Process of PET Bottle Recycling : Step-by-Step Guide

The demand for high-quality recycled RPET (Recycled Polyethylene Terephthalate) flakes has soared among global brands striving to achieve their Environmental, Social, and Governance (ESG) objectives. The usage of recycled PET as source material for food-grade applications or micro denier filament applications has been steadily increasing. This surge in demand indicates a growing trend toward utilizing recycled PET for sustainable packaging solutions. To meet these evolving demands and ensure the best quality of recycled PET flakes, one of the critical factors lies in the right selection or optimizing the PET bottle recycling process and equipment. The right selection of PET bottle recycling process is the grantee to support recycling the waste PET bottles to rPET flakes.

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Adapt the various combinations of modules to suit the diverse sources of waste PET and the downstream applications in different countries. Here are the six main steps of the PET Bottle Recycling Process.

General PET Bottle Recycling Process
De-baling&#;Metal detecting and separation&#;Label Removal&#;Bottle Pre-washing&#;Bottle Sorting&#;optical & Manual&#;Crushing&#;Flotation Washing&#;Hot Washing&#;Rinsing&#;De-watering&#;Dust Removal&#;Flakes Sorting&#;Drying&#;Packaging

Normally, the waste PET bottles will through several similar washing and recycling processes to become clean rPET flakes but are affected by the bottle material composition.

1. Collection and sorting

The first step before the PET bottle recycling process is to collect post-consumer PET bottles from various sources. In European and American countries, specialized large-scale Materials Recovery Facilities (MRFs) are utilized to categorize reclaimed recyclable materials such as paper, plastic, glasses, and metal. Plastics, after undergoing multiple rounds of sorting, can be transformed into homogenous bales of single-polymer compositions. These bales are then transported to plastic recycling facilities for further processing.

2. De-baling

Cut off the baling wire of the PET bottle bale by manual or automatic device, and make the bottles loose into a bottle baler. There are various types of bale breakers when you configure the process, you should consider the density of the bottle bale. An automatic device will save a lot of labor.

Three types of bale breakers from BoReTech, the right choice can support easily breaking up the bottle bales into loose.

Horizontal Type

Vertical Type

Horizontal Type

3. Metal detecting and removal

Ferrous metal separation can be achieved by a magnetic drum, magnetic over-belt, or metal detector with a flapping device. To separate the non-ferrous metal, we recommend the eddy current in the later step.

Magnetic Drum

Magnetic Over-belt

Flapping Device

4. Labels and impurities separation

PVC label is a big problem in PET bottle recycling. A label-scrapping machine that is equipped with a blower will handle these heat-shrinkable labels well. The PP labels and paper labels normally will be separated during the hot washing process. So for the different labels, you should choose the right machine to process.

BORETECH launched a new type of Label scrapping module - LABEL REMOVAL & FLUSHING MODULE

• Combines the label-scrapping and bottle-washing functions.
• Separating the labels, and other impurities, filtering water from the material.
• It is capable of processing 5 tons/h of PET bottles.
• A high label scrapping rate and lower bottle breaking rate

PET flakes hot washing

Soaking and washing flakes, heating the cleaning medium with steam or heat-conducting oil, and dosing the detergent and NaOH to improve the cleaning effect, soften and remove the impurities attached to flakes; oil will be emulsified during the hot washing.

The following are the key factors for the Hot Washing Process in PET Bottle Recycling.

• Automatic Temperature Control
• Washing speed
• Washing dwell time
• Detergent

Qualitative analysis of PET bottle balers in the early stage will support the hot washing process.

BORETECH INTENSIVE HOT WASHING MODULE is one of the great choices

• The process flow is rationalized, compacted, simplified, and occupies less area.
• Unity and renewing of temperature and chemical concentration for batch flake washing.
• The mechanical friction force and friction between materials significantly improve the flakes-washing effect.
• Patented shaft with paddles produces high-speed water flow through the rotary, washing flakes to peel off labels and gules and reach a perfect washing effect;

5. Rinsing Suction

There are several types of rinsing machine to be considered, high speed rinsing tank, screw rinsing tank and combined with ULTRASONIC WASHING MACHINE.

The rinsing process is to separate suspended solids by different gravity of materials.

• High-speed rinsing machine with high-speed stirring to wash the flakes by water vortex force.
• Screw-type washing, further rinsing to separate from semi-floating impurities.
• Through cavitation, the dirt, glue, and impurities on the surface of the flakes are impacted, and then the impurities are separated to achieve the cleaning effect.

