How to reduce plastic waste: innovative process promises recycling of single-use face masks

The COVID-19 pandemic forced the use of disposable face masks. Discarding them has become an environmental challenge on a global scale. This has prompted the Fraunhofer Cluster of Excellence Circular Plastics Economy CCPE and the Fraunhofer Institute for Environmental, Safety and Energy Technology UMSICHT to develop an innovative recycling process for used plastics.

In a conversation with MEDICA-tradefair.com, Dr. Alexander Hofmann, Head of Department Recycling Management at Fraunhofer UMSICHT, talks about the objective of the pilot project and explains how the concept can be advanced to present a sustainable option for the medical sector. After all, even post-pandemic, the healthcare industry will continue to generate tons of waste from single-use disposables.

Dr. Hofmann, Fraunhofer teamed up with SABIC and project initiator Procter & Gamble (P&G) to demonstrate the feasibility of closed-loop recycling of single-use face masks. How does the process work?

Dr. Alexander Hofmann: Procter & Gamble collected used face masks worn by its employees and sent them over to our Institute. We used pyrolysis to convert the masks to oil. That means we thermochemically converted the masks at around 650 degrees Celsius in the absence of oxygen. This process produces -among other things - pyrolysis oil.

The benefit of this process is that the high temperatures will also destroy any biogenic material such as pathogens, residual pollutants, etc.

We subsequently sent the recovered pyrolysis oil to SABIC. The company used it as feedstock for its processes and produced polypropylene, another plastic that is needed to make masks.

Why did pyrolysis become the established method within the scope of the project?

Dr. Hofmann: As I mentioned earlier, the process allows us to neutralize hazardous medical waste. Meanwhile, masks not only feature polypropylene as a material but also contain nose wires or similar objects. Mechanical recycling would not have worked in this case.

The mass and energy balance of the approach is another advantage. The process allows us to track how much oil we ended up recovering from the masks. It amounted to nearly 50 percent, which means 50 percent of the old masks could be converted back into new masks.

Could the single-use mask process be applied to other disposable products?

Dr. Hofman: Yes, it can. We used surgical masks in our endeavor, but you could also use FFP2 (KN95) masks. It can even apply to plastics - especially general plastic packaging. You could also feed in substances that are sorted out during mechanical recycling.

At Fraunhofer UMSICHT, we are enhancing the process to consider composite materials such as electronic waste, rotor blades or hidden plastics that are currently difficult or impossible to recycle.

The project demonstrated the feasibility of closed-loop recycling. Will the process of pyrolysis also take root in recycling beyond the project scope?

Dr. Hofmann: We plan to achieve a technology scale-up. Our Institute has a system that can convert at a rate of 70 kilograms per hour. Our goal is to develop these types of units on a larger scale.

At present, the face masks mostly present a logistical challenge because they are being discarded at multiple locations. This has prompted us to consider medical waste in general. After all, hospitals produce tons of medical waste regardless of the pandemic and this would simplify the logistics problem significantly.

Since the pilot project has proven successful, have hospitals expressed interest and reached out to the Fraunhofer Institute?

Dr. Hofmann: We have already received inquiries and are in talks with several stakeholders in the healthcare system. That’s because material contained in personal protective equipment is presently incinerated for safety reasons, contributing to both soaring CO2 emissions and increasing demand for raw material. Our process not only avoids incineration but also creates a petroleum substitute. It means we could also address existing industrial processes and generate a substitute for petroleum, meaning fossil fuels.