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Ask HN: Methods for removing parts per trillions of PFAS from water?

3 points by westurner ↗ HN
What are the most cost efficient methods for removing PFAS from water?

There is now $1.5b/yr in federal funding for PFAS removal from water supplies [2].

There is a $10-12b 3M PFAS settlement approved 2024-04-01 with hundreds of municipal water supply plaintiffs. There is a $1.2b DuPont/Dow PFAS settlement also with hundreds of drinking water provider plaintiffs. [1]

PFAS and microplastics and Nitrogen and Oxygen are in rainwater, which plants prefer. Crops don't need tap water levels of e.g. chlorine or fluoride, which damage the soil microbiome.

Municipal, commercial, residential, and farm to table customers need solutions for SDG6: Clean Water;

What are the low-cost and gold-standard sensors for water quality? And,

What are the most cost efficient methods for removing PFAS and microplastics from water supplies, ground water, well water, tap water, sea water, and hobbyist rainwater collection systems?

[1] https://apnews.com/article/pfas-drinking-water-settlement-3m-fa41cadfe0d65b9723377a681df43af1

[2] "Biden-Harris Administration Finalizes First-Ever National Drinking Water Standard to Protect 100M People from PFAS Pollution" https://www.epa.gov/newsreleases/biden-harris-administration-finalizes-first-ever-national-drinking-water-standard

6 comments

[ 337 ms ] story [ 630 ms ] thread
tfwnopmt
as my chemist friend who worked with the EPA used to say, “dilution is the solution to pollution”
westurner
/?hn pfas method: https://hn.algolia.com/?dateRange=all&page=0&prefix=true&que...

/? pfas method: https://www.google.com/search?q=pfas+method

"PFAS Treatment in Drinking Water and Wastewater – State of the Science" https://www.epa.gov/research-states/pfas-treatment-drinking-... :

> It is currently known that three treatment processes can be effective for PFAS removal: granular activated carbon, ion exchange resins, and high-pressure membrane systems

/?gscholar PFAS removal method + review: https://scholar.google.com/scholar?q=pfas+removal+method+rev...

Click "Cited by 131" to find Citations of e.g "Comparison of currently available PFAS remediation technologies in water: A review" (2021) https://scholar.google.com/scholar?cites=1170583541201234310...

/?hnlog https://westurner.github.io/hnlog/ Ctrl-F: water, CleanWater, SDG6

https://news.ycombinator.com/item?id=39731290 :

> "Desalination system could produce freshwater that is cheaper than tap water" (2023) : "Extreme salt-resisting multistage solar distilation with thermohaline convection" (2023) https://news.ycombinator.com/item?id=39507692

But does that also filter PFAS or microplastics?

"/?hn PFAS methods" found Magnetic and TODO removal approaches that aren't yet acknowledged by EPA for the purpose, but could be more sustainable and cost-effective.

westurner
OTOH, e.g. Spout has an atmospheric water generator product for preorder with a 98/99 water quality score; but does the water quality score account for parts per trillions of PFAS?

Do any of the solar+water products that sterilize and/or filter the water handle PFAS already?

Some types of under-sink water treatment systems already remove most PFAS.

If the user doesn't replace the filters what should it do?

FWIU reverse osmosis (RO) is a high-pressure membrane method that wastes water, but doesn't require replaceable filters?

unearth3d
Look at the biological "Algal Turf Scrubber" approach, some companies are trying to claim the phrase, but there's much experimentation globally, and a lot of field test installations.

This is a good overview; Sustainable, Decentralized Sanitation and Reuse with Hybrid Nature-Based Systems https://www.mdpi.com/2073-4441/13/11/1583?utm_campaign=relea...

westurner
"review" and "systematic review" are also good keywords for research. /? 'PFAS remov' might be a better search term

"Single-Step Method Swiftly Removes Micropollutants from Water" (2024) https://www.chemicalprocessing.com/industrynews/news/3301747...

"Multifunctional zwitterionic hydrogels for the rapid elimination of organic and inorganic micropollutants from water" (2024) https://www.nature.com/articles/s44221-023-00180-8 https://scholar.google.com/scholar?hl=en&as_sdt=0%2C11&q=Mul...

https://news.mit.edu/2024/zwitterionic-hydrogels-swiftly-eli... :

> Perhaps most importantly, the particles in the Doyle group’s system can be regenerated and used over and over again. By simply soaking the particles in an ethanol bath, they can be washed of micropollutants for indefinite use without loss of efficacy. When activated carbon is used for water treatment, the activated carbon itself becomes contaminated with micropollutants and must be treated as toxic chemical waste and disposed of in special landfills. Over time, micropollutants in landfills will reenter the ecosystem, perpetuating the problem.