5 ms·

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

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" water cleaning. The water handling issues alone in doing 500 trillion GPD seem large. Am I missing something?

icegreentea2 5y ago
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 bacteriacidal agents in same volume of liquid.
- slownews45 5y ago
  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.
  - icegreentea2 5y ago
    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.
    - beerandt 5y ago
      Part of what will prevent mass adoption is it ignores distribution, which will still require chemical residual treatment, like chlorination. If you have to install chlorinating equipment and operate it, then it becomes a matter of if the marginal savings in chlorine is worth it. However there's also a good chance that chlorine concentration is controlled by downstream factors more than initial treatment- which is basically the case at every well/spring that produces drinkable water out of the ground, yet still needs residual treatment. So there might not be any reduction in the required amount of chlorine.
      - icegreentea2 5y ago
        I'm not very familiar with this field, why is chlorination required in addition to peroxide? Is it because it's pretty stable and so provides protection after the water has left the treatment plant? If that's the case, I suspect that the type of decentralized system the authors think that this is useful for would be a nature where that's less of a concern. Smaller system leading to decreased time/distance between processing and use. I'm REALLY going out on a limb here, but we hear about people who have to go and fetch their water supplies every day (perhaps multiple trips per day). I suspect that sources on that scale are where this might be useful.
        beerandt 5y ago
        >provides protection after the water has left the treatment plant? Yes, that is what residual treatment is. I'm not familiar with peroxide systems, but for this industry, you don't change things without a very good reason. If we're talking about new niche uses, then that's a different story, but still merits caution. Related story: Washington DC tried to "upgrade" from a chlorine system to another chlorine derivative that was supposed to have some marginal EPA benefits, and on paper it was a great design. In practice (and many tens/hundreds of millions of dollars later), the water quality had a sharp decline, with all sorts of unexpected chemicals showing up. It turns out the old system had the unintentional side effect of "filtering" out all kinds of nasty reactive stuff (including lead), and the new chemical balance reversed the process. All the chemicals that had been sequestered in the pipe walls for decades or longer, were now getting pulled back into the water. Oops. Then there was the initiative in India where thousands of water wells were drilled, only to discover the water contained arsenic. >I suspect that the type of decentralized system the authors think that this is useful for would be a nature where that's less of a concern. Smaller system leading to decreased time/distance between processing and use. It may, but UV disinfection has similar properties and has been available for a while now, probably at a lower price. Also, if water's getting transported in personal containers, chances are they're dirtier than any water main. It's easy to draw the limits of the system at a convenient point, but these are the situations that probably need residual treatment more than than we do. Of course reality dictates what's feasible, especially in the 3rd world, and "exciting" new tech like this might get funding that boring old school solutions won't.
  - deleted 5y ago
    [deleted]
- wanderingmind 5y ago
  This is the trouble with most academic research which focuses on trying to maximize one aspect of the problem while a useful commercial application needs to simultaneously optimize multiple conflicting aspects. A similar stream of useless papers also are published in energy storage (beyond Li-ion batteries) which are not likely to be ever commercialized.
