Previous in Forum: Speed of Water Through a Culvert   Next in Forum: Thermodynamic Magic Enables Cooling Without Energy Consumption
Close
Close
Close
29 comments
Power-User

Join Date: Jul 2008
Location: Adelaide, Australia
Posts: 403
Good Answers: 14

Recycling Plastics

04/20/2019 5:17 AM

Australia used to send its collected plastics to China and about a year ago China rejected them as they were too contaminated to purchase, either not clean or properly separated.

I have watched with interest products made from recycled plastic and see they are now making some useful products, decking, flower pots etc. They are certainly not using using the full strength potential of these plastics which I assume is because the exact plastic is not identified and even if it was it would not have the same strength as virgin plastics.

Is it possible to add an identifier to the virgin plastic beads at molding time, which could be easily identified at recycling time.

Tony

__________________
The nice thing about Standards is there are so many to choose from.
Register to Reply
Pathfinder Tags: Recycled Plastics
Interested in this topic? By joining CR4 you can "subscribe" to
this discussion and receive notification when new comments are added.

Comments rated to be Good Answers:

These comments received enough positive ratings to make them "good answers".

Comments rated to be "almost" Good Answers:

Check out these comments that don't yet have enough votes to be "official" good answers and, if you agree with them, rate them!
Guru
Technical Fields - Technical Writing - New Member Engineering Fields - Piping Design Engineering - New Member

Join Date: May 2009
Location: Richland, WA, USA
Posts: 21024
Good Answers: 793
#1

Re: Recycling Plastics

04/20/2019 8:28 AM

This may already be happening. Look for a small triangular logo with some letters in it. If they don't already do so, they could be used to identify the plastic.

__________________
In vino veritas; in cervisia carmen; in aqua E. coli.
Register to Reply
Power-User

Join Date: Jul 2008
Location: Adelaide, Australia
Posts: 403
Good Answers: 14
#2
In reply to #1

Re: Recycling Plastics

04/20/2019 9:46 AM

Whilst this exists, it's only any good if the article is whole and the recycler is able to find the symbol in a reasonable time. Tony

__________________
The nice thing about Standards is there are so many to choose from.
Register to Reply
Guru

Join Date: Apr 2009
Location: USA, Florida
Posts: 1587
Good Answers: 125
#3

Re: Recycling Plastics

04/20/2019 10:57 AM

I think paper should be used in place of most plastics.

Practically all liquids could be sold in coated paperboard or aluminum.

Plastic is carbon that is extracted from the ground and put into the environment.

Paper is carbon that has been removed from the atmosphere by trees, which were planted on tree farms, and which will be planted again and again for that use.

__________________
An obstacle is something you see when you take your eyes off the goal.
Register to Reply
Guru

Join Date: Oct 2008
Posts: 42377
Good Answers: 1690
#4
In reply to #3

Re: Recycling Plastics

04/20/2019 11:06 AM

"Paper is carbon that has been removed from the atmosphere by trees, which were planted on tree farms, and which will be planted again and again for that use."

You DON"T really believe this, do you?

Paper Chase | Ecology Global Network

"Around the world, tree farms supply 16 percent of all wood used in the paper industry"

The world's trees are disappearing to make way for human greed.

Recycling is too expensive and labor intensive and to take the time to sort into the many different types of plastics would be impossible.

Maybe turning it back into oil is a future possibility?

Register to Reply
Guru

Join Date: Apr 2009
Location: USA, Florida
Posts: 1587
Good Answers: 125
#6
In reply to #4

Re: Recycling Plastics

04/20/2019 11:34 AM

Yes, around the world. We can't really control what goes on in China or Brazil, however.

In the US we have about 90,000 active tree farms. While these farmers do hope to make a profit (you know, greed), their products are used for lumber, paper, etc.

Their products also absorb and sequester atmospheric CO2.

__________________
An obstacle is something you see when you take your eyes off the goal.
Register to Reply Score 1 for Good Answer
Guru

Join Date: Oct 2008
Posts: 42377
Good Answers: 1690
#8
In reply to #6

Re: Recycling Plastics

04/20/2019 12:24 PM

Christmas tree farms?

