Whether waste plastic is reused depends on the choices made once it is discarded.
This article is not as morbid as the headline suggests; it’s just that life and death are so intimately linked that mentions of both are of a certain necessity. Upon death, our body might find itself six feet below ground, contributing to the earth as the earth had contributed to it during life.
For plastic materials, it is just not the same. What plastic materials can offer in life, they can also offer in death, and then in life again and again and so on. What some humans might call reincarnation, for plastics read recycling or reuse. But, for waste plastic to be used again and again requires the right decisions to be made at every stage of its journey from being discarded to renewal.
Out with the old
Tom is a construction worker. The site on which he is working has just had a delivery of new, higher-quality equipment. His paint-stained, concrete-splattered plastic bucket is now deemed redundant. Tom throws it in the skip, starting a chain of events. At the end of the day, a hire company collects the full skips. The one containing the discarded bucket arrives at the recycling centre, where it can travel in several directions. Bear in mind that the bucket is a rigid plastic, most commonly made out of PP (number 5) or HDPE (number 2) and is fully recyclable. At this stage, there are three main choices:
- the bucket is sent to landfill with other waste;
- the skip’s contents are sent down a sorting line, with workers pulling out the materials they are told to. There are new technologies that allow this procedure to be done by machines and, in some centres, there may even be “artificially intelligent” waste sorting; or
- the bucket is sent for mechanical biological treatment (MBT), and becomes either refuse-derived fuel or solid-recovered fuel (SRF). In layman’s terms, it is incinerated.
Lee Bell, senior researcher at the National Toxics network in Australia, puts the three choices into perspective: “Recycling of plastic waste is becoming a critical issue in a carbon-constrained economy where there are strong indications that we have reached peak oil. As a petrochemical derivative, the fate of plastics is inextricably tied to increasing oil scarcity and growing oil demand. Plastics will become increasingly expensive to produce. Recycling them makes both economic and environmental sense.
“Landfilling plastics is an enormous waste of a resource and leads to groundwater pollution as acidic leachate extracts toxic chemicals from the plastic matrix. Incineration of plastic waste is far worse because it destroys the embedded energy of the plastic item [the energy used to extract, refine, produce and transport the petrochemical-based plastic] and converts many elements of the plastic, such as chlorine and flame retardants, into toxic air emissions and toxic ash for a paltry amount of calorific energy. Recycling plastic such as PET [polyethylene terephthalate] can save 26 times more energy as the calorific energy obtained by burning the plastic in a waste-to-energy incinerator.”
Quality control
In this case the discarded bucket has gone down the route of recycling, and has been picked out on the sorting line. Whether it successfully navigates the next stage of its journey to be turned into a new product depends on the quality control measures in place at the recycling site. The operations manager of a waste-recycling centre will be tasked with informing, educating and overseeing the sorting process. Through his or her guidance, the correct materials must not only be pulled out, but also separated correctly into the distinct types. In terms of plastic, there are seven categories.
If the plastic used to make the bucket is correctly identified it will be squashed and baled with similar material to compact it into a cube. This is fastened tightly with baling wire so that it is at maximum efficiency for transport. The bales will be stored until there is enough to warrant a collection. Scrap plastic dealers buy these bales and move them on to the next step. There are a few decisions that need to be made at this stage:
- Take the material to a UK storage site, where it can be collected in greater quantity.
- Send it to wash plants in central Europe. This is the preferred method.
- Load it immediately on to a container and ship it overseas, usually to China or south-east Asia.
Granulating and washing
At EU sorting plants the material will enter another sorting process, this one mechanical. Each polymer type will be segregated and granulated so that it is turned into little granules or pellets. These are then put through a washing process, in which solvents and liquids clean the plastic and filter off any sediment or alien material.
Often, granulating and washing are done by separate businesses. The old construction bucket is now part of a barrel of granulated plastic, which could be made up of anything from underground piping to wire cabling or kitchen aprons. This granulated polymer will be sold to manufacturing companies to make a new product.
Most of these remanufacturing plants are found in China and south-east Asia, although Germany has a sizeable remanufacturing market. A product remanufactured in China is likely to be shipped to the West, to be sold as something new.
Changing landscape
China is revolutionising its waste management processes, which, as its nascent closed-loop economy matures, will reduce demand for European plastics. When China begins collecting its own recyclable waste on a national scale, and starts to remanufacture at all stages, demand for waste from the West, particularly poor-quality recyclate, will decline. That could result in more of the West’s waste plastic going to incineration. China is already scaling back demand. In 2013, the Chinese authorities introduced their so-called “green fencing” policy, restricting the import of poor quality scrap plastic.
To ensure the “plastic bucket” does not end up in landfill or is incinerated, waste producers are advised to find out what happens to their waste materials after collection. Also, Europe now needs to improve its own capacity to reuse waste materials and not let valuable resources be lost.
Joseph Kennedy is marketing executive at plasticexpert UK.
