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composting

Can compostable PLA materials be composted at home?

Logan Byrd

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posted 1 year ago

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I have a small collection of PLA straws that I've collected over time from restaurants, and they've all been labelled "100% home compostable" and "meets ASM D6400".

But looking it up online, I'm getting mixed opinions about whether or not they can be home composted, and if so, how.

Does anyone have any advice on these, especially in terms of cold composting? I don't mind if they take 2-5 years to compost, but I want to make sure they're actually composting and not just making the soil worse.

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Anne Miller

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posted 1 year ago

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Why not try an experiment by trying to compost just a few of them to see what happens?

Please let us know what your findings are.

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Logan Byrd

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Anne Miller wrote:Why not try an experiment by trying to compost just a few of them to see what happens?

Please let us know what your findings are.

I'd be happy to give this a try, but is there a good way to determine whether it's actually composting or just breaking down into microplastics?

It's never too late to start gardening, and even the smallest project is worthwhile.

Anne Miller

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I have never even seen one of these compostable straws so I have no idea.

To me, this is worth finding out.

I have read that to test the compostable packing peanuts it is as simple as filling a kitchen sink with water to find out.

Has anyone tried composting those?

Invasive plants are Earth's way of insisting we notice her medicines. Stephen Herrod Buhner
Everyone learns what works by learning what doesn't work. Stephen Herrod Buhner

Mike Philips

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posted 1 year ago

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Based on what I’ve read online, my impression is that PLA won’t cold compost (inside of your 5 year timeframe). Hot composting might work.

Specialized material recycling might be an option, since PLA is the most common material used in 3d printing.

Douglas Alpenstock

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Unfortunately, the answer is no -- they won't break down in cold compost. I have some bits and pieces that have been in my compost for years. No change.

I recall that it takes sustained temperatures of 50C to break them down. That requires an industrial scale operation. (I think I posted that here a while back.)

Next time I make char, I need to remember to throw them in a tin can of water and boil them hard to see what happens.

Mike Philips

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If you really wanted I suppose you could “solarize” your compost. Put it in a little cold-frame type greenhouse. (Keep it away from important structures in case it catches fire!).

Think of how hot a closed car can get in the summer, 50 deg.C no problem.

Whether it’s worth it is up to you. I’m just attempting to answer the original question of ‘Can it be done?’.

Douglas Alpenstock

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Mike Philips wrote:If you really wanted I suppose you could “solarize” your compost. Put it in a little cold-frame type greenhouse. (Keep it away from important structures in case it catches fire!).

Hm! And maybe add all the noxious weed seeds that you didn't manage to get into the anaerobic rot barrel. Cooking them to make them inert would be fast and then everything can go onto compost pile.

I'm not sure if a certain humidity is also necessary to break down starch plastics. It would certainly keep the whole thing from catching on fire.

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