  - rdiddly 5y ago
    Remember science is still just science; it's not necessarily for commercializing.
    - Kaibeezy 5y ago
      The researcher himself is directly quoted saying things like “revolutionising water disinfection technologies around the world”. If that’s not backed up by it being feasible or valuable commercially, then the criticism is spot on.
      - azinman2 5y ago
        I think the point is the science can be useful in that endeavor by demonstrating a new approach one can take. That’s not to say it’s all that would be required. It’s unreasonable and incorrect to expect a full commercial solution to come directly out of a set of lab experiments.
        mannykannot 5y ago
        I do not understand why this could be regarded as a relevant response to the post you are replying to. You say "it’s unreasonable and incorrect to expect a full commercial solution to come directly out of a set of lab experiments", but the post you are replying to did little else but point out that this is essentially what the article is claiming. If you do not think the article was making such a claim, then that is a point you could have disputed, but so far have not.
- cratermoon 5y ago
  I'm curious how it does vs Giardia, Cryptosporidium, and Legionella
perihelions 5y ago
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-free_approach_to_water_disinfection_using_catalytic_in_situ_generation_of_reactive_oxygen_species 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/disinfection-guidelines-H.pdf 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). (?)
- lugged 5y ago
  > The team showed that as the catalyst brought the hydrogen and oxygen together to form hydrogen peroxide, it simultaneously produced a number of highly reactive compounds, known as reactive oxygen species (ROS), which the team demonstrated were responsible for the antibacterial and antiviral effect, and not the hydrogen peroxide itself. > 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, and over 100,000,000 times more effective than chlorination, under equivalent conditions. Basically, I'm getting the highly reactive ROS are the key point here, they're creating them in situ so they're able to be exploited where as standing h2o2 is likely much less reactive. The order of magnitude gains are easy to grasp if you take into consideration the literal hours you need to wait for chlorine or similar to sterilize water. If there is a way to speed that up to near instant your gains are going to be relatively immeasurable.
dalbasal 5y ago
"millions of times more effective at killing viruses and bacteria than traditional commercial methods.." "..revolutionise water disinfection technologies" I don't think this is comparable to a water treatment plant. No sediment settling, biofiltration etc. It's comparable to sterilising water using hydrogen peroxide or boiling it, in a camping context. Not sure what the "millions of times" measures.
- lugged 5y ago
  I'm curious how well it does with dirty water, one of the big issues in the camping context is sediment in the water ruin the efficacy of all forms of water treatment.
  - chaps 5y ago
    Like your parent post suggests, it's not really for that step -- you'd still need a filter for that. That said, in the context of camping.. because the need for sanitization is offloaded away from the filter, you're able to get away with a filter that has a much higher flow rate. Hand-powered sanitizing filters are an absolute pain to use and getting enough water for a meal is a.. process. So, it would be a welcome addition to camping setups.
jcranmer 5y ago
> For example, normally you need to filter, do settling for sediment etc - how did they solve all this? The key sentence should be this: > In their study, the team tested the disinfection efficacy of commercially available hydrogen peroxide and chlorine compared to their new catalytic method. In other words, no, this doesn't replace coagulation+flocculation, sedimentation, and filtration; it's only replacing the specific disinfectant in use.

