How the plastic mountain in the healthcare sector could be recycled

Medical disposables - from gloves and blood bags to surgical equipment - generate enormous amounts of waste these days. At best, this waste is incinerated, but in many countries it ends up in landfills and can also end up in the environment. The COVID pandemic has contributed to an avalanche-like increase in the use of disposables. It is estimated that in 2022, used face masks alone will weigh around 2,641 tons per day worldwide - a huge mountain of plastic.

Thermochemical recycling as a solution

Medical waste is often overlooked in the discussion about the circular economy. Disposable medical items are usually made of various plastics that cannot be recycled with current technology. In addition, the items are considered contaminated after use and therefore need to be handled in a way that avoids the risk of spreading potential infections. It is also not possible to use recycled plastic in the manufacture of disposable healthcare items, as the requirements for the purity and quality of materials for medical use are very high.

All of these problems can be solved with the new method developed by Chalmers researchers. The technology is called "thermochemical recycling" and is based on a process called "steam cracking". The waste is broken down by mixing it with sand at temperatures of up to 800 degrees Celsius. The plastic molecules are then broken down and converted into a gas that contains building blocks for new plastic. "You can compare it to a thermal sledgehammer that smashes the molecules and destroys bacteria and other microorganisms at the same time," says Martin Seemann, Associate Professor at the Chalmers Division of Energy Technology. "What remains are various types of carbon and hydrocarbon compounds. These can then be separated and used in the petrochemical industry to replace fossil fuels currently used in production."

Great potential for saving valuable chemicals

To test the technology in practice, the researchers carried out two different projects in parallel in a test facility at Chalmers Power Central. In the first project, a number of different product types, such as face masks and plastic gloves, were subjected to the process. In the second project, a mixture was created that represented the average composition of hospital waste from the region's hospitals. The mixture contained around ten different plastic materials as well as cellulose.

The results of both projects were consistently positive, which shows the great potential of the technology. One of the projects was led by Judith González-Arias, who now works at the University of Seville in Spain. "What makes this technology so exciting is its ability to tackle the environmental problems we associate with disposable medical products. Thermochemical recycling not only addresses the problem of medical waste not being recycled today, but also enables the recovery of valuable carbon atoms. This is fully in line with the principles of the circular economy and offers a sustainable solution to the urgent problem of medical waste disposal," says Judith González-Arias.

The only option for products with strict requirements

Many manufacturers of materials for the healthcare sector are now very interested in creating a circular model in which products can be recycled and reused in a closed loop. However, materials to be used in sterile healthcare items have strict purity and quality requirements that basically cannot be met with sorting and mechanical recycling of plastics. With thermochemical recycling, however, it would be possible.

"It's really the only way to return this type of waste to the cycle," says Martin Seemann. "It's so elegant that the chemical industry can turn the material back into new material after it has been broken down to the molecular level." And he sees even more potential: "The same strict requirements for purity and quality actually also apply to food packaging. For this reason, most of the plastic collected from packaging is currently incinerated or recycled into items for which a lower quality is permitted."

The two projects build on Chalmers' previous research, which has shown how mixed plastic waste can be converted into raw material for new plastic products of the highest possible quality.

The technology works, but other factors also come into play

In order to spread the method, new material flows and functioning business models need to be developed in cooperation between the health and recycling sectors. Laws and regulations may also need to be changed at various levels in order for thermochemical recycling to become established in society. "Certain policy decisions would increase the value of plastic waste as a raw material for industry and increase the chances of creating viable circular business models around this type of recycling. For example, an obligation to capture carbon dioxide when incinerating plastics would create incentives to invest in more energy-efficient alternative technologies like ours instead," says Martin Seemann.

In many countries, the technical requirements for recycling medical waste and other mixed plastic waste through steam cracking are in place. However, the regulations and structural conditions vary, which determines how the players in waste management, the chemical industry and product manufacturing must work together to create functioning value chains in different parts of the world.

Source: Chalmers University of Technology, Gothenburg, Sweden