STEPHENVILLE, Texas - Tarleton State University researchers believe they have demonstrated how combinations of food-grade plant extracts have the power to remove microplastics from wastewater.
Specifically, the extracts came from plants like okra, aloe, cactus and psyllium.
The researchers presented their findings last month at the virtual spring meeting of the American Chemical Society.
Typically, microplastics are removed by either skimming off the items that float at the top or by adding flocculants, or sticky chemicals that attract microplastics and form large clumps. The clumps then sink to the bottom of the water and can be separated from it, according to the university.
Lead researcher Dr. Rajani Srinivasan said some substances used to remove microplastics are potentially harmful. That’s why her team has been investigating non-toxic alternatives.
"We think that microplastics by themselves may not be much of a health hazard, but anything they get into or any type of toxic substance that gets attached to them could go inside our bodies and cause problems," she said in a news release.
Her team tested polysaccharide extracts from fenugreek, cactus, aloe vera, okra, tamarind and psyllium as flocculants to capture microplastics. They also tested compounds from the individual plants as well as in different combinations. They realized that polysaccharides from okra combined with those from fenugreek could best remove microplastics from ocean water, whereas polysaccharides from okra combined with those from tamarind worked best for freshwater samples.
The team said overall, the plant-based polysaccharides worked better than, or as well as, the traditional flocculant polyacrylamide, depending on the combination of extracts and water source.
"The whole treatment method with the non-toxic materials uses the same infrastructure," Srinivasan continued. "We don’t have to build something new to incorporate these materials for water treatment purposes."
The team of researchers said they will continue experimenting with non-toxic alternatives to remove microplastics from a variety of water sources. They would also like to replicate their experiments outside of the lap and hope to commercialize the method on an industrial scale.
There’s a growing concern across the country about microplastics contaminating various water sources.
In 2020, scientists at the San Francisco Estuary Institute found significant amounts of microplastic washing into the San Francisco Bay from storm runoff over a three-year sampling period that ended last year. Researchers believe the black, rubbery bits no bigger than a grain of sand are likely from car tires, said Rebecca Sutton, senior scientist at the institute. They will present their findings at the conference.
A study published in 2019 by Portland State University found an average of 11 micro-plastic pieces per oyster and nine per razor clam in the samples taken from the Oregon coast. Nearly all were from microfibers from fleece or other synthetic clothing or from abandoned fishing gear, said Elise Granek, study co-author.
Other researchers have previously said bans on plastic bags, Styrofoam carry-out containers and single-use items like straws and plastic utensils will help when it comes to the tiniest plastic pollution.
The Associated Press contributed to this report. This story was reported from Los Angeles.