Recycle Polystyrene: Can we do it?
Polystyrene, or plastic number 6, is used extensively to make packaging, disposable dishes, and cutlery. That cappuccino you grabbed on the way to work today? The cup was most probably made of polystyrene.
Remember C.D.s? The clear casing they came in is made of polystyrene. Packing peanuts? Polystyrene. The packaging you pull out of the box of almost every purchase you make? Polystyrene.
Polystyrene is one of the most common plastics used by the human world today. And as such, it is one of the plastics most commonly found polluting the environment.
Furthermost of the applications of polystyrene are single-use and disposable. From the streets of NYC to the middle of the Pacific ocean, polystyrene pollution is everywhere.
Polystyrene is fully recyclable, yet you will be hard-pressed to find a curbside recycler that accepts polystyrene. And if you do find a recycler that accepts polystyrene, the chances are that it will not be recycled and go to an incinerator.
Paradoxical, isn’t it? Read on to find out why.
Types of Polystyrene
Before we talk about polystyrene recycling, we need to know the different types of polystyrene that are used. This is because recycling challenges vary depending on the type of polystyrene.
Sheet Polystyrene:
Sheet polystyrene is the hard and compact type of polystyrene commonly used to make stuff such as CD “Jewel” cases, plastic cutlery, and smoke detector rings, among other things. It is naturally colorless and transparent but can be colored by adding coloring.
The reason that sheet polystyrene is used so widely is that it is cheap to produce and easily moldable. It is produced as a byproduct of the petroleum refining process and becomes moldable at a reasonably low temperature, to be turned into any shape using thermoforming or injection molding.
Polystyrene can be easily sterilized, and this, along with its natural clarity, makes it a prime choice for making medical and scientific equipment such as Petri dishes and test tubes.
Foam Polystyrene:
Foam polystyrene is produced when polystyrene is blown up using air, in a process called extruding. The process creates a bazillion tiny polystyrene bubbles filled with air, and these bubbles form the basic structure of foam polystyrene. Foam polystyrene consists of 95-98% air and is thus an excellent thermal insulator.
Expanded Polystyrene:
Expanded polystyrene or EPS is a flaky rigid material that holds its shape well but cannot take any impacts or breaks apart. It has a rough surface and is very hard to cut cleanly through.
Extruded polystyrene:
Extruded polystyrene is another type of foam polystyrene with air blown into it, but it is smoother and more challenging than expanded polystyrene. It is also known as XPS.
Styrofoam, also known as the blue board, is a patented variety of XPS made by Dupont.
Uses of foam polystyrene
Construction:
Foam polystyrene, both EPS and XPS, are used extensively in construction. They offer excellent thermal insulation and are used as insulating panel systems in walls, roofs, and ceilings.
One problem that arises from using foam polystyrene as insulation in modern homes is the risk of fire: polystyrene, like most other plastics, is flammable. This is often solved by adding fire retardants during the production of polystyrene.
Packaging:
It is an excellent shock absorber since expanded polystyrene has so much air. It is used as packaging to store or transport fragile items, where it provides cushioning without adding any extra weight. Since it is readily moldable, EPS packaging can be made into the shape of the object it will be used to pack, a super handy feature. It is also used as small pieces for packaging, called polystyrene peanuts.
EPS is also great for holding cooked food: it does not allow the heat from the food to reach your hand, is rigid, and does not get wet. Foam polystyrene is used to make cutlery, take away food boxes and hot drink cups, and is sometimes referred to as Polystyrene Paper (PSP).
Foam polystyrene is also used to make other stuff like architectural models and surfboards. Since it is so easy to use for packaging and insulation, polystyrene is also one of the most common types of plastic that end up as waste. And foam polystyrene like EPS or XPS has the added problem of taking up a lot of space.
Can expanded polystyrene go to a landfill?
Like almost all kinds of plastic, polystyrene cannot be broken down or decomposed by natural processes. It will take up space in a landfill for thousands of years on land.
A problem made even bigger by its high volume. It may also leak dangerous chemicals, such as fire retardants, that may be added to the soil.
It will float around for millennia in the sea, progressively breaking down and forming microplastics that find their way back to their human creators. Polystyrene can also be mistaken by marine life as food, and consuming synthetic material such as polystyrene is terrible for their health and the health of others that eat such animals- namely, us.
Can expanded polystyrene be incinerated?
Burning expanded polystyrene or any plastics is a bad idea. Burning under normal conditions does not produce enough heat to break down all the hydrocarbon chains; that’s what plastics are made of, releasing many unburnt molecules that are harmful to both the environment and the person burning it.
Polystyrene breaks down completely to give off carbon dioxide and water when properly incinerated at sufficiently high temperatures. But carbon dioxide produced will contribute to global warming by trapping the sun’s energy.
However, this might seem like a better idea than dumping it in a landfill. That is why polystyrene finds its way into the fuel burnt in the power and cement industries.
Can you recycle polystyrene?
Technically, you can. The process for recycling polystyrene is straightforward and similar to other plastics: wash it, dry it, melt it down and turn it into plastic pellets that can be used to make expanded polystyrene or other polystyrene products.
And almost every recycler will be more than happy to take your sheet polystyrene off your hands. That is unless your recycler is grumpy by nature.
But the gargantuan share of polystyrene pollution comes not from sheet polystyrene but the foam variety, EPS, and XPS. And it is challenging to find a recycler who will recycle expanded polystyrene.
The problem is not with the recycling process, and it is still the same: melt it down, make pellets and produce new products. The problem is that EPS needs to be volume compacted before it can be recycled.
Volume compaction is compacting material to bring it down to its minimum volume. In other words, it gets rid of the air inside the material.
