[HN Gopher] Researcher finds a new method for recycling polystyrene
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Researcher finds a new method for recycling polystyrene
Author : geox
Score : 95 points
Date : 2022-08-24 16:36 UTC (6 hours ago)
(HTM) web link (vtx.vt.edu)
(TXT) w3m dump (vtx.vt.edu)
| ParksNet wrote:
| Why don't we just burn all these plastics in waste2energy plants?
|
| Even with perfect recycling, the limitation seems to be on
| collection and separation.
| shagie wrote:
| Combustion products.
| https://en.wikipedia.org/wiki/Polystyrene#Incineration
|
| > If polystyrene is properly incinerated at high temperatures
| (up to 1000 degC) and with plenty of air (14 m3/kg), the
| chemicals generated are water, carbon dioxide, and possibly
| small amounts of residual halogen-compounds from flame-
| retardants.
|
| > When polystyrene was burned at temperatures of 800-900 degC
| (the typical range of a modern incinerator), the products of
| combustion consisted of "a complex mixture of polycyclic
| aromatic hydrocarbons (PAHs) from alkyl benzenes to
| benzoperylene. Over 90 different compounds were identified in
| combustion effluents from polystyrene." The American National
| Bureau of Standards Center for Fire Research found 57 chemical
| by-products released during the combustion of expanded
| polystyrene (EPS) foam.
|
| Yes, you can burn it... but the things you make out of it
| unless you are _really_ trying to burn it (and then its a burn
| it to dispose of it rather than get energy from it) leave some
| less than desirable compounds.
| noselasd wrote:
| Is there currently a bottleneck that prevents burning it at
| 1000degC and getting energy out of it ? Sounds like business
| opportunities ! Make an practical incinerator ?
| orangepurple wrote:
| Yeah there may be awful byproducts at burn temperatures
| required for optimal power generation but if they can be
| captured/condensed/solidified they can be collected as solid
| waste and buried.
| KennyBlanken wrote:
| Yeah, let's just bury those toxic cancer-causing compounds!
| What could possibly go wrong?
|
| _looks over at the 1300 superfund sites around the nation_
| shagie wrote:
| The energy to condense out and capture the undesirable
| products becomes comparable to the energy capture it.
|
| Japan's approach isn't because they need energy but rather
| that they are trying to minimize landfill (as its an island
| and space is at a premium).
|
| The resulting products are carcinogenic toxic waste - which
| comes with additional challenges for disposal. In the US,
| it is likely more desirable to bury the inert polystyrene
| rather than trying to deal with the PAHs ( https://en.wikip
| edia.org/wiki/Polycyclic_aromatic_hydrocarbo... ) and other
| byproducts.
|
| The article is describing a process where UV light and a
| catalyst break down/transform polystyrene into
| diphenylmethane (
| https://en.wikipedia.org/wiki/Diphenylmethane ) which is a
| feed stock for many other (useful) processes.
|
| The paper referenced in the article is Cascade degradation
| and upcycling of polystyrene waste to high-value chemicals
| https://www.pnas.org/doi/10.1073/pnas.2203346119
| ezconnect wrote:
| That's the solution of the Japanese, and they are very
| efficient on it, burn them and turn them to electricity and the
| extra waste get used as land fills.
| kzrdude wrote:
| Also Sweden burns a lot of waste (landfills for household
| waste are entirely obsolete). Rest heat is used for domestic
| heating.
| loudmax wrote:
| Wouldn't it be better to bury plastic in landfills? Keep the
| stuff out of the ocean, but I don't understand the harm in
| landfills. Put that carbon back in the ground where it came
| from.
| KennyBlanken wrote:
| Plastics recycling is a sham, invented by the plastic industries
| to defuse criticism for an explosion in single-use packaging.
|
| The vast majority of plastics are never recycled and end up in
| landfills or dumped at sea.
|
| It's not economical to recycle plastics because separating
| plastics is expensive, the percentage of material that has to be
| chucked because of contamination (food, chemicals, labels, etc)
| and the recovered material itself has little to no value due to
| degradation of the polymers.
