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hello and welcome to technically speaking where scientists and engineers come together to chat about a common interest share knowledge and satisfy some curiosity I'm Laura and I'm joined by Antonia and Jasmin to talk about glass, whether we can be using or recycling more of it and what the alternative may be. Now I've seen lots of news articles that seem to be talking about plans to increase glass bottle recycling rates and these plans seem to
be controversial. One is that a new osit return scheme in England won't include glass bottles. So, Antonia, what do you know about the deposit return scheme?
I've come across the deposit return scheme in Germany and I found out in a rather abrupt way to be honest uh we were me and my friends were buying some beverages I can't remember what kind of packaging it was whether it was glass or plastic or um cans but the amount that was labeled above the the item was not what they asked us to pay at the cashier and they just kept telling me just pay it and because you went from there you wanted to understand why I assume that
was the extra the deposit for the container it was the deposit for the container and I would get it back if I brought it back but it was just so well established that no one explained it oh that's a shame You' think if they're that well aware of it that they should be able to explain why it exists but I guess maybe they just figured it's just a thing we do need explain I I think at that point it it's just like that no one questions why we have value added tax it's just there um true
so yeah it's been going on for ages yeah and I can see that um having an amount that you then get back when you turn the container makes a lot of sense to incentivize people to recycle um but Jasmine am I right in thinking this is part of something calls the um the extended producer responsibility which is also known as polluter pays um so technically extended producer responsibility is a type of Polla paay principle uh which includes others but polluted paay is essentially it's a
concept in the mental policy where the person or party that is responsible for producing pollution so carbon missions or in the case of Beverage bottles litter and they have to pay uh or take some kind of financial responsibility for the pollution that they'll cause other types of Pluto pay principles are the deposit return schemes for packaging okay so there are a lot of different complexities out there for the packaging people yeah oh I'm intrigued uh can you
uh can you tell me more about this the deposit return is interesting in comparison with other pluta pints in that it's very targeted and specific so most deposit return schemes Focus entirely on bottles it's the consumer that is financially responsible we've seen like glass deposits at festivals as well yeah so sometimes people keep the glass and essentially they've kind of paid for it because they took it home or they get like two or three pounds back when they return it these are sort of
things that you would keep as a souvenir from the festival yeah I think they would be they're not just like single use items hopefully yeah hopefully but you never know so I guess that sort of suggests their their high value if they're not just use it once and then Chuck it away yeah and we've seen it with the plastic bag charge that was introduced to the UK over 10 years ago I can't even remember feel like it was more than 10 years ago similar to Germany we just accept it yeah and
that's what happens yeah yeah it's interesting because is the consumer always the polluter I kind of feel like if you have got a thing from from my shop and you have used it it is your responsibility to then dispose of it correctly you often you would see plastic bags like floating down the street wouldn't you they end up touching themselves trees and whatever else which made it then really difficult to get a hold of or if you remember the Katy Perry song uh firework okay no well this
may be controversial but I'm not a huge Katy Perry fan so I don't think I'd be able to tell you the lyrics from any one of our songs um maybe we should just move on yeah so we've got the plastic bad charge which I I think the retailers can just do what they want with the money once they get paid for the plastic bag so it's a little bit different from the deposit return scheme yeah it's different in that um you don't get your money back if you return the bag it's
true you kind of you paid for the bag in that case so you yeah you own the bag yeah so but it did stop people from just getting bags at the supermarket just for the sake of it didn't because you suddenly had to pay for something that you effectively considered rubbish yeah if you're just used to something being for free and then it's like 5 P 10p like maybe I don't need a bag just take my own keep using the one that I've already got but this deposit return scheme that
I started hearing about not so long ago the new story said that including glass bottles in the deposit return scheme would increase complexity but it didn't really explain what that meant and I assumed it's just because the glass is heavier and more fragile than plastic so it's more difficult to handle but it goes in our curbside recycling and collection bins all the time so I didn't quite understand that point yeah so in general the government want to increase
