Approaches to Plastic Reuse: Mechanical, Chemical, Thermal

An earlier content explains why plastic recycling is gaining attention and why there is an opportunity to solve this problem in chemical recycling. Before starting the explanation of chemical recycling, the comprehension of recycling technology is helpful for an understanding of chemical recycling. There are three principal approaches to the reuse of plastics such as mechanical recycling, chemical recycling, and Thermal recycling. First of all, A simple explanation for mechanical recycling is basically washing, shredding and melting these materials and then re-extruding them.

That is not really transforming the materials. The recycled product is essentially the same material that comes into this system. That is the most common way to recycle plastic, but there is a problem that the quality of recycled plastic will be reduced.

Therefore, the mechanical recycled plastic has lower quality than virgin plastic and repeated recycling further deteriorates the quality of the product. Downgrading is a term sometimes used for recycling when recovered plastic is put into an application that would not typically use virgin polymer.

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For this reason, we have to use recycled plastic for limited use or mix it with virgin plastic. The second measure is chemical recycling. This refers to processes like purification, decomposition, and conversion which are used to turn plastic polymers back into the initial raw material of plastic. This process can recycle plastic without degradation of quality.

The last recycling measure is Thermal recycling. It is a recycling process of converting waste plastic into heat source using combustion. Like mechanical recycling, thermal recycling is widely used.

In some views, It has been pointed out that it isn’t suitable for the circulation of resources, because that process incinerates plastic waste for getting heat energy. Each technology is selected according to the condition of the collected plastic and the use of recycled products. However, the chemical recycling is considered advanced recycling, because chemical recycling helps us overcome the limits of mechanical recycling.

There are 3 categories of chemical recycling. As stated above, chemical recycling is used to turn plastic polymers back into some stage of plastic’s feedstock using various ways. And each category of chemical recycling is distinguished by how far we're taking the plastic and polymer chain back towards kind of the original state. The first one is the purification, which goes back to the polymer stage. Technically, it isn’t transforming chemical structure but using some sort of additive or solvent in order to decontaminate the material. Those chemicals take either the color or the smells out. And then this purified plastic is similar to a pure substance.

The next technology is decomposition, which goes back to the monomer stage. This technology is essentially breaking the molecular bonds. Since it goes back to the raw material of polymer, it works more like virgin material. And the last one is conversion. Conversion is the final category where you're taking it all the way back to its original hydrocarbon or petrochemical state. That processes are often liquid or gaseous hydrocarbons similar to the products derived from petroleum refining. These raw materials may enter different supply chains. Such as fuels, plastic, or petrochemicals. Although each technology has different processes and features, they commonly produce raw material to maintain the same quality as virgin plastic. And compared with mechanical recycling, it can be used for a wide range of plastic waste. But there are still problems such as high investment costs and earlier stages of technology and regulation.

Among conversion technology, pyrolysis is focused by many chemical companies. Briefly, Pyrolysis is a process of chemically decomposing organic materials at elevated temperatures in the absence of oxygen. It uses high temperatures to make polymer into small size molecules. The polymer with the long-chain is divided into short chains and then into small molecules after passing the pyrolysis process. That is almost the same condition as the original feedstock which is produced from crude oil. Actually, Recycling using pyrolysis isn’t new technology. In the early 2000s, research was actively conducted due to rising oil prices, but it failed to commercialize as the decline in oil prices continued. However, Due to the increased demand for recycled plastic and requests for the ultimate solution of the plastic issues, Recently, refinery and chemical companies focus on pyrolysis again. Pyrolysis has obvious benefits among chemical recycling. One of the benefits is that this technology can handle contaminated mixed plastics without the sorting process. Additionally, it has compatibility with a chemical company that produces polymer. For those reasons, pyrolysis recycling companies are more than 30 in the world. Most companies are located in the US and Europe and in the early commercialization phase.

Even though Pyrolysis recycling technology has many benefits, there are two obstacles to implementing technology for chemical companies. One of them is impurity. Using the pyrolysis process, we can get feedstock for chemical companies from plastic waste but it isn’t the perfectly same because recycled feedstock has a higher content of impurity than feedstock which comes from crude oil. That impurity makes problems in chemical plants. For example, chlorine causes process corrosion and oxygenate causes fouling and low quality of the product. As a result, minimizing impurity is a key factor to use feedstock of chemical companies.

