New research will identify how microplastics are transported into waters

Microplastics or microbeads are bits of plastic under five millimeters in size. Image courtesy of Kansas University.
Microplastics or microbeads are bits of plastic under five millimeters in size. Image courtesy of Kansas University.

Microplastics or microbeads are bits of plastic under 5 millimetres in size. They are found in cosmetics, cleaning products and clothes and are listed as a toxic substance under the Canadian Environmental Protection Act.

A 2015 U.S. federal law banning tiny plastic beads in some exfoliating products left many sources of microplastics unaddressed. In Canada, the manufacture, import and sale of toiletries that contain plastic microbeads will be prohibited by July 1, 2018.

“Everyone is reliant on plastics in their daily life,” said Belinda Sturm, associate professor of civil, environmental & architectural engineering at the University of Kansas. “We tend to think about pollution from the plastic that we can see — but we’re putting out a lot of tiny fibres from clothes washing and personal care products, and those accumulate in our environment and climb up in the food chain because they’re small enough to be consumed by zooplankton and fish.”

Once in the water, plastics damage aquatic life and eventually harm human beings, according to Sturm.

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“These plastics can absorb other chemicals and can act as a carrier for drug release through the environment,” she said. “They can absorb microbial communities; a microbial community carried on plastic can be transported much farther than it otherwise would. From a human health perspective, microplastics can be consumed by aquatic organisms and move up the food chain — and eventually be eaten by humans.”

Now, Sturm is leading a three-year US$300,000 effort supported by the National Science Foundation to identify how plastics are transported into waters. Strum said she hopes to reduce harm to marine ecosystems by engaging municipalities through a full-scale sampling campaign and web-based database that is publically accessible.

Extracting microplastics at a wastewater treatment plant. Image courtesy of Kansas University.

According to Sturm, microplastics enter water systems in large part through municipal wastewater treatment plants. But scientists haven’t yet accurately estimated the amount of microplastics that enter the environment through U.S. municipal wastewater treatment plants.

“We’re going to be partnering with utilities across the country, and they’re going to sample their wastewater treatment plants, and we’ll quantify plastics release at wastewater treatment plants,” she said. “We’ll utilize an EPA database that shows how much flow is released by all plants in the country, and we’ll use our measurements and this database of wastewater discharges to come up with national release estimate.”

Sturm said that wastewater treatment plants generally don’t make a special effort to remove microplastics from the water they handle. “Right now, they’re not regulated or purposely removed from the water at all,” she said. “If they’re removed, it’s just happenstance.”

Thus, microplastics can enter the environment as part of plants’ effluent discharge or included in biosolids that are landfilled or spread on agricultural lands.

“Biosolids, depending on the treatment plant, can be land applied,” Sturm said. “In this study, we’re going to be determining if those plastics just end up going into our waterways as runoff — that’s a roundabout way for our water to be contaminated.”

Researchers will work with municipal utilities throughout the U.S. to conduct sampling that will give a better estimate of the amount of microplastics present in their effluents and biosolids. Sturm said the data would offer the most complete picture of microplastics contamination from U.S. sources.

Simultaneously, Sturm will test whether biofilms containing “extracellular polymeric substances” or EPS could help to clean water of more microplastics at wastewater plants.

“We think when there is more EPS in the system we will get better removal,” she said. “If I prove that to be true, then we can investigate how to get microorganisms to produce more EPS. If I can control that with engineering design and operation, I can improve removals.”

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