Non-recyclable plastic waste (V4)
- This topic has 41 replies, 13 voices, and was last updated 2 years ago by .
Hey guys, my name’s Paul and I’m a designer working on PP V4. One of our focuses for V4 is exploring ways to use the non-recyclable plastics (NRP) that we often collect but don’t have a use for.
To be clear, I’m talking about plastics that have no hope of ever being recycled back into useful tools/products/materials. Plastics that have been:
– degraded due to extended sun exposure, saltwater, etc. (common among beach plastics)
– molded with other materials (metal, silicone, etc.) and can’t be separated for recycling
– are simply too dirty to be cleaned effectively for normal recycling
Typically when these materials are collected, they’re sent to the landfill where they waste away eternally, or they’re incinerated to produce energy.
Neither of these options are great… Sending NRP to a landfill means the materials that could be useful will do nothing but take up space in a big pit of waste. And incinerating them releases gases into the atmosphere that contribute to air pollution and climate change.
So.. Our mission is to give hope to the Hopeless. Sounds tricky, but I think we can figure something out. I’ll share progress in this thread. If you’re interested in this issue and would like to contribute thoughts, ideas, and constructive criticisms, they’ll be greatly appreciated
As a quick test to see how the materials would bind together on their own without adding a binding agent, I molded them using the compression machine, which resulted in a substrate that holds together reasonably well… results will obviously vary depending on the mixture used. For some reason there was quite a difference in appearance between the two sides of the substrate. Guessing it’s heat-related.
I’m curious to learn how much of the material’s binding success is due to melted plastic, how much is due to pressure, and how much is due to the glues mentioned above. I’m also curious to see how it performs in a thicker block form (as opposed to sheet).
Direction 2.0 | Alternative construction material
This direction interests me because it could serve as a long-term method to store NRP in a useful way, rather than letting it simply waste away in a landfill. This direction is also appealing because it could serve as an alternative to ubiquitous, environmentally harmful materials such as concrete.
There are a couple of methods I’m interested in starting to explore that might offer viable solutions.
2.1 | Compression to form bricks
With this method, the NRP would be shredded and compressed into forms which could then be used to build long-lasting structures. This could be especially useful in communities where construction materials are limited, but plastic waste is abundant such as coastal communities and towns rebuilding after a natural disaster.
The tricky thing with this direction is that the materials being used will be mixed, so we’ll have to find a way to bind them reliably across all sorts of different mixture ratios.
One way that might work is ensuring that there’s a certain amount of PE in the mix (lowest melting point of common plastics), then heating the mixture to PE’s melting temp and using the molten PE to bind everything together. Or maybe there’s another binding agent or cold-compression method we could use… Again, any experience and insights are greatly appreciated
2.2 | Alternative to conventional concrete aggregate
Concrete, one of the most commonly used commodities in the world consists of cement and aggregate (or filler). Generally, the aggregate is a mixture of sand and rock, which is typically mined. Mining these resources inflicts serious damage on our planet (google ‘concrete mine’).
Using NRP as an alternative aggregate could reduce demand for these environmentally damaging materials and provide a method of storing NRP in a useful, long-lasting manner without releasing its carbon/toxic gases into the atmosphere.
The thing we’d want to be careful of is ensuring that the NRP concrete is used for static applications with low friction that won’t cause the plastic to slowly rub off and emit microplastics into the atmosphere. Buildings and furniture seem like they could be good uses. From what I understand, using the material in applications such as pavement, etc. could lead to problems down the road (hehe) with microplastics rubbing off and being dispersed into the environment, which is something we definitely want to avoid.
One concern that some V4 teammates have voiced while sharing the idea around the workspace is that mixing the plastic with cement might complicate the problem by adding a new material into the mix. My thoughts are that the NRP we’re using is already an unsortable mixture of plastics, metals, rubbers, etc. (part of why it’s non-recyclable) so adding cement would only marginally reduce the NRP mixture’s “purity”. Granted, it would add some complexity in terms of what exactly the concrete is made of, but as I understand it, once concrete reaches the end of its life, its best use is to be ground and used again as an aggregate base for new concrete, so it seems like having the NRP would be okay from my view. Keen to hear others’ thoughts.
