Scientists in the United States announced Tuesday that okra or other slimy plants can filter microplastics from wastewater without using synthetic products.
Their findings, presented at the American Chemical Society’s spring conference, may offer an alternative to the use of chemicals in wastewater treatment plants, which themselves pose health risks.
To filter out these microplastics and other unwanted elements, “we must use natural materials that are non-toxic,” explained lead researcher Rajani Srinivasan from Tarleton State University in Texas in a video.
Bhindi, also called bhindi, is used as a thickener in many cuisines, especially those from the West Indies, Louisiana, or South Asia.
Rajani Srinivasan noticed an application for microplastics, after studying the ability of this type of plant to purify water of pollutants of textile origin. With a size of 5 millimeters or less, these particles harm fish, particularly by disrupting their reproductive system or their development.
Microplastics come from the enormous amount of plastic produced since the 1950s, estimated at about 8 billion tons, of which only 10% has been recycled. Everything else is scattered around the planet, from oceans to rivers, in the air and even in our food.
Their consequences on human health, which are still little known, can be harmful. Microplastics can be carcinogenic and also mutagenic.
Wastewater treatment plants usually remove them in two steps: Those that float to the surface are left intact, and then chemicals called flocculants allow the rest to clump together to form clumps that are easy to filter.
But these flocculants, such as polyacrylamide, can decompose into other toxins.
So Rajani Srinivasan and his colleagues investigated whether easily accessible plants such as okra, aloe, cacti, fenugreek, tamarind or psyllium could take their place. Tests have been conducted using extracts of one or several plants from water contaminated with microplastics.
At the end of their experiment, they determined that the combination of okra and fenugreek extract was most effective in saltwater, and that the okra-tamarind type was the best solution for freshwater.
Polysaccharides, natural compounds derived from these plants, are less effective than synthetic polyacrylamides, if not more. And, above all, plant-based products are both non-toxic and already usable in wastewater treatment plants as they exist today.
Researcher Rajani Srinivasan hopes to eventually be able to commercialize the process to allow for greater access to clean water.
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