For this to happen though, we must implement efficient recycling processes so the plastics are handled correctly, and we can retain the highest possible purity.
Plant operators must opt for the highest-efficiency solution, which today, comes in the form of fully integrated pre-sorting and flake-sorting lines from a single manufacturer, rather than a mix-and-match from different suppliers.
The strain on recycling plants
Despite the ongoing battle against plastic pollution, the rate of plastic production continues to rise on a global scale. The latest figures suggest more than 359 million tons of plastic were produced for the global marketplace in 2018, a 3.2 per cent increase compared to the previous year. In total, the amount of plastic produced has tripled since 1990.
But the majority of this plastic doesn’t have a long-term future. In Europe alone, almost 40 percent of plastic produced is used for food and product packaging which, in reality, is single-use plastic. Most of these products are being incinerated or disposed of in landfills. This, partnered with the fact that more than a million plastic bottles are sold every minute worldwide, means there is more pressure on plastic producers and retailers than ever before.
With this rise in throughput comes the need for efficient recycling systems to ensure all material is handled correctly and brought back in the loop.
There’s a need for higher purity when it comes to recycled plastics to ensure the material meets regulations, too. Recycled content laws introduced in October 2018 mean that producers must now ensure plastic bottles have a minimum of 25 per cent recycled content by 2025 so plant operators must enable systems that can increase the purity and yield of their recycled plastics to a level that is suitable for re-use in food packaging.
Pledges have also been made to the Circular Plastics Alliance to increase the levels of recycled content in products. Those signing up to the initiative are taking action to boost the EU market for recycled plastics up to 10 million tonnes by 2025.
Utilizing the efficiencies of flake sorting
A way in which recycling plant operators can improve the purity and yield of the plastics they recycle is through flake sorting. This can help improve the output quality of the recycling process and also allow for more types of plastic to be efficiently sorted, so that recycled materials can be re-integrated into the loop to help reach the recycling targets set forth by the European Union.
Currently, there is a high demand for polyolefins, but recycling levels are still very low. Polyolefins is the collective name for materials which include polyethylene (PE) and polypropylene (PP), including different variations of the basic polymers, such as high-density polyethylene (HDPE) and low-density polyethylene (LDPE). Although the recycling market for high quality and pure recyclates has been traditionally more focused on PET, the demand for recycled polyolefins signals its importance for the market and the need to recycle these materials efficiently. In order to further accelerate recycling rates and output quality, plant operators increasingly rely on flake sorting: a technology that is already successfully used in PET recycling plants and marks the difference between downcycling and upgrading plastics.
The flake sorting process of PET bottles consists of various steps: after a first step of pre-sorting, rejecting impurities both by color and material type as well as a subsequent washing process, the bottles are put into a grinder or shredder, and turned into flakes. Once the bottles have been shredded, the resulting flakes contain high amounts of PP/PE (which comes mostly from the bottle caps), pieces of metal, PVC from remaining labels and small quantities of other contaminants. The flakes then go through a vigorous cleaning process which involves different combinations of metal separators, sieves and air separators -called wind-sifters- and multiple steps of flotation, hot and cold washing, rinsing and drying, which reduces overall contamination.
Even though very effective, small amounts of remaining contaminants are able to survive the process due to their size, density or magnetic characteristics. In fact, small impurities and color deviations can negatively affect the recyclate, which is later on being used to make another PET beverage bottle. Therefore, sorting out all impurities to generate PET granulates that have the same quality as primary plastics should be targeted . A high-technology, sensor-based solution, is necessary to purify the flakes up to the required standards and to remove any left-over contaminants. Thanks to these highly precise machines, extremely high levels of purity can be achieved, which in the end allow for more PET bottles being recycled and kept in the loop and out of our landfills.