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All of the milk bottles are blue

A solution to sorting plastics for recycling
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One of the hardest problems in plastics recycling is determining what type of plastic a product is made of. Humans and computers can fairly easily pick out milk jugs (LDPE) and soda bottles (PET). Maybe even shampoo bottles (HDPE - usually). The trick is *everything else*. If you spend the time to look for the little recycling number (if it's even readable) your recycling will be really difficult and slow. But if you don't look for the little number, it's almost impossible to tell the chemical composition of the plastic you're looking at.

The solution is to simply make all plastics of a given type the same color. Everything. Every single plastic thing can be made a specific color. This would dramatically simplify manual or computerized picking during the recycling process.

Fashion designers might not love this, but it's our world we're talking about. Any non-recyclable mix of plastics would be required to be baby puke green.

Worldgineer, Sep 22 2020

I darn you to heck https://i.imgur.com/9r8D5Gf.gif
[Voice, Sep 23 2020]

Plastic Separation https://plasticsrec...orting_Resource.pdf
[bs0u0155, Sep 23 2020]

Various Developing Techs For Sorting. https://www.chemist...nge/4011434.article
[bs0u0155, Sep 23 2020]

[link]






       Good idea. I looked into how our local authority does recycling and it's way more complicated. They ask us to put everything (glass, metal, plastic, cardboard, paper) in one bag. Then at the sorting plant, they use eddy currents and magnets to extract non-ferrous and ferrous metals, and a combination of fans, spinning drums and flotation tanks with different salinities of water to sort out the rest - I'm amazed it works.
hippo, Sep 22 2020
  

       // designers might not love this //   

       Overspray the base colour with a paint soluble only in hot water.   

       Overprint or apply label as required.   

       At the recycling hub, hot-wash all incoming plastic, then sort by colour.
8th of 7, Sep 22 2020
  

       ^Ooh, I like that'un.   

       And...   

       PRINT THE BLOODY RECYCLE NUMBERS/TRIANGLE-LOGO LARGE ENOUGH THAT PEOPLE CAN READ THEM. AND 'GARBAGE' PRINTED ON STUFF THAT CAN'T BE RECYCLED.   

       Like large enough that a recycle-droid can just glance then toss into the appropriate bin. The logo should be taking up an entire side of the container/other.   

       Just sayin'.
FlyingToaster, Sep 22 2020
  

       //at the sorting plant, they use eddy currents and magnets to extract non-ferrous and ferrous metals, and a combination of fans, spinning drums and flotation tanks with different salinities of water to sort out the rest - I'm amazed it works.//   

       That's insane. Nothing but a monstrous industrial process that can probably be scaled at will with brutish efficiency. Probably needs about 4 blokes to run and pays for itself in aluminium alone. Will no one think of the modest capital investment for this kind of thing? Shirley there must be an alternative? Well, my old home town has just that.   

       Why have some relentless industrial efficiency when you can mobilize a small army of otherwise idle surgeons /surveyors /solicitors /sommeliers to amateurishly hand-sort the trash? You can avoid that slight capital cost of some silly machine and then use a selection of guilt and fines to make sure the people that are forced to pay you are also forced to work for you. And you'll still make a killing on the aluminium.
bs0u0155, Sep 22 2020
  

       This idea had a bun until the last three words.
Voice, Sep 22 2020
  

       Meh, last three words be danged. This should have been a thing some time ago.   

       [bs0u0155] - Exactly! It's complicated, but also the logical and efficient thing to do. They're also so proud of the engineering of their recycling machinery that (BC - Before Covid19) they were offering tours of the recycling centre.
hippo, Sep 23 2020
  

       And by color, you mean bar-code encoded in particular absorption and emission spectra? [+]
Mindey, Sep 23 2020
  

       It would be possible to embed simple UV-fluorescent barcodes into the item at the time it's created. Then it can be any visible colour, but under UV it can be quickly identified.
8th of 7, Sep 23 2020
  

       I read the original suggestion as a way to make different plastic types more easily discernible to the unaided human eye. Barcodes and UV inks don’t offer that, any more than the tiny embossed numbers on the containers do.
kdf, Sep 23 2020
  

       Ach, Mk. 1 humans ... notoriously fault-prone, spares not available ... time for an upgrade ...
8th of 7, Sep 23 2020
  

       We've discussed this before. We only replace old stock through attrition. No budget for replacements until the old units are *completely* non functional.
kdf, Sep 23 2020
  

       > Barcodes and UV inks don’t offer that   

       [kdf], I'm not talking about physical bar-codes, but making fun of color spectrum. So, imagine each bar as a spike in Fourier frequency spectrum. By adding impurities to plastic, one could design unique arrangement of spikes in the frequency spectrum. A "bar code" is also an arrangement of "spikes" (vertical lines). Perhaps color-engineering could create equivlant of a bar-code in the spectrum of color.
Mindey, Sep 23 2020
  

       Mindey, I don't understand your explanation. The original suggestion was "make each different plastic a different color to help tell them apart." Does your suggestion help people tell them apart by sight? Or help with creating sorting equipment that is more cost effective than what already exists?
kdf, Sep 23 2020
  

       bun
po, Sep 23 2020
  

       //[bs0u0155] - Exactly! It's complicated, but also the logical and efficient thing to do.//   

       It's a surprisingly difficult concept to get across. The general mindset seems to be "good people, like me, recycle. You should do all you can to help, resistance to this means you will be assigned as an Earth-hating capitalist monster".   

