Chemical recycling of plastics | Health Care Without Harm

Health Care Without Harm and its partners are advocating for a strong global convention to tackle the global plastics pollution crisis and for the health care sector to be included in the Global Plastics Treaty, along with other sectors like construction, agriculture, and fisheries.

Summary statement

“Advanced”, “chemical”, or “molecular” recycling of health care plastic waste should be avoided until these technologies are fully understood and have been demonstrated to be safe, effective, and sustainable. All forms of incineration and waste-to-energy technologies should be avoided unless dictated by law.

Plastics and the health care sector

One of the health care sector’s most pressing environmental challenges is finding more sustainable disposal routes for the increasing levels of plastic waste it produces. At the current rate of production, it is impossible to recycle all plastic.

Recycling rates for health care plastics are very low, due to factors including:

Legal restrictions: Recycling waste from health care facilities may be regarded as unsafe, or recyclers may not have the knowledge or interest to take on this special waste stream. Poor waste segregation practices, e.g., for infectious vs. non-infectious wastes, exacerbate this situation.
Economic barriers: The low cost of virgin materials and the comparatively complex process of collecting, sorting, and recycling plastic products mean that it is almost always cheaper to produce plastic from virgin materials than from recycled ones.

Higher-income countries often ship plastic waste to lower-income countries for recycling, even though many of these countries lack the infrastructure to deal with it safely. The waste is often sent to landfills or is incinerated, harming local communities and ecosystems.

Many health care institutions are taking steps to reduce the quantity of waste they produce, particularly from single-use items. Despite this progress, however, plastic waste from health care will continue to pose a disposal challenge in the short- to medium-term.

How much plastic is recycled?
Estimates show that less than 9% of all the plastic produced before 2015 has been recycled, and less than 1% has been recycled more than once.
According to industry sources, recycling rates greatly vary among countries:
India: 60%
South Korea: 45%
Europe: 14%
United States: from 8.7% (2018) to less than 6% (2021)

Plastic waste processing technologies

According to the waste hierarchy, the first priority in any approach to environmentally sound waste management should be prevention. In relation to plastics, that means reducing the amount of plastics used and phasing out those with the most toxic constituents, including additives, especially polyvinyl chloride (PVC), polycarbonates, and polystyrene. Furthermore, recycling should always be preferred over recovery and disposal; however, advice can be confusing and even contradictory.

Image: The waste hierarchy, as illustrated by the European Commission

Plastic recycling can take many forms, each with its own limitations and drawbacks. Most recycled plastics are downcycled into products of lower value than the original products. In addition, recycling is only possible where the infrastructure, transportation, and feedstock sources are organized and available.

Regardless of the method, recycling material always results in:

Material degradation,
energy and water consumption, and
waste generation.

Recovery is less environmentally acceptable than recycling. According to the European Union, recovery refers to any operation the principal result of which is waste serving a useful purpose by replacing other materials which would otherwise have been used to fulfil a particular function, or waste being prepared to fulfil that function in the plant or in the wider economy.

Most standards on waste-to-energy recovery relate to municipal waste and are costly to build and operate because of the infrastructure required to capture energy and send it into the power grid. This means that waste-to-energy plants require large volumes of waste and sometimes burn healthcare waste as well as municipal waste.

In the United States, a waste-to-energy plant can cost 100-300 million USD, contributes to less than 1% of energy generation, and has been assessed as both the most expensive and the most polluting method of generating power.

Plastic recycling technologies can be grouped into two categories: mechanical, where plastics undergo physical processing (grinding, washing, melting), and chemical, where they are broken down to their constituents.

Mechanical recycling

Mechanical recycling is conventional recycling: sorting, washing, and grinding plastic materials to produce pellets that can be used in new products. It is the most sustainable type of recycling as it preserves the original polymer, and can have a far lower carbon and water footprint than creating virgin plastics.

In principle, most types of plastics can be mechanically recycled while preserving quality. Mechanical recycling has the potential to keep materials in circulation to prevent the extraction of more natural resources, although, in reality, loss of quality and accumulation of contaminants mean that most plastics are only recycled once or twice. Mechanical recycling can also release microplastics and does not handle mixed plastic waste well, and is mostly available for two polymers: polyethylene terephthalate (PET) and high-density polyethylene (HDPE).

Chemical recycling

Chemical, advanced, or molecular recycling refers to a number of processes that break down plastic waste using heat, pressure, or chemical solvents and turn it into smaller molecules, which are later used as fuel or raw material for new plastic products, chemicals, and nano-carbon materials. While this may usually result in a one-time gain from plastic, the original material is ultimately lost from the economy, meaning that new virgin materials are needed to produce more products.

Chemical recycling has not been proved capable of dealing with post-consumer or mixed plastics, and its outputs are generally of low quality and contaminated with toxic substances. Most chemical recycling technologies are at the experimental or pilot stage, and only a minority of them create plastic. One optimistic projection is that plastic-to-plastic chemical recycling could tackle 6% of plastic waste by 2040.

There is still a lack of transparency on the environmental and health impacts of chemical recycling technologies. Therefore, a precautionary approach should be adopted unless a recycler provides details about their process, products, and use, and how emissions are controlled.

Since UNEP, EU, ISO, and other institutions exclude “use as fuel” from the definition of recycling, any process that generates fuel should not be considered recycling, but recovery.

Pyrolysis

Pyrolysis is the most established chemical recycling technology. It refers to the process of converting plastics into solid, liquid, or gaseous fuels through thermal degradation, without oxygen, at temperatures from 300 to 900°C. This breaks down long-chain polymers into less complex molecules, including high calorific gas, carbonized char, and pyrolysis oils.

