3 ms·

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,

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
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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]