Like many municipalities, San Diego provides homeowners with 2 large trash containers. One for debris that can be recycled and another for garbage than cannot. We regularly generate twice the volume of the former. Two questions:
How are various recyclables (paper, aluminum, etc) separated? Can’t imagine a machine can do so.
Secondly, I’ve heard not all the recyclables are actually recycled. Some say less than 50%. How much actually is?
Some recyclables are removed with magnets. Others are sorted by hand. Yeah, it’s yucky. Where I live, a lot of it is done by jail inmates in exchange for reduced sentences.
IDK what percentage of “recyclable” materials actually ends up getting recycled. In my brother’s town, a recycler truck was observed at the landfill, which led my SIL to be very skeptical about the whole process (and good luck explaining that to their two teenagers! :smack: ). Chances are, something was in that load that rendered it unusable by a recycler, and it really WAS garbage.
There was a How It’s Made (or some other similar type show on) about this and they showed how it was all sorted. IIRC they used a combination of magnets, air, vibration and people. Nothing too fancy. Other than the magnets, it’s more or less trying to move heavy things one way and light things the other way.
What I found interesting was how they recycle (car) batteries. I had never really given it any thought until I saw it. They take the entire battery, grind it up into water, plastic case and all. The plastic floats, the lead and other metal sinks. Then they add a chemical to the water that causes the acid to solidify (or something like that) so it can be removed.
ETA, there is a How It’s Made-Recycling video on youtube, but I’m not in a position at the moment to watch it and see if it’s the one I think it is. But even if it’s not, there’s quite a few other recycling videos as well. Pick through a few, I think you’ll find that it’s a combination of machines that can sort (ferrous) metal from non-metal. Machines that can sort heavy from light and people that can sort through the rest.
Both steel and other metals can be sorted using magnets, though in different ways. Steel is easy: You turn on a big electromagnet, sweep it through your mixed trash, and what it picks up is steel (or some other form of iron, or cobalt, or nickel, but those are less common).
For other metals (aluminum, say), you pour a stream of mixed trash down some distance, and have an electromagnet off to the side. While the trash is falling, you turn on the magnet very quickly. The change in magnetic field will induce currents in the metal, causing it to produce its own magnetic field which pushes it away. A separate bin off to the side will catch the metal, while the non-metallic trash continues to fall straight down. In principle, you could even separate various metals from each other this way, as the strength of the effect depends on the conductivity of the metal.
For some other materials, you might be able to partly separate them using a fan (which will blow some materials more than others), or by immersing them in water or other inexpensive liquids (which will let some materials float but not others).
I recently read that plastic bags in the recycling stream get discarded into waste piles and not opened to check for reciclables.
This is necessary because if you ask Joe Citizen to separate his recyclables into X different categories, there will be X different bins on the sidewalk on pickup day, a pain in the ass for everyone.
And Joe Citizen will inevitably screw it up, putting plastic #3 in the bin for plastic #5, or steel in the aluminum bin, or pizza-slimed cardboard in the “clean cardboard only” bin. Since you have to double-check Joe’s work no matter what when all that stuff gets to the recycling center, you might as well just tell Joe “never mind, put it all in one big-ass bin” and save everybody some time/money/hassle.
Except that double-checking a sort that someone else has already done has to be a lot quicker than sorting it all from scratch.
Consider: 50% of things that can be recycled aren’t vs. 50% of the stuff put in the recycling bin is not recycled because much of it can’t. I suspect you’re thinking of the former, when the latter is more likely the case, e.g. many municipalities only recycle certain numbers of plastic like #1 and #2, but people put #3 to 7 in there anyway.
The way Waste Management does it is that you need to tag any extra bags with a sticker that you purchase ahead of time. Presumably they open those, but not just any bag. I don’t know what they do with improperly tagged bags, if they just ignore them no matter how ripe they get.
I forgot about the other half of this equation: the collection truck would also need to have X different compartments on it. Single-stream recycling facilitates a cheaper collection truck with one compartment and a simple robotic arm for picking up the one recyclables bin.
Not to mention, people don’t do the sorting. When people have to do that much work, they just throw everything away. But garbage in one, recyclables in another, you can get people to do. Especially if you do what they are doing in my mother’s neighborhood, and selling or giving away colored bags for extra stuff. Overflow recyclables are free (green bags) but overflow trash bags cost a dollar. Supposedly the collectors pick them up at roadside, and check, and you can be fined $50 for putting what is obviously trash in a recycle bag. The guys probably hate having to get off the truck and pick up trash bags enough that they actually do check, and are happy to report you.
Plastic bags jam the machine that the recyclers here use for sorting, so they don’t want them in the bins. They also don’t want glass in the bins. They’ll pick up glass if put at the curb in a separate container; bags I take to the grocery store where they have a bin at the entrance for them.
I don’t know exactly how that machine works, but apparently it sorts plastics, metals, and paper in some mechanical fashion.
Your recycling authority may not want glass in the recycling bin but that’s hardly universal. My local authority does want glass (bottles and jars, not things like drinking glasses) in the recycling bin.
My apartment complex has big bins for ordinary trash, but no provision for recycling. So if I want to recycle (I do), I have to take it all to the city waste disposal facility myself. And even taking it to the facility myself, they still want me to just toss it all in the same place, even though I have sorted it myself.
I guess it might be because the city facility isn’t the final destination, and they still have to truck it somewhere else from there.
The answer to this depends totally on your local area. Check with your local recycling agency. They probably have statistics.
This is how they do it in Devon, England:
Different counties have different schemes.Some recyclable materials need to be rinsed out before they’re put into a bin … just takes one person, one milk jug, to ruin it for everybody …
I don’t doubt that people believe this, but my experience with recyclers is that this idea doesn’t hold true.
More than likely, that milk jug has a label glued to the outside that is more of an issue than any residue inside.
I’ve been to Carbonlite, the largest PET bottle recycler in the US and their whole process boils down to grinding and washing. The bottles entering the process are often disgustingly filthy. Doesn’t slow them down a bit.
Because their business model depends on them producing a clean product, they have figured out how to wash the ground plastic flakes and remove any dirt/residue/labels and they do it quickly and efficiently and by the ton every day.
I half-expected that Devon link to be a joke, but no, it’s good, solid information. Thanks, bob++!
I once visited a paper recycling business where they turned (mostly) newspapers into cardboard. The start of the process was a pit full of strong alkaline liquid into which the paper was dumped. The liquid was rotating creating a vortex, and there was a simple rope hanging down the centre. Any bits of plastic bag, string or wire wrapped themselves around the rope to be pulled out. The paper slurry went on to be processed.
I get that, and for something water-based like milk, it’s easy to rinse out the container. But what if you’ve got a plastic jar of peanut butter, that’s just about empty? Even then, there are peanut butter remnants clinging to the inside of the jar, and cleaning it thoroughly would, I think, consume more resources than you’d gain in recycling the jar.