BORETECH HIGH-SPEED RINSING MACHINE

In addition to the main PET bottle recycling processes mentioned above, there are indeed numerous processing methodologies applied for PET bottle recycling based on the diverse conditions of the PET bottle sources. Presently, the challenge lies in the persistent presence of impurities within PET bottles on a global scale. These impurities are a consequence of the ongoing utilization of PET bottles that incorporate multiple materials. Consequently, the successful implementation of PET bottle recycling and cleaning hinges on the adept selection and integration of processing techniques tailored to the specific characteristics of the PET bottles being processed.

Customized Modules : Tailoring PET Bottle Recycling Line to Diversity

ES process PET bottle recycling is a multifaceted process that transcends traditional methods. While the core processes highlighted earlier lay the foundation for PET bottle recycling, it's essential to recognize the intricate variations necessitated by the diverse origins and conditions of these bottles. Customized process modules play a pivotal role in achieving efficient recycling outcomes, particularly when dealing with the complexities of mixed-material bottle structures.

Informed Machinery Selection : Key to Successful PET Bottle Recycling

Understanding the PET bottle recycling process is crucial for making informed decisions when it comes to selecting suitable PET bottle recycling machines. The nuances of the recycling process underscore the importance of choosing machinery that aligns with the specific requirements of your operation. Factors such as the source of waste PET, desired recycled material quality and intended downstream applications all contribute to determining the most appropriate recycling equipment.

If you want to learn more, please visit our website plastic flakes washing line.

Learn more : 3 Minute to Know PET Bottle to Bottle Closed Loop Recycling

Case study : BoReTech's Role in Advancing Turkey's Plastic Industry Through PET Bottle Recycling Line Expertise

Empowering Sustainable Choices : BoReTech Recycling Machinery's Expertise

As a leading manufacturer of PET Bottle Recycling Machines, our expertise lies in offering cutting-edge solutions for PET bottle recycling. With a wealth of experience in the field, we possess the knowledge necessary to guide you in making well-informed choices regarding plastic bottle recycling machinery. If this article has piqued your interest in delving deeper into the realm of PET bottle recycling equipment, we invite you to explore "The Latest Recycling Technology for PET Bottle Recycling&#;ES PROCESS PET BOTTLE RECYCLING SYSTEM." This comprehensive resource provides an in-depth understanding of our advanced technology, further enriching your insights into PET bottle recycling.

BoReTech stands as your partner in this journey, prepared to provide support and empowerment as you strive for a more environmentally responsible future. Feel free to reach out to us to explore potential synergies. Alternatively, you can visit our PET Bottle Recycling Equipment or connect with us on our social media platforms to delve deeper into the wealth of information we offer.

Bearing in mind the aspiration of the world economy to create as complete a closed loop of raw materials and energy as possible, it is important to know the individual links in such a system and to systematise the knowledge. Polymer materials, especially poly(vinyl chloride) (PVC), are considered harmful to the environment by a large part of society. The work presents a literature review on mechanical and feedstock recycling. The advantages and disadvantages of various recycling methods and their development perspectives are presented. The general characteristics of PVC are also described. In conclusion, it is stated that there are currently high recycling possibilities for PVC material and that intensive work is underway on the development of feedstock recycling. Based on the literature review, it was found that PVC certainly meets the requirements for materials involved in the circular economy.

Poly(vinyl chloride) is mistakenly considered difficult to recycle due to its complex composition and its low thermal stability. This misconception is true not only with respect to public opinion, but also with respect to many people interested in the subject of other polymer materials. However, there are a number of technical possibilities for the management of PVC waste. The aim of this article is to present the possibility of PVC recycling to a wide group of readers, especially those who do not deal with PVC recycling on a daily basis. It is extremely important in the pursuit of a circular economy to be a conscious consumer, processor and scientist.

Such widespread and common applications of PVC are correlated with the generation of a waste stream that should be managed in a safe manner.

More than a quarter of polymer products used in medicine is made of PVC, owing to its biocompatibility, chemical stability and resistance to sterilisation. It is used to make flexible blood containers, urine ostomy bags, flexible tubes, inhalation masks, oxygen masks, or PPE such as gloves and footwear [ 16 , 17 , 18 ]. Moreover, PVC in the form of painting dispersions or mats is used to coat floors and walls, ensuring sanitary safety [ 19 ]. PVC is also utilised in the packaging industry as food wrap. Such wrap-foils offer good oxygen barrier properties, translating into a long shelf life of the food [ 20 ]. Various blisters for pharmaceuticals [ 21 ] and cosmetic packaging are also made of PVC. Plasticised PVC is exploited to manufacture coated fabrics as materials for tarpaulins and coverings for large tents and halls, floor linings and, above all, so-called artificial leather [ 22 ], employed in the clothing, automotive and furniture industries [ 23 , 24 , 25 ]. As far as the automotive industry is concerned, PVC is mainly applied as a material for cable insulation, in addition to the fabrication of fuel hoses and soundproofing mats, as well as for anti-corrosion coatings.

