Tarleton State University researchers have demonstrated that food-grade plant extracts, especially those from okra, have the power to remove microplastics from wastewater.

The health effects of ingesting microplastics are unclear, but studies suggest that people unintentionally consume thousands of particles every year.

They can be released from your clothing in the washing machine and end up in the city water treatment facility

In the typical wastewater treatment process, microplastics are removed from water 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.

Dr. Srinivasan, the Endowed Munson Research Professor of Chemistry at the Texas university, and her team have been investigating more healthy alternatives to the commonly used flocculant, polyacrylamide.

"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," said Associate Professor Dr. Rajani Srinivasan, the principal investigator for the project.

She has studied the use of food-grade plant extracts as non-toxic flocculants to remove textile-based pollutants from wastewater. "I was working with the removal of microorganisms and things like that, and I thought, ‘Why not try microplastics?'"

So she and a team of undergraduate and environmental science master's students tested polysaccharide extracts from 7 plants: fenugreek, cactus, aloe vera, okra, tamarind, and psyllium. They tested compounds from the individual plants as well as in different combinations.

They found that polysaccharides from okra worked the best. Paired with fenugreek extract, microplastics could be removed from ocean water, and the okra paired with those from tamarind worked best for freshwater samples.

Overall, the plant-based polysaccharides worked better than, or as well as, the traditional flocculant polyacrylamide.

Importantly, the plant-based flocculants can be implemented in existing water treatment processes.

"The whole treatment method with the non-toxic materials uses the same infrastructure," said Dr. Srinivasan. "We don't have to build something new to incorporate these materials for water treatment purposes."

She and her team will continue tailoring the ratios and combinations to optimize removal of different microplastic types from a variety of water sources. They also plan to scale up the removal process in field studies outside the lab.

Ultimately, they hope to commercialize the method and remove microplastics from water on an industrial scale.

The study and its results, funded by the National Science Foundation and a water development district in Lubbock, were presented at the March 20-24 spring meeting of the American Chemical Society, according to the University.

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