According to the Environmental Protection Agency (EPA), plastic waste accounts for nearly 20% of what’s going into landfills. That’s after recycling and combustion has reduced the total amount of plastic waste. Now according to this article by David Nield at ScienceAlert engineers at the University of Texas have developed a way of depolymerizing the plastic (breaking it down into more basic molecular units) quickly:
In tests, products made from the polymer polyethylene terephthalate (PET) were broken down in a week and, in some cases, 24 hours – these are products that can take centuries to degrade properly in natural conditions.
“The possibilities are endless across industries to leverage this leading-edge recycling process,” says chemical engineer Hal Alper from the University of Texas at Austin.
They also demonstrated the ability to repolymerize it chemically to make new plastic. Equally interesting is the method they used:
The team has called the enzyme FAST-PETase (functional, active, stable, and tolerant PETase). They developed the enzyme from a natural PETase that allows bacteria to degrade PET plastic and modified it using machine learning to pinpoint five mutations that would enable it to degrade the plastic faster under different environmental conditions.
Clearly, there’s a lot left to be done. Can the enzyme be used at scale? Are mitigation measures needed to control its use? Does it bear additional risks? Is it cost-effective? Once these issues have been resolved this newly-discovered enzyme or one like it has important benefits in reducing the amount of plastic waste going into landfills.
More here.
I also wonder what the energy requirements might be for either the depolymerization step, the repolymerization step or both. Thermodynamics tells us that there will be some. That’s one of the reasons that I think that producing more energy more efficiently is a better solution for us than producing less energy. It expands the possibilities open to us.
Scientifically, it should be feasible, but because I could not read the paper, I do not know the details. The energy requirements should be to keep the critters alive, but there should be some thermal energy produced. It could offset what is required. Also, there should be other byproducts.
Petroleum products are just hydrogen and carbon atoms arranged in differing configurations and numbers, but not all plastic is configured the same. Plastic is susceptible to being affected by hydrocarbon molecules, and leaching into food and water stored in plastic containers is what causes the plastic taste.
I think that the plastic type that is more resistant to this leaching would be more resistant to the enzymes, and this would apply to fuel containers, as well. In any case it sounds better than banning plastic straws and bags.
(I love how Starbucks has a paper straw sticking out of the plastic lid.)
Unless the process is done in Wuhan, my concern is that the critters could escape into the wild. Horizon Zero Dawn is a video game that has a similar scenario. An AI software bug causes militarized self-replicating biomass eating nanobots to become unresponsive, and they eat all the organic matter on Earth, including humans. (The game is awesome.)
Interesting stuff. There are any number of PET depolymerization schemes. I guess only time will tell about the issues you point out with this one.
“Petroleum products are just hydrogen and carbon atoms arranged in differing configurations and numbers…”
And, generally, N, O, and S. *
* Ok. Ok. I know you know that. Just tweaking your nose. Must be the crack.
@Drew
Usually, my “crack pipe” comments are based upon your argument, but that one was based upon the sentence structure. You included part of my comment in sentences in two paragraphs, but they were not actual quotes.
Honestly, it was bizarre. I was trying to find a golf reference, but I am fairly certain there was none. While I may disagree with you, I mostly understand what you write.