PLA does not break down naturally. It will last centuries in the environment.

PLA does break down naturally, it is a good source of carbon for many types of bacteria. It takes a long time, and happens more quickly in industrial composters where it's shredded to microplastics first but it does happen.

Take a look at something people have been using for eons with saltwater aquariums: bio-pellets. These are tiny beads of PLA that are fluidized to allow high turnover of water through the PLA, this encourages bacteria to colonize and digest the PLA, then break off and move into the water column (the bacteria) and be removed by the protein skimmer. Because of the red field ratio, each 106 mols of carbon from PLA removed this way also removes 16 mols of nitrate, which is a major pollutant in aquariums. It also removes 1 mol of phosphate, a major pollutant as well, but that's not significant. Phosphate is best done by fluidized reactors with ferric oxide

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zenith_is_tired 3 hours ago | parent [-]

CNC Kitchen put 3D printed PLA into their composted for over three months. I don't remember the specifics, but results were underwhelming.

As someone who constantly prints temporary jigs and spacers, I'm interested in compostable filament. Bonus points if it is comparable to PLA in price.

	▲	tmp10423288442 3 hours ago \| parent \| next [-]
		There are a decent amount of plant parts that don't break down much at all in 3 months - doesn't mean they aren't biodegradable ultimately, although hoping for biodegradation as a way to eliminate litter is a nonstarter with this approach.
	▲	malfist 2 hours ago \| parent \| prev [-]
		3 months? Most organics will not break down in that time. 6-12 months is recommended, and even then, not everything is broken down. I've had egg shells last 2 years or more in my compost bin. I made no claims about the speed at which PLA breaks down, only that it does. Biopellets in reactors tend to last years.