recycling rates of single use drink containers because it's currently about 70% and they're hoping that a deposit return scheme would increase it to 90% that would reduce a lot of litter the idea of a deposit return scheme is fairly new to the UK so it's not entirely certain how much extra it's going to cost for flight drinks that come in bottles or aluminium cans but 20p per bottle is usually floated around and I guess maybe the complexity comes from do we price things differently
glass is heavier and generally more expensive so are they going to put a higher deposit on that and you know vary it by size of container but then would that be too confusing for the consumer and they just want a flat rate of 20p for whatever it is true I still would thought assumed you could just apply that amount to any container regardless of what it's made from but maybe I'm missing something there is something that I read and I can't find this information anymore it was when I first
started looking into this months ago but the idea behind the deposit return scheme was um partly based on what ends up as litter in the streets which is either in a bin or just floating around on the grass or down the curbside or whatever apparently 55% of litter by volume is plastic and metal drinks containers but less than 4% is glass bottles so I think part of the justification for having a deposit return scheme in general is it would help out local authorities who would
ultimately you have to dispose of the waste that's in the street or on the bin and the deposit return scheme would incentivize people that don't already recycle or maybe less responsible their waist and don't mind it floating around out there would make them do something with it um so I it could be that one reason the glass is excluded is it the so little of the litter on the street being glass there was a impact assessment by defra that estimated how much money goes into just tidying up
litter in general so is that part of the reason for doing it the cost benefit analysis it's like yes the scheme will cost this much to implement but will save this much money yes there is a net Financial benefit to having a deposit return scheme not just because they've taken in revenue from the deposit but they'll save money from not having to pick it up off the street fair enough so I will say that it looks like very little of the glass litter near me and there is a lot of it is ever picked up
because there some of it has been sitting there for years from what I can tell I've swept some of it to the side of the path and it still sits there in a pile nice apparent Curr the UK spends £560 million tidying up litter is that a lot in the grand scheme of local Authority budgets this is a bit of a side point I think because it sounds like a lot it's millions of pounds but is it if you put it in context uh total revenue expenditure by local authorities in England is budgeted to be
13.8 billion in 2024 to 2025 so that's like okay more than a third on picking up litter that does seem like a lot in that case that's worrying I guess and allegedly a third of local Authority expenditure in England is to education so we're spending as much picking up litter as we are educating our children nice we're definitely spending more than on police well that's not good see this yeah I guess you're pointing about education again it makes me wonder about
glass why specifically exclude glass what's so different about it potentially one part of the reasons why glass is excluded is because the represent the body for the glass industry in the UK did write an open letter to the government opposing including glass bottles in the deposit return scheme their main arguments were that because there's already like curbside collection for glass if you had another recycling scheme it would confuse people and could be um yeah and they did have some points
on people who pay a deposit for their glass bottles they would probably want it back but they don't have the means to get to a recycling point where they can claim theit back they're probably not going to recycle their bottles or potentially may not recycle their bottles because they don't have the financial incentive to do so British glass were also had concerns that deposit return scheme could make glass beverages more expensive and therefore people would buy less glass Beverages
and therefore would increase plastic bottled beverages but doesn't that entire argument also apply to other materials that you would put a drink in it just it seems odd to me I because British glass are advocating for the glass industry they don't care what Plastics and metals are doing yeah it's an interesting one because in other countries that have plastic return schemes glasses included and it has like really impacted recycling rates for drinks beverages in a good way yeah in a
good way in a good way recycling rates in countries that already have deposit protection no return schemes are much higher than what they were pre- deposit return schemes and Wales is going to keep it in their scheme yes it's England Ireland and Scotland that have differed yes okay so British glass saying keep out because it would be confusing is essentially just creating a bit more confusion because it differs depending on where you are in the UK marvelous yes
so just to put into context of what reducing glass littering could look like if we managed to capture 90% it would just in Scotland allow 54 million glass bottles every year to be recycled cord and that's an increase from whatever it is now to 90% so it's not like from0 to 90% having that much more of an impact yeah that would save 1.2 million tons of carbon emissions over the next 25 years fair enough IID also read that the deposit return scheme could reduce glass littering by 85% if
