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Instant water cleaning method ‘millions of times’ better: study

cardiff.ac.uk

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Re: Instant water cleaning method ‘millions of times’ better: study

#31

Post by mabbo »

rmah wrote: post #20

Yeah, the use of "millions of times better" just doesn't pass the sniff test. Given that current commercial methods kill 90%+ bacteria in water, thus, nothing can be even 2x better...and makes me suspicious of any claim in the article. Hopefully it can help people in areas that are currently without clean water, but I'm not holding my breath.

> Given that current commercial methods kill 90%+ bacteria in water, thus, nothing can be even 2x better

That depends how you look at it. Is it 90% killed, or is it 10% survived? If it's 10% survived, then 100m times better is a system where 10/100m % survived instead.

Re: Instant water cleaning method ‘millions of times’ better: study

#32

Post by icegreentea2 »

slownews45 wrote: post #23
icegreentea2 wrote: post #14

Earlier quoted context omitted.

The specific measure appears to be in CFU/mL of E. Coli in their test sample before and after. As you suspected, this does not include filtering or settling, just clearing out bacterial contamination. I haven't read the paper yet (paywall)- just looked at their supplementary data. The increased effectiveness appears (guessing here a bit) to be in terms of bacteria load reduction given similar concentration of bacteri…

The thing is, commercial methods can already do 4 or 5 log reduction on E Coli. I'm not even sure that is necessary usually. I'd focus on other benefits - ie, removal of other compounds etc.

Right, I don't think these they were really gunning for developed commercial systems for this. Their pitch would be this would be more useful for situations where we might not want to be tied to a chemical supply line. Thanks to fellow poster, I have now started reading the paper. The last sentence of their intro reads:

> This approach offers the potential for in situ water purification that could, we propose, be suitable for decentralized applications.

Re: Instant water cleaning method ‘millions of times’ better: study

#33

Post by kapp_in_life »

gentleman11 wrote: post #19
gundmc wrote: post #8

How much gold and palladium are required? Those are massively expensive catalysts and it feels borderline disingenuous to talk about how this will bring clean drinking water to the masses without so much as mentioning cost.

> The catalyst-based method was shown to be 10,000,000 times more potent at killing the bacteria than an equivalent amount of the industrial hydrogen peroxide Even if it required a fair bit, 10M is a really big number. Long term savings would be huge since the catalysts aren’t consumed in the reactions

Is hydrogen peroxide "good enough" such that it doesn't matter? Like saying I'm 10 million times less likely to drown watering a lawn than I am washing a car isn't important, because the odds of either happening is vanishingly small.

Re: Instant water cleaning method ‘millions of times’ better: study

#34

Post by nine_k »

gundmc wrote: post #8

How much gold and palladium are required? Those are massively expensive catalysts and it feels borderline disingenuous to talk about how this will bring clean drinking water to the masses without so much as mentioning cost.

How much platinum and palladium catalytic converters in cars [1] consume? There are at least tens of millions of cars with such converters.

Catalysts don't get used up, and metals of platinum group are 100% recycleable.

[1]: https://en.wikipedia.org/wiki/Catalytic_converter

Re: Instant water cleaning method ‘millions of times’ better: study

#35

Post by gus_massa »

rmah wrote: post #20

Yeah, the use of "millions of times better" just doesn't pass the sniff test. Given that current commercial methods kill 90%+ bacteria in water, thus, nothing can be even 2x better...and makes me suspicious of any claim in the article. Hopefully it can help people in areas that are currently without clean water, but I'm not holding my breath.

Here the 10^8 improvement means that if the commercial method kills 99% of the bacteria, this method kills 99.99999999% of them.

Re: Instant water cleaning method ‘millions of times’ better: study

#36

Post by jimmaswell »

tristor wrote: post #4

Wow, that’s incredible. Since it uses electricity for it’s energy input, this could be readily adapted for use in remote areas powered by solar plus battery. Even in Western nations this is a boon to treat well water sources instead of shock chlorination. This combined with GAC filtration can produce very clean water anywhere you can get sunlight.

