Plastic recycling

Plastic recycling is the process of taking plastic waste materials and making them into another product. Plastic is a petroleum-based synthetic or semi-synthetic material composed of malleable polymers that do not decompose over time like organic materials and can stay intact for decades or centuries. Plastic can break down from sunlight exposure, but this becomes a problem because it degrades into very small toxic particles and can enter the food chain or environment. In fact, one million oceanic animals die each year from ingesting plastic waste. It also is toxic and damaging to the environment when burned, so a logical solution to the management of plastic waste products is recycling.

Since 1950, an estimated eight billion tons of plastics have been produced and that 380 million tons of plastic are manufactured each year, yet the market for plastic is ever-increasing. While residential households use many plastic products and contribute to the burden of plastic waste, the majority of plastic waste is produced by businesses, industries, and manufacturing. The plastic recycling industry is expanding and the manufacturing of more easily recycled plastics is also increasing as demand for recycled plastics in goods increases with public awareness of the consequences of not recycling plastics. However, unlike aluminum and glass recycling, plastic recycling faces unique challenges.

Background

Plastic was invented in the early twentieth century when Leo Baekeland created the versatile synthetic material Bakelite. As industries grew rapidly, plastic manufacturing and application in both industrial and consumer goods increased. After World War II, plastic goods began to be mass-produced, and by the 1960s and 1970s, plastic began to be used as a common replacement for materials such as glass, metal, and wood. It was known for durability, safety, and cost-effectiveness. However, the problem of the disposal of plastic soon became a concern.

The 1960s was a time of awareness of the importance of environmental preservation and waste management in the United States. Plastic was becoming common in many everyday items and, like other waste, was usually just sent to landfills. But the synthetic material did not quickly decompose, so the idea of taking waste plastic and making it into new items was embraced as a viable solution to the burgeoning plastic waste problem.

The first plastic recycling plant was built in Conshohocken, Pennsylvania, in 1972, setting the standard for other recycling centers across the nation. In the 1970s and 1980s, education campaigns informed consumers about the importance of recycling and the consequences of not doing so. In 1970, the Environmental Protection Agency (EPA) was formed in the United States, which regulated waste disposal and encouraged environmentally friendly practices. The 1970 Resource Recovery Act also encouraged recycling.

Pressure from proposed plastic taxes, government programs, environmental activists, and informed consumers encouraged manufacturers to produce types of plastic that were easier to recycle, and by the 1980s, these types of plastics became more widely used in products and municipal curbside recycling programs started to take shape. By 1984, 100 million pounds of plastic were collected for recycling. In 1988, the US Society of the Plastics Industry created a trade association, the Council for Solid Waste Solutions, which further raised public awareness of plastic recycling.

However, since it was difficult for the average person to distinguish which types of plastic were recyclable and which were not, the closed-loop triangular symbol, which was promoted by the Council for Solid Waste, was adopted in 1988. This symbol with a number inside allowed people to quickly identify which plastics were recyclable by their local recycling centers. By the end of the twentieth century, recycling programs in communities became commonplace, and many manufacturers produced plastic products with recycling in mind.

Thus, by the twenty-first century, recycling was part of daily life in America and many other developed countries. Less-affluent and developing countries also were beginning to institute programs and build recycling centers to deal with the issues of plastic waste. In addition, in many of these countries, recycling could be done less expensively, so more-developed countries exported their plastics to less-developed countries for sorting and processing. However, by the late 2010s, some countries, such as China, which recycled low-quality mixed plastics and used them in manufacturing began to restrict the import of recyclables. Consequently, the illegal import of plastics to other countries increased. In 2019, the Basel Convention implemented regulations for the international plastic waste trade and worked to manage the increasing exportation and importation of plastics for recycling in a legal and more environmentally positive manner.

Sustainability initiatives that encouraged recycling also continued as the environmental impact of plastic waste became more widely understood. Research in the 2010s showed that the environmental and health consequences of plastic pollution from landfills and incineration might become irreversible. Even though by the twenty-first century recycling collection and facilities were common in most communities and industrial centers, the actual amount of plastic that was recycled into a new product was estimated to be only around 5% in 2022, according to the Greenpeace organization. Reports showed that most of the plastic being sent to recycling centers after collection was still being sent to a landfill for disposal. In 2021, the Plastic Waste Reduction and Recycling Research Act proposed a tax on virgin plastic in an effort to encourage recycling and place greater accountability on the plastic manufacturing industry.