|
| Methods like these are important, but what's more important is
| replacing, reducing, etc.
| mediaman wrote:
| This is a claim that's often repeated ad nauseum: plastic
| recycling doesn't work and it's a sham.
|
| There's an element of truth to it: plastics recycling in the
| USA today is, in aggregate, in a sorry state.
|
| But it's become "common knowledge" that there's no way to make
| it better. That's not true.
|
| Turn, for example, to British Columbia, which passed an
| Extended Producer Responsibility (EPR) law several years ago,
| which created a system to stabilize the prices of recycled
| plastics so that recyclers could raise money to build the
| facilities to process the material.
|
| Now they have the most sophisticated sortation and recycling
| centers in North America. Laser-based systems identify plastic
| types and use shots of compressed air to automatically direct
| plastic onto the proper conveyor.
|
| Each stream is shredded and ground, and then hot washed and
| dried. Then it's sorted again, this time for color, by computer
| vision and more compressed air to create streams of clear
| material and streams of green or other colors.
|
| The result is that 56% of rigid plastic packaging in BC is
| recycled. That's not perfect, but it's pretty good, and
| definitely not a "sham".
|
| The problem we have in America is that, broadly, we need
| public-private partnerships to invest in the sort of equipment
| that can do this. The technology exists, it works, and it's
| already being used. Virgin plastic should be taxed and then
| that tax should subsidize and stabilize the price of recycled
| material so that private capital can supply the equipment
| financing. And regional authorities should organize recycling
| so that enough material can go through one facility to amortize
| the $30m in equipment over the poundage. (These contracts can
| be bid at auction to keep them fair.)
|
| In other words, this is not an area where a pure free market
| works, and it typically requires coordination across regional
| population centers of 7m+ to get enough poundage through the
| system.
|
| If we can do what BC did, the rewards are big: plastic is, by
| far, a lower emitter of GHG than paper-based packaging, does a
| better job reducing food shrink than any other material, and
| offers massive weight savings (and GHG savings) versus glass.
|
| Today, of course, it's become much more en vogue to pursue high
| GHG packaging solutions ("because everyone knows plastic is
| bad!") rather than build public pressure to adopt the political
| steps required to implement already proven production
| technology.
| ZeroGravitas wrote:
| California has something like this passed recently:
|
| https://calmatters.org/environment/2022/06/california-
| recycl...
|
| In the EU:
|
| https://packagingeurope.com/news/how-the-soft-drinks-
| industr...
| coryrc wrote:
| > The result is that 56% of rigid plastic packaging in BC is
| recycled. That's not perfect, but it's pretty good, and
| definitely not a "sham".
|
| Or, we could say with all of the advanced systems possible,
| massive subsidies, and creation of large amounts of inferior
| recycled product, still 44% is rigid plastic packaging is
| wasted (let alone all the other kinds): "Sham" seems fair.
| algo_trader wrote:
| I was just reading about TheOceanCleanup [1] and its
| depressing. It is hard to collect the garbage, it cant be
| disposed off, and there is a huge ongoing flow of new garbage.
|
| Can we at least recycle plastics into other low-quality plastic
| which can be degraded/mix-quality/blended or something? I am
| not an expert.
|
| [1] https://theoceancleanup.com/
| aaaaaaaaaaab wrote:
| And what happens with this low-quality plastic when it's no
| longer needed? Make even lower quality plastic?
| ISL wrote:
| In some countries, lower-quality garbage is incinerated to
| generate electric power.
| and-not-drew wrote:
| Not disagreeing, but do you have a source? I'd like to know
| more about this.
| aaaaaaaaaaab wrote:
| "Plastic recycling sits quite low in the waste hierarchy as a
| means of reducing plastic waste. It has been advocated since
| the early 1970s,[11] but due to severe economic and technical
| challenges, did not impact plastic waste to any significant
| extent until the late 1980s. The plastics industry has been
| criticised for lobbying for the expansion of recycling
| programs, even while industry research showed that most
| plastic could not be economically recycled and simultaneously
| increasing the amount of virgin plastic, or plastic that has
| not been recycled, being produced."