Register to Reply
3
Guru

Join Date: Apr 2009
Location: USA, Florida
Posts: 1587
Good Answers: 125
#10
In reply to #8

Re: Recycling Plastics

04/20/2019 12:44 PM

Mostly soft pine.

When I lived in Virginia our property was next to a 10,000 acre pine farm. We could get a $5.00 hunting permit from them each year.

They planted a fast growing pine developed by VA Tech that could be harvested in 12 years.

__________________
An obstacle is something you see when you take your eyes off the goal.
Register to Reply Good Answer (Score 3)
Guru
Hobbies - CNC - New Member Popular Science - Biology - New Member Hobbies - Musician - New Member

Join Date: Dec 2008
Location: Canada
Posts: 3524
Good Answers: 146
#12
In reply to #10

Re: Recycling Plastics

04/20/2019 12:58 PM

I was reading not long ago that fast growing trees up to 40 y old absorb the most CO2, more than older stands of forest. From a farming pov it makes environmental as well as economic sense to use these fast growing species.

I have a European Alder (Alnus glutinosa) here that has been used in France to grow firewood, by pollard. The trees regrow in short time. The wood traditionally is said to make the finest charcoal, too. They've done pretty well here and after twenty years have produced a few seedlings, even though the flower too early for optimal weather.

__________________
incus opella
Register to Reply
Guru

Join Date: Mar 2007
Location: by the beach in Florida
Posts: 33232
Good Answers: 1807
#13
In reply to #8

Re: Recycling Plastics

04/20/2019 2:47 PM

..."The American Tree Farm System® is a network of 74,000 family forest owners sustainably managing 20.5 million acres of forestland."...

https://www.treefarmsystem.org/about-tree-farm-system

..." Currently, forests cover about 749 million acres of the U.S. or about 33 percent of all land."..

https://www.thoughtco.com/us-forest-facts-on-forestland-1343034

__________________
All living things seek to control their own destiny....this is the purpose of life
Register to Reply Score 1 for Good Answer
Guru
Hobbies - CNC - New Member Popular Science - Biology - New Member Hobbies - Musician - New Member

Join Date: Dec 2008
Location: Canada
Posts: 3524
Good Answers: 146
#7
In reply to #4

Re: Recycling Plastics

04/20/2019 11:39 AM

"Maybe turning it back into oil is a future possibility?"

This is the only consolation for the unrecyclable plastic which makes up pretty well all of garbage once you recycle or compost the rest. I tell myself, some day they will mine the landfills for that fuel.

I wonder though, if renewable energy becomes the norm, that sort of busts the notion that y'olde plastic will ever be useful.

__________________
incus opella
Register to Reply
Guru

Join Date: May 2018
Location: Under the spreading Bunya Trees, South Burnett, Queensland, Australia
Posts: 759
Good Answers: 64
#16
In reply to #3

Re: Recycling Plastics

04/21/2019 4:11 AM

Wow tree farms that actually work. Around here in Qld Aust good arable land was used for tree farms supported by tax incentives but before long the use of good land for trees has died out and they have been bulldozed out and more profitable crops have returned to the land.

The use of Aluminium cans and plastic bottles that can be recycled sounds like a good idea, why even our state gov decided to bring in a 10c per can levy but the actual price of items went up by 30c to 50c and then the number of recycling depots have not expanded.

The result is it costs more to take the recyclables to the nearest town with a recycling facility.

I even see now the great solar panel boom has led to them being recycled frames are recycled but the panels go to landfill but I suppose it is only sand doped with whatever is required either Phosphorus or Boron but how stable is the structure.

Then we add tinned copper wire to connect them together so what is the tinning, lead, tin, antimony so lets add heavy metals to the land fill as well, good idea.

As for plastic in the oceans what is needed is to cross whales with cats that way when they ingest too much plastic they can just hack up a plastic fur ball filling the oceans with larger congealed lumps of plastic.