The use of PVC in the European Union, broken down into applications, is shown in . Approximately 70% of PVC output is employed in the construction industry, mainly as window and door profiles, water and sewage pipes, cable insulations, gutters, floor lining, and roof membranes [ 14 ].

The high economic significance of PVC is the outcome not only of its low production costs but is primarily determined by its good properties, the most important of which are high chemical resistance [ 8 ] and favourable mechanical properties, as well as resistance to water and weather conditions [ 9 ]. Its good adhesive properties enable printing in, e.g., wallpaper, advertisement and floor-panel manufacturing [ 10 ]. The high transparency of this polymer means it is used in the manufacturing of foil, blisters or light-transmitting panels. PVC exhibits numerous unique, additional features, such as resistance to biofilm formation [ 11 ], high-impact strength, universal flexibility modification, gloss formability and easy binding. It is classified as a self-distinguishing material (LOI of rigid PVC is approximately 44&#;49%) [ 12 ]. Through the possible application of significant amounts of plasticisers, it enables the obtaining of hard and soft variants, which considerably differ in terms of glass transition temperature and flexibility at a specific operating temperature [ 13 ].

Sodium chloride (rock salt) is one of the raw materials used in the synthesis of PVC. As a result, only 43% of the polymer mass comes from petrochemical raw materials. The low carbon footprint of the elements made of PVC with a long service life is an additional ecological advantage. For example, the carbon footprint of the manufacturing stage and the entire life cycle of PVC products can be significantly lower compared to other materials, even those generally considered to be environmentally friendly [ 3 , 4 , 5 ]. In addition, there are prospects for the further reduction of the carbon footprint of PVC through the use of new technologies for the production of vinyl chloride from natural gas [ 6 , 7 ].

Poly(vinyl chloride) is one of the oldest thermoplastic polymers. Since the beginning of industrial PVC synthesis, in the early s, its production volume has been constantly growing [ 1 ]. It is currently third in the world in terms of production volume [ 2 ].

2. PVC Recycling

The basic PVC recycling system is schematically shown in . PVC can be subject to both mechanical recycling processes and feedstock recycling.

The most-recommended way to recycle PVC is mechanical recycling. The easiest way is to recycle the material directly in the production plant where the waste is generated. Such waste arises, for example, during the start-up and end of production and the mechanical processing of finished products or waste resulting from production errors. In such a case, with little effort the recycled material can be carefully selected so as not to lead to its contamination. PVC waste after mechanical milling can be used as an admixture for the original material. It is also important that PVC waste processed in the same production plant is of known composition. This allows for its simple modification by adjusting additional PVC components (e.g., process lubricants, thermal stabilisers, increasing the proportion of plasticiser) and designating such material for the production of a different range of products when dosing the original material is impossible.

It is slightly more difficult to obtain the consistency of the composition of the raw material during the recycling of post-consumer materials. In this case, the need to clean the raw material should be taken into account. Additionally, it may be necessary to modify the composition of PVC in order to obtain the specific processing and performance properties required for a new application. In some cases, it may be justified to remove modifiers (e.g., thermal stabilisers or some types of plasticiser); however, this process may turn out to be uneconomical due to the high investment costs related to the purchase of specialised technology.

Another method of PVC-waste management is feedstock recycling. For economic and environmental reasons, this type of recycling should include waste that cannot be mechanically recycled. A relatively simple method of this type of recycling is energy recovery, which consists of gasification of fuels or direct combustion in specialised thermal utilisation plants. Importantly, in the case of energy recovery, PVC can occur as a fraction mixed with other types of waste. However, it should be borne in mind that the resources contained in waste are irretrievably excluded from the circular economy.

A slightly more advanced method of feedstock recycling is the processing of PVC into valuable raw materials for the chemical industry. These processes are carried out in appropriately designed thermal decomposition. In this case, a large investment expenditure related to the construction of specialised installations is required. This type of recycling, in many cases, may turn out to be uneconomical. However, in an attempt to close the circulation of materials in the global economy, such investments may be necessary. It should also be remembered that scientific and technological progress provides new possibilities for processing PVC into other raw materials, as well as prospects for the further development of already existing technologies.