The global pyrolysis oil market is supplied by the processing of plastics, rubber (eg, tyres), and biomass, and around 85% of the output is destined for fuel use. Pyrolysis oil is a low-quality product, contaminated with elements such as chlorine, bromine, nitrogen, oxygen, metals, dioxins, furans, polycyclic aromatic hydrocarbons (PAHs), and other organic chemicals formed during the pyrolysis process.

Pyrolysis is associated with significant environmental problems. Depending on the composition of the input materials, and facility design and operation, pyrolysis often generates toxic by-products such as dioxins, polycyclic aromatic hydrocarbons, and hydrogen chloride.

According to a 2022 report from the Natural Resources Defense Council, a single chemical recycling facility produced half a million pounds of hazardous waste in one year, including benzene, lead, cadmium, and chromium, which were ultimately incinerated.

Gasification

Gasification is a form of pyrolysis in which the main output is gas rather than oil. The main use of the gas is as fuel. In some research, it is directly compared to incineration, except that gasification is carried out in two stages: first, converting the waste into a gas, and second, burning it.

Chemolysis and solvolysis

In plastic recycling, solvolysis means treating the plastic with a solvent to break the polymer down into its molecules (monomers) or into shorter chains of a few monomers (oligomers). Solvents used for this process can include alcohols, water, acids, or bases, often in the presence of a catalyst. The process is most effective on plastics that contain nitrogen or oxygen in their structure, such as polyesters, polyamides, and polyurethanes.

Solvents can also be used to break or extract longer polymer strands from plastics, but this results in a mixture of additives that need to be treated and disposed of. Post-consumer plastics are almost always a mix of products with different additives, and the residual mixture can be complex and unpredictable.

“Advanced”, “chemical”, or “molecular” recycling of health care plastic waste should be avoided until these technologies are fully understood and have been demonstrated to be safe, effective, and sustainable.

Plastic recovered from waste can be repurposed, for example, as a replacement for some of the bitumen used in road construction or used as input to generate energy (waste-to-energy). However, this is inefficient, as it wastes all the energy used in creating the original product. High temperature processing or burning of plastics inevitably leads to pollution in the form of incomplete combustion products (PICs). Among the most well-known PICs are the dioxins and furans, which include some of the most toxic and persistent chemicals known to science.

Waste-to-energy can either be:

waste burned in an incinerator (waste-to-energy incineration) equipped with heat exchangers to capture the heat of combustion and use it to generate electricity; or
waste processed into a solid or liquid fuel (refuse-derived fuel), which is then sold to cement factories or other facilities that use it instead of conventional fossil fuels.

Waste-to-energy incineration

According to the waste hierarchy, incineration and landfilling are the last resort options for plastic waste and should be considered only if no other options are available. They inevitably produce toxic products of incomplete combustion, including dioxins and furans. These have many health impacts, including cancer and immune and endocrine system disruption, among others. Other emissions include hazardous volatile organic compounds, particulates, and greenhouse gases.

Dioxins are among the most persistent organic pollutants known, can be transported globally, and remain undegraded for thousands of years. The USEPA conducted a comprehensive assessment on dioxins and furans in the 1990s and concluded that municipal and medical waste incinerators were the largest sources of dioxins and furans to the atmosphere. They estimated that emissions from these sources were reduced by 75% between 1987 and 1995, a period when many incinerators were closed down.

Refuse-derived fuel

There are no specifications for solid refuse-derived fuel (RDF), which can contain a mixture of plastics and other materials. Burning this material can have an unpredictable impact on the emissions to the environment. Campaigners report that refuse-derived fuel is being used as a mechanism to circumvent international law preventing waste imports.

The moment is now: Action points for a sustainable health care plastics recycling program

The Organisation for Economic Co-operation and Development (OECD) estimates that, even if recycling rates doubled, recycled plastics would only make up 12% of plastic products by 2060. And, according to Plastics Europe, less than half the plastics collected for recycling are in fact used in new plastic products. Reducing consumption and switching to reuse systems are the most impactful actions that health systems and organizations around the world can take.

Health Care Without Harm drafted these action points for health care organizations working on plastic waste recycling:

Strategic planning: Set goals to phase out non-essential plastics.
Procurement contracts: Purchased products should be reviewed for not only clinical effectiveness and safety but also recyclability, reuse, and packaging reduction. Extended producer responsibility should be included in procurement contracts to encourage suppliers to either take back materials or help create recycling programs for the materials they produce.
Baselining and audits: Accurate baselining of waste streams can help reduce waste and increase recycling. Reports should include data on recyclable plastics and, if possible, require waste management service providers to deliver accurate weight data for waste recycled and other waste streams to track the quantity and percentage of waste recycled.
Capacity building: Educate staff on the importance of waste reduction, recycling, and correct segregation procedures, including refresher training at least annually. Consider incentives for complying with recycling projects.
Contractor and process selection: Work with trusted national recyclers or waste management companies that can advise on what is recyclable and demonstrate that it is being processed safely. Do not recycle plastics, including PVC, which contain toxic additives. Prioritize mechanical recycling and avoid processes that include pyrolysis, incineration, refuse-derived fuel, and energy generation.
Waste management and recycling contracts: Waste management and recycling service contracts should include requirements for accurate data reporting, clear waste acceptance policies, and certificates of recycling or destruction. Waste management service providers would outline the end-of-life process for each waste stream and document the recycling process and the markets the recycled material is entering.

The road ahead

The whole life cycle should be further detoxified by phasing out products and processes that use or produce the most hazardous groups of chemicals. Products should be designed for reuse to reduce the carbon footprint, maximize the value obtained from the resources used in their production, and minimize the amount of waste generated.

Chemical recycling of plastics: Overview and general assessment