|
| https://en.m.wikipedia.org/wiki/Plastic_recycling
| xxs wrote:
| It's pretty much a well known fact. Recycling is extra hard
| due to the need to separate the plastics and then the molding
| new plastics requires specific type of plastic molecule. Many
| plastics are even blends, e.g. ABS + PC, or glass fiber
| filled ones.
|
| "Plastics" are just so many types, different in all kinds of
| ways. So separating them and using them in anything sensible
| doesn't happen often at all.
| mackal wrote:
| Someday I'll have something to do with my Warhammer sprues I
| guess
| Silverback_VII wrote:
| Would be very nice to have many worms and bacteria who start to
| eat away the synthetic garbage. However, the will als start to
| eat solar panels and your shoes.
|
| But I'm still very much for the engineering of such creatures.
| MassPikeMike wrote:
| Burning plastics isn't great because of all the awful combustion
| products.
|
| Plasma gasification sounds like a good alternative. The molecular
| bonds in the plastics are broken and you end up with mostly
| carbon monoxide plus hydrogen gas, itself a nice fuel source.
| Metals and other heavy elements are typically allowed to settle
| into some molten glass to keep them contained.
|
| A publicly traded company called StarTech trying to do this was
| getting lots of publicity as recently as 2007
| (https://www.popsci.com/scitech/article/2007-03/prophet-garba...)
| but went bankrupt in 2013 after the death of its founder, Joseph
| Longo (https://www.ctpost.com/news/article/Wilton-s-
| environmental-d...).
|
| A company called InEnTec claims to have the technology deployed
| in a few places (https://inentec.com/pem-technology/deployed-pem-
| technology/) but overall one doesn't hear much about this
| possibility. I wonder why not.
| theplumber wrote:
| The best form of recycling is not producing it in the first
| place. Less plastic produced = less harm. It's no longer an
| unanswered questionx
| CatWChainsaw wrote:
| einpoklum wrote:
| Up until the last word of the title I was sure it was going to
| say:
|
| "Virginia Tech researcher finds a new method for recycling
| papers"
|
| :-P
| proee wrote:
| Why don't we promote more single-use aluminum containers? Are
| aluminum cans considered a success in terms of recycling and not
| going into the landfill? Why don't we have aluminum yogurt
| containers, aluminum milk cartons, etc? Has the 5-cent deposit
| program by some states been a success? If so, this seems like a
| good solution for more products than just beverages.
|
| Aluminum seems like a really cool material for packaging. One
| obvious downside though is that aluminum is not clear.
| TonyTrapp wrote:
| From what I know aluminium is also not safe to use with all
| kinds of foods, especially if they are acidic. Among your
| examples, this might be a problem with yogurt.
| thfuran wrote:
| It's already regularly used for soda, which is a good deal
| more acidic than yogurt. The cans are all coated in plastic.
| eatbitseveryday wrote:
| Agreed, though some folks will remind us that alu cans are
| lined with plastic (which is more a health argument than
| recycling), but similar to paper cartons, that may need to be
| stripped prior to recycling.
| eptcyka wrote:
| Aluminum is no panacea - its expensive to mine both
| ecologically and energy wise, and its energy intensive to
| recycle. I'd be more interested in reusable containers.
| abraae wrote:
| Not a panacaea but another benefit of aluminium (the correct
| term for many of us around the world :) is that the process
| acts as electricity storage, providing a useful way to soak
| up excess power when it is cheap.
| shagie wrote:
| American Companies Still Make Aluminum. In Iceland. -
| https://www.nytimes.com/2017/07/01/us/politics/american-
| comp...
|
| > Electricity in Iceland costs about 30 percent less than
| what Alcoa might pay in the United States. That's a crucial
| consideration, because the Alcoa smelter alone uses more
| than five million megawatt-hours of electricity each year
| -- about the same as the half-million people and all the
| businesses in the city of Colorado Springs.