__________________
Hare today, goon tomorrow!
Register to Reply
Guru

Join Date: Mar 2007
Location: by the beach in Florida
Posts: 33232
Good Answers: 1807
#5

Re: Recycling Plastics

04/20/2019 11:11 AM

What we need is mechanized sophisticated sorting technology, which then adds to the cost.... that seems to be the only way to get clean, pure, properly sorted waste streams...

__________________
All living things seek to control their own destiny....this is the purpose of life
Register to Reply
Guru

Join Date: Oct 2008
Posts: 42377
Good Answers: 1690
#9
In reply to #5

Re: Recycling Plastics

04/20/2019 12:27 PM

The seven types of plastic include:

  • Polyethylene Terephthalate (PETE or PET)
  • High-Density Polyethylene (HDPE)
  • Polyvinyl Chloride (PVC)
  • Low-Density Polyethylene (LDPE)
  • Polypropylene (PP)
  • Polystyrene or Styrofoam (PS)
  • Miscellaneous plastics (includes: polycarbonate, polylactide, acrylic, acrylonitrile butadiene, styrene, fiberglass, and nylon)
  • Note that there are seven types listed in the misc. catagory.
  • Many of these can be modified by different fillers. (Glass fibers, colorants, flame retardants)
Register to Reply Score 1 for Good Answer
Guru

Join Date: Mar 2007
Location: by the beach in Florida
Posts: 33232
Good Answers: 1807
#11
In reply to #9

Re: Recycling Plastics

04/20/2019 12:49 PM
__________________
All living things seek to control their own destiny....this is the purpose of life
Register to Reply
Power-User

Join Date: Sep 2012
Location: Brecksville, OH, USA
Posts: 230
Good Answers: 1
#20
In reply to #11

Re: Recycling Plastics

04/21/2019 12:39 PM

Couldn't agree more. I also think the public (not just in the US) is responsible for the greed associated with petrochemical/plastics production. Everyone worries too much about minimizing their costs. I don't recall their being problem when we used/reused glass containers.

Register to Reply Off Topic (Score 5)
Guru

Join Date: May 2016
Posts: 1746
Good Answers: 87
#23
In reply to #20

Re: Recycling Plastics

04/22/2019 10:14 AM

Glass containers sink.

Register to Reply Off Topic (Score 5)
Guru

Join Date: Sep 2008
Location: Where the sun sets on OZ
Posts: 1381
Good Answers: 28
#27
In reply to #5

Re: Recycling Plastics

04/24/2019 9:56 PM

I think Tony is saying that the sorting method could be improved if some sort of identifying substance could be included in the virgin material. Then a sophisticated sorter could identify at high speed and accuracy the type. One major problem is that the PET bottle has a cap that although detached leaves a collar of coloured 'foreign' material. Not to mention the labels. Jim

__________________
Where's the KaBoom? There should be a KaBoom!
Register to Reply
Power-User

Join Date: Jul 2008
Location: Adelaide, Australia
Posts: 403
Good Answers: 14
#29
In reply to #27

Re: Recycling Plastics

04/24/2019 10:47 PM

You've hit the nail on the head Jim.

I've followed the various links in this thread and like the idea of a manufacturing ship dragging the floating plastic on board and coming home with a ship full of recycled products. I know its a dream and probably requires many litres of fresh water, but it's something to aim for.

Tony

__________________
The nice thing about Standards is there are so many to choose from.
Register to Reply
Guru

Join Date: Aug 2012
Posts: 1071
Good Answers: 92
#14

Re: Recycling Plastics

04/20/2019 9:35 PM

You might be interested to know there is an Australian company that uses recycled plastics to VERY full strength.

https://citygreen.com/products/stratacell/

They make these modules to go under pavements etc. The glass- reinforced ones are strong enough that you could pick up a fire truck and put it down on four of them- they'd hold it.

The problem you run into isn't actually the plastic identifier. It's that each family of plastics is more like a race of them- there are literally thousands of different formulations for HDPE alone, each with its own strength and temperature requirements. So when you start to look at recycled products like these what happens is that the company specs a certain need, and then has to work with reputable recyclers to formulate a consistent product to meet that.