glass were included which I would prefer because as I say there's a lot of broken glass on the streets near me um and my dog has got his porw on it and neighbors's dogs have as well so I think it would make sense and I found statistics about household recycling rates so in the UK bu Mass 68% of glass is currently recycled 51% of plastic glass is only slightly lower than the recycling rates of paper or metal and that's just from our home recycling so the curbside collection schemes or
taking things back to the supermarket and putting it in their bins so it sounds like those rates aren't that dissimilar to me glass is slightly better but not by a massive amount i' have said there's room for improvement in both both areas I think yeah for sure and increasing recycling rates is definitely something where deposit return schem could have an impact if we look at what other countries have experienced so in Finland they introduced deposit return and
within one year their um recycling M recycling rates uh increased to over 90% And in the Netherlands um they managed to reduce plastic bottle litter by uh 70% so you can see places where they've have deposit return schemes it's made a really big impact in Germany which is going to go back and make Antonio relive her trauma yeah Germany's the most successful example of deposit return scheme since implementing it in 2003 so was ages their recycling rate specifically for plastic bottles is 98%
98% yeah it's pretty high that is impressive almost all the glass bottles going back out in the wild and then coming back to them uh plastic bottles only PE oh okay sorry I think I was thinking glass because of one time I've been to Germany and done this it was with glass bottles that we had and it was like a reverse vending machine and you had to have yeah you had to have the label on the bottle intact which we didn't realize in quite a few has been peeling the labels off so you put it in
the vending machine and it reads yes it's this company's beer bottle and the label tells me this about it yes you can recycle this so we ended up with these bottles that we couldn't get the deposit back on oh no yeah I guess they could still be recycled though yeah for glass and Germany it's 85% so not as high as plastic bottles but still much higher than UK yeah I wonder if they looked into the reasons for that but I guess that gets us uh a little bit distracted
so moving back to the UK If glass bottles are going to be excluded from the deposit return scheme it sounds like instead they will have an extra cost charge to the drinks producer that works out at about 9p per 500 mil bottle and some drinks industry people are saying this would make glass bottle drink too expensive for the consumer and would lead to switching to plastic which the industry also seems to be saying that well if you have a deposit return scheme that will also make people switch to
plastic which just makes me sound like they don't want to change what they're doing I mean that is likely but I suppose if they're not applying the deposit onto the consumer the way they're going to apply this charge is through the extended producer responsibility is that what that article was suggesting I think so from the numbers they quoted because I found the extended producer responsibility suggested charges per ton of material and it did seem to roughly work out so I
assume it is but the article didn't specifically say and this is a a scheme again that is in other countries where as a company you would log how much packaging material you imported or introduced to the UK market so say I bought 50 tons of plastic to package my things then I would have to pay an additional however much per ton for said materials that would put back into the recycling scheme infrastructure to improve the system and it's an incentive to move away from excessive packaging
hopefully the tariffs make sense in terms of environmental impact so I said I looked at the tables these are only suggested ranges at the minute so they're not set in stone but for a heavy 500 mil glass bottle so 400 G charg is equate to about 9p if you use the higher fee but for plastic a heavy one of those apparently is 40 gr it would only be 2p a bottle so the producer would be paying far less if they were switching to plastic rather than glass or and the retailer I guess it also sounds like
that means the deposit return scheme would add an additional charge so you play the producer is paying something that helps improve the infrastructure for recycling then the deposit return scheme also has its own charge applied I guess that would make the scheme more complicated but from my experience in Germany I brought the container back to the supermarket and they just paid it me back so in that case what does that achieve no money for the industry just encouraging the person I guess but I I
think they also assume that some people just won't bring it back they will make some money somewhere yeah and then I guess that is going towards the litter management or for recycling or improving recycling rates in other ways maybe you would hope so but then I guess this means that the the different way that glass is being treated compared to Alternatives like plastic from what we've said so far it's partly about littering an objection by the glass industry to making things happen a
