We are surrounded by plastic. It may be a water bottle, shopping bag, ID card and lots of other everyday use plastic. Most of this plastic comes from petrochemicals.
Plastic causes a lot of litter and hence pollutes the environment. This has put human beings and the environment in danger. Also, if you do not manage plastic correctly, making new ones is a waste of resources. Hence it is reasonable to reuse and reprocess plastic to prevent waste. Plastic recycling is an essential procedure in the production of plastic, so it is necessary to know how recycling occurs.
Plastic recycling is the method of gathering waste plastic and reconverting them to new and useful plastic products. The world produces and makes use of more than billions of kilograms of plastic material. Plastic recycling ensures that this huge amount of plastic does not go to waste.
What plastics are generally recycled?
Most of the plastics we come across in our day-to-day life are recyclable. Below are some of the more common plastic types that you can recycle.
PET
PET (Polyethylene Terephthalate) is thin and is perfect for producing low-pressure products. Clothing fibers and soft drink bottles are popular products made from it.
PVC
PVC (Polyvinyl Chloride) is also one of the commonly used plastic materials around the world. It is used to produce wires, pipes, bottles and clings films.
HDPE
HDPE (High Density Poly Ethylene) is softer and more flexible compared to PVC. HDPE is commonly used to produce pipes.
LDPE
LDPE (Low Density Poly Ethylene) is the opposite of HDPE. It is used to make plastic bags. It may not easy to recycle this material. So instead of recycling, you can clean and reuse them for other purposes.
Some types of plastic cannot be recycled easily. Either the process is very long or costly. Sometimes the equipment itself is not capable of doing the job. So, it becomes unviable economically and hence not recycled. Since recycling plastic depends on the type of material, the plastic materials that you don’t recycle get destroyed or disposed of in landfills.
The plastics that fall under this category are as follows:
PS
PS is a polymer and examples of products that come from this type of plastic include plastic cutlery and yogurt containers.
PP
PP is also a polymer and manufacturers frequently use it to make plastic boxes, plastic furniture, and plastic jar lids. In most cases, recycling companies will reject it for recycling.
How is Plastic Recycled?
Since there are different types of plastic, it makes it impossible to recycle all plastics in the same way. Hence, there are two methods of recycling plastic.
Traditional Recycling
This method also called as mechanical recycling is the widely used recycling method. This method is suitable for recycling thermoplastic materials. This method involves melting plastics and processing them into new plastic products. After recyclers melt the plastic, they make them into new products through a process called injection molding.
Advanced Recycling
Advanced recycling is a process wherein chemicals break down plastic material. This method consists of three other techniques. These techniques include pyrolysis, chemical recycling, and gasification.
Pyrolysis is a technique that involves recycling plastic waste into crude oil.
Chemical recycling reduces a polymer into a monomer that can create new products. For example, manufacturers apply chemical recycling to make nylons.
Gasification converts plastic to gas. Producers use the gas generated from this process to create energy.
Both traditional and advanced recycling methods have their benefits. However, applying any of the two methods depends on the facilities available. Depending on the end product a recycler wants to produce also determines the recycling method. In any case, all methods involve similar steps during recycling.
Step-by-Step Process of Plastic Recycling
The recycling of plastic is not as complicated as manufacturing new plastic products. At the same time, plastic recycling is not a simple process. It involves multiple procedures, a lot of attention to detail and the processes may take months. The six essential steps to recycle plastic materials are mentioned below.
Step 1: Collection of Waste Plastic
This process of collecting waste may seem like an easy task, but in reality, it is not entirely so. Employees or volunteers go around collecting waste plastic from homes, offices, and public places. At the same time, there are designated areas that have collection sites where people can dispose of their plastics. Recycling bins are placed around public locations, residential areas, and industrial zones to ease collection. People can dump their plastic waste into these bins. The recycle bins then get collected and transferred to recyclers to continue the process. Recyclers retrieve all types of plastic and send them to a collecting yard.
Step 2: Sorting of Plastics into Categories
After collecting, recyclers send the plastic they have gathered to facilities where they separate the plastics depending on the type of plastic. Plastics differ in size, color, thickness, resin content and use, so recycling machines sort the plastic based on the properties of the material.
Step 3: Washing to Remove Impurities
After sorting, the recyclers wash the materials to remove impurities. The impurities in the plastic include paper labels, dirt, and particles. Washing plastic also removes glue and additional chemicals that plastic materials may contain. This step is essential because failure to remove impurities may damage the new product. The impurities contained in plastic products are not plastic material and so it may not be recyclable.
Step 4: Shredding and Resizing
There is a need to resize the plastic material to a form that can be recycled. So, during this process, the material will be put into shredders to reduce the plastic into fragments. A plastic material cut into tiny pieces is easier to process than when it is in its original form. Shredding also makes it possible to reprocess plastic to other materials aside from plastic products. Resizing also makes it easier to identify impurities like metal that recyclers failed to discover during washing.
Step 5: Identification and Separation of Plastics
The next process is to identify and separate plastic materials. Here plastic particles undergo testing procedures, in order to identify the class and quality of the plastic. The plastic materials are then separated based on their features for further processing. There are several features tested in this process. The next quality is density where the plastic particles are placed into a container of water to determine the density of plastic. The denser ones sink while the less dense particles float.
Air classification of plastic materials is the next process that determines the thickness of plastic. The plastic particles are put into a wind tunnel, where the thicker and bigger plastic stay at the bottom of the wind tunnel and the thinner particles float.
This step also identifies other qualities like color and melting point of plastic. Samples of plastic material are tested to determine the melting point and color of each material.
Step 6: Compounding
Compounding or extrusion is the final process that transforms plastic particles into materials that manufacturers can reproduce. It involves smashing and melting plastic particles to create pellets. At the end of this stage, new plastic and non-plastic products originate from the pellet processing. This final process also consumes maximum time and energy. Recyclers must fully understand the end product they aim to get and the entire process to manage time and energy efficiently.
After all this, new plastic materials then emerge. Or other materials that the recycler intended to create.
Benefits of Plastic Recycling
Recycling of plastic looks long and costly, but it comes with many benefits and as mentioned below and hence recycling should be encouraged at all times.
- Reduces the amount of trash that ends up in the oceans
- Reduces the release of carbon dioxide and harmful gases into the environment
- Reduces the emergence of all forms of pollution
- Helps reduce activities like deforestation that happen when making new plastic
- Prevents global warming
- Conserves the space used as landfills. It makes it possible to use those landfills for other purposes
- Creates new jobs
- Creates additional revenue for the government and private organizations
- Saves petroleum that producers may use to make new plastics
- Lessens the energy that manufacturers consume in creating new products
- Encourages a Sustainable Lifestyle among People
Conclusion
Plastics serve lots of purposes in our daily life, but the world stands to gain if we recycle plastic. So, the next time you empty a plastic bottle, don’t just throw it away. Dispose it in a way so that it is possible to get it recycled.