The recent European switch to attached bottle lids for recycling is very interesting to me, because as an American I've always been told that plastic bottle caps *cannot* be recycled, and should be thrown in the trash while only the bottle itself gets recycled.

Anybody know the origin for this? Was it just a desire to sell more single-use plastics? Are detached lids so small that the effort to extract them from the waste stream is too much to justify the amount of material you get? Something else?

@azonenberg it's attached so they don't end up in the water was my understanding, not to do with recycling per-se, just that you don't want them coming off and going into stormwater.

@dotstdy ah, interesting.

So there is still ~no recycling for bottle caps? Attaching them seemed weird to me because they're typically a different type of plastic than the bottle itself, so you'd need to separate them before you could recycle either.

@azonenberg If I understand correctly, it's much more important to prevent people throwing the lids into the environment, either accidentally or on purpose. The ecological impact of recycling or not recycling the lids should be very minor in comparison as plastics recycling is a frustrating story on its own (doesn't really make economical sense atm and it's an engineering headache as recycled thermoplastics have worse mechanical properties).
I'm not sure about the process of separating the lid.

@whoami Ah I wasn't considering the litter side of things, I was assuming the potential outcomes were either recycle bottle + cap, trash bottle + cap, or recycle bottle and trash cap.

@azonenberg not really sure, as far as i understand it plastic recycling in general is uh... not really recycling in general. so my expectation would be that it makes no real difference.

@dotstdy Yeah I know, that's why I was confused. Like, it seemed silly to go through all this engineering effort to hold onto a tiny bit of what's essentially garbage and isn't going to be usefully recycleable anyway.

@azonenberg Afaik bottle caps are more valuable than the bottles, there are even dedicated collection campaigns for them around here

@azonenberg @whoami
I guess it's the bottle equivalent of pull tab vs. stay-on tabs on cans.

@azonenberg @whoami - first thing that happens is shredding everything. Next is hot water bath. Labels detach, paper plus adhesive gets filtered out, ideally while paper is still small bits and not yet dissolved to fibers. PET bottle material is just a tad heavier than water and sinks to be collected from the bottom. Plastic labels and bottle caps are slightly lighter than water and float to the top. And yes, they are all sought-after, high grade recycling material streams that do get used again. Much less contamination than general plastic waste streams.
Just like the stapler needles and paper clips in paper recycling: seems insignificant, but that's a ton of valuable metal that accumulates every couple of days...

@axel_hartmann @whoami Huh, I was under the impression that containers were normally sorted by type as solids and only *then* separated and shredded as relatively homogeneous materials.

Back when I was a kid we had separate recycling cans for HDPE/LDPE, metal, clear glass, green glass, and brown glass.