Microplastics are defined as "extremely small pieces of plastic debris in the environment resulting from the disposal and breakdown of consumer products and industrial waste.". They are so common in our environments that they are introduced to sewer systems and municipal wastewater treatment plants through everyday tasks like doing laundry or using the bathroom. These microplastics, less than 0.2 inches, come from hundreds of sources including, textiles (washing machines), human waste (food packaging), water bottles, storm sewers, tire wear, etc.
You might be wondering, what happens once the microplastics get to the wastewater plants? Once they arrive at the treatment facility, roughly 99% of these materials are retained in the solids removal processes of both primary and secondary sludges. In the United States, about half of these sludges are land applied. Although biosolids are subject to several regulations to prevent harm to the environment, limits on microplastics have not been developed.
Research into sources, volumes, and potential impacts of microplastics are currently underway in both the EU and the United States. At this point in time, the primary efforts to control microplastics are through source control, such as limiting plastics in packaging.
Citation
“How Plastics Breakdown into Microplastics.” How Plastics Breakdown into Microplastics | Plastic Action Centre, plasticactioncentre.ca/directory/how-plastics-breakdown-into-microplastics/.