In the ongoing debate over whether plastic recycling is viable, we rarely hear frank discussions about the two methods by which plastic can actually be recycled. Those two methods are mechanical and chemical. Mechanical recycling makes up the lion’s share of all plastic recycling being conducted today. Chemical recycling is possible, but it is not very popular.
The Fundamental Processes
Before getting into the pros and cons of both recycling methods, it is important to define the basic processes. Mechanical recycling is an easier method to explain. According to Seraphim Plastics, a Tennessee company that recycles scrap industrial plastics in seven states, mechanical recycling is about as simple as it gets.
When Seraphim picks up a load of plastic purge, for example, the material is already clean and sorted. They haul it back to their processing plant where it is sent through a series of grinders that reduce the material to small pellets or flakes. The resulting material is known as regrind. It is sold to manufacturers who mix it with virgin plastic pellets to make new products.
Chemical recycling is substantially more complicated. It involves treating plastics with a variety of chemicals that break the material down into its basic components. Those components can then be harvested and either used for other purposes or disposed of. As things currently stand, chemical plastic recycling has yet to be developed for large-scale deployment.
The Pros and Cons
Moving on to the pros and cons of both recycling methods, there really is no clear winner. The positive and negative aspects of both methods end up canceling one another out. Unfortunately, mechanical recycling doesn’t get the love it deserves while chemical recycling isn’t getting the attention it needs.
1. Sorting and Cleaning
Sorting and cleaning is the biggest problem for municipal plastic recycling. It is not a problem at all for industrial recycling. In a mechanical recycling scenario, materials need to be cleaned and sorted before being ground up. You cannot mix multiple types of plastic to create regrind. Furthermore, the plastic absolutely cannot be contaminated.
Sorting and cleaning are not as much of a problem for chemical recycling, within reason. Chemical recycling processes can deal with multiple types of plastic mixed together. It can also deal with a minimal amount of contamination.
2. Energy Consumption
One of the biggest benefits of mechanical recycling is that it uses very little energy compared to the amount of end product it produces. Mechanical grinders can be run very cheaply. Transportation costs can also be managed. On the other hand, chemical recycling consumes a tremendous amount of energy. Transportation costs remain about the same.
3. Single-Use Plastics
Mechanical recycling does not handle single-use plastics very well due to the sorting and cleaning issue. That’s why companies like Seraphim Plastics focus on industrial plastics. They could not make money recycling single-use products. On the other hand, chemical recycling handles single-use plastics very well. Again, cleaning and sorting is not an issue. All sorts of single-use plastics can be combined in a single chemical recycling process.
4. Toxicity
Next to energy consumption, chemical recycling’s biggest downside is the toxicity of both the chemicals and the byproducts recycling produces. Using chemicals to break down petroleum products creates toxic chemicals. There is no way around it. On the other hand, mechanical recycling is non-toxic in every sense of the word.
The differences between mechanical and chemical plastic recycling are significant. But to say that one is better than the other is to misunderstand both processes. Both have a place at the recycling table.