Many chemical companies which want to adopt pyrolysis try to develop post-process for eliminating the impurity. Another obstacle is inefficiency. Pyrolysis recycling is an earlier stage of commercialization. So that is a small size and has a low yield. In economic aspects, the competitiveness of pyrolysis recycling is insufficient. according to a study conducted by Licella which has pyrolysis technology, the current cost of production is $575 per ton for producing recycled Oil which is produced by the pyrolysis process. It is higher than $320 per ton which is average crude oil during 2006~2007. Normally, the chemical industry has believed that the improvement of yield and scale-up are the solutions of inefficiency. they will be able to solve the problem through same frame.

Even though it is difficult to implement chemical recycling, the reasons people are interested is because it could be a new solution for the plastic issue. The chemical recycling, especially pyrolysis, can transform from a linear economy to a circular economy. That refers to “cradle to cradle”. Another impact of conducting chemical recycling is that the Chemical companies consider recycled feedstock that came from plastic waste. Until now, the chemical company’s feedstock is only crude oil. But Pyrolysis makes it possible to have another source of feedstock. After then, they try to make it easier to get that recycled feedstock for ensuring the more stable and cheaper sources. As a result, we will be able to make a more complete loop of recycling.

This affects not only the chemical industry but also Sustainability in other aspects. In economic terms, it is an opportunity for new businesses of plastic recycling which can be placed by other products such as glass, paper, and steel. and it is able to minimize environmental impact by substituting crude oil to recycled oil. according to research, using pyrolysis to convert non-recycled plastics into ultra-low sulfur diesel (ULSD) fuel reduces greenhouse gas emissions by 14% and water consumption by 58%, and it saves up to 96% in traditional energy use as opposed to ULSD from conventional crude oil. It also addresses social issues such as plastic waste and microplastic issues. because it can be helping to reduce disposal like landfills and leaking to the ocean.

Even if there are many advantages to chemical recycling, there are still a lot of barriers and limitations. Because of many reasons, so many places have not yet adopted this technology. Few plastics can be recycled-only 9% in the United States and 15% in Europe. Today's dominant machinery recycling is hampered by pollution and various plastic waste. And those recycled plastics often turn into less valuable products. Recycling of chemicals may help. Depolymerization breaks down polyester and polystyrene into raw materials, which are then converted into new polymers. Pyrolysis can convert the mixed plastic waste into naphtha, and then crack the naphtha into petrochemical products and plastic products. But experts say chemical recovery will not work unless it is implemented on a large scale. Chemical companies are investing in this. So chemical recycling has many limitations.

First of all, there is a big problem with recycling and separating recyclable garbage. The report shows that the U.S. population accounts for only 4% of the world's population, but produces 12% of the world ’s municipal solid waste. This is in stark contrast to China and India, which account for 36% of the world's total population but produce only 27%. Trash. According to the BBC, the per capita waste production in the United States is three times that of China and seven times that of Ethiopia. The Environmental Protection Agency released a report in 2015 saying that the United States produced 262 million tons of municipal waste, of which 13% was plastic waste. Half of this over 200 million tons of garbage was transferred to landfills with a recovery rate of less than 25%. However, the data in recent years have not improved much. There is also no concept of garbage separation in the American people. They do not classify according to the type of waste, which makes recycling of plastic waste more difficult. But some people say they can be sent to the factory for classification. This is very costly in terms of human and financial resources and is very inefficient.

As I said before, there are very few companies and factories doing chemical recycling now. Because this technology requires a lot of capital, the scale is still very small and results in very low efficiency. This technology is not only because of the need to digest a large amount of money but also because technology has shortcomings about purity. Chemical recovery is already at a very preliminary stage so it cannot be done very well in terms of purity. After chemical recycling, many companies still do not need these substances, so this will cause them to be reluctant to use this technology. Some of these companies have also started using recyclable materials. Consumer products companies such as Coca-Cola, Pepsi, and Unilever have made ambitious commitments to separate recyclable materials from their packaging, in some cases 50%.

