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(Last picture, Product trial made by the new team)
Hey guys, sorry for the delay : life is crazy (in a good way). I felt like I owned this community a feedback from my experience. Make yourself comfortable, this is going to be a long post summarizing our experience.
As part of my studies in environmental engineering, I did an internship in a Swiss research institute (EAWAG; department Sandec). The municipal solid waste management group of this institution previously did a waste audit in a Nepalese boarding school and found out 10kg of plastic were openly burnt daily. This is not only an issue for this boarding school but for the whole Nepal.
Let’s look a little bit closer at the waste generated. Half of has a recycling market (PET bottles, Hard plastics, milk and oil pouches). There were little plastic bags within this boarding school. The majority of the remaining plastics were “soft-plastics”, mainly food (biscuit, instant noodle) packages. How could we deal with these plastics at the community level?
This waste fraction is currently not recycled in Nepal for three main reasons:
– Quality: The amount of printing decreases the commercial value the plastic. Often, the plastics are dirty
– Quantity: These wrappers are disposed by diffuse source, all over Nepal. Their weight is little and one has to gather a big volume before a recycler is interested.
–Diversity: Of polymers, mixtures (multi-layer) of polymers, mixture of materials (aluminium foil, …) making recycling difficult or impossible.
We did a fieldwork of 2 month. This was my first working experience in a developing country. We collaborated with a local NGO (Clean Up Nepal) and, in particular, I worked as a tandem with a local mechanical engineer. We were both new to the field of plastic recycling.
Several solutions are possible for handling such waste (incineration, pyrolysis, use as construction material (ecobricks, roads, …), handicraft) but Precious Plastics was the one we decided to go for, as their option was:
-Scalable to the community
-Generating revenue (multiple objects)
-Maintaining the plastic lifecycle (further recycling) possible
Among the 4 Precious plastic machines, we choose compression as the injection and extrusion required solid fragments, and as the shredder is not designed to shred films. The compression machine allowed us to melt films directly, without preliminary shedding. We built the compression machine for 170 CHF (~170 USD, ~155 Euros; excl. masks, small equipment and workspace rental).
We followed the precious plastics blueprints. Electronic components were bought in Switzerland before leaving. We had to solve SSR-relay over-heating issues that were not anticipated by reading the Precious Plastics documentation. We found a pretty big oven and we decided to not set it on top of the compression frame. We built a higher compression frame (1m20) to not break our backs during operations.
In a first phase, we had to experiment with the plastics. Understanding what worked, what didn’t and why. We found out that most of the wrappers were multilayer films, composed of different plastics and materials. Moreover, most of these items were heavily printed. We developed a procedure allowing to asses the dominating polymer by melting successively at different temperatures.
Few biscuits were PET-based (can’t guarantee this was pure PET). These were not recyclable using compression, as the product was brittle (breaking like a cookie). Other wrappers (biscuits, rice, …) were made of distinct PP and PET layers (clear incomplete melting at 215°C), usually not separable by hand. A notable exception were the instant noddle packages, present all over Asia. These were made of an outer, metallized and heavily printed outer PET-based layer and of an inner, transparent, PP layer. These layers could be separated by hand (time intensive, but possible). The inner layer melted completely at 215°C and produced a nice and solid product. As no solution was found for the outer layer and as it was time intensive to gather enough inner layers, no further work was done on the noodle packages. Rising awareness about the impossibility to recycle such packages could wake-up policy makers and manufacturers… but I don’t expect a rapid radical change.
Other food packages were mainly PP. They melted completely at 215°C and samples produced nice and solid plastic chips when compressed. Melting was achieved with transparent packages (often wrapping veggies in local markets), toast bread packages, (imported) pasta packages, (imported) korean ramen packages and biscuit packages (I don’t want to blame Nepal, but often imported from India). Melting was achieved with both metallized and non-metallized wrappers.
Recycling process 1.0
Based on the knowledge acquired, the second phase was dedicated to make value out of non-recycled waste. Our attempts were mainly done using toast-breads packages (that could be recycled but have little value due to printing), that were collected in significant amount (7 kg in 2 hours, by 2 persons) thanks to a local waste management company (Doko recyclers).
The process is described in the Figure below. We melted toast bead packages in an antiadhesive baking plate on which we added a tin frame (Second picture, sorry for the quality). Plastics were added by batches of 50-100g (10 to 20 previously cleaned and dried wrappers). Melting temperature was set at 218°C. I recommend carefully checking if the plastic is totally melted (use a wooden spatula) before adding more plastic : sometimes, a kind of air-bubble shielded wrappers from melting, in the middle of this “dough”. After melting sufficient amount, this sticky dough was transferred in a a pre-heated mold before compression.
