How Does It Work: Recycling Plastic

How Does It Work: Recycling Plastic

We all know that recycling is important – it’s one of the best ways we have to conserve resources and to keep our environment clean. But how do we actually get new products out of all those old soda bottles, packing peanuts, and shopping bags?

First things first – what’s in plastic, anyway?

Plastics are basically long chains of molecules all bound together into compounds called polymers. These polymers can come from a number of different sources, but right now almost all plastics are derived from fossil fuels like oil and natural gas (although new technology is being developed to build plastics from biological sources like corn). The molecules in these polymers can be arranged in lots of different ways, and each polymer creates a unique plastic with its own distinct properties. For example, the plastic HDPE (high density polyethylene) is commonly used to store reactive liquids like bleach and detergent while PVC (polyvinyl chloride) is used in construction because of its durability. The recycling symbol we’re all familiar with – a number surrounded by three arrows – is actually stamped on plastics to identify the type of polymer from which it’s made.



How do we recycle it? The recycling process starts with those numbers on the bottom of your packaging or milk carton – because mixed polymers can’t be reused, all waste must be sorted before the plastic can be processed. We can look at the identification numbers, but most recycling facilities use infrared or other types of scanners to quickly and efficiently sort plastics. Once the plastics are separated, they are shipped off to a larger facility where they will be cleaned, shredded, melted down, and then cooled into pellets of pure polymer (known, for some reason, as nurdles). These pellets are then used by manufacturers to make new products – that’s how the bottle you drop off at your local recycling center eventually gets turned into carpets, platestoys, or other plastic products.

Sounds easy – so why don’t we recycle more?

The process sounds simple enough, but only a small amount of our annual plastic waste gets recycled. Of the 31 million tons of plastic thrown away in the U.S. in 2010, only 12% was recovered for recycling. A lot of the problem is getting people to recycle, but it’s also true that not all plastics can easily be recycled. Because each type of polymer has to be handled separately, it can be financially difficult for smaller recycling centers to accept and sort all plastics, and some polymers are more difficult to reuse than others. Right now there is a large market for recycled PET and HDPE (#1 and 2, respectively), which are the two easiest polymers to recycle, but fewer facilities exist to process harder-to-recycle plastics like polypropylene (#5).

Another problem with plastics is that the process of recycling degrades the polymers, which means that even when we put plastics in the green bin, those products don’t make their way back to us as bottles or food packaging. Instead, recycled plastic is used to make lesser quality products like textiles, car parts, and construction materials that are themselves not recyclable. For example, the main end product for recycled PET is carpets and textiles while shopping bags usually get turned into plastic lumber. This process, known as downcycling, means that eventually all plastics will reach a point where they can’t be recycled anymore and will end their lives in a landfill.

How can I help?

Recycling plastic starts at the local level, so the first step is to learn what kinds of plastics are accepted by the waste facilities in your area. Once you’re familiar with your city’s programs you can make sure all the plastic from your home or office is getting where it needs to be. You can also help by being a smart shopper: look for plastic products and packaging you know will be accepted for recycling in your area and support businesses that make products using reclaimed materials. Lastly, try to make recycling plastic easier for everyone by getting  involved with your community. Lobby for your city to accept all types of plastic and for bins to be available in public spaces like parks, schools, and shopping centers. After all, the recycling process can’t get started until you put all that plastic in the right bin.


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