3 ms·

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 t

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.

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.