Flexible plastic packaging (plastic bags, stretch and shrink film, sterilization wrap, medical device packaging, and so on) represents a significant percentage of the healthcare waste stream, yet is rarely recycled. Due to their lack of standard composition and the potential for mixed resins across different layers, utilizing these materials presents numerous challenges for recyclers. Flexibles are also easily confused visually with other materials, making manual on-site sorting challenging for hospital staff. In hopes of bringing value to an otherwise untapped feedstock, HPRC undertook a pilot project to try and determine if and how flexibles can become a viable resource for recyclers.
Materials were collected from Cleveland Clinic’s Main Campus; Lehigh Valley Health Network’s Cedar Crest, Muhlenberg, and 17th Street Hospitals; and Dartmouth Hitchcock Medical Center. The flexibles were then shipped to EREMA, a manufacturer of plastic recycling equipment, for processing, and then on to the Plastics Engineering Department at the University of Massachusetts Lowell to test whether commercially available compatibilizers improved blend properties when compounded with multi-material flexible plastics.
Building a Pilot Process
The HPRC team recognized that in order to encourage manufacturers to reuse healthcare plastics, we had to combat concerns around the risk of hazardous contamination from hospitals. To accomplish this, we designed a rigorous, facility-specific collection process and put the necessary controls in place to minimize the risk of contamination. This collection process was based on both HPRC’s Hospicycle guidance and site-specific programs for collection for other materials and products.
Following sorting and characterization, the flexibles were sent for mechanical recycling at the EREMA facility composed of eight steps:
Feeder: Materials were removed from their plastic bags and added to a conveyor system. A metal detector helped screen out any metallic films not identified during visual segregation.
Preconditioning unit: The material fed into the machine was cut, mixed, heated, dried, pre-compacted, and buffered.
Extruder screw: The material was plasticized and degassed.
Melt filter: The material being extruded was cleaned and returned to the extruder again.
Melt homogenization: The material went through one final melt homogenization.
Degassing zone: Once the melt had been filtered and homogenized, it was degassed.
Discharge zone: The melt in its final form was conveyed to the end of the machine and to the pelletizer tool being used for output.
Pelletizer: The melt was cooled and pelletized at extremely low pressure.
Following processing, the pelletized material was packaged and shipped to the University of Massachusetts Lowell for analysis and testing. Once there, the recycled pellets were compounded with two different compatibilizers to investigate their effects on performance.
The Results Are In
Our results indicate that a mixed-material stream of flexibles from multiple sources can be processed and pelletized into a resin for use in a secondary application, which could be a game changer for healthcare plastics recycling.
Specifically, based on the testing results, the resin produced from Stream 1, composed mainly of header bags, vent bags, Tyvek, formed package, and tear bags (no blue wrap), demonstrated similar tensile performance to LPDE, and could be a potential candidate for applications that use LPDE resin. The resin from Stream 2, which contained about 60% blue wrap and 40% of Stream 1, demonstrated properties that could make it a replacement for some PP-like resins. We also demonstrated the efficacy of compatibilizers in improving the compatibility of waste streams that include both blue wrap and mixed flexible films.
On the other hand, the pilot uncovered a number of barriers that would need to be resolved in order to properly scale the process. Metallic films were difficult to distinguish in the OR and needed to be removed by hand from the waste streams prior to processing, adding a time-intensive additional step. Additionally, while coordinating waste from the four participating pilot hospitals was manageable, adding the requisite number of additional hospitals to scale the effort would create additional logistical challenges. Lastly, to make the recycling efforts financially viable, a market would need to develop for these new recycled resins, which would require adding a level of homogenization and consistency to the waste stream.
A More Flexible Future
While overcoming these barriers can seem daunting, overall results were promising, and HPRC believes progress is possible through collaboration. Private industry, public entities, and NGOs around the world are working together to drive solutions for mixed flexible recycling. We believe a sustainable solution for flexible plastics recycling is on the horizon, and see this pilot project as an encouraging step forward.