This is reminding me of the water purification device in Fallout 3.

Re: Instant water cleaning method ‘millions of times’ better: study

#37

Post by perihelions »

slownews45 wrote: post #5

Anytime you read things like 100,000,000 times more effective - you should be asking, what was the numerator or denominator in this. Or are they just describing some tiny part of the system. For example, normally you need to filter, do settling for sediment etc - how did they solve all this? Given the orders of magnitude involved here a 5 MGD plant could produce 500 trillion gallons per day of "commercial approach" w…

If I've understood correctly, the denominator being compared against isn't a "best available alternative" treatment solution of H2O2. It's against the concentration that's an "equivalent amount"-- which is actually a pretty dilute concentration (for H2O2), that *isn't* effectively bactericidal.

>"...are over 10^7 times more potent than an equivalent amount of preformed hydrogen peroxide..."

Per fig. 2(c,d), the "commercial H2O2" items are solutions of 100 and 200 ppm (0.01% / 0.02%), and have nearly zero effect (less than 1 order-of-magnitude reduction in bacterial/viral viability).

([edit]: or quoting the paper itself: "These standardized preformed H2O2 samples, produced either commercially or catalytically (100–200ppm), exhibited limited bactericidal activity [my emphasis] against...")

Their actual point is that this H2O2+ROS is highly effective at a concentration at which H2O2 alone is not effective.

https://www.researchgate.net/publication/352882305_A_residue...

~~~~~

[edit]: In attempt to find further context, here's some data about disinfection with H2O2 solutions (in entirely different experimental setups which probably have important caveats I don't know):

>"...organisms with high cellular catalase activity (e.g., S. aureus, S. marcescens, and Proteus mirabilis) required 30–60 minutes of exposure to 0.6% hydrogen peroxide for a 10^8 reduction in cell counts, whereas organisms with lower catalase activity (e.g., E. coli, Streptococcus species, and Pseudomonas species) required only 15 minutes’ exposure [657]..."

https://www.cdc.gov/infectioncontrol/pdf/guidelines/disinfec... (page 47)

So, as a hand-waving non-expert: it looks like you can get the same order of magnitude of effect (factor of 10^8 bacterial reduction) as the stuff in the OP paper, at a hydrogen peroxide concentration that's ~60 times higher than what OP uses (0.6% = 6000 ppm). (?)

Re: Instant water cleaning method ‘millions of times’ better: study

#38

Post by jay_kyburz »

grenoire wrote: post #2

It seems that for both desalination and sanitation (as discussed in the article) of water is now an energy issue. What are some other basic problems (food, water, temperature management, etc.) we're facing that are primarily energy-bottlenecked?

I don't think its fair to say they are "energy" issues, or that they are bottlenecked by a lack of energy.

When building the desalination plant, we can build a solar farm right next door.

The problems are political. Nobody is willing to go out and spend the money.

My hope is that when automation starts taking peoples jobs, governments will employ and train people to build these big infrastructure projects. Desalination, Green Energy, Reforestation, better Agriculture and Land Management.

Re: Instant water cleaning method ‘millions of times’ better: study

#39

Post by kleton »

pitched wrote: post #7

I just hope the Reactive Oxygen Species that are 10M times more lethal to bacteria aren’t equally more lethal to humans. Also, if this requires electrolysis-level power, it might still not be worth it in most cases.

Chlorine is produced with alkaline electrolysis

Re: Instant water cleaning method ‘millions of times’ better: study

#40

Post by jhloa2 »

A tangentially related development recently has been peroxide generators to put inside buildings to generate enough hydrogen peroxide to sterilize the air/surfaces without being a health hazard. I've recently had a local school district request that we analyze these devices as an option for COVID mitigation: https://synexis.com/science/reports-data/
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