certain way and the charges suggest that plastic is somehow better than glass but it does make me wonder which is easier to recycle if this is the whole point of doing this it's to get people to recycle which is the easier one glass or plastic if we're talking about easier are we saying it takes less energy to recycle we could do I guess I mean you could Define that as how many different steps do you have to have involved or how complex is it to get a thing that's gone out into consumer
space back to the Factory and then back into being like a new product for both plastic and glass recycling is pretty similar so we use what's called mechanical recycling where basically you need to sort out your types of packaging to certain types because you don't want contamination and then you clean it you cut or crush it then you do Extrusion to it um so for plastic it's usually you just pelletize it and then you melt it and then you use that molten plastic to
make new plastic and similar with glass you just crush it and then turn that into new glass sounds relatively simple but I guess because there are lots of different types of plastic so you like just the base polymer like polypropylene or poly ethylene but then they get all sorts of different additives added to that that might be difficult to distinguish and from what I can tell this mechanical recycling method it doesn't remove any of those additives and I get the impression that when you
extrude the plastic so you kind of you melt it that added temperature can lead to a lot of bond breakage you get reactions going on with the additives I assume this some oxidation apparently and it kind of makes the polymers get shorter which makes them more difficult to then to form into new products I say it's like I know what I'm talking about I literally read this the the challenge then is how do you separate materials you know you can come up with some sort of clever way to try
and make the feed stock as similar as possible but would it be easier if people just sorted it at the source you know when people throw away it's already sorted rather than having infrared camera or flotation to work out different densities of plastic which they're very similar so you're not really going to get a nice clean separation but if you even if you melted them down and hoped that one would float above the other you've got you're going to have some mixing so yeah it would
seem to me that trying to keep plastic suitable after you've recycled it starts with the feed stock even the color would be a problem because I suppose by weight you've got more color or all the other added relatives relative to plastic material I found a journal article it's only a few years old so I guess it's still relatively um useful I reckon that sorting rates for plastic can vary a lot between about 30 to 95% and this is in the facilities that do the Sorting of
the plastic before sending onto the recycling facility and that sorting rate depended on the plastic and the technology used at this material recovery facility and the higher rates seemed to be brought about by facilities where they used emerging technology such as these highdefinition cameras that could detect contamination so I got the impression from reading this and they surveyed about five or six different facilities their focus seemed to be on the industrial process of getting the
waste back and sorting it rather than on the consumer I often think consumers are treated a bit unfairly here so I was quite pleased to see that the authors also noted that these um recovery facilities and the collection systems as well as the packaging could all be better designed if they wanted to get to the same 95% that they saw in one of the plant basically in addition to like increasing actual packaging being sent to recycling other things need to be improved so basically the packaging
design recycling salty plants and generally the whole recycling infrastructure just needs to change if you want to see really big improvements in recycling overall y makes sense and when plastic is recycled I always assumed before I started reading into this that you would process the polymer and I've got a bit of background in polymer science cuz my PhD was modeling polymers on a computer but I assumed that you would process the polymer by breaking it up into its monomers its
individual building blocks and then just make them chemically react together till you made a polymer of the same length as the one that you wanted or the one that you would originally have started off with but it sounds like most recycling schemes don't do this because they stop at just the mechanical Recycling and don't go those extra chemical steps I got the impression it's because these chemical processes are more costly and still in development yes they are
okay good I got something right you would have to literally break the bonds and so what kind of energy requirement is there and to guarantee that you break those particular bonds as opposed to I don't know just completely degrading the entire thing and turning into a whole another chemical or just end up burning it so people have suggested you could do this for pyrolysis it's quite high temperature and it's a the absence of oxygen to make sure you don't burn it
and turn it into a bunch of carbon okay it's still in development it's not really something that is used yeah I'd also seen that it's a lot easier for polymers that are made by what's known as a condensation reaction which is essentially where you drive off some hydrogen and oxygen molecules from the monomers to make the polymer you effectively release some water so things like P plastic it could be used for cuz they're made by condens ation reactions uh the condensation reactions it sounds
