Recycling medical waste, a feasible option?

The incineration of single-use plastic consumables and devices in laboratories after just one use leads to the waste of high-quality plastic materials, and hence to the waste of valuable resources. It was an observation that led the Clinical Microbiology laboratory at Odense University Hospital (OUH) in the Region of Southern Denmark, to attempt to find an alternative means of disposal for these products.

To that end, a feasibility study was conceived and conducted with a focus on the extent to which PET material from blood collection tubes used in healthcare settings could be recovered and recycled without compromising hygiene, safety or quality of the material. It was decided to focus on blood collection tubes as these constitute a homogenous source of high-quality PET material. In the Region of Southern Denmark alone, seven million tubes are used and incinerated every year. This adds up to an annual total of some 21 tonnes of PET plastic. In fact, by transitioning from incineration to recycling, it was calculated that 33 tonnes of high-quality plastic would be diverted from incineration in the region each year.

OUH collaborated on the study with partners from across the value chain. These included the Health Innovation Centre of Southern Denmark (SDSI) and BD, a global supplier of numerous single-use plastic devices, who joined the consortium through its Sustainable Medical Technology Institute (SMTI) to address environmental concerns and meet customers' sustainability needs. As Amit Limaye, director of the BD Sustainable Medical Technology Institute, explained: "Single-use plastic revolutionized health care, but we know there are environmental considerations that come with this critical innovation.”

Another participant was the Danish Technological Institute, that contributed expertise in materials recovery and microbiological testing. Lastly, GMAF Circular Medico/EcoFITT, which has a proven track record in producing and recycling medical devices, also became a partner.

Used blood collection tubes are considered biohazardous and regulated medical waste, and in Denmark, are currently incinerated after use. Made from PET, they cannot be cleaned and reused like some other medical devices made of glass or metal, even though PET plastic in itself is not only highly suitable for recycling but is one of the most recycled plastic materials today.

Asked why that was, I was told that, while, due to similar container requirements, both PET bottles and blood test tubes are made from bottle-grade PET, blood test tubes are not used for food contact. Most PET recyclers focus only on food contact packaging such as bottles or trays. Used plastic blood collection tubes contain remnants of blood, which in some cases can also contain carriers of infection and blood collection tubes also often have an internal anticoagulant coating, which is removed during cleaning and decontamination. In an appeal to the recycling community, the study participants hope to be able to find recyclers ‘who might find the PET fraction valuable anyhow,’ said Peter Sommer-Larsen, business manager at the Danish Technological Institute.

Contamination challenges
The researchers conducting the pilot study tested different methods for cleaning, shredding, washing, drying, and recycling the blood test tube PET waste.
The initial cleaning test carried out demonstrated that with the methods used, the microbial load could be lowered, but that microbial levels still remained too high. Heat treatment reduced the microbial load to below the detection limit, although the environmental impact of the process made this an undesirable choice. More research is needed to identify the most effective cleaning methods that can improve the quality of the material, meet hygiene regulations and standards, and reduce the environmental and climate footprint.

Blood collection tubes are typically also extensively labelled – another contamination source. The researchers found that the established industry washing and drying process for removing labels also worked on blood collection tubes – but only on shredded tubes, as when the tubes were left whole, label debris clumped together inside the tubes.

Could dissolvable labels offer a solution? “Dissolvable labels were not specifically considered. However, in a larger study we plan to test different types and adhesions of labels. The partner developing the cleaning and disinfection technology is aware of dissolvable labels but only for products with a different label-to-product weight ratio. Blood collection tubes typically have a standard paper label with an additional local label added on top, making the labels' weight about 20% of the total weight,” said Sommer-Larsen.

On the plus side, he did say that the caps used on the tubes were not an issue, even though made from a different material, as the automated analysis procedures in clinical biochemistry labs make removing and collecting the caps early in the process possible.

“Both caps and sealant are valuable and easy to recycle. However, colour sorting is essential as caps come in various colours indicating their use,” he said.

Shredding and moulding
Different batches of shredded flakes were tested to assess whether the quality of the mouldings varied depending on their source. Dummy parts were moulded from shredded flakes from unlabelled and unwashed freshly produced tubes from BD and compared to flakes derived from decontaminated labelled and used blood collection tubes from OUH and to flakes from labelled and unused blood collection tubes. According to Sommer-Larsen, flakes were used as part of the decision to minimize the number of steps during recycling prior to moulding.

“In the next larger study, we aim to find a recycler who can process the recovered material through the established PET recycling process,” he said. “ We aim to maintain an unbiased perspective on the materials recovery process to determine if local cleaning and decontamination processes at the hospital can save steps in downstream recycling. In the pilot, we chose to work with the minimal number of steps in recycling  o see if moulding was still feasible.” The injection moulding company did notice challenges controlling the hopper feeding with the irregular flakes, he added.

Asked about whether the follow up had already been planned, he revealed only that ‘Efforts are being made to create a national project, and we have a strong interest in collaborating across Europe as well.’

Closing the medical waste loop
Although this pilot only looked at mechanical recycling, other technologies are emerging that could open the door for a broader use of medical waste as feedstock for new products, and even – in the future – closed-loop rcycling.

“The HPRC  - Healthcare Plastics Recycle Council – has published both a ‘Circularity for Healthcare Plastics White Paper’ and its ‘Guiding Principles for Advanced Recycling’, pointing to chemical recycling as the option that could allow closed-loop recycling presently,” explained Sommer-Larsen.  “We aim to explore the value chain for depolymerization of PET as well.”

Other methods, such as enzymatic processes have not yet been looked at. A recent paper by Uerkert et al. in ACS Sustainable Chemistry & Engineering classifies enzymatic hydrolysis at a low technology readiness level, he noted. But: “We will of course maintain an unbiased look at various technologies in the future.”

After all, the use of plastic single-use products is widespread throughout the medical sector, and there are other products besides blood collection tubes that may also offer potential for recovery and recycling.

“Other laboratory consumables, such as pipette tips and petri dishes made from PP and PS are considered low-hanging fruits,” agreed Sommer-Larsen. “A new study aims to provide general insights about recycling plastic products from hazardous waste fractions in healthcare laboratories to enhance circularity and reduce the healthcare sector's climate footprint.”

In short
The present study showed that it is indeed possible for  used blood collection test tubes to be cleaned, shredded and moulded into new products, although further research is required to determine the best method for cleaning and recycling that optimize both the quality of the material and the climate impact of these processes.
“We need to further investigate how the recycling processes can be optimised to reduce impurities and haze, while increasing transparency. This will need to be done with larger quantities to ensure validated results,” said Caroline Strudwick, project manager at the Health Innovation Centre of Southern Denmark. The Health Innovation Centre of Southern Denmark facilitates collaboration and partnerships across the value chain to develop innovative solutions  or green transition of the healthcare sector.

As well, additional clarification is needed on the required transparency levels in the light of those achieved with the recycled material. While were lower than the usual level within the industry, the question is whether the current requirements are truly in accordance with actual needs for optical transparency in clinical workflows.

Moreover, more research is needed into the quality measures for determining the suitability of the recycled material for making medical devices, while ensuring safety and efficacy of the end product. Using the recycled material to make new blood collection tubes was not investigated in this study, emphasised Strudwick.

The collaborative effort was funded by the Region of Southern Denmark and is part of a broader effort to further progress toward Denmark's Climate Action Strategy, which aims to reduce the country's greenhouse gas emissions by 70 percent in 2030 compared to 1990 levels.

This article first appeared in the July/August edition of Sustainable Plastics .