       Maybe we should have recycling bins for other waste? One for solid toilet waste, one for liquid. I'm sure it would simplify things for the good people down at the sewage plant. After that, I've got 25 minutes spare on thursday that I'm happy to dedicate to national defense. I don't know what I'm doing but I think I have a pointy stick somewhere.   

       //one could design unique arrangement of spikes in the frequency spectrum.//   

       Plastics (unless wrapped or black) are already pretty easy to distinguish in the near infra-red <link>.
bs0u0155, Sep 23 2020
  

       So rather than invest in educating people about different grades of plastic and then consume people's time laboriously sorting their recycling, the investment should be in design of packaging materials to make the automatic recycling sorting machines at the recycling plant more efficient and less likely to make errors. And composite materials (e.g. a metal film, bonded to cardboard or plastic) should be illegal.
hippo, Sep 23 2020
  

       That's Boeing and Airbus out of business for a start, then ...
8th of 7, Sep 23 2020
  

       ... or find some technology that recycles composite materials
hippo, Sep 23 2020
  

       Find a way to pry them out of the landscape first. Once the fire's out and the air crash investigators have taken the bits they want for evidence, there's not a lot left ...
8th of 7, Sep 23 2020
  

       Yep. A few tweaks to the some of the almost deliberately tricky packaging designs and it's all solvable.   

       Conveniently about half of common plastics float, the other half sink, in water so you can design a mechanism to discriminate unknowns by shredding> settling tank.
bs0u0155, Sep 23 2020
  

       That begs the question as to whether it's worthwhile making buoyant FDRs and CVRs, rather than going fishing for them in 1000m of water ...
8th of 7, Sep 23 2020
  

       //imagine each bar as a spike in Fourier frequency spectrum//
While I'm not sure that is useful to the present concept, it IS a brilliant idea in it's own right. The incident light would have to be precisely defined (although I don't know much about the UV->fluorescence process...).
neutrinos_shadow, Sep 23 2020
  

       //That begs the question as to whether it's worthwhile making buoyant FDRs and CVRs, rather than going fishing for them in 1000m of water ...//   

       Even if buoyant*, a CVR/FDR isn't going to be able to float unless a precise minimum of damage occurs. Either because it'll be physically attached or trapped.   

       //The incident light would have to be precisely defined (although I don't know much about the UV->fluorescence process...).//   

       We're very good at precisely defining light, and optics in general as a species. Probably related to our particularly nifty eyes. It's important to realize that fluorescence isn't specific to UV. It's just handy that we can't see it, so you can flood the place with UV and it's easy to pick out the green thing on an otherwise dark background. But, fluorescence occurs all over the optical spectrum, for example, fluoroscein absorbs blue light (say 480nm) and emits green (500-550nm ish). If you block blue light with a long-pass filter that cuts light below 500nm, then you're not blinded by the illumination light which can be an order of magnitude or more brighter. There's really wuite the selection, we have things that absorb and emit all over the place, and the filters to discriminate are cheap.   

       *I'm going to start pronouncing that as "boo-ee-yant" until the colonials realize they've been pronouncing "buoy" in a frankly embarrassing way.
bs0u0155, Sep 23 2020
  

       // unless a precise minimum of damage occurs. //   

       Not a problem, not a problem at all ... <Sniggering/>   

       // pronouncing "buoy" in a frankly embarrassing way. //   

       The spelling of "buoy" was created specifically to torment the welsh; since it contains two vowels and a semi-vowel ("y") and no double consonants, they are unable to pronounce it. It's rather like asking a German to pronounce "squirrel".
8th of 7, Sep 23 2020
  

       Love the idea but the title sounds like the name of a forlorn blues song from the '60s. (Hi World, thanks for thinking of us, signed; The World.)
blissmiss, Sep 24 2020
  

       <Gravelly Blues voice>   

       "Ah woke up this mornin' ... an' all the milk bottles was blue ... "   

       <Gravelly Blues voice/>   

       Yes - oddly, it works.
8th of 7, Sep 24 2020
  

       ^
pertinax, Sep 25 2020
  

       The ugly thing is that recycling isn't all that we wish it was, unfortunately. Most plastics used for commercial products specify a minimum amount of virgin material to keep the properties stable.
RayfordSteele, Sep 26 2020
  

       ^ Ah, the cycle of life.
wjt, Sep 26 2020
  

       I really like [8th]'s overspray idea. Especially if you apply the label over the water soluble spray, making removing them for recycling easy.   

       Though I also like to imagine walking into a drug store and seeing a whole aisle of orange shampoo bottles. Or some overengineered product being a dozen different colors (each easily separated back into their recyclable parts).   

       Hi [bliss].
Worldgineer, Oct 01 2020
  

       // the cycle of life //   

       Of plastic ? That's the North Pacific Gyre, isn't it ?
8th of 7, Oct 01 2020
  
      
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