Our wastewater treatment plants are one of the biggest sources of microplastics that are polluting our rivers, according to new data from the American Geophysical Union. The data points to these tiny pollutants – pieces of plastic less than five millimeters wide – that escape treatment plant filters as having the potential to contaminate drinking water and enter our food system.
Rivers are important sources of drinking water for many communities and are also home to various fish and invertebrates that eat the tiny plastics, causing them to make their way up the food chain and possibly onto our dinner plates. Just as they do in the oceans, the presence of these materials in our rivers can lead to the presence of harmful bacteria and pollutants.
"Rivers have less water in them (than oceans), and we rely on that water much more intensely," Timothy Hoellein, who participated in the research, said in a press release.
The new study examined 10 urban rivers in Illinois and found that there is a significant amount of microplastics being released into rivers daily, with anywhere from 15,000 to 4.5 million particles per day, per treatment plant. Furthermore, in 80 percent of the rivers studied, wastewater treatment plants were a source of these dangerous plastics, regardless of the size of the river or type of wastewater treatment plant.
"[Wastewater treatment plants] do a great job of doing what they are designed to do - which is treat waste for major pathogens and remove excess chemicals like carbon and nitrogen from the water that is released back into the river," Hoellein said. "But they weren't designed to filter out these tiny particles."
Hoellein and his team are currently trying to determine how much of these plastics remains in the rivers and how much makes its way into the oceans in an attempt to better understand the entire lifecycle of these materials.
"The study of microplastics shouldn't be separated by an artificial disciplinary boundary," he said. "These aquatic ecosystems are all connected."
The study will be presented at the 2016 Ocean Sciences Meeting on Thursday, Feb. 25.