like easily reversible compared to other types of polymerization reactions yeah and I suppose pet is already widely recycled because it's one of the main Plastics used for plastic drinking bottles so if you've already got clear P then you can just shred it and melt it why would you go through the effort of reversing a chemical reaction because then you could in theory infinitely just recycle that plastic bottle rather than only being able to recycle it like two or three times before it becomes
unusable because the polymer chains are too short as a result of mechanical recycling I suppose as well as the high temperature that I suggested through paralysis you could use other methods with higher temperature or with chemicals and then it's more complicated more costly so you'd get extra waste but despite all that even with the recycling rates that we have and with mechanical recycling a lot of plastic drinks packaging does contain uh recycled plastic so in the UK it's legislation
for all plastic packaging to have a minimum content of 30% recycled plastic or you get charged more money for not meeting that a tax as so producers can't just keep on extracting more oil out of the ground or buy products of the oil industry that they can use to make new Plastics we have to recycle some of it does make me wonder though if you only recycle Plastics via mechanical methods a few times how often can those bottles that are 30% recycled content be recycled but I feel like I'm getting
into too much detail um so I'm going to shift away from talking about plastic and in comparison does anyone know how much recycled glass goes back into a glass bottle yeah so there's a study carried out for the UK and they found that for a Clos Loop cycle so that's glass bottles being recycled and turned into new glass bottles uh it's about 36% kind of similarish to what government is legislating for for plastic yeah that start really surprised me because I feel
like I remember seeing this said about glass and some metals that they are infinitely recyclable I think the operative word missing from that statement that you've probably seen floating around the internet is in theory it's infinitely recyclable which I would imagine is the same for plastic if you went beyond mechanical Rec um I mean I used to work on glass in lab so I know roughly how glass is made so you take a really high Purity starting ingredients so your sand or your silicon
dioxide and whatever else you want to add to the glass um you stick it in a furnace at at least about 600° C depending on the chemical elements that you want to put in the glass Pyrex which is the sort of stuff you put in the oven requires temperatur of 1,000° C to melt it but we're talking specifically about glass bottles they're not made of Pyrex so I would assume you melt them at about 600° C and as Jasmine mentioned the glass recycling process is similar to
the Plastics you get the glass back from the wild the people that have used it you sort it somehow you crush it and then you stick it back into your melting process uh I also read that green glass has a higher tolerance for impurities in that recycled feed but the quality specifications of clear glass only allow 60% of recycled glass in their content because they're clear so any defects in color will stand out quite well which means the needs to be segregated first
and the contamination removed and different types of glass going into that glass stream have to be quite limited which I think puts an unnecessary burden on clear glass bottles really I don't really care if my wine bottle looks a bit of a funny color yeah if we limit it to talking about bottles yeah maybe you know that's why it's beneficial to have brown bottles because it's like a mix of every color yeah and there's a reason that beer bottles are brown it's to stop
sunlight getting through or particular wavelengths of sunlight getting through and breaking down components of the beer and making it just taste weird yeah it's the same with some Cosmetics too but um in terms of like recycled glass versus verion glass like there is a benefit in terms of it reduces energy consumption and therefore carbon but it is limited just because the melting temperature of glass that's being recycled versus virgin Glass isn't that big so there was
a study by the national renewable energy laboratory in the US and they found that for making bottles from 100% recycled glass it would only be maximum 13% Energy savings versus completely virgin glass so there's a benefit but not that big no and I guess again that's cuz they have to get to quite a high temperature and that's probably where a lot of the energy consumption comes from yeah it is yeah but I guess if that's just the process side of it the uh the chemical
processing and the energy intensity I guess there's more to consider if you're talking about what is best or what is uh the right thing to do for the environment which is the point of the recycling in the first place so there's things like where your starting materials come from if you're adding recycled content to new content how hazardous is the process you creating extra jobs uh resource other resource use all these things are factors of sustainability aren't they yeah