The problem here is that the recycler needs fairly consistent raw materials to be able to do that. With post industrial scrap it can be easier as the particular material(s) may be known, but with post consumer material it's often a crap shoot. What most of these companies do is establish a few commonly used profiles and then run batches that are blended to meet these specs.

For some reason grey nd black are the most commonly available colours....

Register to Reply Score 1 for Good Answer
Power-User

Join Date: Jul 2008
Location: Adelaide, Australia
Posts: 403
Good Answers: 14
#15
In reply to #14

Re: Recycling Plastics

04/21/2019 12:35 AM

I wonder how they separate their scrap.

I was hoping there is a marker similar to DNA that could be added to the manufactured plastics so that each main group could be identified and separated and this subgroup separated if practical. Governments would need to legislate to make this worth while.

Plastic is not a cheap raw material and if it were financially viable to make a half strength plastic, then business opportunities would exist.

Tony

__________________
The nice thing about Standards is there are so many to choose from.
Register to Reply
Guru

Join Date: Feb 2013
Posts: 2004
Good Answers: 31
#24
In reply to #15

Re: Recycling Plastics

04/22/2019 12:27 PM

Separation is done 90% by manual labour. As the Malaysians say, "Keep your own rubbish" as your rubbish is messing up their lovely country.

And I agree with them. Start reconsidering what you buy and throw away and from what I see, the west has a very 'throw away' approach to life.

See here how your car is pushed up in price. Wastage.

https://www.youtube.com/watch?v=qYpLk65rbps

Register to Reply
Guru

Join Date: Oct 2008
Posts: 42377
Good Answers: 1690
#19
In reply to #14

Re: Recycling Plastics

04/21/2019 11:02 AM

"For some reason grey nd black are the most commonly available colours...."

Carbon black is readily available, cheap and effective.

"different formulations for HDPE ", but the basic polymeric structure is there. The molecular weight and chain length vary.

Any way it's sliced, dividing plastics into distinct type groups is almost impossible and very expensive.

Register to Reply
Guru

Join Date: Feb 2013
Posts: 2004
Good Answers: 31
#17

Re: Recycling Plastics

04/21/2019 9:22 AM

https://www.youtube.com/watch?v=lqrlEsPoyJk

This might answer your question. And Au is not the only country doing this, UK, USA are all in trouble.

Register to Reply
Power-User

Join Date: Jul 2008
Location: Adelaide, Australia
Posts: 403
Good Answers: 14
#18
In reply to #17

Re: Recycling Plastics

04/21/2019 10:36 AM

That looks encouraging and the molder at the end must have some sort of separation system.

Tony

__________________
The nice thing about Standards is there are so many to choose from.
Register to Reply
Guru

Join Date: Feb 2013
Posts: 2004
Good Answers: 31
#21
In reply to #17

Re: Recycling Plastics

04/21/2019 1:13 PM

In India they recycle plastic bottles into concrete for building, I recall it is 20% max, inclusion of recycled plastic into concrete. They were also experimenting with cigarette butts being recycled into road surfaces, that also seemed to work well. So why is the west with all it technology and money ignoring what others are doing? Ah, the following must be applicable:

There was an important job to be done and Everybody was sure that Somebody would do it. Anybody could have done it, but Nobody did it. Somebody got angry about that, because it was Everybody’s job. Everybody thought Anybody could do it, but Nobody realized that Everybody wouldn’t do it. It ended up that Everybody blamed Somebody when Nobody did what Anybody could have.

Register to Reply
Guru

Join Date: Jul 2012
Location: Madison, WI.
Posts: 2092
Good Answers: 80
#22

Re: Recycling Plastics

04/22/2019 9:46 AM

The problem Tony, is the term "recycling" is accurate. At no point in the products life cycle does it ever return to anything close to a natural state. At least not in anything short of a geological time scale.(not sure if injecting reprocessed crude into the ground is a good idea anyway. Think frakking water only worse.) So ultimately you end up with a waste product that is accumulating with no end in sight and no more practical uses. Thus it remains pollution and all you have done is kick the problem down the road.