What’s so difficult about compacting foam polystyrene? Remember when we said that polystyrene is so desirable as an insulating and packaging material because it is mostly air?
That’s the problem: you need to compress a truckload of foam polystyrene to get a football-sized amount of packed polystyrene, which can then be recycled.
This makes it uneconomical for most recyclers. To add to the problem, compactors that can handle polystyrene are costly.
Often recyclers will have to transport huge amounts of polystyrene to a central plant before it can be compressed, then haul it away to another plant where it can be pelletized and recycled, adding to the costs.
So it’s costly to compress foam polystyrene, and the amount of polystyrene that can be recycled drastically reduces once it is compressed. This is why recyclers do not want to invest in the equipment and logistics needed to recycle polystyrene.
Sometimes, recycling plants may accept expanded polystyrene but cannot find enough polystyrene scrap because hardly anyone wants to collect and transport foam polystyrene.
So that is the sad reality, polystyrene is fully recyclable, but because of the hassles and added costs of transporting and compacting it, no one wants to do so.
Some recyclers accept it for recycling, but you will have to look around to find them. While many municipalities do not accept expanded polystyrene, some do, like Los Angeles and Toronto.
Even if a recycler or a store accepts expanded polystyrene, mainly due to laws that require them to take back their own waste, this polystyrene will most likely go to a landfill or an incinerator.
Only about 12% of the expanded polystyrene used in the U.S. is recycled, and it is just cheaper to produce new polystyrene than recycle old scrap.
But don’t be disheartened, compaction technology is becoming more affordable every day, and soon most recyclers may accept EPS. Other than that, new developments in recycling like polystyrene munching bacteria also offer hope.
Many states are also passing legislation to stop using foam polystyrene, thus cutting waste production at the root or making it compulsory for EPS producers to take back their polystyrene.
Polystyrene Eating Bacteria
We have discovered bacteria that can degrade polystyrene and can be a possible solution to the polystyrene waste problem.
These bacteria are present in the gut of mealworms, wood-boring larvae of some beetles, and when they are allowed to feed upon polystyrene, they have been found to ingest and digest polystyrene. Research is also ongoing to use the bacteria extracted from the gut of these worms.
While more research is needed in this field, the use of worms and their gut bacteria presents assuring possibilities for a plastic pollution-free future.
Reuse Polystyrene
Some forms of foam polystyrene can be easily reused. For example, packaging peanuts can be reused right after use to pack something else. Some carriers, such as UPS, will accept packing peanuts from their deliveries if you mail them back to them.
Larger forms of packaging can be broken down to form smaller loose packaging.
Easy ways to reuse polystyrene:
Keep expanded polystyrene for use later:
Hold onto some EPS boxes or packaging. They will be helpful if you need to move and have to pack your fragile items such as cutlery for the journey.
Use EPS boxes as planters:
While it is not a good idea to grow big plants in an expanded polystyrene box, it won’t be able to take the weight of the soil if you ever need to move the thing; you can use such boxes to grow smaller plants such as herbs or as seedling planters.
Use foam polystyrene as filler in planters:
You can break expanded polystyrene down into chunks and add this to the bottom of your planters, then add soil on top. This will improve the water drainage while keeping your planter lightweight.
Expanded polystyrene as a substitute for perlite:
Perlite is a naturally occurring mineral added to soil to improve its aeration and drainage. You can substitute perlite for sheet polystyrene. Take polystyrene, and cut it into small pieces using scissors.
Then add the pieces to the blender and add lots of water. The polystyrene pieces should float near the surface. Blend properly. Drain the water, and you have a perlite substitute.
Energy from Waste
Polystyrene has a high calorific value, which means it produces a good amount of energy to its weight if it is burnt. This makes polystyrene an excellent choice to be used in energy from waste programs, where organic waste such as plastics is either burnt to generate electricity or used to produce fuel.
Producing energy by burning waste like expanded polystyrene is not completely clean. Delicate particulate matter, heavy metals, and acids are produced in trace amounts, and fly ash can be toxic and hard to control.
But considering the poor state of polystyrene recycling in most areas, it is still a better method of disposal when compared to dumping in a landfill.
Polystyrene can also be converted to fuel for cars and other machines through pyrolysis. In this, the plastic is exposed to very high temperatures in an inert atmosphere to change the material’s molecular structure. Once the desired change is achieved, it can be mixed with gas or fuel.
Banning Polystyrene
Considering the recycling problems, many countries and states are opting to phase out foam polystyrene. This includes complete or partial bans on the production and use of foam polystyrene and necessary legislative measures.
Countries like Australia, Belgium, and India have enacted bans on foam polystyrene. You can check out the complete list of nations banning foam polystyrene here.
In the United States, the following states have banned the use of polystyrene containers:
- Colorado (effective from January 2024)
- Maine
- Maryland (effective from July 2022)
- New York
- New Jersey (effective from May 2022)
- Vermont
- Virginia (effective from July 2023 for large businesses and July 2025 for small businesses)
- Washington (effective from June 2024)
- Washington, D.C.
Conclusion
Most recyclers do not accept foam polystyrene due to the costs of compacting and transporting it. You can look around for recyclers that accept expanded polystyrene.
Or you can reuse your polystyrene waste and reduce the amount of polystyrene you use by using disposable paper cutlery, among other things.
References
https://journals.asm.org/doi/pdf/10.1128/AEM.01361-20
https://www.science.org/doi/10.1126/sciadv.1700782
https://pubs.acs.org/doi/10.1021/acs.est.5b02663
https://www.sciencedirect.com/topics/chemical-engineering/polystyrene