recycling has benefits like it reduces the demand for raw V material so less petroleum product demand less silicon sand and other stuff used to make glass demand and also lower greenhouse gas emissions because recycling does generally have lower emissions and producing things from Virgin materials I guess you also have to think about where your factory is located we hear quite a lot in the UK that our plastic waste is just kind of shipped off to another country and we just leave it to them to
deal with in potentially unsafe conditions and I suppose if the producer is responsible they might be more inclined to think about them locally because they still have to pay for buying the material in the first place and then they're paying for its end of life why don't we just go back to you know when we used to have milk bottles delivered to our front door they get taken away washed I presumed not recycled and then you got it refilled why don't we go back to that good
question I can only imagine it's because that was quite a local supply chain I don't know how far the dairy would have been from your house but it might have only had to travel a few miles in that bottle so it's quite a short recycling loop I have looked into it as one near me given that there is a a dairy farm near me that has a Bend machine for milk W yeah they don't deliver though so I'd have to go there myself which I'm not sure is particularly efficient in terms
of time or energy use and it would have been much more efficient because they were electric milk floats and they basically did the entire Street y yeah I remember the Milkman that was a long long time ago no I live in London and I don't think anyone in my area gets milk delivered to them I tried getting bread delivered to me by a brand that was supposed to be sustainable Eco all the buzzword but they left my bread outside of the cardboard box and it was just in a thin plastic film just on your
doorstep on my doorstep because it was too early oh dear and they were like if it's before 6:00 a.m. we're not going to ring your doorbell by the time I got up it had been eaten by birds the early bird catches the erant love oh dear so I feel like we've talked an awful lot about the recycling methods and how the recycled material gets to that recycling plant and we talked way up top about why glass is being excluded from the deposit return system and I still can't help
thinking that it is just glass companies that don't really want to change what they're doing I'm not convinced by the arguments that the industry has put forward and I like glass I'm a glass scientist to an extent I kind of can see where drinks companies come from when they use glass because supposedly cocacola spent a lot of money developing a coating to make the taste of Coca-Cola the same from a plastic bottle as it did in a glass bottle and they have vast
resource to do that you know ultimately drinks company want to sell drinks that are attractive to the consumer and people think drinks in glass bottles are of a certain quality and plastic is not I I mean Coca-Cola started off being sold in glass balls as well didn't it and they shifted to plastic and they must have had a reason for doing it if they had to invest research in making the drink taste the same so would it be so farfetched to say wine start being delivered in plastic bottles instead
would you want wine out of a plastic bottle I mean there's wine in a box so why not I don't I've never seen wine in a plastic bottle but I've definitely seen cider in a plastic bottle i. e the cheap one the really cheap one exactly the wine that comes in a plastic bottle is the one that's in the value or Basics range of a supermarket maybe they just don't trust that it won't degrade in plastic and they're also concerned about plastic leeching into drinks and stuff or
chemicals leeching from plastic into drinks or is that only Plastics with BPA I assumed it was just BPA cuz that is the one that you hear about quite a lot don't you and Plastics aren't I think aren't allowed BPA in them anymore what about microplastics or also emerging resar we've all got microplastics in our bodies anyway at this rate yeah like pasas but ultimately I guess it's kind of inert in our bodies I think this could be another episode because I think
there's a lot of research going on in that space at the minute I've definitely seen a lot of research papers that have said plastic is in pretty much every part of your body and your body has to do something with it normally just kind of encapsulates a foreign object doesn't it but I don't know if it would encapsulate something that's on the Nano scale or the micro scale so we have another problem pot actually I'm not seeing anything yet that said yes this person
died of plastic pollution we know it affects animals though smaller animals I don't know why that's relevant CU I'm sure the the length scale of their cells is the same as humans I feel like that's probably a good place to leave it though cuz we've gone way off topic now yep so we're kind of saying the glass bottle industry doesn't necessarily want to change and the glass industry suggests that recycling rate is already high even though bottles can't really be made from
100% recycled material we also recognize that plastic recycling processes could definitely be improved by quite a lot so there's a lot more science to go there and a lot more engineering so thank you for listening and we'll uh see you in the next episode The Views expressed in this podcast belong intirely to the person that said them they did not represent any industry or organization if you enjoyed listening to these views it would really help us out if you could
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