icegreentea2 5y ago

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 bacteriacidal agents in same volume of liquid.

slownews45 5y ago
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.
- icegreentea2 5y ago
  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.
  - beerandt 5y ago
    Part of what will prevent mass adoption is it ignores distribution, which will still require chemical residual treatment, like chlorination. If you have to install chlorinating equipment and operate it, then it becomes a matter of if the marginal savings in chlorine is worth it. However there's also a good chance that chlorine concentration is controlled by downstream factors more than initial treatment- which is basically the case at every well/spring that produces drinkable water out of the ground, yet still needs residual treatment. So there might not be any reduction in the required amount of chlorine.
    - icegreentea2 5y ago
      I'm not very familiar with this field, why is chlorination required in addition to peroxide? Is it because it's pretty stable and so provides protection after the water has left the treatment plant? If that's the case, I suspect that the type of decentralized system the authors think that this is useful for would be a nature where that's less of a concern. Smaller system leading to decreased time/distance between processing and use. I'm REALLY going out on a limb here, but we hear about people who have to go and fetch their water supplies every day (perhaps multiple trips per day). I suspect that sources on that scale are where this might be useful.
      - beerandt 5y ago
        >provides protection after the water has left the treatment plant? Yes, that is what residual treatment is. I'm not familiar with peroxide systems, but for this industry, you don't change things without a very good reason. If we're talking about new niche uses, then that's a different story, but still merits caution. Related story: Washington DC tried to "upgrade" from a chlorine system to another chlorine derivative that was supposed to have some marginal EPA benefits, and on paper it was a great design. In practice (and many tens/hundreds of millions of dollars later), the water quality had a sharp decline, with all sorts of unexpected chemicals showing up. It turns out the old system had the unintentional side effect of "filtering" out all kinds of nasty reactive stuff (including lead), and the new chemical balance reversed the process. All the chemicals that had been sequestered in the pipe walls for decades or longer, were now getting pulled back into the water. Oops. Then there was the initiative in India where thousands of water wells were drilled, only to discover the water contained arsenic. >I suspect that the type of decentralized system the authors think that this is useful for would be a nature where that's less of a concern. Smaller system leading to decreased time/distance between processing and use. It may, but UV disinfection has similar properties and has been available for a while now, probably at a lower price. Also, if water's getting transported in personal containers, chances are they're dirtier than any water main. It's easy to draw the limits of the system at a convenient point, but these are the situations that probably need residual treatment more than than we do. Of course reality dictates what's feasible, especially in the 3rd world, and "exciting" new tech like this might get funding that boring old school solutions won't.
- deleted 5y ago
  [deleted]
wanderingmind 5y ago
This is the trouble with most academic research which focuses on trying to maximize one aspect of the problem while a useful commercial application needs to simultaneously optimize multiple conflicting aspects. A similar stream of useless papers also are published in energy storage (beyond Li-ion batteries) which are not likely to be ever commercialized.
- rdiddly 5y ago
  Remember science is still just science; it's not necessarily for commercializing.
  - Kaibeezy 5y ago
    The researcher himself is directly quoted saying things like “revolutionising water disinfection technologies around the world”. If that’s not backed up by it being feasible or valuable commercially, then the criticism is spot on.
    - azinman2 5y ago
      I think the point is the science can be useful in that endeavor by demonstrating a new approach one can take. That’s not to say it’s all that would be required. It’s unreasonable and incorrect to expect a full commercial solution to come directly out of a set of lab experiments.
      - mannykannot 5y ago
        I do not understand why this could be regarded as a relevant response to the post you are replying to. You say "it’s unreasonable and incorrect to expect a full commercial solution to come directly out of a set of lab experiments", but the post you are replying to did little else but point out that this is essentially what the article is claiming. If you do not think the article was making such a claim, then that is a point you could have disputed, but so far have not.
cratermoon 5y ago
I'm curious how it does vs Giardia, Cryptosporidium, and Legionella

perihelions 5y ago

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-free_approach_to_water_disinfection_using_catalytic_in_situ_generation_of_reactive_oxygen_species 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/disinfection-guidelines-H.pdf 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). (?)

lugged 5y ago
> The team showed that as the catalyst brought the hydrogen and oxygen together to form hydrogen peroxide, it simultaneously produced a number of highly reactive compounds, known as reactive oxygen species (ROS), which the team demonstrated were responsible for the antibacterial and antiviral effect, and not the hydrogen peroxide itself. > 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, and over 100,000,000 times more effective than chlorination, under equivalent conditions. Basically, I'm getting the highly reactive ROS are the key point here, they're creating them in situ so they're able to be exploited where as standing h2o2 is likely much less reactive. The order of magnitude gains are easy to grasp if you take into consideration the literal hours you need to wait for chlorine or similar to sterilize water. If there is a way to speed that up to near instant your gains are going to be relatively immeasurable.

dalbasal 5y ago

"millions of times more effective at killing viruses and bacteria than traditional commercial methods.." "..revolutionise water disinfection technologies" I don't think this is comparable to a water treatment plant. No sediment settling, biofiltration etc. It's comparable to sterilising water using hydrogen peroxide or boiling it, in a camping context. Not sure what the "millions of times" measures.

lugged 5y ago
I'm curious how well it does with dirty water, one of the big issues in the camping context is sediment in the water ruin the efficacy of all forms of water treatment.
- chaps 5y ago
  Like your parent post suggests, it's not really for that step -- you'd still need a filter for that. That said, in the context of camping.. because the need for sanitization is offloaded away from the filter, you're able to get away with a filter that has a much higher flow rate. Hand-powered sanitizing filters are an absolute pain to use and getting enough water for a meal is a.. process. So, it would be a welcome addition to camping setups.

jcranmer 5y ago

> For example, normally you need to filter, do settling for sediment etc - how did they solve all this? The key sentence should be this: > In their study, the team tested the disinfection efficacy of commercially available hydrogen peroxide and chlorine compared to their new catalytic method. In other words, no, this doesn't replace coagulation+flocculation, sedimentation, and filtration; it's only replacing the specific disinfectant in use.