| shagie wrote:
| https://recycling.world-aluminium.org/review/sustainability/
|
| https://citizensustainable.com/recycling-aluminum/
|
| https://www.treehugger.com/the-benefits-of-aluminum-
| recyclin...
|
| From the last link:
|
| > Recycling aluminum saves 90% to 95% of the energy needed to
| make aluminum from bauxite ore. It doesn't matter if you're
| making aluminum cans, roof gutters or cookware, it is simply
| much more energy-efficient to recycle existing aluminum to
| create the aluminum needed for new products than it is to
| make aluminum from virgin natural resources.
|
| > So how much energy are we talking about here? Recycling one
| pound of aluminum (33 cans) saves about 7 kilowatt-hours
| (kWh) of electricity. With the energy it takes to make just
| one new aluminum can from bauxite ore, you can make 20
| recycled aluminum cans.
|
| > Putting the energy question into even more down-to-earth
| terms, the energy saved by recycling one aluminum can is
| enough to power a television set for three hours.
|
| Aluminum is _extremely_ recyclable and energy efficient at
| doing it. Estimates put it at 75% of all aluminum that has
| ever been created is still in circulation having been
| recycled because it is so easy to do it.
|
| https://archive.epa.gov/epawaste/conserve/smm/wastewise/web/.
| ..
|
| > Aluminum can be recycled using less than 5 percent of the
| energy used to make the original product.
|
| https://en.wikipedia.org/wiki/Aluminium_recycling
|
| > Recycling aluminium uses about 5% of the energy required to
| create aluminium from bauxite; the amount of energy required
| to convert aluminium oxide into aluminium can be vividly seen
| when the process is reversed during the combustion of
| thermite or ammonium perchlorate composite propellant.
|
| > Aluminium die extrusion is a specific way of getting
| reusable material from aluminium scraps but does not require
| a large energy output of a melting process. In 2003, half of
| the products manufactured with aluminium were sourced from
| recycled aluminium material.
|
| That wouldn't be the case if it was intensive to recycle.
| forgotmypw17 wrote:
| One drawback of aluminum is that it still has to be lined with
| plastic, which is burned off before recycling the aluminum. The
| plastic also leeches into food.
| samstave wrote:
| 100%, but know that hte 5-cent program has been literally one
| of hte biggest frauds.
|
| But here is where I am, "Are you a 'millenial'? NO I am anti
| petro. Period.
|
| I literally look at every product I purchase and see micro-
| plastics.
|
| When I look at any product on the market, I evaluate how much
| micro-plastics I am buying.
|
| If you are a company that builds products with plastic
| containers, I do my best to avoid you.
|
| But your point is spot on.
|
| THE BIGGEST TAX PAYERS IN THE WORLD SHOULD BE ANYONE THAT
| SUPPLIES THEIR PRODUCT IN SINGLE_USE PLASTIC.
|
| My "recycling" bin should contain less bullshit than my
| garbage.
|
| Its a weird phenom that we are conditioned to be "proud" of the
| amount of fill in our recycle bin.
| theplumber wrote:
| >> Its a weird phenom that we are conditioned to be "proud"
| of the amount of fill in our recycle bin.
|
| I really believe the subject of banning plastics has been
| hijacked by oil interests to ecourage "recycling" knowing
| that it's a broken model. Just like the ESG stocks where you
| have oil companies being on top of the sustainability chart
| due their diversity score and high wages.
| ryanmarsh wrote:
| I have a way of recycling polystyrene that's also good for
| dealing with tyrants.
| lsllc wrote:
| Even with this development in recycling, Styrofoam should just be
| banned for packaging. Aside from disposal, it's very brittle and
| you end up opening a box only to find smashed up Styrofoam that
| now escapes all over the house/outside/car which is nearly
| impossible to clean up adding yet more micro plastics to the
| environment.
|
| There's nothing wrong with using formed cardboard packing instead
| of styrofoam and it can be recycled again, or at least if it ends
| up in a landfill, it'll biodegrade instead of still being there
| at the eventual heat death of the universe.