Our best achievement was a clip board (see third picture below). As it was our first experience, we learned by doing:
– The mold was a bit convex. Once I pressed too hard and the product broke when releasing the pressure.
– Soldering was not continuous, and plastic infiltrated in the jointure.
-Air bubbles were in the product. Maybe due to a “too rapid” pressing.
-Plastic did not spread in the mold corners (Maybe due to too rapid pressing too).
The project was reconducted for a second phase. Three new interns started last week (@Gem.Wrong is one of them)! Their mission is to remediate to the previous issues, to think about other end-products, to produce nicely finished end-products and to optimize the process. I think they are doing well (see 4th picture).
As for me, I’m out. Starting my master thesis on another passionating topic (Organic waste conversion through Black Soldier Fly conversion). In a few months, I’ll almost be able to set-up a complete waste recycling facility :D.
I’ll do my best to answer further questions and comments, but can’t guarantee this.
Thank’s again to all of you for your support!
Love the idea of the jenga game!
Keep it up!
At first, I was a a little confused by the polymer names you used. Some of them were actually the French abreviations. Let me reformulate with english terms
“Food bag-in-box (composition)
-The plastic bag are composed of 2 flexibles layer (EVOH & VLDPE)
-The tap (VITOP) are composed of 3 plastic (PP, HDPE, élastomère)
-The neck are made with LDPE
Non-Food bag-in-box (composition)
-The plastic bag are composed of 2 flexibles layer (EVOH & VLPDE)
-The tap (VOP) are composed of 2 plastic (PP & LDPE )
-The neck are made with LLDPE ”
I didn’t know about EVOH so far, but did a quick research. According to a study by EVAL, it has been demonstrated that EVOH does not affect the recycling stream of PP and HDPE. Here’s another link suggesting that EVOH/PE multilayer can be recycled in the usual streams. So I think you could try recycling the plastic bags.
As the taps are composed of a mix of PP and (HD)PE, I would remove the taps and try recycling the plastic bags and necks. Precious plastic ideas can probably be applied for these tests, then it depends on the scale you want to implement their recycling.
@s2019 Maybe a few more words on this “plastic supply” issue could be intersting for you. Don’t take me wrong: these wrappers are laying all over the place. We partnered with a local organization to collect this material for us but it took more time than expected (someone threw away the wrappers that were saved for us).
Indeed, it could be interesting to assess the construction material opportunities. Pilot portions of “plastic roads” have been built recently (600kg waste for a 200m street). But if PET is brittle, could we still make durable construction material, without other plastic/crude oil?
@frogfall Apparently this website is blocked from Nepal (For telling the truth?). I could access it through my VPN.
Weekly update # 4 (2/2)
Following @donald ‘s links (thank’s, I should improve my research skills) I found out how difficult it was to recycle PET compared to PP. Moisture makes PET recycling challenging and now it’s monsoon time in Kathmandu. An additional step of drying would therefore be needed to limit PET’s breakability (more info on this nice link). @microtransactions built a vaccum drying system for extruding PET, I don’t know what’s the conclusion of this (see these links: link1 link2
Given the limited time we have, considering drying add a degree of complexity to a process that I have to present as simple and easy to replicate. So I think we won’t focus on recycling these PET wrappers on this project.
Noodle packages in Nepal consist in fact of two layers. An inner transparent PP layer and an outer PET metallized layer. The two layers can relatively easily be separated by hand (it’s like unsticking a sticker from plastic matterial; depending on the wrapper’s condition).
The inner layer melts nicely at 210°C and produces a solid and resistant chip. The outter one can be melted around 270°C but leads to a brittle result (as with the PET biscuits).
I’m now considering to iron these outer layer together (not sure it would hold, though) to product some kind of canvas sheet. Otherwise, if none of you guys have an easy suggestion to cope with PET brittleness, we’ll focus on other wrappers. Future research could also focus on how to separate these two layers on a bigger scale (out of the scope of our project, but if you have suggestions, I’ll document it in my report).
Today, we started melting different wrappers to see how they behave at 210°C. Many of them (metallized or not) melted nicely and allow us to press small chips (see third picture below). We are listing the PP wrappers (melting at 210°C) as well as the other/mixed wrappers to ease future replication.
For the time we have left (approximately 2 weeks) we will focus on gathering enough of these PP wrappers and to mold an usefull object (most probably small sheets to make paper boards), as a proof of concepts for the locals. We hope to end our fieldwork with a workshop/demo/discussion day.