__________________
Knowing is the end result of learning, not believing.
Register to Reply
Guru
Australia - Member - New Member

Join Date: Feb 2008
Location: Australia
Posts: 2169
Good Answers: 253
#25

Re: Recycling Plastics

04/23/2019 8:16 AM

Hello Tony,

Good sentiment about utilisation of the post consumer products.

There are a couple of steps that deserve effort to minimise the volumes to be managed. There was a program in Aus based on 5R's.

Replace: Use an alternate material that was sustainable. eg take your own packaging to the shops instead of them providing more plastic bags every time you go.

Refuse: Choose to shop at places that didn't utilise those products.

Re-use: Get products that had multiple lifecycle uses rather than single use. Think keep-cups.

Reduce: Choose a product that uses less of the offending material.

Anyhow, you would be aware of many of those already.

I was in plastics industry for some years. Unfortunately, there are so many variations of each plastic with different melt temperatures it is challenging. Add to that, some "plastics" have as much as 60% filler in them that could be anything from talc (volume) through to glass beads or fibres (Strength and toughness)

The nursery industry was at around 80% reprocessing of pots, so only needs around 20% contribution of post consumer materials and they can get that from plastic drink bottles relatively easy.

Glass recycling is nearly as bad. Isolated places like Mt Isa just stockpile the deposited bottles as the value doesn't warrant return to the coast for re-processing.

As far as adding a "fingerprint" in the materials that might already be available using refracted/reflected light and some smart sensors, but the cost /benefit isn't there for the manufacturers. Raw plastics for those low end items that this re-processed material might be used is also VERY cheap, about the same price per weight as ULP in Aus. The use of virgin material means consistent processing, less downtime and so on. Manufacturers will chase that efficiency over whatever cost benefit there might be in cheap materials.

__________________
Just an Engineer from the land down under.
Register to Reply
Guru
United Kingdom - Member - Indeterminate Engineering Fields - Control Engineering - New Member

Join Date: Jan 2007
Location: In the bothy, 7 chains down the line from Dodman's Lane level crossing, in the nation formerly known as Great Britain. Kettle's on.
Posts: 32048
Good Answers: 838
#26

Re: Recycling Plastics

04/23/2019 8:35 AM

It's good to learn that <...Australia...> is now dealing with its unwanted detritus at source.

__________________
"Did you get my e-mail?" - "The biggest problem in communication is the illusion that it has taken place" - George Bernard Shaw, 1856
Register to Reply
Guru

Join Date: Sep 2008
Location: Where the sun sets on OZ
Posts: 1381
Good Answers: 28
#28

Re: Recycling Plastics

04/24/2019 10:07 PM

Smart chemical engineers managed to work out how to separate crude oils into a multitude of different products i am sure a similar process could be used to separate a combined charge of all plastics after they melted. Maybe even mixing plastic with crude before cracking? Just requires the will and dollars, yens, dongs or pesos.

__________________
Where's the KaBoom? There should be a KaBoom!
Register to Reply
Register to Reply 29 comments
Interested in this topic? By joining CR4 you can "subscribe" to
this discussion and receive notification when new comments are added.

Comments rated to be Good Answers:

These comments received enough positive ratings to make them "good answers".

Comments rated to be "almost" Good Answers:

Check out these comments that don't yet have enough votes to be "official" good answers and, if you agree with them, rate them!
Copy to Clipboard

Users who posted comments:

artsmith (2); Dr. Harry (1); IQ (3); JIMRAT (2); JNB (1); Jpfalt (1); Just an Engineer (1); lyn (4); PWSlack (1); rashavarek (1); SolarEagle (3); Stef (1); Tonymech (4); Tornado (1); WJMFIRE (3)

Previous in Forum: Speed of Water Through a Culvert   Next in Forum: Thermodynamic Magic Enables Cooling Without Energy Consumption

Advertisement