Are we eating enough plastic already?

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[–] 106 points 2 days ago* (last edited 2 days ago) (5 children)

Before the yeast can start feasting, the PET plastics are subjected to a process called oxidative hydrothermal dissolution to break them down into smaller bits that the microbes can digest.

Sensationalism aside, this could actually be a big deal. We use a lot of PET (polyethylene). Plastic drink bottles, plastic bags, plastic wrap, tape, fabrics, even some car parts. PET is a huge market segment of consumer products that are difficult to replace with environmentally friendly alternatives.

If we can boil it and then feed it to a vat of yeast to break down, that would be fantastic. Even better, it could remove some of the difficulty of plastic sorting which is a major part of the recycling problem. Basically, if you dump some plastic into the vat that the yeast can't eat, well it just won't eat it, so just sift it out of the vat later for a different disposal process, no big deal.

Even if humans can't directly consume the byproduct, I'm sure we can use it for something else.

My biggest question is how long this takes, which they don't address in the article. How long do you have to boil the material (how much energy, how much water, how much oxygen, how big a facility to process X volume of waste), and how long does it take the yeast to break it down? If it can be done in hours or days that's well worth spending some resources to build a processing center. If it takes months or years it will require more planning and analysis.

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  • [–] 4 points 1 day ago* (1 child)

    These "food cookies" could be used as compost or animal feed no? Just transforming it into something that can return to nature is really cool.

    Also opens up the door to possibly finding a way to remove microplastics from people or animals. If it was possible to safely get those yeast into people, would break them down.

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  • [–] 3 points 1 day ago*

    Absolutely. Nothing can break down those polymers naturally, so just getting that process started makes a big difference. The very worst case is that the output material ends up in landfill - if it's just a sugar molecule at that point, it will break down relatively quickly. Way, way better than letting the plastic break down in the environment.

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  • [–] 33 points 2 days ago (2 children)

    My biggest question is how long this takes, which they don't address in the article. How long do you have to boil the material (how much energy, how much water, how much oxygen, how big a facility to process X volume of waste), and how long does it take the yeast to break it down? If it can be done in hours or days that's well worth spending some resources to build a processing center. If it takes months or years it will require more planning and analysis.

    They don't put in a direct answer, but there is an indirect one: $60 per kilo. That needs to come down A LOT before there is a real future for this. I heard of projects that try and turn plastics into fuels. Sooner or later somebody will figure it out.

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  • [–] 2 points 20 hours ago*

    $60 per kilo

    That's not bad for a prototype! With lab-growth meat, the initial cost was $2.3 million / kg. It's come down since then because of process and scale improvements, but when it starts off that high, it's going to be a while for it to become affordable.

    A quick non-AI figure is $0.60 per kilo to recycle plastic... so we just need improvement by a factor of 100 which is quite realistic.

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  • [–] 17 points 2 days ago* (2 children)

    Yes, I'm assuming that this is being done in a lab environment without purpose-built equipment, and also that developing the specialized yeast strain was part of the cost.

    Assuming that the genetic change is stable and that the yeast is self-propagating like normal yeast, then engineering the rest of it into an assembly line shouldn't be too difficult and should bring the cost down by orders of magnitude.

    Plus, if we can turn the output hydrocarbons into a viable market product then the recycler can offset the operating cost, which would make this even more interesting. Right now plastic recycling is just losses.

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  • [–] 3 points 2 days ago* (2 children)

    Assuming that the genetic change is stable and that the yeast is self-propagating like normal yeast, then…

    …we will have to stop using so much plastic, because it won’t be reliable shelf stable packaging one the yeast that eats it is loose.

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  • [–] 4 points 2 days ago (1 child)

    Possibly, but:

    Before the yeast can start feasting, the PET plastics are subjected to a process called oxidative hydrothermal dissolution to break them down into smaller bits that the microbes can digest.

    "Oxidative hydrothermal dissolution" - basically they boil the plastic and oxidize it, I think at the same time. Maybe hydrogen peroxide + water? Essentially this is kind of an accelerated aging.

    Anyway, the yeast can't eat the plastic without some processing first, which is probably good because it means existing plastic packages won't just start falling apart. On the other hand if this does get loose, it might be able to eat any PET litter that has started breaking down in the environment due to exposure to sun, rain, ocean water, etc. The absolute easiest waste for this to eat would be any PET that has broken down into microplastic particles and ended up in soil or water, which would be kind of an ideal situation.

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  • [–] 3 points 1 day ago

    Evolution finds a way.

    But seriously I thought the article implied the oxidation process just made the particle smaller so they’d have more surface area and get consumed quicker. Even if it’s slow, won’t the yeast that have a taste for PET still want to grow on it, like they do with bread.

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  • [–] 7 points 2 days ago (1 child)

    Introducing picoplastics to a cookie near you (hopefully not)

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  • [–] 3 points 2 days ago (1 child)

    Aren’t they just hydrocarbons at some point?

    Like burnt toast?

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  • [–] 1 point 2 days ago (1 child)

    Burnt toast doesn't accumulate in the body

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