I think this problem mostly exists in places where people have a single recycling bin. If each type of material is collected separately, it's easy to establish when recycling makes sense. And then you can also create incentives for using packaging materials that can be recycled.
Agreed, the single stream is the biggest joke ever. Like, what kind of recycling can you really do with paper covered in food drippings from yogurt containers, food and beverage cans, etc. And what's the exact process for washing those plastic containers just caked in food? And given that they're commingled on the scale of entire buildings or residential blocks, do people really believe that 100% of such large numbers of people meticulously wash their garbage? Personally I would just recycle aluminum and that's it. Everything else is just a roundabout trip to the landfill in the current setup.
How exactly does multi-stream recycling solve any of the problems you've mentioned?
It's pretty easy for recycling centers to sort out most of the glass and metal from that stream and then as technology improves they can sort and recycle even more of the plastic.
As for the food waste, I just assumed it was mostly destroyed by the recycling process. The high temperatures for metal and glass recycling make that seem easy to me. Plastic would be harder, but I think that's also part of the reason plastic can only be recycled a couple of times (it's not "pure" after it's recycled.)
There isn't and won't be a technology that is going to ever economically recycle (closed loop, meaning used for a similar purpose over and over) most of the plastic containers in the trash, especially when it's 40 different types of plastic all mixed together (with generous amounts of contaminants mixed in). Sure, it can sometimes be downcycled once, like shredded into some kind of filament and used to stuff a low-quality cushion or something. That's about it.
If it were economic to really recycle it, China wouldn't have stopped taking ours. And most of the rest of Asia followed suit, which is why municipalities are sheepishly hoarding it in warehouses now without a plan, or just admitting to themselves (if not their citizens) it's a sham and diverting most of those plastics we put in the blue bins straight to the landfill.
One more thing: You're right that multi-stream recycling wouldn't fix the problem for the plastics, though just collecting metal and glass and letting the plastic take a more direct route to the landfill would be more efficient and would have a chance of getting people to understand that the blue bin doesn't redeem any of their sins when it comes to plastic.
It goes through a process. It doesn't make metal or glass useless.
Biological Treatment: Organic waste, including food waste, is often separated either at the beginning of the process through manual sorting or through processes like anaerobic digestion. In some facilities, organic waste is processed separately to produce compost or biogas.
I don't know about glass, but any junk in molten metal just burns up and the ashes can be skimmed off the top. It's not really the metal I'm talking about, it's the plastic and paper which are pointless to even have in the system.
