Hi everybody, I'm a french student and I have to create a robot which sort the waste in the ocean. I'm a beginner in arduino so I'm asking for your help.
Firstly I thought that I can sort the differents waste by using an IR sensor. The waste will arrive on a conveyor belt and after they pass in front of the sensor which activate a jack to push the waste in different bins depending on their composition.
Please tell me what do you think about that. Thank you
Inks, dyes, adhesive labels or marine life on the surface of the plastic will give false readings.
The cost of cleaning the plastic is greater than its value.
Marine waste will probably contain little metal as most of it will have sunk. You will get some glass bottles but most of the waste will be plastic in a poor condition. Normal waste sorting does use IR but it does not seem able to handle black items. Like @mikb55 I doubt you will be able to sort the waste into useful batches.
Maybe you could just try to use pyrolsis on the waste after removing non-plastics or perhaps without any kind of sorting at all.
mikb55:
Inks, dyes, adhesive labels or marine life on the surface of the plastic will give false readings.
The cost of cleaning the plastic is greater than its value.
Does that value include the lives of birds, fish and marine mammals that dies from eating it?
Sorting might better be done once the plastics are dried.
Scoop them up as fast and in great quantities. Then wash them.
Then look at the chemical composition and how land based sorters can sort through plastics.
It may not be easy or even possible as a production of plastics will have more or less air in the final product.
The machine to just 'harvest' the debris is valuable.
The waste industry and re-cycling industries should offer clues on how they do it now. That is the most authoritative place to look. once you find HOW they do it, the sensors can be connected to an Arduino for your application.
GoForSmoke:
Does that value include the lives of birds, fish and marine mammals that dies from eating it?
Getting the stuff out of the water or better still stopping it getting in there in the first place is where the real value is. Recently I saw a couple of fledglings in the water fighting over a bit of plastic that they obviously thought was food - very distressing.
As well as the big bits of plastic microplastics are also an issue, how on earth do you get those out of water? I am a bit sceptical about items that are made of bio-degradable plastic, does that mean that they just disintegrate into micro-plastic or does the plastic itself decompose?
Plastic will disintegrate. Nature will take care of it. There's a LOT of energy in the stuff, so sooner or later organisms will evolve to take care of it.
There are already several strains of bacteria around that feast on PET (found a.o. on garbage belts in Japan - one of just a few places where people have actually searched fro such bacteria), and PS (stryrofoam) is used as feed for worms.
In places like the Gulf of Mexico and the Persian Gulf there are lots of bacteria that live off crude oil, which for millions of years has been leaking from the sea floor. Those bacteria had a good time after the first gulf war (making sure the oil leaked from the destroyed oil pits was cleaned up very quickly), as well as after the Deepwater Horizon accident more recently - there it's even said that adding surfactants to disperse the oil actually hindered the natural clean-up of the stuff. PE and PP plastics are chemically very similar to oil, so those bacteria are a candidate to evolve into PE/PP eating bacteria.
PA (nylon) is chemically very close to proteins. That makes this plastic another easy target as food source.
Considering there's just very little research done in this field, and the prevalence of plastics (including in convenient small size: the microplastics) I would not be surprised at all if there are many more bacteria already actively eating plastics. I would be more surprised if there are NO such bacteria, considering how fast life evolves, especially when it comes to lifeforms such as bacteria.
Back to OPs project. Plastics scooped out from the sea are most likely pretty much exclusively polyolefins and styrofoams, as pretty much all the others sink. Plus of course closed PET bottles which float due to the air trapped inside. Excellent fuel for power stations, not useful for anything else: mixed (plastics can't be recycled if mixed, just a couple hundred ppm of PVC in otherwise pure PET bottle flakes makes the batch worthless), dirty (lots of toxic chemicals tend to bond to the plastic surface), and severely affected by the sun (breaks down polymer chains).
Machine sorting of plastic can be done but it's very, very difficult. IR is a common way of determining what plastic you have, but only work reliably when it's clean. Cost is high, and the resulting plastic is still low value due to the many impurities. Seaborne plastics are far lower value than worthless in recycling.
Biodegradables - if the material is uniform, that is, all biodegradable, should be little or no problem as the smaller the pieces become, the faster they degrade since mass (volume) reduces faster than surface area.
That is to say, they should not persist very long at all as "micro-plastics" and should not be able to persist once ingested. Some - such as polycaprolactate - should indeed be digestible.
Paul__B:
Biodegradables - if the material is uniform, that is, all biodegradable, should be little or no problem as the smaller the pieces become, the faster they degrade since mass (volume) reduces faster than surface area.That is to say, they should not persist very long at all as "micro-plastics" and should not be able to persist once ingested. Some - such as polycaprolactate - should indeed be digestible.
