Where does the microplastic come from? So far there has been one main answer: from the tire abrasion that is rubbed off the tires when driving. Given the current volume of traffic, this adds up to significant amounts. In Germany alone, the rain washes almost 100,000 tons of abrasion from the streets into the soil and the sewage system. calculated the Federal Institute of Hydrology. However, researchers suspected that there were other significant sources; after all, the small plastic particles can now be found all over the world from Antarctica to the eleven kilometer deep Mariana Trench. According to the International Union for Conservation of Nature, 3.2 million tons of microplastics enter the environment every year.
We have now made a step forward in finding the cause: a significant part comes from recycling plants, determined environmental scientist Deonie Allen from the Scottish University of Strathclyde. She systematically examined the emissions from a recycling factory. There, huge mills chop the waste into small pieces – into microplastics, if you will. Allen found that 13 percent of the mass of plastic waste goes directly into the factory’s wastewater as microplastics. If it is not filtered, the company washes it into the next river, where the researcher was also able to detect it in large numbers. However, if the wastewater is filtered, the amount of escaped microplastics drops to six percent of the total amount of waste processed. Still a lot, according to Allen. Each recycling plant processes tens of thousands of tons per year.
Recycling factories, along with road traffic, are significant contributors to planetary microplastic pollution. This raises a fundamental question: Is recycling plastic really a sustainable solution?
The industry is committed to recycling, although many problems have not yet been solved
The answer should be better available before the course is fully set for a circular economy. It was only at the beginning of September that the Federation of German Industry, the Association of the Chemical Industry and Plastics Europe Germany committed themselves to a concerted initiative to convert plastic production to recycling: reused instead of “virgin”, as experts call “new plastic made from petroleum”. , consumer goods made of plastic will be the majority in the future. The Packaging Act has stipulated a material recycling quota of 70 percent for plastic packaging since 2022. However, Germany is still a long way from that: so far, the vast majority of the yellow bin is burned and only the waste heat is used.
The fact that recycling, of all things, is making global microplastic pollution worse has a mixed response among experts. “You shouldn’t throw the baby out with the bathwater,” warns Hans-Josef Endres, head of the Institute for Plastics and Circular Technology at Leibniz University Hannover. “Recycling is the right way to conserve finite resources such as petroleum and to make wise use of a material on which the entire modern world depends, from smartphones to shoes, cars and wind turbines.”
“Recycling is not the solution,” says Lisa Zimmermann, a biologist who did her doctorate on the subject of microplastics and works at the Food Packaging Forum Foundation. Microplastics are created from every plastic item. These small particles enter the environment, animals and humans breathe them in and swallow them with their food. The consequences are unclear, as is the ecological damage caused by pollution. When taken to its logical conclusion, Zimmermann’s argument calls for a gradual exit from the age of plastic.
Consumer goods must be designed in such a way that cycles can be closed
That would take time. This makes the question of how dirty recycling really is and what solutions there could be even more pressing. When shredding, most microplastics are created when brittle and hard plastics are shredded, Australian researchers led by Michael Stapleton from the University of Wollongong reported in August 2023. Polycarbonate, which bicycle helmets are made of, for example, left behind the most microplastics. This was followed by polyethylene terephthalate PET, the material for plastic bottles. This was followed by the packaging plastics PP (polypropylene) and HDPE (high density polyethylene).
If the mills that crush the plastic run quickly, more microplastics are created, says recycling researcher Hans-Josef Endres. Deonie Allen also found that the cutting mill in the factory she examined produced a lot of microplastics. That in the wastewater can be filtered. However, according to the researcher, this only removes the coarse particles larger than ten micrometers. The smaller ones passed through the filters of the system examined unhindered. “The problem with finer filters and membranes is that they become clogged with microplastics very quickly,” says Endres. The removal of microplastics from household wastewater as well as from plastic recycling companies is still an unsolved technological problem.
But there are no recycling processes for which the plastic waste does not have to be shredded – with only one exception: PET deposit bottles. They are simply cleaned and refilled up to five times. Multiple use would involve less microplastics – and also be more energy efficient – than recycling the material.
It is a demand as old as recycling itself that consumer goods must be designed for reuse so that cycles can be meaningfully closed. Deutsche Umwelthilfe has long been calling for even more deposit systems like those for PET bottles. The federal government is initially extending the deposit requirement to plastic milk and juice bottles from 2024.
“Design for recycling” is a theme, says Plastics Europe Germany. But the industry also relies on chemical recycling, for which packaging does not have to be reused and the waste does not have to be sorted. The initiative of the Federation of German Industries, the Association of the Chemical Industry and the Plastics Manufacturers is committed to these processes, in which the massive crackers of the petroleum industry are fed at the end of the process. But chemical recycling also doesn’t work without shredding, says Hans-Josef Endres. The microplastic problem would therefore remain.
After all, it is easier to avoid a pollutant that escapes at certain points, like in a factory. It would therefore be more possible to reduce microplastic emissions in factories than in millions of driving cars – assuming appropriate environmental technology existed.
But at the moment, fresh plastic made from petroleum is still so cheap that many recycling companies are closing, according to Plastics Europe Germany. As long as recycling remains a second choice during periods of high oil prices, it remains unlikely that the industry will voluntarily improve production standards to protect the environment. Endres is nevertheless confident that things are developing in the right direction: “We get quotas for recycled plastics everywhere. According to a proposal from Brussels, 25 percent of new cars should be made from used plastics from old cars. These requirements will be more for recyclers Provide planning security.” Then they would just have to become cleaner when their order books are full.