One truckload of plastic is thrown into the ocean every minute. Let's think about it.
Modern life cannot be imagined without polymer materials. Usable items, clothing and footwear, means of transport, construction materials and haberdashery, means of communication and modern media are made of various types of polymer materials. Some of the first materials that man began to use were actually natural polymers such as wool, wood, and cellulose. At the end of the 1980s, the production of polymer materials overtook the production of steel both in terms of volume and mass (Figure 1).
Figure 1. Comparative presentation of the production of steel and plastic materials in the second half of the 20th century
Figure 2. Presentation of plastic production in Europe and the rest of the world in the period from 1950 to 2018
As an accompanying phenomenon that occurs during any production, there is waste that is generated both in the production facilities themselves, and as a consequence of the use of the products themselves around the world. The logical conclusion that emerges is that, due to the growth in the production of plastic materials, the amount of waste that is created over time is increasing and is growing every day. The biggest jump in the production of plastic happened when juice producers started using plastic because of the faster time to market, and that's how disposable plastic was born.
Waste is primarily generated in plants that produce plastic items. Also, the raw material for obtaining plastic objects for mass use is very cheap, which favors its application in a large number of industrial sectors.
Figure 3. Presentation of the degree of production of plastic objects by a certain branch of industry, for a given number of products per year (for the year 2015)
Any products that have a problem due to inadequate storage or transportation also become waste.
Figure 4. Graphic representation of the amount of waste per capita, given in kg of waste per capita per day (for 2010)
Hyperproduction, ease of movement of goods and consumer habits result in large amounts of waste being created in the world on a daily basis.
How to deal with waste?
Plastic waste, like all others, was first disposed of in landfills. It soon became clear that this is not a long-term solution considering the very long period of decomposition of plastic materials, from 100 to 600 years. Ideas about the reuse of plastics that are out of use appear already in the 70s of the 20th century. In industrial circles, recycling is not welcomed with enthusiasm because such a phenomenon negatively affects the creation of new products. Today, states have their own citizen-focused plastic collection and recycling programs.
What does the recycling process look like?
Recycling or recycling of polymer materials implies the reuse of polymers as materials and/or obtaining new raw materials and/or fuel from polymers, as well as the use of polymer materials as an energy source. The molecular structure of polymers has a decisive influence on the properties, processing and application of polymer materials, and later on the recycling process.
In order to standardize and globalize the recycling process, special markings on products have been adopted at the world level that indicate the material from which the object is made, and for easier collection later and sorting before the recycling process. By law, it is mandatory that every object must have a label indicating the material it is made of.
Figure 5. Tabular presentation of universal markings that indicate the material the object is made of (each type of plastic has only one marking)
When it comes to the recycling process itself, it should be emphasized that there are 4 types of recycling: primary, secondary, tertiary and quaternary . This division was made on the basis of the life cycle of the object, which further dictates its subsequent application after the end of the recycling process.
Table 1. Presentation of the types of recycling procedures and the application of polymers after them
| Type of recycling | Application of polymers after recycling |
| Primary and secondary | material for making other items |
| Tertiary | raw material for obtaining chemical products |
| Quaternary | energy source |
- Primary recycling: If waste occurs during the process of forming plastic products (for example, material left after trimming the edges of the product, material that first passes through the machine during the start of the processing process and is then discarded, a product that is not satisfactory in terms of shape, etc.) that remains in the factory circuit, it is considered uncontaminated and can be returned to the polymer processing process.
- Secondary recycling: When the material leaves the production facility and after its useful life is collected again, freed from impurities of other materials, washed, dried, that object can be shaped by some processing process, pure or mixed with pure polymer and other impurities.
Figure 6. Schematic representation of the secondary recycling procedure in the recycling plant
Example of an industrial recycling plant: https://www.youtube.com/watch?v=I_fUpP-hq3A
- Tertiary recycling: If the collected used polymer for some reason does not undergo a secondary type of recycling, it can be used as a raw material for obtaining certain chemical species by subjecting it to thermal or chemical treatment procedures.