Below are some resources I’ve found in my research so far:
Alternative construction resources
– Earlier forum discussion: http://onearmy.world/community/forums/topic/help-on-a-earthquake-rebuilding-project/
– Plastic waste compression molded into bricks: https://www.byfusion.com/the-blocker/
– Henry Miller’s research into using NRP as concrete aggregate: https://inhabitat.com/plastic-concrete-repurposes-landfill-waste-into-building-bricks/
– Article about NRP as concrete aggregate: http://useofcement.cembureau.eu/2018/04/09/cements-solution-to-plastic-waste/
– Plastic legos construction concept: https://www.youtube.com/watch?v=SR2N_USfFzE&feature=youtu.be
– Cement life cycle overview: http://www.designlife-cycle.com/new-page-40/
Thank you for your constructive criticism @plaspod
I recently heard about plans of a collaboration between a UK-based company, Plastic Energy and a Saudi Arabia-based company, SABIC to build a commercial plant here in NL that will refine plastic waste (including non-recyclable) into oil to be used for alternative fuels and the creation of food-grade plastics. If you haven’t seen it, you can read a short article about it here
I’d say this serves as some level of proof that larger chemical/oil companies are exploring this technology and finding ways to make it work.
Additionally, the Plastic Odyssey team claims to have developed a functional, efficient, small-scale pyrolysis unit which produces fuel-grade oil that they’ve successfully powered their prototype vessel with. They came to Eindhoven several weeks back to share their experience with us and showed us some footage of the unit in operation and, if everything they say about it’s true (no reason to think it wouldn’t be) they’ve managed to find a way to make this technology work effectively at a smaller scale.
Granted, elements of the units that the above groups have developed are far more advanced than what I’ve been testing here. Our first prototype was just meant to be an exploration into the topic to get our feet wet – we’re not expecting fuel-grade oil from it in its current state.
In my opinion, Plastic Energy’s method of turning waste back into virgin-quality material seems to be the best application of pyrolysis tech I’ve seen so far… while it’s true that if fossil fuels will be burned, better to come from a pyrolysis source than virgin, we don’t need another reason to keep burning them – much better if we can transform waste into a useful material to act as carbon storage. There’s enough carbon in the atmosphere as it is.
Precious Plastic has created a unique model that allows plastic to be re-purposed on scales that are beneficial to both society and ecology. That fact is an important driver!
The collective aim here should be to bolster and enhance that model with the addition of beneficial technologies (micro-scaled) that can support and sustain the development of social enterprise at community scales.
The images that follow have been taken from a ‘work in progress’ document. This document details the levels of energy used to collect and recycle certain types of plastic via current industrial processes (UK model). It also details an alternative community-based model, built around PP machines and Plas-Pod. This model does not include the production and use of pyrolysis oils and still achieves zero-waste.
We have determined the value of the waste to the community in terms of energy generated from non-recyclable plastics. We will endeavour to determine the carbon footprint of this model for comparison but would be confident to suggest that it will be more efficient than the industrial status quo.
Determining value to the community via the production of products will be more challenging. Selling high-grade plastic on to recycling companies has been included here as one option: other options, including manufacturing products that can embedded into the community will be added as the work progresses. The opportunity to develop a cashless economy is exciting but requires careful planning.
We need to ensure that the energy that we generate from non-recyclable plastic is used wisely (restricting waste). We can do this by producing electricity that we need to run the PP machines and we can generate the energy needed to heat the workplace over winter using the same process. This makes sense because it is the most efficient way to produce and utilise energy – at the point of use. Theoretically, this plastic becomes embedded into the community as well.
Added to this, we have made the Plas-Pod mobile, hoping that we can take it to various locations within the community to generate energy that can be fed straight into existing water heating systems: this would work well in schools, where reasonable volumes of waste plastic are generated. Reducing the energy costs for the community offers benefits to everyone in that community.
Key for us has been to develop smarter methods of heating and storing water. We are currently working with a team of engineers from Romania (where it can get very cold!) to develop a low-cost boiler which can run directly from the Plas-Pod machine. We don’t want to reveal the entire design until we are confident that it meets expectations, but you can see the test here –https://youtu.be/IHlxDLldnzw
The reason that we have tested to steam-point is because we have been working with a company in Holland (Green Turbine) to develop a unit that can produce super-heated steam to drive their micro-turbine to produce between 1.5 – 15kWhe.
We have more than 20yrs experience of producing pyrolysis oils, both as a primary product, via the Biogreen Technology (http://www.biogreen-energy.com) and as a co-product via several other methods of pyrolysis. As Dan suggests, we are also yet to see anyone making anything useful from these oils.
Our experience would be to steer others away from pyro-oils to focus purely on more efficient conversions to energy from non-recyclable plastic.
