Under the outbreak, stay indoors. Preparing food at home for a period of time has become a matter that many urban residents must consider. The basic sense of security comes from foods with a long shelf life, such as canned foods, sausages, mustard tuber, instant noodles, and boxed milk. The reason why they can be stored longer depends on the proper food packaging. In fact, even the meat, eggs, vegetables and fruits bought by group purchase have been packaged before they can enter every household through the turbulence of logistics.

It can be imagined that most of the daily garbage generated by many residents in Shanghai today is precisely this type of food packaging. Because they are contaminated with food fats or multi-layer complexes are difficult to decompose, they may be classified into dry waste and enter the incineration system after consumption.

In fact, food packaging plays a huge role in our lives, whether we are in an epidemic or not. Thanks to the technological development of the food industry, we have more ways to keep food. When the food is taken by us, the food packaging completes its mission and becomes garbage that needs to be discarded. Perhaps, while sitting at home enjoying their success, we should also seriously consider how we can better be responsible for them.

The Finnish National Technology Research Centre (VTT) has published a report entitled "Food Packaging Recycling: Status and Prospects (Recycling Food Packaging)", which provides an overview of the current state of recycling in Europe and the United States, as well as the social and technical factors affecting recycling rates. The report also introduces recent innovations in food packaging recycling technology and highlights those solutions that are expected to be commercialized in the next five years.

The research report was commissioned by the global sustainable packaging solutions provider Huhtamaki Pule Group to establish a food packaging recycling system to provide reference for the cooperation of stakeholders from industry, society and government. Huhtamaki Pule Group believes that it is not enough to produce recyclable products; they need to be recycled. With a century of history and Nordic heritage, Huhtamaki Pule Group plans to achieve carbon-neutral production by 2030 and design 100 percent of its products to be recyclable, degradable or reusable.

Today is World Earth Day on April 22. The last part of the report released by the surging city hall and Huhtamaki Pule Group is to introduce the mature and exploring plastic recycling paths, including physical recycling, chemical recycling and PET recycling, and to summarize and discuss the main obstacles and market prospects for expanding the scale of packaging recycling.

plastic packaging recycling

Europe generates nearly 30 million tons of plastic waste every year, and the amount is increasing. Food packaging accounts for nearly 60% of this plastic waste (Kerman and Sundqvist-Andberg,2021). When collected separately, used packaging is recycled through physical heat treatment for the production of plastic pellets (physical recycling), or through the breakdown of polymer structures into chemicals or monomers/oligomers (chemical recycling), physical recycling processes have matured globally, while chemical recycling is only now beginning to be fully commercialized.

Physical recovery

Plastic physical recycling refers to the processing of waste plastic products into secondary raw materials without significantly changing the chemical structure of the material (grinding, washing, separation, melting, compounding and granulation). At present, it is the main method of recycling plastic waste in Europe. For polypropylene (PP), polyethylene (PE) or polyethylene, terephthalate (PET), etc., it is a mature plastic material recycling technology.

In order to ensure the quality of recycled materials, physical recovery needs to be finely classified into single-class polymers. As a result, multilayer and composite packages are generally not accepted by existing recycling systems.

Physical Recycling of Multilayer Composites

APK's Newcycling technology is one of the few commercial-scale physical recycling processes for multi-layer plastics, a solvent-based recycling process. It can selectively dissolve the desired polymer in the composite material, and then extract the desired polymer type from the multilayer composite material and other mixed plastics, obtain LDPE that can be reused for packaging, and remove odors and impurities.

APK has a commercially operated recycling facility in Germany, specializing in the production of plastic pellets, with an annual capacity of 8000 tons. APK also plans to expand a production facility with an annual capacity of about 20000 tons in 2022-2023. Another rising star is Repetco in Spain, which has developed a process using pressurized steam stratification for the recovery of PE-PET composite materials. The company is building a plant in Albacete, Spain, planned to be operational by the end of 2022, with an expected annual capacity of 45000 tons of rPET.

