Most of us are familiar with the concept of recycling thanks to curbside programs that have us tossing paper and plastic into a small bin for weekly collection. Yet for many of us, our knowledge of plastic recycling doesn’t go any further. It is an ‘out of sight, out of mind’ kind of thing. That is unfortunate. If more people knew the truth behind recycling, the world would probably not continue doing what it does.
There are three processes through which most plastics can be recycled: mechanical, combustion, and chemical. Mechanical recycling is the most common by far. Combustion and chemical recycling work, but they are cost prohibitive in most cases. Perhaps that’s why recycling proponents are calling for more research into the two processes.
1. Mechanical Recycling
Mechanical recycling is what most of us think of in terms of recycling plastic water bottles and kitchen food containers. It is the primary means of recycling industrial plastics as well. According to Seraphim Plastics, a Tennessee company that recycles industrial plastics from five states, mechanical recycling is a fairly straightforward process.
Plastic waste is collected and shipped to a processing center. In the case of industrial waste, recyclers are working with clean material that doesn’t require separation or washing. Once collected, it is reduced through grinding and shredding. The resulting material is sold to manufacturers who mix it with virgin plastic to make new products.
The key to making mechanical recycling work is eliminating the need to sort, wash, and otherwise process plastic waste. The more complicated the processes, the more time-consuming and costly they become. This explains why the vast majority of all consumer plastics are not recycled whereas a lot of industrial plastics are.
2. Combustion Recycling
Mechanical recycling is limited in the sense that recycled materials are not as structurally sound as virgin plastic. This inherent limitation means that plastics can only be recycled so many times via mechanical means. Enter combustion recycling.
Certain types of plastics can be burned in order to harvest waxes and fuels. Burning breaks the bond between molecules with heat. Unfortunately, the amount of energy expended on combustion recycling isn’t always justified by the waxes and fuels harvested. As such, burning plastics is often a strategy to keep them out of landfills rather than a way to recycle.
3. Chemical Recycling
Last but not least is chemical recycling. This form of recycling relies on chemical catalysts to break the bonds between plastic monomers. When done successfully, the monomers can be recovered and used elsewhere. The key is finding the right catalyst for each type of plastic.
Like combustion recycling, chemical recycling is quite expensive. Recyclers can choose both open and closed loop recycling processes, both of which are capable of harvesting monomers. Yet without a profitable market for those monomers, chemical recycling can be difficult to justify financially.
Finding Ways to Make It Work
It is entirely possible to recycle just about every plastic product. The top three recycling processes can account for just about any plastic we make. The reason we do not recycle more boils down to a single word: cost. Right now, it’s just cheaper to make virgin plastic for most practical applications.
The one exception is clean industrial plastic that can be recycled through mechanical means. Manufacturers save money by supplementing virgin raw material with recycled regrind. As for materials produced through combustion and chemical recycling, finding ways to make them work is the main goal. We could recycle a whole lot more plastic if we could figure out a way to do it efficiently and cost-effectively.