Overview

Several different types of plastics exist, and not all are considered recyclable. In general, the heavier and denser the plastic, the less likely it can be recycled. While the plastics most commonly used in goods can be recycled, how easily and to what extent depends on the type of plastic polymers used in the plastic’s creation. Seven major categories of plastic are each given a different recycling number from one to seven, displayed in the closed-loop triangular symbol, which corresponds to how easy the plastic is to recycle. These categories are: 1. polyethylene terephthalate (PET), 2. high-density polyethylene (HDPE), 3. polyvinyl chloride (PVC), 4. low-density polyethylene (LDPE), 5. polypropylene (PP), 6. polystyrene (PS), and 7. other.

Plastic recycling centers will only recycle a certain type of plastic due to the process or machinery required, so this requires plastic waste materials to be sorted into categories. Some plastic products, such as plastic bags or films, can jam machines and cause problems if not sorted correctly. Different types of plastics also require different types of processing to create usable recycled plastic. Mixed types of plastic in a product or packing material, and contamination by food or other contents (such as laundry detergent), commonly prevent a plastic good from being recycled.

Some community recycling programs have adopted commingled recycling collection to encourage compliance and prevent sorting difficulties. This involves all recyclable materials being put into a common bin, including paper and metal, and the sorting is done by professionals at a recycling facility. Although comingled recycling does have advantages, it also increases the cost of processing and often leads to contaminated materials. This ultimately reduces the output of usable recyclables, which lowers the recycling rate.

Manually sorting plastics is the most basic method for determining which items to recycle. This method requires workers to look at and then separate plastics into types as the objects move along a conveyor belt. This method is inefficient and prone to error; however, it remains a common method in developing countries where labor is inexpensive. In more advanced recycling facilities, plastics can be separated by machines that determine the plastic type by measuring the density or electrostatic charge. In the most advanced facilities, machinery can sense the plastic polymer type. It is important that the types of plastic not be mixed or errors in sorting occur, since these can prevent the plastic from being successfully recycled.

Once the plastic waste is sorted, it is processed at the recycling facility. Recyclable plastics are shredded into smaller particles and then sorted again and washed to remove dirt, labels, or other contaminants. Next, they are compounded into pellets that can be melted and reformed into new products. Depending on the type of plastic polymer, the plastic is melted at 300–600 degrees Fahrenheit. This reforming process can affect the final quality of the recycled product, causing unpleasant tastes, odors, discoloration, or poor strength. However, more advanced recycling techniques have improved the process by adding chemical stabilizers and other techniques.

A few products, such as clear PET water bottles, can be endlessly recycled into the same product without much disintegration of quality or contamination. However, in most plastic products, the quality of the plastic is reduced each time it is recycled, and there is a limit to its ability to be recycled. Technology is under development to break down plastic polymers into their most basic components or to find chemicals that will allow mixed-type plastics to be melted down together. This research is all in an effort to produce better and more cost-effective recycled plastic materials.

The end use or application varies depending on the type of plastic recycled, and so does the composition or the quality of the recycled material. Packing material can be made from plastics like PET, LDPE, HDPE, and PP, while construction and automotive products are often made from PVC. Textiles, such as polyester and nylon, can also be made from recycled plastics, such as PET bottles, nylon fabric, or fishing nets. For recycled plastics that come into contact with food, more extensive processing needs to be done to meet food-safety standards and often this is too expensive and difficult to be worthwhile for a manufacturer. The market for recycled plastic is limited due to the cost and lack of wide application of recycled plastic.

Recycling programs can save companies money, which promotes recycling initiatives. Many companies that generate large amounts of plastic waste use private recycling facilities that pick up the plastic waste to process it for free. For example, warehouses and distribution centers use large amounts of plastic stretch wrap and films. Recycling programs save the company money by eliminating the disposal costs of these packing materials, which adds up for large-scale operations. In some cases, businesses are even able to sell their plastic waste to recycling centers and generate a small profit.

The collection, sorting, and processing all affect the value and market for recycled plastic. For example, clear plastic is considered more valuable, since it can be dyed, once recycled, to any desired color, while colored plastics cannot be changed. The higher the recycling number, the more difficult and costly a plastic is to recycle, and PS and plastics designated as “other” are typically non-recyclable by conventional means. However, in some cases, products made from these plastics can be repurposed. Goods that are still usable can be sold if no longer wanted, and others can be used as parts for other products. For example, PVC pipes, which have additives that become toxic when recycled, can often be repurposed into a framework for outdoor furniture.

Many environmental activists and consumer advocate groups feel that plastic recycling is nothing more than a placebo that does little actual good for the environment or consumers since most plastic still ends up in landfills. Plastic waste is difficult to collect and sort properly, and reprocessing can release toxic materials into the environment. In addition, the economic value of plastic recycling continues to remain low. Many researchers recommend manufacturers and consumers instead turn to plastic alternatives and reduce the production of plastic goods, rather than rely on recycling to curb the problem of plastic waste.

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