Chemical (Advanced) Recovery

Chemical recycling (also known as advanced recycling in the United States) aims to convert plastic waste into chemical raw materials. It is a chemical or thermochemical process (such as pyrolysis) in which the chemical structure of a polymer is changed and converted into chemical building blocks, including monomers, oligomers and higher hydrocarbons, which are used as raw materials for the manufacture of new products, rather than for the production of fuel or energy. Chemical recovery processes are not as mature as physical recovery processes, but industry cooperation and investment are taking shape. According to a 2019 report, there are more than 40 chemical recycling plants in commercial operation (Closed Loop 2019).

The term "chemical recovery" means the breaking down of plastic waste into fuel or new plastic components via various techniques, I .e. via some combination of heat, pressure, oxygen consumption, catalysts and/or solvents. Pyrolysis and gasification, for example, use heat to break down the plastic and sequester oxygen to prevent combustion. Other techniques are solvent-based, such as solvolysis.

In Europe, a number of chemical recycling plants have been up and running as pilot or small commercial plants, and the production of recycled materials has also received REACH approval. Chemical recycling technology around plastic waste is advancing by leaps and bounds, and significant progress will be made in the next five years. It is mainly based on pyrolysis technology, I .e. the material is gasified under oxygen-free ambient thermal conditions. This technology can break down biological waste and plastic waste into valuable basic chemical materials that can be used to make new products.

Chemical Recycling Plant

Plastic Energy is one of the leading providers of chemical plastics recycling technology. It operates two demonstration plants in Spain, each with an annual capacity of 5000 tons. Its pyrolysis can produce 80-85% TACoil, 15% synthesis gas and a small amount of carbon, which can be used as industrial raw materials. Plastic Energy has partnered with a number of (petro) chemical companies in joint ventures or as contracted users, such as Saudi Basic Industries, Exxon and Total. In France, Spain, the Netherlands and the United States (Texas), there are at least six plants under construction or in the planning stage, which can process a total of 15,000-33,000 tons of plastic waste per year. The expected implementation time is 2022-2024. TACOIL recovered oil is REACH certified for chemicals and complies with the EU Food Contact Materials Regulation. It has been used for Unilever's Magnum and Knorr brands.

Brightmark is nearing completion of a 100000-ton-a-year pyrolysis plant in Indiana and building another in South Korea. The downstream customers are BP and SK Global Chemical. BlueAlp and Pryme's chemical recycling Dutch plants are scheduled to start production in 2023 and 2022, with an annual production capacity of 30000 tons and 60000 tons (Mapleston 2021a), respectively, and the customer is Shell Oil.

water-based technology

In addition to pyrolysis, water-based recycling technologies are also evolving. The principle is that at lower temperatures, no solvent is used to complete the recovery to reduce the ecological footprint. UK-based Mura and Dow Chemical will complete the first of its four HydroPRS Cat-HTR production lines in Germany by 2022, with an annual output of 20000 tons. Mura, in partnership with Mitsubishi, expects to build a similar-sized plant in 2023. The technology uses supercritical water, heat and pressure to convert waste plastics into valuable chemical raw materials and base oils, and provides hydrogen by decomposing long-chain hydrocarbons to produce short-chain, stable hydrocarbon products for the chemical industry.

Aduro Clean Technologies is a Canadian company that holds patents on water-based technology to chemically recycle plastics and convert heavy crude and renewable oils into higher-value fuels and other recycled chemicals. In cooperation with Brightlands, Aduro will build a demonstration plant in Limburg, the Netherlands, which will use Aduro Hydrochemolytic technology (HTC) to demonstrate the process of converting polyethylene (PE) waste into chemical raw materials at a scale of one ton per day. The reported advantages of HCT over more traditional refining technologies, such as pyrolysis and gasification, are favored (Canadian Plastics 2021) due to its lower operating temperature (240-390°C) and reliance on hydrogen production.