The third is about those consumer companies. There are still many companies that must use traditional recycling processes. These processes simply clean the plastic and dissolve there. In contrast, chemical recycling methods can recover their original raw materials before completing the replacement resin.

Although there are so many limitations in this technology, we have also found some solutions, some of which may already be implemented in some countries. The first is to start with collecting and sorting. The most important thing is to learn to sort garbage from people's daily life. People in some countries in Europe and the United States certainly lack awareness of garbage classification and do not understand how to classify garbage. In this case, the local community should provide them with education on waste separation. This method can refer to Japan, the Japanese people attach great importance to garbage classification. And environmental education from kindergarten. It is no exaggeration to say that the Japanese learn how to sort garbage from their mother's hands since birth. Children who have attended kindergarten already have some general knowledge of environmental protection and use this to urge their parents and elders to consciously obey. Everyone should first understand if sorting garbage is being sorted strictly. This requires local communities and some environmental organizations. They need to evaluate, reward or punish people based on their waste classification. This is to solve the most fundamental problem because it greatly improves the efficiency and reduces the cost of garbage classification.

The second solution is to increase scale and increase efficiency. One way is to invest in this chemical recycling plant to promote scale and technical flaws. Brands are already investing in these technologies. Large brands including Adidas, Unilever, P & G, Danone, and Interface have signed off-take agreements with multiple chemical recycling startups to support their growth and ensure a limited supply of recycled plastic. Plastics manufacturers Indorama and SABIC have also made strategic investments in Plastic Energy, Loop Industries and Ioniqa, and chemical companies including BASF, Eastman Chemical and LyondellBasell have integrated chemical recycling technology in their manufacturing and supply chains. Technology expansion is slow. From concept to growth, these technologies take an average of 17 years. With many brands promising to include a higher percentage of recyclable ingredients by 2025, the industry needs investment to accelerate growth.

To effectively close the cycle in the plastic supply chain, the industry needs not only technological breakthroughs, but also scalable business models, flexible technology platforms that can evolve, and market incentives driven by public and private policies. This is related to the third solution. Consumer product companies such as Pepsi, Coca-Cola, and Unilever need to show consumers changes in their products to boost their profitability. Therefore, they should make special distinctions on plastic products produced through chemical recycling, such as formulating labels or applying for certificates.

The government is not mentioned in the above solution, because if the government manages and invests in each step, it will cause the government and the people to become unfit. Because once the government enters management, it will become very compulsory and make people have resistance. And this promotion of chemical recycling requires a lot of funds and financial resources, which will cause pressure on government funds and possibly increase taxes. So government intervention is not a good choice anyway. However, the government still has significant uses to advance this project. Rather than putting pressure on the people, let the government use their rights to change these consumer goods companies and the big ones.

Through this project, we have looked at many aspects of Chemical Recycling. It is obvious that chemical recycling has many advantages for sustainable development. Nevertheless, technology is in an earlier stage to commercialize. However, there are reasons that chemical companies should be included in the chemical recycling area. The total demand of plastic is constantly increasing. Especially food contact grade plastic is remarkable. It will be made up of virgin plastic because the mechanical recycled plastic which has low quality cannot replace food contact grade. Because of this situation, the Chemical Company is constantly reviewing investments to increase the capacity of existing plants or to construct new plants. If we change that investment toward chemical recycling which produces the same grade as virgin plastic, that investment in the recycling industry will lead to drastic changes in the recycling technology and industry and It will be a solution in the fundamental area.

Works Cited

Hopewell, Jefferson, et al. “Plastics Recycling: Challenges and Opportunities.” Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences, The Royal Society, 27 July 2009, www.ncbi.nlm.nih.gov/pmc/articles/PMC2873020/.
“Advancing Circular Systems for Plastics.” Closed Loop Partners, www.closedlooppartners.com/research/advancing-circular-systems-for-plastics/.
“Recycling 101: Advanced Recycling.” This Is Plastics, 2 Mar. 2020, www.thisisplastics.com/recycling-101-chemical-recycling/.
Chemical & Engineering News. 2020. Plastic Has A Problem; Is Chemical Recycling The Solution?. [online] Available at: [Accessed 15 March 2020].
Basf.com. 2020. Chemical Recycling Of Plastic Waste. [online] Available at: [Accessed 15 March 2020].