Figure 7. Schematic representation of the process of tertiary recycling of certain types of polymer waste and the end products of recycling
- Quaternary recycling: Part of the waste, most often certain types of polymers that cannot be processed by some of the previous procedures, can be used as energy and fuel, both alone and in combination with other waste and fuel, with the aim of using the thermal energy that is generated due to the breakdown of chemical connection.
Figure 8. Schematic representation of the quaternary recycling process
Recycling in Serbia
In Serbia today, there are 2,200 companies engaged in waste collection and recycling, which is a huge improvement compared to 2009, when there were 200 of them. What is the current situation in Serbia regarding the production and processing of waste can best be seen based on the official data of the Environmental Protection Agency, which states that currently around 5% of waste is recycled in Serbia, in contrast to EU countries where the percentage of recycling is around 50%, while the other 95% refers to landfills, of which there are currently 164 registered municipal landfills and about 2,170 registered wild landfills, and only 10 sanitary landfills in the entire country.
Regional sanitary landfills built until 2017 are located in Užice, Lapovo, Kikinda, Jagodina, Leskovac, Pirot, Sremska Mitrovica and Pančevo, while two are local in Vranje and Gornji Milanovac, according to the records of the Environmental Protection Agency.
When it comes to plastic waste, according to the data of the Republic Institute of Statistics for the year 2019, 56,801 t of plastic waste was created on the territory of the Republic of Serbia, and the industrial branches leading in terms of the amount of plastic waste they create are the processing industry, the service sector and the management sector watercourses.
In 2013, the Association of Recyclers of Serbia was founded in Serbia by the leading companies from the recycling industry sector, which aims to improve relations between member companies of the Association and the Government of the Republic of Serbia, and also to promote and popularize the recycling industry in Serbia, including smaller companies and natural persons who want to deal with the collection and recycling of waste.
In addition to experts, engineers and ecologists, the recycling industry also employs collectors of secondary raw materials throughout the country, who often come from marginalized social groups, provides them with social protection and includes them in legal flows, which is another benefit of the recycling industry in addition to the positive impact on the environment.
Activist movements in the world in the fight to reduce waste
There are a large number of small organizations and associations in the world that deal with the popularization of ecology and the ecological way of thinking. Also, there are those who gather volunteers and deal with waste collection and cleaning of certain areas that are polluted with plastic or other waste. One interesting movement that originates from the Netherlands and is the brainchild of Dave Hackens is the Precios plastic movement. In 2012, Dave began to think about making plastic recycling machines that would be copies of industrial machines and that would be able to perform the same function as industrial ones, only on a smaller scale, easy and cheap to make and available to the general public. The whole idea started after, for the needs of a project at the university, he started to deal with the topic of recycling in "home conditions". Already after a year, he managed to design and build the first version of the machine, which consisted of two machines: a plastic cutter (so-called shredder) and an extruder whose function is to melt plastic. He was soon joined by four other colleagues and by 2016 they managed to develop the second version of the machines, perfecting the previously developed prototypes of the machines. This movement is gaining momentum, thanks to the website and postings on the Internet, and it soon becomes international and slowly spreads around the world. Meanwhile, volunteers from all over the world, primarily from France, the Netherlands and the USA, come to the Netherlands and help develop the machines. This results in the appearance of first the third and then the fourth version of the machine, which is presented to the world in 2018.
Since 2020, Precious Plastic Universe , as the activists of this movement call "their world", is a global organization that has a large number of members from almost every country in the world, striving to become a global alternative system for plastic recycling. Access to this universe is free, everything is available through the official website, and the goal is to involve more and more people over time and support the project, so that the development goes on an upward path, and also so that the project is increasingly popularized and implemented around the world. Unlike conventional industrial plants, the construction of which requires a huge amount of money, many permits and the willingness of the local community and certain ministries to invest and develop this industry, the goal of the Precious Plastic commune is for recycling to start point by point from enthusiastic individuals and for them to follow their example around themselves gather people interested in plastic recycling and thus spread knowledge about this movement and this type of recycling method. The machines are designed in such a way that they can be made from scrap pieces of metal, with minimal machining, and considering that they are designed by mechanical engineers, their functionality is not lacking even though this method of production is in question. The best thing about it is that the manufacturing is not very expensive and for 2000 - 5000 € you can have a set of 3 - 5 machines that allow you to make new items from recycled plastic using multiple manufacturing processes.