catalytic pyrolysis

Anellotech's Plas-TCat technology uses a one-step reaction thermal catalytic process to directly convert disposable plastic waste into basic chemicals, such as benzene, toluene, xylene (BTX), ethylene and propylene, and used in plastic production. The company and R Plus Japan Ltd. In cooperation with Japan's plastic waste recycling organization, this recycling technology is expected to be commercialized in 2027. Since no catalyst is used, it may not be necessary to use a steam cracker to upgrade the pyrolysis product to obtain the desired composition. The same applies to the non-catalytic pyrolysis of (mixed) plastic waste. Non-catalytic pyrolysis usually produces a large proportion of wax, limiting its direct use in the subsequent (petrochemical) chemical industry and increasing the environmental footprint of the overall regeneration process.

Recycling of PET

Currently, the majority of food grade recycled polymers are polyethylene terephthalate (PET).

PET has been commercialized for physical recycling by washing and re-melting, and can also be chemically broken down into its constituent materials for the manufacture of new PET resins.

After sorting, the recycled PET is ground into chips. The purity of the chips is essential to guarantee the value of recycled plastics. Further separation techniques include water washing and air separation, as well as density-based flotation in water, I .e. separation of impurities according to material sinking or floating.

After grinding, washing and separation, the material is thoroughly rinsed to remove residual impurities or cleaning agents. Drying is also required before further processing (usually melting and extrusion).

Melt filtration can further purify the material by removing residual non-melt contaminants from prior sorting. The extruded material is passed through a series of screens to form particles, while the unmelted particles are blocked out of the screens. The granular plastic is uniform in size and can be reintroduced into the manufacturing process (LeBlanc 2020).

As an alternative to physical recovery, depolymerization technology has been developed, although food-grade processing has been established and processing efficiency has been improved, but it is still under development. The Swiss company Gr3n is developing microwave technology to depolymerize PET. The goal is to build a demonstration plant with an annual capacity of 30000 tons by the end of 2024 (Mapleston 2021b). Ioniqa has a production plant in the Netherlands that extracts monomer materials from PET bottles, with an annual capacity of 10000 tons. In this process, PET is a depolymerization process that uses a solvent (glycolysis) and a reusable ionic ferromagnetic catalyst (Vilaplana et al., 2014). In addition, the process of the Canadian Loop Industries uses a solvent and a catalyst for depolymerization (Essaddam 2017). The company is working with SK Global Chemicals to expand its scale and build a factory in Ulsan, South Korea, which is planned to be put into operation in 2022 and is expected to produce 70000 tons/year. Loop is also partnering with Zurich with the goal of establishing a manufacturing facility in Europe, which is expected to be operational by 2023 (Mapleston 2021b).

French Carbios are expanding the application scale of special enzyme depolymerization PET process. At present, it is in the demonstration stage (single cycle can be 2 tons), and the goal is to build a 40000 ton/year plant by 2025.

The industrial applications of PET are numerous, and many packaging and textile brands have pledged to increase the proportion of recycled PET in their products. Coca-Cola plans to use 50% recycled PET in its beverage containers by 2030. Companies are increasingly recognizing the urgency of recycling PET into food-grade products. The supply of recycled PET raw materials is becoming a challenge, and the quality of PET waste raw materials from recycling plants is generally low. Meanwhile, U.S. recycling rates have been flat or declining in recent years.

There are indications that there are multifaceted challenges to scaling up packaging recycling, which are getting more and more attention, and we are committed to overcoming them. New directives, new regulations and multinational companies have made commitments on recyclable packaging and the use of recycled materials and sustainable design. On the one hand, they have established an industry cooperation platform for recycling and recycling, and on the other hand, they have created potential downstream user groups for recycled materials.

However, the main obstacle to expanding the scale of packaging recycling is not only the recycling capacity, but also the collection and sorting infrastructure. In many countries, such infrastructure is still inadequate.