As usual, any question, feedback, comment is welcome!
Answering my question, after little research :
PET-drying equipment exists and is capital.
@microtransactions tried few things for extruding PET filament:
Regarding my situation, it might just add a degree of complexity to a process that I have to present as simple and easy to replicate.
I’m in a similar situation than @edwardmartinhill. I am working with PET biscuit wrappers and obtain pretty brittle pieces after melting 9min at 260°C.
@tajdark If I understood good, the brrittleness of my plastics is due to incorrect temperature (“killing the PET”) or the humidity (which is clearly a problem, it’s the monsoon here in Nepal).
If the humidity’s the cause, is it possible to reduce the water content of my plastics (by drying it 15 minutes at 120°C by example)? I currently wash it in a clothes bag before letting it dry in the sun.
Weekly update #4
Upgrading the oven
We decided to add the insulation we found and it just works well. While re-insulating, we understood why we were struggling to achieve a higher temperature: the upper side of the oven was in really bad condition (see photo). As a temporary solution, we removed some of the rust and wrapped the top with aluminium foil before covering it with insulation material.
@s2019 Thank you also. The second switch idea sounds to be a good alternative. We added a fan on the other side of the heat sink and there’s no longer overheating (see picture 2; the casing is temporary). Concerning the healthy margin, is there a way to estimate the amperage of an oven in advance (I mean, without using a multimeter). By the size of the heating elements, maybe?
We don’t really have a strategy if the lid gets tuck. We have plastic supply issues and didn’t gather enough plastic yet to fill this mold.
Other nice upgrades would be to have a window anda light to follow the melting process without opening the oven.
As a reminder, we are conducting trials on two different packages, which each have three model/brand variations : Transparent biscuit packages and metallized noodle packages.
We were expecting PP, but the biscuit packages seem to be made of PET: It melts around 260°C and leads to a brittle product that sinks in water.
The three different packages melt at the same temperature and bind well together, which may allow us to play, to some extent with the different colors. You’ll see hereafter that the small batch we produces isn’t the most aesthetic. However, focussing on a waste managment perspective, I am convinced we can have an impact by finding the appropriate end-product.
Has anyone an experience on recycling PET wrapper? What would be the minimal thickness for a resistant end-product? We have produced small pieces up to 3-4 mm only, they are all pretty easy to break.
(To be continued)
Picture of the insulation material mentionned above.
Weekly update #3 (On week 4)
I didn’t update you last week. I was busy solving the overheating issues of our SSR. I think we managed it now : we added an heat sink and will have an additional fan on our electronic box.
We didn’t melt any plastic yet, but we made slow but steady progress: The compression frame is almost built, our first mold is ready to use (a bit a dodgy setting of two stainless steel kitchen pots that should allow us to make bowls), our supply in plastic should be insured thanks to a local women association of waste pickers and the cleaning procedure is established.
We decided to work on these “thin arrowroot” biscuits and these “waiwai” noodle packagings.
Our oven has poor insulation and is degraded on top (rust and hole); so it’s not really energy efficient. I needed 25min to go from 27°C to 200°C; and the SSR heat sink was really hot after 45 min. Moreover, we never reached a temperature higher than 214°C and I saw several case studies of melting PP at 220°C.
Oven insulation is hard to find in Nepal; but I found this box containing some foam at home. I don’t really know what material it’s made of: Will it be temperature resistant? Can it start burning if I use an inappropriate one? Otherwise, do you guys have a solution for “DIY” insulation of an oven?
As Donald, I’d be happy to hear more about your goals and means! My colleagues and I are newcomers to this project, but we’ll be happy to help if we can.
Thank you all for your feedback, comments and enthousiasm. We decided to start working only with the lower heating element to limit the risk of burning the top layer of films.
@s2019: Yes, we are adding a thermocouple connected to a PID controller (temporary/testing setting on the picture down there, it seems to work pretty well!). You mentionned “several” controller. We just have one. Would you still recommend adding a fan in the oven?
@donald True, I didn’t plan the timer. I’ll look for one or I’ll use my phone.
Sure, I know the banger of smoke. We’ll experiment gradual temperature increase, work with open doors and windows and use the good masks I have with me. Moreover, as we’re in a co-working space (next neighbors are maybe 10m from the oven, we’ll be really precautious and communicate a lot on our activities.
Weekly update #2
Our second week is going well!We finally got this big oven; so we won’t have to build it ourself (precious time is saved!). We just removed the circuits we didn’t need (the four electric plates) and are now experimenting with the electronics. We also got the metal and car jack for the compression frame.
