Here at Seraphim Plastics, we rely on a mechanical recycling process to turn scrap industrial plastic into reusable regrind. Although our process is both simple and effective, we are not able to recycle every type of plastic. There is always some plastic that goes to waste. That may eventually change thanks to a Danish research project that utilizes pyrolysis to reclaim plastic waste.
Pyrolysis is not a new process by any stretch. But the Danish researchers have come up with a way to harness it to reclaim plastics that otherwise cannot be recycled. These are end-of-life and mixed plastics that normally go to landfills or incinerators. The researchers believe they have a workable system with numerous commercial applications. Their goal now is to scale it up before releasing it into the wild.
Mechanical and Chemical Recycling
Fully appreciating what the researchers have accomplished starts with understanding the differences between mechanical and chemical recycling. We practice mechanical recycling here at Seraphim Plastics. All the industrial plastic we recycle gets run through a series of grinders and magnets to reduce it to small pellets. The pellets are packaged as regrind and sold to manufacturers.
Other recyclers who specialize in PET plastic do much the same thing. They run PET scrap through shredders that reduce it to flakes. The flakes are then combined with virgin plastic or melted down and made into fibers or new products.
Meanwhile, chemical recycling is a process of treating plastic waste with a combination of chemicals and heat. Doing so breaks the bonds between molecules so that the plastic can be separated into its base components. Pyrolysis is a chemical recycling process.
The big benefit of chemical recycling is being able to reclaim larger volumes because you are able to recycle more types of plastic by chemically deconstructing it. But there are downsides. Chemical recycling is energy intensive and somewhat polluting. It is also expensive, which is why it’s not utilized so often.
More About the Danish Project
Researchers at two Danish universities have been working with industrial partners to maximize pyrolysis’ potential for recovering plastic waste. Pyrolysis involves treating plastic waste in a high-temperature furnace filled with nitrogen. Because there is no oxygen in the furnace, the plastic waste gasifies rather than burns. Gasses are then condensed in a process remarkably similar to distillation.
The process works well enough that researchers have been able to recover a pyrolysis oil that can be further distilled and purified for a variety of purposes. But here’s the kicker: the plastic waste that feeds their process does not have to be separated. It doesn’t need to be completely free of contamination, either.
Unseparated and Contaminated
The rule of thumb in pyrolysis is that you need to have a clean furnace environment to make it work. That means plastics of different types need to be separated prior to processing. They must also be free from virtually all contamination. However, the Danish researchers discovered that’s not necessarily true. Their process allows for both mixed plastics and at least some contamination.
It’s not clear how much contamination is acceptable. Nonetheless, the researchers have proved they can successfully reclaim unusable plastic waste that would otherwise have been incinerated. Now they only need to scale the process up to make it commercially viable.
We will be keeping an eye on this project as it moves forward. These are the types of things that get us excited and make us appreciate the opportunity we have to be involved in plastic recycling. The more plastic we can keep out of landfills and incinerators, the better.