In addition, when the infrastructure to collect waste is in place, the system will only be effective if consumers are actively involved and have a basic understanding of environmental awareness and relevant information. A prerequisite for recycling is the separate sorting of the waste generated; here, the system relies heavily on the motivation of consumers and businesses to sort the waste. Despite the willingness, the proportion of consumers who actually sort recyclable waste is low, and the sorted recyclables usually contain a large amount of non-recyclable impurities (CITEO 2021,HSY 2019).

The actual recycling process, pre-classification is essential. Most recycling processes generate a certain proportion of waste, I .e. the collected unsuitable or heavily contaminated parts, such as halogen-containing parts, which are transferred to the recycling and reduce the value of further use. In the physical recycling of waste, this proportion can be as high as 30% of the total raw material. The waste can be recycled through chemical recovery and further recycling. Chemical recycling can be used for the regeneration of more different types of raw materials. However, chemical recycling is not a panacea, and waste still needs to be pre-screened in order to produce recycled products that meet industrial (re) use quality standards. Both the recovery process itself and the downstream processes (distillation, halogen removal, etc.) generate a certain amount of waste. Therefore, with today's existing technology, packaging recycling theoretically cannot even achieve complete recycling. Comparing the volume of packaging placed on the market with recycled products, it is clear that the actual average recovery rate is much lower than the officially reported level. In the EU, the current country-level reporting will shift from focusing on the amount of packaging produced and the waste collected, to eliminating the proportion of collections that do not meet the conditions for disposal. Increasing the actual recycling rate is a challenge for the EU as a whole.

At the same time, recyclable design is also on the agenda of packaging manufacturers, and industry participants have accelerated the development of high-potential recycling technologies. At the packaging level, the goal is to design the package so that it has (IK 2021):

Can be collected by consumers-this means that it can be clearly identified by consumers as plastic packaging;

Can be identified by the recycling plant-this means that it can eventually be sorted to the corresponding recyclable part;

It can be recycled through state-of-the-art recycling technology-so recycled materials can be produced according to market demand.

The key to improving the recycling process, especially in relation to mixed plastic waste, is the sorting technology of the future. For example, digital watermarking, visual identification or optical tracking agents. The recycling technology requires a certain amount of input to produce recycled materials that meet quality standards. This results in the generation of residuals, which cannot be further processed by existing techniques. In the future, with the increase in recycling, it is expected that the effective hierarchical linkage of different technology deployment will be feasible in terms of economy and technology.

Currently, only a small portion of recycled materials are approved for food contact, mainly recycled PET, excluding paper and cardboard, but recycled fibers are used to make other packaging, soft tissue, etc.

With the current rapid development of chemical recycling and the construction of new facilities, it is expected that Europe will reach a comprehensive production capacity of more than 200000 tons/year in the next 2-3 years, which is more than twice that of the United States, which will strongly stimulate the recycled food-grade plastics market. Chemical recycling plants will also be able to process multi-layered materials, as physical recycling methods on a large scale will do little for multi-layered materials. Chemical recycling is new globally, and there is still a long way to go for this technology and the infrastructure to provide raw materials for waste. In fact, current technology suppliers and investors, often in cooperation with raw material suppliers (waste management organizations), ensure the safety of raw materials in their facilities.

Chemical recovery is a more complex process that usually requires a larger investment and higher energy than physical recovery. Chemical recycling may not be the main route for plastic recycling in the future, but it can make a significant contribution to the recovery of waste plastics, especially for parts that do not meet physical recycling requirements.

To ensure the sustainability of recycled materials, ISCC plus certification is widely used in the packaging industry. It guarantees the accuracy and complete traceability of the materials used in the packaging through a mass balance method, and confirms that the processed materials actually come from sustainable (recycled or renewable) sources.

Overall, today's recycling industry is vibrant. With the shift to sustainable practices and the application of automation, the development of high-potential recycling technologies in the waste industry is also accelerating. Its technical, economic and sustainable viability will increase and drive participants across the value chain to adopt more sustainable initiatives in their business models.