Also, viewed on a micro level, this can be a kind of business for individuals or smaller companies, especially in poor areas, such as for example African or some Asian countries. The business can be based on several things: plastic recycling and the sale of semi-products (flakes, granules, larger pieces), final products of a specific design and purpose, parts for machines and upgrading them, etc. This leaves a lot of room to involve people from other professions who can contribute to the development of the process or the final product (designers, engineers, architects, economists, etc.) in the local recycling process. Also, this project is quite suitable for educational institutions, such as primary and secondary schools, for several reasons:
1. the educational character of the project - children and teaching staff can directly learn about the conventional way of recycling and gain education about the recycling process and the processing procedures of the plastic materials used
2 . environmental protection - children and employees in educational institutions can participate in the collection and sorting of waste, organize waste collection within their school community and recycle the collected waste using their machines or the machines of partner organizations
3. raising awareness about recycling - participating in the recycling process, members of the school community raise their awareness about the importance of reusing plastic materials and the negative consequences on the environment due to the disposal of this waste in landfills, and indirectly they can influence the development of awareness about the importance of recycling among their family members, comrades, friends, colleagues and neighbors
4. developing creativity - children, in cooperation with teachers and school authorities, can include some segment of this project (collection and sorting of waste, redesign of machines, upgrading, development of processes, design of the final product,...) in some of the teaching units and so on to develop their creativity, apply the acquired knowledge and work on some areas on a concrete, close to them example
5. the possibility to make money - after establishing the process of collection, sorting and recycling, the end product of the process, whether it is a semi-finished product or a finished product, can be offered to the market and receive some amount of money for it, which can be the budget for paying for the purchase of garbage, purchase of additional equipment, rental of space or rewards for people who work.
Figure 9. Presentation of Preciuos Plastic community department
On the official website of the movement ( https://preciousplastic.com/index.html ) you can see in detail the entire development of the movement and machines, but also join the movement in a certain way and thus become part of the community where everyone's primary goal is to recycle plastic objects and in who are all there to share their experiences with you and also to give you ideas for crafting plastic items, machine parts, there is even a unique bazaar where you can display your work and crafted items to the rest of the community and offer them for sale, and also see also the work of other community members.
Precious Plastic in 3D Republic
3D Republika, as an environmentally conscious company, has started to develop the plastic recycling sector over the past year because it itself generates smaller amounts of waste due to material testing. After making the machines according to the technical documentation that is available on the website of the Precious Plastic community (V2), the assembly of the machines and their trial operation began. For now, we have a shredder for cutting plastic into flakes of a minimum size of up to 4 mm and an extruder, and we are planning to establish plastic processing by injection molding and pressing. Currently, the test operation of the extruder is still in progress, followed by the validation of the entire line and an attempt to make the process continuous as much as possible, in order to increase the efficiency of the process and reduce the costs and contact time in each of the devices as much as possible.
Figure 10. The original layout of the shredder - V2 (taken from the Precious Plastic community site)
Figure 11. Original extruder layout - V2 (taken from the Precious Plastic community site)
As far as the final products of the entire recycling process are concerned, our idea is to make specific products that will be functional and that can be offered to the market. What has been determined by the market research is that in Serbia the recycling of plastic material is done most often by waste separation - pressing - shredding - washing flakes - extrusion to granulate and that granulate is packaged and sold to other companies or exported abroad. We would try to make the whole recycling process complete and in our production process we have the transformation of the input plastic item which is waste into the output plastic item of a new form that gets a new life. Also, we would try making filament for 3D printing from recycled material.
Our desire is to enter into a partnership with one of the leading companies that operate in the territory of the Republic of Serbia and that are socially responsible, so that together we can try to raise this project to a higher level and increase the volume of production.
Nemanja Stojanović
Final year student of the Faculty of Technology and Metallurgy - majoring in polymer engineering