I saw in V2 compression video that the oven was flipped by 90°, having the heating elements on the side. Is that better? We planned to use the oven racks to nicely melt our plastic in molds, on grids.
Also, if we don’t rotate the oven, I considered only using the lower heating element to avoid foil burning on the top, as it occured in previous experiments of this community. Any inputs?
We are looking forward to build this oven soon, and start crazy-melting stuff!
Yep, wet blending could be an alternative and could be combined with the washing step.
@donald About infrared, that’s the benefit of still being a student. I’ll try to document different alternatives for optical identification. But it doesn’t seem there’s a really low cost one.
Thank’s @frogfall @donald for the reply. Great thing is that I’m staying in Asia (Nepal) to run my test. The major producer of noodles produces 2100 packets a minute; so the 1000 a resource is definitely applicable.
Before leaving, I had access to an infrared spectrometer and ran tests on 8 random noodle packaging (export grade) and they all matched with polyproylene on the library.
Concerning shredding, we’ll start with scissors. Then, I have different creative ideas on the scale-up phase.
This discussion takes a different direction than the original subject. I invite you to follow our progress (and to help solving our problems) on this topic :).
Hey @donald @frogfall!
Thank’s for this topic, it’s really inspiring.
Do you think this PolyAl alloy have comparable properties than metallized films? Would similar output products be possible to achieve with silver coated packaging?
@rorydickens : In Switzerland, few tetrapacks are half-recycled: the cardboard is recovered and the PE-Al is incinerated (see this website, in French or in German). Large scale collection is not yet established though: a pilot test was done with Aldi Switzerland but, due to a “too large demand”, Aldi did not reconduct it. The decision is now to be taken by big economic actors and politics.
Weekly update #1
The goal for this week was to meet stakeholders and to find a workspace. We are happy to share that we’ll work at Nepal communitere; where we can use an container and an equipped makerspace.
We aim on gathering all the material to build the compression this week. We’re now facing a challenge: “european sized” ovens are rare in Nepal; so you can’t really find one in scrap (at least we didn’t find one yet). However, what’s common are there smaller ovens (up to 30 litter).
For the first trials, we are considering using a smaller oven. The quantity of plastic to be treated will thus be limited; but I think that’s OK. However, I’m worried about heat uniformity in these kind of ovens; some films might burn. Has anyone experienced working with these small ovens? Would it be difficult to upgrade a small oven to a bigger one (by reusing the heating element and making a new insulated box)?
Dear and precious community,
I am relaunching this passionating topic as we are leading a research on small-scale and local solutions for food wrappers recycling in Kathmandu, Nepal. We’ll be working on this toping for two more month, I’m sure that there are interesting results to come.
We are currently building a compression machine to run some tests on plastic films. However, many films here are metallized (noodles, biscuits, …; I’m pretty convinced they are PP). We will try to use as much as possible the same material (noodle packages). Could I have some feedback from the people who tried to work with these metallized wrappers? @imuh @borbala; do you maybe have some input?
@charlotteallen @jas1092 You mentioned the idea of big sheets as shelter. I read that metallized PP is manufactured to reduce permeability of light, water and oxygen; it sounds great for a shelter to me! This kind of plastics are all over Asia (one factory here in Nepal produces 2100 noodle packages a minute, imagine the quantity of waste). What if we could make something new out of it while keeping these properties? On the idea of @imuh ‘s poncho, imagine if we could iron these packaging into a kind of canvas sheet; that would be super useful for shelters!
We’ll keep you updated on our problems and progress on this topic:
In the meanwhile, I wish you a really pleasant day!
They mix PP and PE in the process, which represents most of the soft plastics (as you seem to have on your pictures).
I can’t really help on the electricity issue. For sure, to recycle plastic, you’ll need heat and energy.
Maybe you could contact cementries or other industries that could be interested in using your mixed plastic in their process?
You might want to check out this file by wasteaid:
Basically, you can apply the idea ot paving tiles to roof tiles. However, it is possible that this technique can lead to issues (tiles getting soft with heat b.e.).
Also, I’m wondering to what extend this new composite material is recyclable into new material (once the tiles are borken)? Does anyone has an input on this point?
After solving the moisture content issue, I think the problem you’ll have to deal with a mixture of polymers. It seems you already work at a pretty big scale, so getting inspired by what these guys do (combining mixed polymers of soft and hard plastic in a recycling process) might be of interest to you:
I am wondering if we could bring this process to a smaller scale. Any thought?