Neither washing machines nor wastewater treatment plants can filter microplastic fibers from our clothing satisfactorily. With the wastewater from our households, the tiny microplastic fibers that break during washing get into the wastewater treatment plants.
However, countless particles escape the filter systems and make their way into our waters. According to a study from the University of California at Santa Barbara, an average of 60% – 99% of the microplastic particles can be filtered out of the water.
In Germany, only 20 of about 10,000 wastewater treatment plants have the so-called treatment stage 4, whose primary purpose is to purge our wastewater of medical waste.
Microplastic fibers are exceedingly difficult to filter. Due to their shape and streaming properties, they pass the filter systems much more often than other types of microplastics, such as pellets, microbeads from cosmetics and other plastic fragments.
Even if they can be filtered, the plastic particles end up in the environment via sewage sludge. If the sewage sludge is not incinerated, it is used as fertilizer in the fields. From here, the microplastic particles bound in the sewage sludge make their way into the oceans.
Another problem is collective sewer overflows. They act to relieve the sewage system in rainy conditions. In order to prevent backwater in households in case of heavy rain, the wastewater flows through the sewers untreated.
Incidentally, wastewater from the gullies does not take the detour via a wastewater treatment plant, but gets into our water widely unfiltered. This way, microplastic particles from tires and shoe soles, as well as microplastic fibers that are in the air and in the sewage sludge, pollute our environment.
To sum up: For technical reasons, the filter facilities of the wastewater treatment plants are not sufficient to prevent the pollution of our oceans by microplastics.
What can we do about it? We have to rethink our buying habits, as well as conforming our washing habits.