrical about Polymateria.

For one thing, the additive adds roughly 10 to 15 percent to the overall cost of packaging. There’s also the question of whether plastics should be made biodegradable in the first place.

British environmental groups including RECOUP and the Environmental Services Association wrote to the BSI, insisting the standard “will increase the prevalence of litter in all environments.” They fear that the concept of being able to throw away litter and assume it will biodegrade supports the continued use of plastics.

But Dunne said that most of the problem with plastic waste is due to exports to non-EU countries where it’s “not being recycled and is winding up in unmanaged waste systems,” he said, estimating that littering only accounts for 2 percent of the issue.

He argued that the solution is “innovative technologies which permit reuse and recycling” as well as redesigning materials to be biodegradable at the end of their useful life “if we are really serious about actually solving this global problem.”

The European Commission on Tuesday adopted new waste shipment rules going into effect in January that ban the export of plastic waste from the EU to non-OECD countries, except for clean plastic waste sent for recycling.

The scientists behind re-engineering of the plastic-guzzling enzyme PETase have now gone a step further. These scientists have created an enzyme medley, which is up to six times faster to digest plastic.

Another enzyme, found in the same rubbish dwelling bacterium like PETase, has been combined with the latter to speed up the disintegration of plastic. PETase disintegrates polyethylene terephthalate into its building blocks. This creates an opportunity to reprocess plastic infinitely and reduce greenhouse gases and plastic pollution driving climate change.

Meanwhile, PET is the commonly used thermoplastic to make clothing, carpets, and single-use drink bottles. It takes hundreds of years for PET to disintegrate in the environment, but PETase can reduce this process to days.

Discovery of Plastic-eating PETase first step in Plastic Recycling revolution

With the discovery of PETase, it set up the prospect of a revolution in plastic recycling, thereby creating a potential low-energy solution to deal with plastic waste. To establish this, the natural PETase enzyme engineered in the laboratory featured to be almost 20 percent faster at disintegrating PET.

Going further, the same team of scientists have combined PETase and a second enzyme MHETase, for much bigger improvements. The mixing of PETase and MHETase doubled the speed of breakdown of PET, and designing a connection between the two enzymes created a super-enzyme, which further increased the speed of the activity by three times.

The study published in the journal Proceedings of the National Academy of Sciences was co-led by scientists who engineered PETase.

“In the natural phenomenon, PETase attacks the surface of the plastic and MHETase chops it further. Likewise, for it seemed natural if the two enzymes could be used together, to mimic the natural phenomenon,” opine the associates of the study