| purpleblue wrote:
| Styrofoam should absolutely be banned. It should be considered
| toxic waste at this point. There are incrementally more
| expensive solutions that companies can use instead of
| styrofoam, there's no excuse for its use anymore. It's
| literally single-use and no one else can use a piece of
| styrofoam efficiently. It often takes up so much space that it
| fills up your landfill garbage bin. As a planet we should ban
| its use with prejudice.
| crazygringo wrote:
| I'm really trying to think, but I don't think I've encountered
| styrofoam in _years_. All the packaging for mid-sized consumer
| products that would have used it in the past (small blender,
| air purifier, dust buster, etc.) seem to use either formed
| cardboard or else folded cardboard with cutouts.
|
| The last times I remember seeing it were when I bought a window
| AC unit and a portable digital piano. Both of which weigh 25+
| pounds, where I think only styrofoam is the only economical
| material which exists that is both protective enough but also
| able to support all that weight. I'd guess heavy blenders would
| also still need it.
|
| So not sure we need to ban it if manufacturers have already
| mostly stopped using where cardboard is a viable replacement?
| Unless there are categories of products still using it that I'm
| missing?
|
| Same with styrofoam for to-go food containers -- everything I
| see is plastic or cardboard now, haven't seen styrofoam in
| years. Unless this is regional?
| Tronno wrote:
| I have encountered it as building insulation recently.
|
| In my neighborhood, millions of styrofoam beads blew away
| from a construction site, then settled like snow on grass
| fields, in gutters, and in other nooks and crannies. I
| reported it to the city and they did nothing. Now that
| styrofoam will be out there forever.
|
| I would not be opposed to a ban.
| HappySweeney wrote:
| They got mealworms to eat styrofoam, so that stuff will likely
| be everywhere soon as the "environmental" container material.
| Apocryphon wrote:
| Doesn't that mean microplastics will end up in the food chain
| from the animals that eat mealworms
| shagie wrote:
| Nope - its digested (chemically processed).
|
| https://www.sciencedaily.com/releases/2020/05/200527105055.
| h...
|
| > The team placed 50 superworms in a chamber with
| polystyrene as their only carbon source, and after 21 days,
| the worms had consumed about 70% of the plastic. The
| researchers then isolated a strain of Pseudomonas
| aeruginosa bacteria from the gut of the worms and showed
| that it that could grow directly on the surface of
| polystyrene and break it down. Finally, they identified an
| enzyme from the bacteria, called serine hydrolase, that
| appeared to be responsible for most of the biodegradation.
| This enzyme, or the bacteria that produce it, could someday
| be used to help break down waste polystyrene, the
| researchers say.
|
| It is decomposed into simpler components that can be used
| by the bacteria itself for energy.
|
| https://en.wikipedia.org/wiki/Serine_hydrolase
| Apocryphon wrote:
| That's reassuring. Perhaps biopunk will allow us to
| create a brighter solarpunk future.
| happymellon wrote:
| Now to try and gather all the styrofoam...
|
| It still doesn't feel like a reasonable picture.
|
| Not when we have alternatives such as corrugated
| cardboard.
| shagie wrote:
| Gathering all the styrofoam is a problem. However,
| cardboard doesn't fit all the roles that styrofoam fills
| (in particular insulation).
|
| There's certainly a need to use the most recyclable
| solution (rather than cheapest) of the practical options.
| It is also important to remember that not all recyclable
| solutions are practical.
|
| For packing fill and protection, switching from styrofoam
| to cardboard increases its carbon footprint because of
| the increased weight of the cardboard needed for
| packaging.
|
| https://theecobahn.com/packaging/plastic-vs-cardboard-
| packag...
|
| Having better recycling with plastic products can mean
| reduced shipping footprint, reduced water usage
| (recycling paper products is water intensive) and a
| reduced demand for wood pulp meaning that planted trees
| can capture more carbon before they're needed as a
| resource.
|
| Our current use of plastics (lack of recycling options
| leading to disposal in landfill) is not something that is
| sustainable but going with solutions like corrugated
| cardboard can hide other costs.
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(page generated 2022-08-24 23:02 UTC)