Respectfully – @plaspod
Direction 1.0 | Pyrolysis: Waste to oil
Pyrolysis can be used to transform materials into oil which can then be used for energy. It might also be possible to synthesize the oil into a cleaner, more useful material with other applications..
1.1 | Alternative energy source to virgin fossil fuels
Transforming the NRP into oil could offer an alternative to virgin fossil fuels for communities that rely on fossil fuels for energy and don’t have access to renewables. In this way it’d help reduce reliance on virgin fossil fuels and simultaneously give purpose to the abundant material resource of NRP. Using the oil for energy would still emit greenhouse gases, but at least the energy source would be plastic waste that’s useless rather than newly extracted fossil fuels. Along with that, saving money on fuel could enable communities to save enough money to eventually transition to renewable energy sources. In this way, this solution could serve as a sort of stepping stone for some communities.
1.2 | Back into useful material
Once we convert the plastic waste into hydrocarbons (oil), we might be able to synthesize it into a cleaner, more useful material. If so, there’s a variety of purposes that the material could serve that would likely be better than what we’re able to do with it in its current state. Plus it wouldn’t be burned, keeping the carbon and other greenhouse gases embedded in the material rather than emitting them into the atmosphere. Not sure if this is doable, but seems interesting. If anyone has any insights I’d be keen to hear.
I’ve seen Pyrolysis discussed here before and am including a link to the earlier forum as well as some resources I’ve come across in my research so far.
– Earlier forum discussion :http://onearmy.world/community/forums/topic/small-scale-pyrolysis-plant-for-making-fuel/#post-132354
– Pyrolysis research article: https://www.researchgate.net/publication/281064326_CONVERSION_OF_PLASTIC_WASTES_INTO_LIQUID_FUELS_-_A_REVIEW
– DIY pyrolysis: https://www.instructables.com/id/Waste-Plastic-to-Fuel/
– Group developing open source pyrolysis unit: https://plasticodyssey.org/technologies/?lang=en
– Plastics-to-Fuel Report by Ocean Recovery Alliance: https://www.oceanrecov.org/about/plastic-to-fuel-report.html
– Plastic to fuel market review 2017: https://www.planning.act.gov.au/__data/assets/pdf_file/0008/1043657/Appendix-G-Review-of-Pyrolysis-Worldwide-RICARDO.pdf
– Intriguing case study, and links shared between @craig89 and @frogfall: http://onearmy.world/community/forums/topic/precious-plastic-in-the-scottish-highlands/
– @plaspod ‘s work with Pyrolysis: https://docs.wixstatic.com/ugd/52d1ea_187cf3d94bfc45688ed4ec5ce32afb5f.pdf
– Study on performance and emissions of pyrolysis oil: https://www.sciencedirect.com/science/article/pii/S0378382016307135
I would never discourage research, learning, innovation or human-desire to investigate, but on the matter of developing a process to utilise pyrolysis oil from NRP, I may have to dampen your spirit.
We have been involved in extracting energy from human waste streams, including wood and plastic for more than 20 years and in that time we have collaborated with hundreds of engineers from all over the world. We have worked through several top universities in the UK, Europe, USA, China and India, and to this day we have yet to see the development of an appropriately scaled system that can produce a high-grade oil that can be utilised efficiently.
In that time I would think that $Millions have been invested into projects that start off with a lot of enthusiasm only to end up in a yard full of plastic containers that are full of various grades of oil that nobody can do anything with.
I would be pretty confident to suggest that the Plas-Pod unit and Dan’s (@lwfbiochar) unit are about as good as we are going to get with regard to appropriately-scaled technology for dealing with NRP to energy. Burning NRP is not ideal but when it replaces virgin fossil fuels there are benefits.
As previous, I would not want to deter you from your path of exploration, but just remember that if it was possible to convert plastic into oil then I am pretty sure that the oil-industry would have built the machines to do this. And they would be buying back all the waste plastic on the planet to do it….
What temperature do you use for melting – it is a very difficult find appropriate regime because of different types of plastic?
Thank you for your thorough responses. Your input will be super helpful moving forward.
@lwfbiochar The article you shared about incorporating pyrolysis by-products into building materials is super interesting… the Biochar Journal as well as other resources that it led to are proving to be helpful for research as well. I’m very keen to explore the other applications that pyrolysis might be used for beyond energy production.
