Doing This May Remove 80% of Microplastics from your Drinking Water

There is a growing level of concern and awarness about microplastics in water, but a new study suggests that boiling water may remove many of these tiny particles.

What are Microplastics and Nanoplastics?

If you have not heard of microplastics in the past, the National Oceanic and Atmospheric Administration gives a quick recap here. (or just google "what are microplastics" and it should come up near the top of the list).

Essentially, microplastics are small pieces of plastics that are less than 5 millimeters long.  They are caused when small plastics are washed away or discarded, and they can also be created when larger plastics break down over time.  The widespread use of plastics combined with the difficult of filtering these small pieces has caused to them to become increasingly prevalent and widespread in our drinking water, lakes, and oceans.

And as you might expect, nanoplastics are similare but are even smaller.

Some microplastics with common examples include:

• polystyrene
  • foam-forms like in insulating coolers and cups, as well as packing peanuts
  • hard forms include items like some disposable razors and CD cases
• polyethylene (the most commonly produced plastic)
  • "HDPE" (high-density polyethylene) is used to make many common containers, like milk jugs and detergent bottles, as well as industrial-size products like municipal water lines
  • microbeads that are used as exfoliants in some health and beauty products, which were thankfully banned as part of the Microbead-Free Waters Act of 2015)
• polypropylene (2nd most commonly produced plastic)
  • found in many food-grade products (including many water bottle lids)
  • some clothing (though polyester has become a common replacement)

Does Boiling Water Remove Microplastics?

The experiment is titled "Drinking Boiled Tap Water Reduces Human Intake of Nanoplastics and Microplastics." According the the abstract, the authors claim to:

"present evidenence that polystyrene, polyethylene, and polypropylene NMPs can coprecipitate with calcium carbonate (CaCO3) incrustants in tap water upon boiling. Boiling hard water (>120 mg L–1 of CaCO3) can remove at least 80% of polystyrene, polyethylene, and polypropylene NMPs size between 0.1 and 150 μm. Elevated temperatures promote CaCO3 nucleation on NMPs, resulting in the encapsulation and aggregation of NMPs within CaCO3 incrustants."

Essentially, this means that boiling water causes the plastics to combine with calcium cabonate (aka the "hard" in "hard water" that is in most people's homes), then the combined particles then drop to the bottom, leaving a layer of cleaner water on top.

Visualization of the Precipitation of Microplastics ("NMP") and Calcium Carbonate (credit to the authors Yu, Wang, Liu, Li, and Zeng)

I do not have full access to the article, but I would expect two followup questions should be considered that weren't covered in the abstract.

1. Does the water need to be filtered after boiling (likely), and if so, what type of filter would be effective to remove the precipitate?
2. How does this compare to other filtration methods, such as reverse osmosis?

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