Boiling removes microplastics from water

Published 3 March 2024
- By Editorial Staff
In hard water containing 300 milligrams of CaCO3 per liter, up to 90% of microplastics were removed after boiling.

Boiling water can remove microplastics, according to a Chinese study. Boiling hard water could remove up to 90% of plastics.

The study, published in Environmental Science & Technology Letters, sampled water from the city of Guangzhou in China with so-called nano- and microplastics. Microplastics are plastic particles that are 5 millimeters or smaller and are found in everything from water to soil to air.

The samples were boiled for five minutes and allowed to cool, then the team measured the levels of free-floating plastic. Water can be “hard” or “soft,” the difference being the amount of calcium and magnesium ions it contains, the more of these the “harder” the water.

Boiling hard water, which is rich in minerals, produces a chalky substance called lime or calcium carbonate (CaCO3). This substance has been found to form crystal structures that encapsulate microplastics.

In hard water containing 300 milligrams of CaCO3 per liter, up to 90 percent of free-floating microplastics were removed after boiling; even at lower concentrations, such as 180 milligrams, up to 84 percent were removed. In soft water, with less than 60 milligrams per liter, about 25 percent of the plastics were removed.

Wide variation in water quality

A 2022 study tested the levels of microplastics in participants and found that 80% had them in their bodies. Very little is known about how microplastics affect health, but some studies have shown that they affect the bacteria in the stomach.

Asian countries have a long tradition of drinking cooled, boiled water because it is believed to be good for health, but this has not been scientifically tested. The researchers suggest that boiling water could be a simple but effective way to reduce unhealthy consumption of microplastics.

“Because the presence of NMPs (nano/microplastics) and water quality is uneven around the world, the effect of boiling water to reduce NMPs may vary from region to region”, the researchers wrote. “Nevertheless, our results have confirmed a very feasible strategy to reduce human exposure to NMPs and laid the groundwork for further investigations with a much larger number of samples”.

The study was conducted by researchers from Guangzhou Medical University in collaboration with Jinan University.

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