Actually there are more streams than than. The big, bulky items aren’t handled by either stream–you either have to call for separate pickup, take them to the landfill yourself, or perhaps there will be a Spring cleanup day pickup. Likewise hazardous waste is not allowed in either stream (household chemicals, etc). You need to take them in to a separate hazardous waste day… [although almost everyone ignores that and puts them in the regular garbage]
Part of getting people to use the hazardous waste stream is to make it at least somewhat convenient to use - hazardous waste days in my area are under-advertised, often have but one location per county, and occur at irregular intervals throughout the year. “What, I have to store this crap in my house for 4-5 months, and if I miss the day for another 4-5 months? **** that, I’ll just chuck it in the dumpster” often becomes the result.
I’ve been wondered how those eddy current things worked since they were mentioned on a program about recycling plants. (I’d offer the name if I could remember it).
Magnets and eddy current things separate metal. large flat sheets (i.e. most paper) are separated out with a star conveyor*. sending items across a grated conveyor with an updraft can sort out the lighter items, as can “tossing”* them across a small (a few inches) gap.
- star conveyors: similar in shape to a conveyor belt. Except instead of a belt it’s a series of evenly spaced and staggered small wheels driven by a common axle. It has a similar effect to a colander or strainer. From above, it looks kind of like this (each * is a wheel):
Large items will skate across the gaps while smaller items will fall through.
** items move up a sloped conveyor and off the end. Items will fall in different piles (or receiving conveyors) based on their weight/air resistance.
North Minneapolis has the lowest voter turnout in the city, little old asian women included. So that area gets less attention than others.
Regarding the OP, “how does this work?” – in most cities, they offer regularly-scheduled tours of the garbage & recycling facilities. So you can go on a tour, and see for yourself how it works.
Not quite the same, but the last time the regional sewer district here hosted a tour, they advertised it with flyers saying “You’ve really gotta go”.
There are multiple reasons for separating waste, but the four that come to mind are:
Keeping non-biodegradable products (most plastics, tires, certain metals, etc) that won’t degrade out of landfills or dumps. In Hawaii non-biodegradable plastics bags are banned and there’s always talk about banning styrofoam plates and cups. Land is limited and valuable. New York City sends their waste to other states and overseas because the land is to limited and valuable to be used for landfills or dumps.
Next are hazardous materials which can seep through the ground and end up in the water supply. It may not seem like much, there’s lead in the solder in the billions of electronic devices dropped into the ground.
Then there is recycling. It usually costs more to recycle materials (plastic, metals, tires, etc), but natural resources are limited and have effects on the environment to produce them. And some materials like electronics have small amounts precious metals like gold, platinum and silver that can be profitably removed.
Small work makes a job easier. It’s far cheaper to have 10,000 households individually separate their waste than hire a crew to separate it after the fact. If a crew must be hired to do the separation, the cost is passed along to the individual households through taxes or removal fees. In Hawaii individual households have to separate their waste (plastics, cardboard, green waste) and there’s a potential fine if you don’t.
Recycling, Once Embraced by Businesses and Environmentalists, Now Under Siege
Local officials raise fees and send recyclables to landfills as economics erode
There’s a paywall at the WSJ, but I’ll note that their comedian reporters aren’t writing about anything new. Recycling didn’t pay for itself when Cecil wrote about it in 2000:
[INDENT][INDENT][INDENT][INDENT] All that having been said, the fact that something can be recycled doesn’t mean it should be. Forget the esoteric arguments about externalities, finite resources, and so on — in the end recycling will (or won’t) work because it is (or isn’t) cheaper than throwing stuff away. This varies with the material being recycled. As a general proposition, any manufactured product that is (a) heavy or expensive in relation to its bulk, (b) homogeneous, and (c) easily separable from the waste stream by consumers can be recycled economically. Metals, notably steel and aluminum, are the obvious examples; both have high recycling rates. Surprisingly, so does newsprint. The poor candidates, at the moment, are plastics and mixed paper (including magazines). Plastics are too light and heterogeneous, while mixed paper contains too many contaminants. In the end we may conclude that this junk is best consigned to landfills. But given the advance of technology, who knows? We’re in the midst of a great national experiment, and we’d be foolish at this stage to prejudge the results. [/INDENT][/INDENT][/INDENT][/INDENT] I doubt whether aluminum cans are being landfilled now. Not so sure about mixed paper and plastics - just like it was back in 2000!
I can see why some do this, out of sheer frustration - in my area, my mixed recycling collection accepts plastic bottles (but not their lids), paper/card, cans. Forbidden items include plastic trays, bags, yoghurt pots, etc
So I can put a PET bottle in there, but not a blow-moulded PET food tray. I can put a steel can in there, but not the steel lid of a jam jar. I can put in an HDPE detergent bottle, but not an HDPE lid from the same bottle.
I know it’s about the capability of the sorting process, as well as the raw material, but it’s a frustration to see good recyclables going into the non-recycle bin.
For some needs, like wire which may have copper, aluminum and plastics they will grind the materials into particles that are the consistency of coffee grounds, use a magnet to remove ferrous materials then use jets of air. These jets of air will result in materials of different density to travel different distances which can be used to separate them into those groups.
Related to comments above, China has recently resulted in lots of Seattle recycling heading to landfills. Well intended city rules on mandatory recycling resulted in more contamination and China decided to quit importing these contaminated streams. So the City sorts and then ships the material to Oregon for disposal vs. being recycled.
http://www.waste360.com/recycling/recyclables-seattle-are-being-landfilled-due-china-s-restrictions
I think liquid-based processes (analogous to panning gold, but on a much bigger scale) are also used for some of that.
Did they actually say you can’t put steel lids in the recycling? I can understand the issue of the plastic lid. These sometimes contain some additional substance which changes the properties of the plastic so that it’s more rigid or flexible or something. But a steel lid should recycle exactly the same as a steel can.