A recent research has found that coriander leafs are a potential biosorbent that can remove lead and other toxic heavy metals from water.

Coriander or cilantro, the leafy herb used to garnish a wide variety of everyday Indian cuisine, has started attaining fame in the United States as a possible low-cost herbal remedy to purify drinking water.

The discovery holds the potential to address the heavy metal contaminated groundwater problem in the industrial belts of the country. P.S. Harikumar, who heads the water quality division of the Centre for Water Resources Development and Management (CWRDM), told The Hindu that Kerala has a serious heavy metal contaminated water problem for various reasons.

The industrial areas of Ambalamedu, Kalamassery, Eloor and Chavara are some of the highly contaminated areas. Lack of proper solid waste treatment also aggravates such contamination when items like batteries, cosmetics and electrical appliances are carelessly dumped, Dr. Harikumar says.

The discovery of the coriander potential to purify such water could also compliment the ongoing CWRDM programme to find various methods to address the heavy metal contamination problem in the State, he says.

Possessing a flavour that everyone savours, the coriander leaf (Kothamalli in Malayalam) “has the ability to drink up heavy metals like lead and nickel that have leaked into groundwater.” Studies are continuing to learn how well the herb can remove other heavy metals such as arsenic and mercury.

The discovery was presented on September 12 at the 246th annual National Meeting and Exposition of the American Chemical Society (ACS) by scientist Douglas Schauer of Ivy Tech Community College of Indiana, who led a research team to Mexico to find low-cost materials that could filter away industrial pollutants in groundwater. The research report has been published by the ACS.

Cilantro is also a commonly used cooking herb in Mexico, which also has a serious groundwater pollution problem, Prof. Schauer said. “Our hope is for somebody who lives in such regions to simply be able go in their backyard and grab a handful of cilantro, maybe let it dry out for a couple days sitting on a rock in the sun, and then maybe a handful of that would purify a pitcher of water,” he said.

He also believes that dried cilantro could someday be packaged like teabags, or as reusable water-filter cartridges to remove heavy metals from impure water.

Prof. Schauer says a handful of cilantro would neatly filter away lead from a pot full of highly contaminated water. He say the secret of cilantro’s purifying power lies in the structure of the outer walls of the microscopic cells that make up the leaves. The architecture of these walls makes them ideal for absorbing heavy metals. On the basis of the finding, the Voice of America in September-29 ‘Learning English Newsletter’ described coriander as a “miracle herb”.

Though activated carbon is the most popular material used in water purifiers, it is too expensive for most developing countries. Prof. Schauer says that coriander is an inexpensive way to purify drinking water. it is not only cheaply available but also available in plenty, he adds.

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