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There seems to be a lot of debate about whether, and how, plastic degrades in a landfill.

There are many different types of plastic, from polypropylene to polystyrene. With this variety, it seems possible that each polymer could have a different behaviour.

At any rate, some argue that plastic degrades after several decades, others after hundreds of years, and others still after thousands of years. Whereas, others argue that plastic does not degrade at all.

Then there's the argument of "biodegrading" vs "degrading". While plastic may "break down" in a landfill, does it every completely erode? Or, does it merely break down into micro-plastic and remain in the earth forever?

In short: does plastic degrade entirely in a landfill? If so, how does this process work? If not, why?

Adam McKenna
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  • There are microbes that break down some plastics, but slowly and seemingly not if there's other food. That's being actively researched, but it beats burning the plastic. Which is the other way plastic is known to break down. Unless the landfill catches fire I doubt anything much breaks down in it - they emit some methane but nowhere near as much as a composting operation does. – Móż Feb 15 '21 at 07:39

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I would be surprised if it did. Los Angeles in excavating land fills finds that newspapers hot dogs, lettuce, guacamole still appear fresh. Isolated from air not much happens in a landfill.

See this story https://www.nytimes.com/1992/08/13/nyregion/seeking-the-truth-in-refuse.html

This actually is useful info. It means that appropriatly designed landfills could be a good way to dispose of plastic, paper -- anything with carbon that isn't easy to recycle can be used to remove carbon from the cycle.

Sherwood Botsford
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