@plaspod Couldn’t agree more – Precious Plastic’s micro-scale is a key part of what makes it so valuable. Our goal in exploring uses for NRP is to develop ways that we can make use of the mixed, dirty, non-recyclable waste that we currently have no use for. As I understand it, a lot of communities simply burn the waste with no filtration system as a way of getting rid of it. Finding a solution that’s more useful than burning will help mitigate the negative environmental and personal health impacts for those living in the communities where this occurs. @mattia-io and I were chatting this afternoon and he mentioned that you guys have spoken previously about pyrolysis. I’d love to learn more about your experience and particularly what sort of plans you have moving forward with Plas-Pod. We’re interested in running some pyrolysis tests to get a better understanding of what the process offers. Is there any chance you’d be willing to assist at some level?
@rorydickens I agree with you that the simplicity of the concrete aggregate application would make it easy for communities to implement – in fact I’ve already seen some doing it. I haven’t looked into biocrete much, but am keen to check it out. Adding plaster to the surface of plastic-concrete to avoid solar degradation is a good thought. I’ve seen the Eco-Brick before and find it interesting. Aside from its labor intensity, it seems like a good use for this material. I wonder if there’s a way that we could streamline the process to make it more efficient…
Thanks again for your input and support.. More to come 🙂
2.2 | Alternative to conventional concrete aggregate
Firstly thank you for tagging me into this conversation,
To contribute a little I completely support this direction and would like to make some points from my time in Eco Architecture.
This solution (2.2) is the easiest to implement from my experience compared to creating solid plastic blocks mainly because it utilizes basic technology that most countries understand fully, and are trained to work in (Concrete work). Concrete is based on ratios to acquire different strengths and those mixes can be edited to use different aggregates (no extra tools required). If clever we could also come up with a mix to make hollow blocks, using standard hollow block machinery.
Have you by any chance investigated Biocrete? (Hemp Crete, Coco Crete, or Rice Crete?) all substitute the 3/4″ gravel aggregate to utilize a waste fiber or material. In some cases, lime is also added, this allows the material to hold moisture. So that in tropical climates moisture is collected at night and evaporates during the day to create naturally ventilated buildings through evaporative cooling.
The fiber or waste also tends to provide a certain level of tensile strength, not found in standard concrete. This could be a good selling point when pitching the idea of inserting plastic into standard concrete to communities. Cheaper & Better….always a good pitch.
My only comment about plastic in this method of construction is that we would need to ensure that it is not exposed to the sun. Solar degradation will cause the surface layers to decay, and create a fine plastic dust. This can be avoided by plastering the surface layer.
While we are on the topic of utilizing waste materials, the island I am currently running our project on doesn’t have any glass recycling. Could we not take this one step further, Cement, fine glass (Sand), Plastic (Aggregate)?
Another method is Eco Brick, they use a standard bottle and pack it with NRP, however, this is very labor intensive, and most developing countries will stick to traditional methods with a limited adaptation of the method.
Keep up the great work, if you have any questions I’ll be happy to help.
PS. We are building a few walls in a recycling center in a few months, it would be great to pilot these methods if we get the facts straight. Then we can create an instruction video?!
Glad to see you guys are looking into this.
This article has some interesting figures about adding pyrolysis products into building materials. The author focuses much on wood charcoal, but I suspect solids from the plastic pyroysis (aka carbon black) could have a role in improving concrete and plastic composites. Energy in the form of heat or liquid fuel could be extracted from the plastics prior to tying up the remaining carbon in building materials.
We run our heavy pyloysis oils through a babington style burner we modded from a conventional oil heater. We’ve also used these oils as an asphalt binder (tarmac) – our sample isn’t much to show for, but it’s held up for over 3 years outside now. I suspect raw plastic oils could be used in a similar process. Though I doubt we’ll be able to find a contractor that would let us use their equipment and scale up…
I hear alot about people saying they COULD make diesel/gasoline from plastic pyrolysis oils, but I don’t see much of it actually being done on small scale.
Although the gas didn’t condense once reaching the water, I did leave the reaction chamber to cool for awhile before opening it to look inside. During that time, the gases that remained in the reaction chamber were given time to cool. As they cooled, they formed a liquid layer on top of the remaining plastic in the chamber, which smelled very similar to gasoline. Curious, I held a flame to it to see if it would catch – it did.
While the system still has some kinks to work out, this showed me that we were getting closer to a functional pyrolysis unit.
A few things to fix moving forward :
– colder water to condense gas
– increase vertical length of condensation chamber to increase amount of time gas spends trapped in water
– make gasket with heat-resistant material
Experiment 2.0 | Low-tech pyrolysis
Switched directions a bit and began to explore the possibility of using a low-tech pyrolysis unit to process NRP. It seems like it could be a good way to transform the unpredictable, unsortable mix of NRP into a more predictable, more uniform material that could either be used as an alternative to virgin petroleum fuel sources or potentially synthesized into a useful material that can be used for building/making.