2.2. Feedstock Recycling

Feedstock recycling is an alternative to mechanical recycling and the disposal of post-consumer waste. It is more suitable for an unsorted PVC waste stream for which material recycling is not achievable or is uneconomical. Its main purpose is to reintroduce raw materials into a closed circuit and recover the energy contained in the material. The chemical substances produced in the process of PVC decomposition have various applications ( ), especially in the chlorine industry [30].

The thermal recycling of PVC waste includes the thermal treatment of the waste stream towards the recovery of hydrogen chloride, which is recycled for the production of PVC or other processes. PVC is a material whose thermal recycling method was indicated as ineffective and therefore not future proof. However, there is currently a lot of intense work aimed at subjecting this waste to thermal recycling. Several thermal recycling processes are used, for example pyrolysis, gasification, incineration and modifications thereof. Many problems in thermal recycling are caused by process additives, such as stabilisers and plasticisers commonly used in PVC processing, which are currently on the list of prohibited substances [86].

Incorrect thermal utilisation of Cl-containing waste, including PVC, may cause significant damage to installations due to the corrosive properties of the resulting gaseous products. The formation of dioxins at unsuitable temperatures is also dangerous, which is why the control of the process is so important.

The thermal treatment of PVC waste essentially consists of two steps: dechlorination to remove Cl from the PVC macromolecule and the use of the remaining hydrocarbons portion. For thermal recycling, dechlorination is necessary to reduce the potential environmental hazards and to increase the recovery of hydrocarbons from PVC waste. Additionally, the neutralisation of HCl in the tail gas is required. Currently, the work on the thermal recycling of PVC is focused on obtaining chlorine, hydrogen chloride and salt. These products are not treated as a waste material causing technical complications but as a full-value source of raw materials for further processes [30]. The issue of chlorine removal from PVC waste before its proper disposal is one of the main research topics of the thermal recycling of waste materials [30,87,88,89,90,91,92,93,94,95,96].

The dechlorination and recovery of Cl during the thermal recycling of PVC, for example, can be completed with ethylene glycol and NaOH [97,98,99]. The resulting NaCl salt and glycol are separated by electrodialysis and reused in various processes. The obtained hydrocarbon fraction can be utilised in thermal treatment or used for further processes, e.g., fuel production. Such a procedure ensures protection against corrosion of the installation and the best energy recovery from the remaining hydrocarbon portion [87,98,100,101,102,103].

Hydrothermal dechlorination with moist biomass is another method of thermally recycling PVC waste [93,100,104,105,106,107]. In the face of an increasingly serious environmental and energy crisis, it has aroused great interest in recent years. The presence of PVC in the process of hydrothermal carbonisation promotes the formation of a higher content of carbon residue [104,105,106,107,108,109,110,111,112], thus increasing the carbonisation of cellulose and coke yield, while reducing the emission of gases and oily substances [104]. PVC biomass co-pyrolysis can also be used to produce sorption materials [93,113], such as chlorinated carbon black used for mercury absorption [114,115], hydrocarbon for methylene blue adsorption in an aqueous medium [107], and porous carbon spheres with high CO2 greenhouse gas absorption potential [116].

Waste PVC, due to the reactive chlorine built into the polymer chain, may turn out to be a valuable raw material for the production of efficient sorbents and dangerous, as well as valuable, metal ions [88,117].

There are reports on the catalytic acceleration of the PVC waste dechlorination in the presence of various substances [114,118,119,120,121,122]. The process of dechlorination, by binding chlorine and HCl, is also influenced by additional substances, such as Na2CO3, KOH, NaOH, NH3·H2O, CaO and NaHCO3 [87,100,101,123,124,125,126,127,128].

Studies are also conducted on the thermal recycling of PVC waste on an industrial scale. They are run by companies such as Solvay, Suez and Resolset. The process uses the technology of chlorine neutralisation (through a dry scrubber with sodium bicarbonate), as a result of which NaCl is obtained, which, after cleaning, is used by Solvay for the production of caustic soda.

Another example of the thermal recycling of PVC waste on an industrial scale are the processes implemented under the Thermo Vinyl project in Switzerland, based on the recovery of energy and HCl by wet scrubbing of the gases formed in the process of the incineration of municipal waste. Hydrochloric acid is reused to extract the metals contained in the ashes after combustion. This process uses the already available infrastructure of waste-treatment plants.

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