I had the misfortune to store some things in plastic bags from a shop. When I came to use the things the bags crumbled to dust in my hands. My reaction was heck I now have a load of plastic dust. Your post sounded reasuring but I thought I would check it out. A quick search revealed "nano" plastic - I had never heard of it before. It turns out that at least some biodegradable plastics turn into harmful nano-plastics "...suggesting that biodegradable plastic does not mean safe for the environment in the case of PHB";
biodegradable plastic does not mean safe for the environment
ardly:
biodegradable plastic does not mean safe for the environment
Most biodegradable won't degrade anyway: conditions in a typical landfill (dry, no oxygen) tend to prevent any bacteria or fungi to grow and break down anything in there.
All your posts are very interesting and I really thank y'all but the main question isn't about the valuability of this robot but how can we create a machine which can sort the wastes. So if someone wants to work with me on this project or even if someone has an idea please tell me.
I don't really see this as a specific Arduino question.
Such a machine is likely to be huge simply to be viable and maintain structural integrity is a very harsh environment, and as such, require more resources than a simple eight bit microcontroller can provide - you should be looking at a community of processors, IMO.
Clemdacq:
All your posts are very interesting and I really thank y'all but the main question isn't about the valuability of this robot but how can we create a machine which can sort the wastes. So if someone wants to work with me on this project or even if someone has an idea please tell me.
start with a machine that will actually handle, either pick up or operate gates to direct material to an exit. And make the machine able to move the material to the location where it is gated or picked up. No sensors or Arduino needed.
Only when that is working as you want, then investigate one or more sensor to determine the type of material and what to do with it.
Don't get so far ahead with your project that you will never be able to test it.
Paul
Instead of trying to sort every bit of flotsam and jetsam out there narrow your focus (it's a school project, right?). Consider distinguishing between only two materials, like plastic vs. wood.
The Arduino part, if indeed an Arduino is ultimately involved, is easy; the hard part is getting the sensors to work.
and/or, After drying, you can shred the payload, and use air to lift & separate some plastic types.
While they’re nasty, if you contain them in a closed ‘system’, solvents can help... clean and recirculate the liquid after each cycle.
Flash ignition can remove surface residues.
You don’t want the process to cause other forms of pollution!
wvmarle:
PA (nylon) is chemically very close to proteins. That makes this plastic another easy target as food source.
Nylon eating bacteria were discovered in the soil around the Playtex plant in Delaware long ago. It was a matter of a mutation that made a new enzyme.
With the right enzyme mix, perhaps all plastics become vulnerable. Ringworld Engineers, anyone?
Clemdacq:
Hi everybody, I'm a french student and I have to create a robot which sort the waste in the ocean. I'm a beginner in arduino so I'm asking for your help.
Firstly I thought that I can sort the differents waste by using an IR sensor. The waste will arrive on a conveyor belt and after they pass in front of the sensor which activate a jack to push the waste in different bins depending on their composition.
Please tell me what do you think about that. Thank you
You can detect conductors from insulators using magnetic fields. Conductors and insulators in the same bit will look like conductors, but weaker ones.
If you grind the trash you might centrifuge the bits to separate by density.
If you burn it all with a plasma torch, you get mixed elements out though some percent of pollutants would form.
Clemdacq:
how can we create a machine which can sort the wastes.
With current technology, economics aside, I don't thing this is possible to do.
Metals you could sort out easily - but metals will be a tiny tiny fraction of the waste you get, as they're heavy, sink to the bottom, and are out of reach.
Your waste stream will be plastics, and plastics are nigh impossible to sort - even if you manage to get rid of all the marine life that's growing on it. When it's really clean and you can get it sorted you probably end up no better than 95% pure.
At best you may be able to use the sorted waste for very low end applications, but even so I doubt any plastics recycler is willing to risk their machines on ocean waste.
tl;dr: not.
Clemdacq:
...
Please tell me what do you think about that. Thank you
People are telling you that they think it will not work at least for general waste collected from the sea or the sea shore if you intend sorting different types of plastics.
Your idea is to separate waste from the sea using an IR sensor. My initial reaction would be to get a small pile of real sea waste typical of what you hope to sort and put the items one at a time under an IR sensor. Can you tell the items apart from the IR reading with the accuracy that you require?
If you can, great, move on to the next step. If you cannot then it is back to the drawing board.
You need to be very careful how you define the scope of your project. If as suggested by @dougp you limit the scope to sorting plastic from wood and perhaps glass then you have a project that you stand a chance of delivering.
Also consider your testing/evaluation environment.
Working on a school benchtop will return completely different numbers to the results you’ll find in a surging tank of brined seawater at varying temperatures and volumes.