Many people wonder what happens to the plastic containers they deposit in curbside recycling, bring to redemption centers, or drop into recycle bins in classrooms and offices all over the world. The plastic recycling process requires several steps to turn discarded plastic into new products. One thing that people should be aware of when thinking about this process is that the plastics are usually downstreamed. In other words, instead of turning old yogurt containers into new yogurt containers, the material from the original container is used to make a different type of product, because it cannot be used in the same way twice.
The first step is sorting out the different types of recyclable products at a recycling facility. Many regions use single stream recycling, in which all items are collected at once, so first it's necessary to separate out basic categories like paper, plastics, and metals. Next, the plastic needs to be sorted for recycling.
During sorting, plastic is divided by type. Some facilities will only process certain types of products, which means that items they can't handle may be sold to another facility that can handle them, or put into a landfill, depending on company policy. Consumers who are worried about whether or not their plastics will be recycled may want to ask their recycling company about what they do with items they cannot process.
After sorting, the plastic is ground into chips or flakes. At this point, it is usually mixed with a lot of impurities, including pieces of labels, bits of the material the plastic once held, and so forth. As a result, it needs to be washed in a bath that will get the plastic clean, before it is dried and then melted. Once melted, the material is formed into pellets known as nurdles.
The nurdles can be used as feedstock for other manufacturing processes. For example, they can be turned into fibers to make products such as artificial fleece, or they can be worked into engineered wood products, used to make carpeting, and utilized in the production of products like floor mats and tiles. Companies that want to use recycled plastic can buy these pellets by the truckload for various applications.
Plastic recycling is not simple. One problem is that dyes can contaminate the material, making it difficult and sometimes impossible to recycle. Plastics can also be contaminated with impurities like heavy metals, pharmaceuticals, and pieces of biodegradeable plastic that accidentally get mixed in with items made from petroleum. Recyclers attempt to identify these impurities before they contaminate an entire batch, but this is not always possible.
While recycling is definitely a good thing to do, it does not necessarily reduce the demand for virgin plastic. Products made with virgin plastic usually cannot be made from recycled materials. Recycling plastic does reduce the demand for other resources, however. For example, by making engineered lumber with plastic, it is possible to save trees.