Plastics have revolutionized consumer goods. Cheap, versatile and durable, they’ve made whole classes of new products possible and reduced the price of others to the point where everyone can afford them. They’re a nightmare from a waste disposal point of view, though. Many types of plastic can take hundreds or even thousands of years to biodegrade. Huge quantities have ended up in landfill since the early 20th century and more is floating in the oceans, sometimes forming artificial islands of trash dozens of miles across. As well as the environmental damage of all this junk there’s the resources used to make it; most plastics are made from oil, a vital but finite resource. Efficient recycling of plastic waste is vital.
Because there are so many different plastics a wide range of recycling technologies are used to deal with them. Efficient sorting is key; different types often can’t be mixed to produce even low-grade material. Early systems worked with bulk waste that had been presorted by type but modern recycling plants use infrared technology to identify and automatically sort different varieties of plastic. These can then be processed appropriately.
One of the biggest challenges is plastic drinks bottles, made from polyethylene terephthalate (PET). Tens of millions of these are discarded every day in the USA, and unlike older glass bottles they can’t be reused. They can be processed into other products though.
First, bottles are sorted by color. Most of them are clear, making the process easier. Once sorted they’re washed and shredded into small flakes. The washing and shredding process removes scrap like labels and bottle tops, which are made of different materials. The clean, flaked PET is compressed into bales and sold for reuse.
Flaked PET can be heat-formed into a variety of products. It’s often used for packaging materials; clear PET waste can be made into clamshell or blister packs, used for packaging many small items. If it’s appropriately sterilized it can be made into new food containers; molten PET is blown into molds to produce new jars or bottles. It can also be injection molded for a variety of purposes.
One use that’s becoming increasingly popular is fabric manufacture. Heated PET flakes can be spun into fibers, which can then be woven into cloth. The result is a strong, hard-wearing fabric, although it’s usually too rough to be work next to the skin. It’s widely used for heavier duty items though, including bags, coats and hats. As recycling becomes more widespread environmentally friendly consumers are increasingly demanding these products.
Recycling plastics tends to be energy intensive, as heat is needed for most stages of the process, but it’s also something that needs to be done on a larger scale than it is now. Plastic in landfills can take a very long time to decompose, and as it does it releases toxins into the soil (and sometimes the water supply). Burial of plastics also adds up to a huge waste of valuable resources. Luckily improved recycling technology is making the process more economical and opening new uses for the recycled material.