I began by building a very simple pyrolysis unit based on this instructables https://www.instructables.com/id/Waste-Plastic-to-Fuel/ included below is an oversimplified illustration to explain the general process.
To start, I used an IR thermometer to read the temp of the chamber to make sure it’d be hot enough using a propane burner, but realized the reading might be inaccurate due to the chamber’s shiny metallic surface, so I painted the chamber with a heat-resistant paint that can withstand up to 800 deg C. The paint burned off, so if the product claim is true, the reaction chamber was at least 800 deg C.
Experiment 1.0 – Processing raw NRP using existing PP machines
After collecting non-recyclable plastic waste from our burn bin last week, I wanted to see if there’s a way that we can make the waste more useful and/or manageable using machines that we already have.
First, I ran most of the material through our shredder. Grinding the material up makes it more manageable to store, which is nice. It also opens up some possibilities in terms of molding. There may also be ways to use the material in its grain form.
One downside of using the shredder for this is that the mixed materials made the machine quite dirty (and unusable for other purposes) so afterwards I had to disassemble and clean it before it could be used again for normal processes. The messiest materials seemed to be the packaging and tapes that used glues/adhesives. After a while the glue built up on the blades, causing material to stick to them.
Some items were simply too messy to run through the shredder, such as caulking tubes which had leftover material in them.
@pauldufour, great posts, thanks a million !
Seems there have been some weird things happening with this forum topic… apologies to all tagged if you’ve been receiving sporadic and/or broken emails referring to this post. I think we got it worked out… tagging those I saw throughout the forums who might be interested one last time to be sure
Hi Paul, I red the artical (the beginning). I have a question about plastic that is partially plastic, and partially plant based plastic. I think if there is any combanation out there like this kind. as for example Innocence claimas yes there is, how do you recycle this mixed plastic? To my knowlidge it is impossible, but maybe I am wrong. 🙂
To improve the temp resistance of the seal, I dug around our local area to see if I could find anything sufficient. This was the highest temp resistant material i could find, and since the goal is to use accessible materials, I figured it’s worth a shot. Pretty sure that the chamber reaches temps above 300 deg C, but it’s possible that since the gasket is at the top of the chamber away from the flame, the temps won’t be as high.
I made the new seal, increased the amount of water and added ice to the condensation chamber, then tested it out.
The silicone seal worked, however a small hole opened up where the clamp was attached to the chamber (brittle due to welding mild steel to stainless) so the fumes escaped rather than traveled through the tube to the condensation chamber. Our mig welder is currently being repaired, so we tried to patch the holes with stick weld but it only made the problem worse. Once our welder is back up and running, I’ll patch the holes and try again.
Once I added the silicone seal, the chamber was finally airtight and the gases flowed from the reaction chamber into the condensation chamber. Unfortunately, the water wasn’t cool enough or the gas wasn’t given enough time to travel through the water in order to condense to liquid so the gas escaped.
After about 45 minutes, the silicone seal could no longer withstand the heat and began to fail.
I patched the leaks and added 4 more clamps in an effort to keep the chamber air tight. My hope was that clamping tightly enough would work as a seal without having to use a rubber gasket (non-recyclable), but imperfections in the chamber made it very difficult to form an airtight seal so I decided to experiment with a silicone seal.
As a control, I began my experiment using 300g of clean polypropylene – this way I’d be able to know that the unit was working. Once proven, I’ll begin using NRP. My initial 2-clamp design wasn’t enough to keep the chamber air tight and there were a couple of leaks in the weld.
If you use stainless steel to build the shredder, it should be ok with oil and dirt as long as you take the time to clean it properly when needed, which will probably mean disassembling it every so often to ensure that the parts are completely clean.
With regard to your second question – it’s tough to answer from afar. Are you asking what to do with shredded PET bottles after separating oil from them? If all they have is oil, they shouldn’t be too difficult to clean using a soap/water mixture. PET is very challenging to recycle though, so in my opinion it’d be best to reuse the bottles as they are rather than use energy/time/resources to recycle them, though without knowing more about your project it’s hard for me to advise much beyond that. Hope this helps – feel free to reach out with any other questions 🙂
As long as I know at least in my city (Barcelona) the plastic from copper wires is used to this spacers which allows bikes to ride freely.
You must be logged in to reply to this topic.