I recently had the occasion to read a Phys.org article on closed loop plastic recycling via a process developed by the Department of Energy’s Oak Ridge National Laboratory. While I found the article fascinating in every respect, I also found myself wondering why research projects of this type rarely get beyond the laboratory. I hit upon the answer when I compared chemical plastic recycling with its mechanical counterpart.
It is true that Oak Ridge researchers have come up with a novel process that can chemically reduce mixed plastics to pristine monomers. But the process is complicated, expensive, highly technical, and energy intense. It is likely that researchers will never be able to scale it up to make it economically viable. Meanwhile, mechanical recycling continues to work. Its success lies in its simplicity.
The Basic Process
Seraphim Plastics is a Tennessee company that acquires and recycles industrial plastic scrap in multiple states. As a commercial plastics recycler, Seraphim converts waste companies would otherwise throw away into a material that manufacturers can use to make new parts. Their basic process is pretty simple:
- Seraphim picks up a load of plastic from a customer.
- The load is transported back to their processing facility.
- The plastic is reduced to pellets by a series of grinders and magnets.
- The pellets are packaged and sold to manufacturers as regrind.
Although Seraphim has to maintain tight controls to ensure that its regrind meets manufacturer standards, the principle on which they practice mechanical recycling is as simple as it gets. There is nothing complicated about their approach. Implementation can get complicated, but the company has procedures in place for maintaining streamlined operations.
Only Sorted Plastics
A key component in mechanical recycling is plastic sorting. Having to sort mixed plastics adds time and costs money. Incidentally, the extra time and money contributes to consumer recycling programs being unprofitable. As for companies like Seraphim, they require their customers to do the sorting. Seraphim pays for plastic scrap, so customers still benefit from handling sorting themselves.
Customer sorting relieves Seraphim from the responsibility to do so on their end. When they pick up a load of plastic purge from a manufacturer, plastic purge is all they are getting. It can go from customer to truck to grinders without any intermediate action.
Only Clean Plastics
Contamination is also a concern in plastics recycling. Even the slightest bit of contamination can ruin an entire load. But again, mechanical recyclers who specialize in commercial plastics head that problem off at the pass. They require sellers to clean their plastics in addition to sorting them.
Fortunately, certain types of commercial plastics do not need a whole lot of cleaning. Plastic pallets immediately come to mind. Likewise for plastic cutoffs and purge. But when materials do need cleaning, customers take care of them before pickup.
If you think about it, sorting and cleaning plastics prior to pick up amounts to preparation. Sorting and cleaning impact the recycling process, but they are separate from the process itself. Therein lies the simplicity mechanical recycling is known for.
It Works Well
Mechanical recycling works well in commercial and industrial environments because the need for recyclers to clean and sort plastics is eliminated. Waste generators – the same companies that sell their plastic waste to recyclers – handle sorting and cleaning on their end. That allows a recycler to pick up plastic waste, transport it to a processing facility, and immediately grind it into pellets.
Mechanical recycling’s success ultimately lies in its simplicity. If everyone involved does what is expected, plastic gets recycled cheaply and efficiently. Companies like Seraphim prove it every day.